การดูแลทำความสะอาดกล้องถ่ายภาพ

ส่วนที่จะให้แสดง ส่วนที่เหลือ

เทคนิคการถ่ายภาพระยะชัดลึก Dept of Field

ส่วนที่จะให้แสดง ส่วนที่เหลือ

วิธีการเก็บรักษากล้อง

วิธีการเก็บรักษากล้อง

SUPER CCD

SUPER CCD



ของ FUJIเป็น CCD ที่ทาง FUJI คิดค้นออกแบบโครงสร้างใหม่ เพื่อต้องการพัฒนาให้ได้คุณภาพที่ดีขึ้นในหลายๆด้านทั้ง ความไวแสงที่สูงขึ้น, dynamic range ที่กว้างขึ้น, noise ที่ต่ำลงและความละเอียดที่สูงขึ้น โดยเริ่มจาก ในปี 1999 ทางฟูจิได้เปิดตัว 1st generation SUPER CCD สู่ตลาด โดยรูปแบบของ super CCD จะเปลี่ยนจาก CCD ปกติที่ใช้ photo diodes เซลรับแสงแบบสี่เหลี่ยม อยู่บนแต่ละพิกเซล ซึ่งวางเรียงต่อๆกันอยู่บน CCD กลายเป็น SUPER CCD แบบรังผึ้งแปดเหลี่ยม โดยวางหันเฉียง 45 องศา (ตามเส้นประในภาพ) ซึ่งทำให้สามารถวาง photo diodes ที่มีขนาดใหญ่มากขึ้นได้แน่นมากขึ้น2001 ทาง fuji ได้ออก generation ที่สอง พัฒนาให้ขนาด CCD เล็กลงเพื่อให้ใช้รองรับความละเอียดที่สูงขึ้นในกล้องดิจิตอลขนาดเล็ก และระบบลด noise ในภาพก้อได้ถูกเพิ่มมาใน generation นี้2002 จึงได้ออก generation ที่สามออกมา โดยความสามารถหลัก คือ การ interpolate จำลองพิกเซลของภาพที่มีความละเอียด 6ล้านพิกเซล ให้เป็น 2เท่า 12ล้าน fuji S2 pro แม้ภาพที่ได้จากการ interpolate จะไม่สามารถทำได้เท่าภาพที่ถ่ายจากกล้อง 12ล้านพิกเซลจริง แต่ก้อเป็นที่ยอมรับกันว่าให้รายละเอียดที่ดีกว่ากล้อง 6ล้านพิกเซลgeneration นี้เองที่ทาง fuji ได้พัฒนาด้านความไวแสงอย่างมากสามารถปรับได้ถึง iso1600 และการบันทึกรูปแบบวีดีโอ vga 30frame/sec เทียบเท่าปัจจุบัน2003 ได้เกิด generation ที่ 4 ซึ่งแยกออกเป็นสองรูปแบบ คือ เหมือนกับการพัฒนา ใน generation ที่สอง คือ พัฒนาขนาด CCD เล็กลงเพื่อนำไปใช้กับกล้องขนาดเล็ก โดยความสามารถอื่นๆจะเหมือนในยุคที่สามSUPER CCD SR เป็นเทคโนโลยีที่น่าสนใจมากๆ จากเดิมที่จะมีเพียง 1 photo diode ที่เก็บภาพในแต่ละ photo site* เปลี่ยนเป็นการมี 2 photo diodes ในแต่ละ photo site โดยแบ่งเป็น S-pixel และ R-pixel ซึ่ง S-pixel จะมีขนาดใหญ่กว่าค่าความไวแสงที่สูงกว่า คอยเก็บภาพในส่วนปกติและส่วนมืด และ R-pixel จะมีค่าความไวแสงที่ต่ำ คอยเก็บภาพในส่วนสว่าง หลังจากการประมวลผลออกมาจะทำให้ สามารถเก็บภาพรายละเอียดทั้งส่วนสว่างและส่วนมืดได้อย่างครบถ้วน ถึงแม้ว่ากล้องที่ใช้ super ccd SR ความละเอียดในกล้องฟูจิที่อ้างถึงเช่น 6ล้าน จริงๆจะมีแค่ 3ล้าน โดยแบ่งเป็น S-pixel 3ล้านพิกเซล และ R-pixel 3ล้านพิกเซล ซึ่งเหมือนกับการ interpolate ให้เป็น 6ล้านพิกเซล แต่ยังไงคุณภาพโดยรวมที่ออกมา นั้นถือว่าดีมากๆ โดยเฉพาะในด้าน dynamic rangeณ ปัจจุบัน ฟูจิได้ออก กล้องรุ่นใหม่
S3PRO ซึ่งพัฒนาเป็น SUPER CCD SR II โดยแยก S-pixel และ R-pixel เป็นคนละ photo site โดยทางฟูจิอ้างว่า dynamic range ของ SUPER CCD SRII นั้นสามารถทำได้เหนือ 3rd generation super CCD ถึง 4 เท่า

SUPER CCD
Super CCD
 
หลังจากนั้นในปี
ถัดมาในปี
พิกเซล ในกล้องรุ่น
ปกติ รวมถึงใน
ต่อมาในปี
SUPER CCD HR

Component Removal, Surface Mount Gull Wing Components, Hot Gas/Air Method

Component Removal, Surface Mount Gull Wing Components, Hot Gas/Air Method
 

 TOOLS & MATERIALS
Caliper
Cleaner
Flux, Liquid
Hot Air Removal Tool with Tips
Microscope
Oven
Positioning Table
Rework Stand
Vacuum Pen
Wipes

PREPARATION

Figure 1: Nozzle at left heats the leads and pads. Nozzle at right heats component, leads and pads.

This method uses hot air nozzles that do not touch the component. Gas or air is heated and forced through a specially designed nozzle and directed onto the component leads and surface pads.

Hot gas/air nozzles come in several sizes to accommodate many of the different styles and sizes of components. Measure the overall length and width of the component to select the proper size tip. Check the nozzle for proper fit prior to processing the part. Some hot gas/air nozzle designs will heat only the component leads and pad area. (See Figure 1, Left Side). Some hot air nozzle designs heat the entire component, the leads and pad area. (See Figure 1, Right Side).
Hot gas/air can be used to remove a number of different styles of SMT components but the heated gas/air must be directed onto the leads and pads and away from the top of the component and circuit board surface.
Hot gas/air nozzles may or may not include vacuum assistance to lift the component off the circuit board surface.

PROCEDURE    Preview a Video Clip   (Size - 240KB)

1. Figure 2: After solder has melted lift component straight up.

   Place the pre-heated circuit board on the Positioning Table. A heated positioning table is available to pre-heat the circuit board, or can be used to maintain the pre-heated temperature when many components need to be removed from one circuit board. 
   
2. Apply a small amount of liquid flux to all leads of the component.
   
3. Place the nozzle directly over the top of the component and activate the air flow. When the solder has melted actuate the vacuum assist or lift off the component with a vacuum pen. Lift the component straight up. (See Figure 2). It's difficult to precisely know how long to dwell prior to safely removing the part. This is further complicated by the fact that when removing a bank of components, parts subsequent to the first come off much faster. Obviously, the smaller the part the quicker it reflows. Small SMT components may reflow in a few seconds and large SMT components may take more than a minute.
   
4. Clean the area.

Component Removal, Surface Mount Gull Wing Components, Conduction Method

Component Removal, Surface Mount Gull Wing Components, Conduction Method

Surface Mount Gull Wing Component

TOOLS & MATERIALS
Caliper
Cleaner
Conduction Removal Tool with Tips
Flux, Liquid
Microscope
Oven
Positioning Table
Rework Stand
Soldering Iron with Tips
Wipes

PREPARATION

Figure 1: Conduction tip shown with solder added to enhance removal operation.

This method uses tips that are designed to fit over the top of surface mount components, and to reflow all the solder joints at once. The tip fits over the component with just a slight amount of extra space for solder. Measure the overall length and width of the component with a caliper to select the proper size tip. Check the tip for proper fit prior to processing the part.

The tip should not fit the component so tightly that it will get lodged in the tip, but the tip should not be so loose that it will not conduct heat to all the leads simultaneously
Conduction tips come in several sizes to accommodate many of the different styles and sizes of components, but the component must fit properly in the tool cavity. Since these tips have a cavity, they require special cleaning and tinning procedures.

NOTE
Carefully inspect the tip to ensure that all surfaces will properly contact the component leads.

1. Remove any solder from inside the tip cavity with a fiber tool.
   CAUTION
   Do not use a wire brush for any tip cleaning procedure. A wire brush can severely scratch a metal tip. Scratches allow oxidation to form on the base metal of the tip. This will decrease the useful life.
   
2. Remove any oxidized solder by shocking the tip on a wet sponge. Remove stubborn residue using an orange stick or polishing bar.
   
3. Add solder to the properly prepared tip. Fill the cavity until there is a fillet on the entire length of each side of the tip. (See Figure 1). Add enough solder to help transfer the heat quickly but not so much that it will fall out when the tip is turned upside down. The entire conducting surface of the tip should be tinned with solder to promote proper heat transfer to the leads of the component to be removed. The solder provides surface tension to lift the component off the pads after reflow. Since the tip has more metal surface area than the pads on the circuit board, the solder will be drawn toward the metal tip and so will the component.
   
   NOTE
   Determine the direction the part is to be swept off the circuit board surface. Densely packed circuit board assemblies often leave only one direction for the rework tool to follow when sweeping the part off the surface.

PROCEDURE
    Preview a Video Clip
     Flux Application (450KB)
     Alternate Bridge Fill (400KB)
   

1. Figure 2: After solder has melted lift tip out and up.

   Apply a small amount of liquid flux to all leads of the component.
   
2. Place the tip directly over the top of the component. The extra solder on the tip will melt all the solder joints. When the solder has melted slide the component out and up. (See Figure 2). It's difficult to know precisely how long to dwell prior to safely removing the part. This is complicated by the fact that when removing a bank of components, parts subsequent to the first come off much faster. Obviously, the smaller the part the quicker it reflows. Small SMT components may reflow in a few seconds and large SMT components may take more than a minute. On the smaller components you can usually see solder reflow and can then sweep the component off and up. On larger components it is wise to attempt to view reflow but often this is not possible. If you cannot clearly see reflow very lightly rock the component to test for movement. If the component moves freely then it is ready to be swept off the pads and lifted up.
   Once the component is removed from the circuit board it can be removed from the tip by the shocking sponge or with a dull blunt instrument applying downward pressure on the component.
   
3. Clean the area.
   

Component Removal, Surface Mount J Lead Components, Hot Gas/Air Method

Component Removal, Surface Mount J Lead Components, Hot Gas/Air Method



TOOLS & MATERIALS
Caliper
Cleaner
Flux, Liquid
Hot Air Removal Tool with Tips
Microscope
Oven
Positioning Table
Rework Stand
Vacuum Pen
Wipes

PREPARATION

Figure 1: Nozzle at left heats the leads and pads. Nozzle at right heats component, leads and pads.

This method uses hot air nozzles that do not touch the component. Gas or air is heated and forced through a specially designed nozzle and directed onto the component leads and surface pads.

Hot gas/air nozzles come in several sizes to accommodate many of the different styles and sizes of components. Measure the overall length and width of the component to select the proper size tip. Check the nozzle for proper fit prior to processing the part. Some hot gas/air nozzle designs will heat only the component leads and pad area. (See Figure 1, Left Side). Some hot air nozzle designs heat the entire component, the leads and pad area. (See Figure 1, Right Side).
Hot gas/air can be used to remove a number of different styles of SMT components but the heated gas/air must be directed onto the leads and pads and away from the top of the component and circuit board surface.
Hot gas/air nozzles may or may not include vacuum assistance to lift the component off the circuit board surface.

PROCEDURE    Preview a Video Clip   (Size - 190KB)

1. Figure 2: After solder has melted lift component straight up.

   Place the pre-heated circuit board on the positioning table. A heated positioning table is available to pre-heat the circuit board, or can be used to maintain the pre-heated temperature when many components need to be removed from one circuit board. 
   
2. Apply a small amount of liquid flux to all leads of the component.
   
3. Place the nozzle directly over the top of the component and activate the air flow. When the solder has melted actuate the vacuum assist or lift off the component with a vacuum pen. Lift the component straight up. (See Figure 2).
   

   Figure 3: A - Dot indicates pin 1;B - Indicates pin 5;C - Indicates direction of pin count.

   It's difficult to know precisely how long to dwell prior to safely removing the part. This is further complicated by the fact that when removing a bank of components, parts subsequent to the first come off much faster. Obviously, the smaller the part the quicker it reflows. Small SMT components may reflow in a few seconds and large SMT components may take more than a minute.
   
4. Clean the area.

Component Removal, Surface Mount Chip Components, Hot Tweezer Method

Component Removal, Surface Mount Chip Components, Hot Tweezer Method


NOTEThe goal when removing any component is to remove the component as quickly as possible.

CAUTION - Glued Components
A small dot of epoxy is often used to hold chip components in position during wave soldering processing. Typically these components will be located on the bottom side of a circuit board that has through hole components located on the other side. Whenever you see a board like this, you can generally assume that the chip components will be glued onto the board. You'll need to leave the tip on the component for one or two additional seconds in order to transfer enough heat to overcure or soften the adhesive. If required take a wooden stick or curved tweezers and push the component sideways until the glue joint finally gives way.
TOOLS & MATERIALS
Caliper
Cleaner
Flux, Liquid
Hot Tweezer Tool with Tips
Microscope
Solder
Wipes

NOTE
Determine the direction the part is to be swept off the circuit board surface. Densely packed circuit board assemblies often leave only one direction for the rework tool to follow when sweeping the part off the surface.

Figure 1: Place the tweezer tips in position. When the solder melts, lift the component off the circuit board.

PROCEDURE
    Preview a Video Clip
     Chip Component Removal (400KB)
     SOT Component Removal (450KB)

1. Tin the hot tweezer tip.
   
2. Apply a small amount of liquid flux to both ends of the component.
   
3. Place the tweezer tips in contact with both ends of the component. When the solder melts, lift the component off the circuit board. (See Figure 1).
   
4. Clean the area.

Chip Capacitors generally have solid color bodies.

A - Stripe;B - Beveled Surface;The striped or beveled end is the "positive" (+) or "anode end".

Component Removal, Surface Mount J Lead Components, Conduction Method

Component Removal, Surface Mount J Lead Components, Conduction Method



TOOLS & MATERIALS
Caliper
Cleaner
Conduction Removal Tool with Tips
Flux, Liquid
Microscope
Oven
Positioning Table
Rework Stand
Soldering Iron with Tips
Wipes

PREPARATION

Figure 1: Conduction tip shown with solder added to enhance removal operation.

This method uses tips that are designed to fit over the top of surface mount components, and to reflow all the solder joints at once. The tip fits over the component with just a slight amount of extra space for solder. Measure the overall length and width of the component with a caliper to select the proper size tip. Check the tip for proper fit prior to processing the part.

The tip should not fit the component so tightly that it will get lodged in the tip, but the tip should not be so loose that it will not conduct heat to all the leads simultaneously
Conduction tips come in several sizes to accommodate many of the different styles and sizes of components, but the component must fit properly in the tool cavity. Since these tips have a cavity, they require special cleaning and tinning procedures.

NOTE
Carefully inspect the tip to ensure that all surfaces will properly contact the component leads.

1. Remove any solder from inside the tip cavity with a fiber tool.
   CAUTION
   Do not use a wire brush for any tip cleaning procedure. A wire brush can severely scratch a metal tip. Scratches allow oxidation to form on the base metal of the tip and this will severely decrease the useful life.
   
2. Remove any oxidized solder by shocking the tip on a wet sponge. Remove stubborn charred residue using an orange stick or polishing bar.
   
3. Add solder to the properly prepared tip. Fill the cavity until there is a fillet on the entire length of each side of the tip. (See Figure 1). Add enough solder to help transfer the heat quickly but not so much that it will fall out when the tip is turned upside down. The entire conducting surface of the tip should be tinned with solder to promote proper heat transfer to the leads of the component to be removed.
   

   Figure 1: Conduction tip shown with solder added to enhance removal operation.

   The solder provides surface tension to lift the component off the pads after reflow. Since the tip has more metal surface area than the pads on the circuit board, the solder will be drawn toward the metal tip and so will the component.
   
   NOTE
   Determine the direction the part is to be swept off the circuit board surface. Densely packed circuit board assemblies often leave only one direction for the rework tool to follow when sweeping the part off the surface.
   

PROCEDURE
    Preview a Video Clip
     Flux Application (400KB)
     Alternate Bridge Fill    (500KB)
     Alternate Solder Wrap    (900KB)

1. Figure:3;A - Dot indicates pin 1;B - Indicates pin 5;C - Indicates direction of pin count.

   Apply a small amount of liquid flux to all leads of the component.
   
2. Place the tip directly over the top of the component. The extra solder on the tip will melt all the solder joints. When the solder has melted slide the component out and up. (See Figure 2). It's difficult to know precisely how long to dwell prior to safely removing the part. This is complicated by the fact that when removing a bank of components, parts subsequent to the first come off much faster. Obviously, the smaller the part the quicker it reflows. Small SMT components may reflow in a few seconds and large SMT components may take more than a minute.
   On the smaller components you can usually see solder reflow and can then sweep the component off and up. On larger components it is wise to attempt to view reflow but often this is not possible. If you cannot clearly see reflow very lightly rock the component to test for movement. If the component moves freely then it is ready to be swept off the pads and lifted up.
   Once the component is removed from the circuit board it can be removed from the tip by the shocking sponge or with a dull blunt instrument applying downward pressure on the component.
   
3. Clean the area.

Component Removal, Surface Mount Chip Components, Forked Tip Method

Component Removal, Surface Mount Chip Components, Forked Tip Method

NOTEThe goal when removing any component is to remove the component as quickly as possible.

CAUTION - Glued Components
A small dot of epoxy is often used to hold chip components in position during wave soldering processing. Typically these components will be located on the bottom side of a circuit board that has through hole components located on the other side. Whenever you see a board like this, you can generally assume that the chip components will be glued onto the board. You'll need to leave the tip on the component for one or two additional seconds in order to transfer enough heat to overcure or soften the adhesive. If required take a wooden stick or curved tweezers and push the component sideways until the glue joint finally gives way.
TOOLS & MATERIALS
Caliper
Cleaner
Flux, Liquid
Microscope
Soldering Removal Tool with Tips
Wipes

TIP PREPARATION

Figure 1: Forked tip shown with solder added to cavity to enhance removal operation.

Forked tips are designed to fit over the top of chip components, and to reflow both solder joints at once. The ends of the forked tip fit over the component with just a slight amount of extra space for solder. Measure the overall length and width of the component with a caliper to select the proper size tip. Check the tip for proper fit prior to processing the part.

The tip should not fit the component so tightly that it will get lodged in the tip, but the tip should not be so loose that it will not conduct heat to the leads simultaneously. The size and shape of the forked tip will have an effect on the rate of heat transfer. Larger tips with more surface area will transfer heat faster than smaller tips.
Forked tips can be used to remove a number of different styles of chip components but the component must fit properly in the tool cavity. Since forked tips have a cavity, they require special cleaning and tinning procedures.

1. Figure 2: Removing SMT chip component with forked tip. After solder has melted lift tip out and up

   Remove any solder from inside the tip cavity with a fiber tool.
   CAUTION
   Do not use a wire brush for any tip cleaning procedure. A wire brush can severely scratch a metal tip. Scratches allow oxidation to form on the base metal of the tip and this will severely decrease the useful life.
   
2. Remove any oxidized solder by shocking the tip on a wet sponge.
   
3. Add solder to the properly prepared tip. Fill the cavity until there is a fillet on each side of the tip. (See Figure 1). Add enough solder to help transfer the heat quickly but not so much that it will fall out when the tip is turned upside down.
   

Chip Capacitors generally have solid color bodies.

The solder provides surface tension to lift the component off the pads after reflow. Since the tip has more metal surface area than the pads on the circuit board, the solder will be drawn toward the metal tip and so will the component.


NOTE
Determine the direction the part is to be swept off the circuit board surface. Densely packed circuit board assemblies often leave only one direction for the rework tool to follow when sweeping the part off the surface.

PROCEDURE
    Preview a Video Clip
     Chip Component Removal (170KB)
     SOT Component Removal (370KB)

1. A - Stripe;B - Beveled Surface;The striped or beveled end is the "positive" (+) or "anode end".

   Apply a small amount of liquid flux to both ends of the component.
   
2. Place the forked tip directly over the top of the component. The extra solder on the tip will melt both solder joints. When the solder has melted slide the component out and up. (See Figure 2). Once the component is removed from the circuit board it can be removed from the tip by the shocking sponge or with a dull blunt instrument applying downward pressure on the component.
   
3. Clean the area.

Component Removal, Through Hole Components, Solder Fountain Method

Component Removal, Through Hole Components, Solder Fountain Method

Component Removal, Through Hole Components, Vacuum Method

Component Removal, Through Hole Components, Vacuum Method

TOOLS & MATERIALSCleaner
Flux
Microscope
Solder
Solder Removal Tool, Vacuum Type with Tips
Soldering Iron with Tips
Wipes
PROCEDURE - Straight Leads, Standard Method

1. Figure 1: When the solder melts, activate the vacuum to remove the solder while oscillating the tip.

   Inspect the size of the solder joints on the component to be removed. If the size of the solder joint fillets are minimal, it may be desirable to add additional solder to form an "excess solder" joint. This will improve the thermal linkage.
   
2. Apply a small amount of liquid flux to the solder joints of the component to be removed.
   
3. Align the desolder tip with a component lead end and lightly make contact with the solder joint. Keep the desolder tip off the pad by allowing it to slide around on a film of solder.
   
   CAUTION Do not apply pressure with the solder extractor tip to the lands or other conductive patterns.
   
4. After the solder has melted, start a rotating or oscillating motion with the desolder tip. Continue the rotating motion until a change in the "feel" of the rotating motion occurs. At this instant the solder in the solder joint is completely molten. Immediately activate the vacuum, extracting the solder from the solder joint. (See Figure 1).
   
5. Maintain rotation of the desolder tip while continuous vacuum is being applied. This allows air to cool both the component lead and the plated-through hole preventing the component lead from resweating to the side of the hole.
   
6. After the solder has been extracted from the solder joint, remove the desolder tip from the component lead while maintaining continuous vacuum.
   
7. Maintain continuous vacuum for a few seconds to clear the desolder tip.
   
8. Turn off the vacuum.
   
9. Desolder each of the remaining component leads individually using a skipping method to reduce thermal buildup at adjacent hole locations.
   

10. Figure 2: Lower the tip to melt the solder, then gently straighten the lead to a vertical position.

    Probe each component lead to be sure that they are not soldered to the side of the plated hole and then remove component.
    
    NOTE If each lead is not completely free, resolder the joint and repeat steps 2 - 10.
    
11. Clean the area.

PROCEDURE - Partial Clinch Leads, Standard Method

1. Inspect the size of the solder joints on the component to be removed. If the size of the solder joint fillets are minimal, it may be desirable to add additional solder to form an "excess solder" joint. This will improve the thermal linkage.
   

2. Figure 3: Align the desolder tip with the fully clinched lead. Lower the tip to melt the solder and activate the vacuum to remove the solder from the joint.

   Apply a small amount of liquid flux to the solder joints of the partially clinched leads.
   
3. Align the desolder tip with the partially clinched lead. Lower the tip to melt the solder. Then gently straighten the lead to a vertical position. (See Figure 2). After each lead has been straightened, continue desoldering each lead as described beginning in step 3 above.

PROCEDURE - Fully Clinch Leads, Standard Method

1. Apply a small amount of liquid flux to the solder joints of the fully clinched leads.
   

2. Figure 4: Use a flat nose pliers to gently rotate the lead laterally break any remaining solder sweat joints.

   Align the desolder tip with the fully clinched lead. Lower the tip to melt the solder and activate the vacuum to remove the solder from the joint. (See Figure 3).
   
3. Use a flat nose pliers to gently rotate the lead laterally break any remaining solder sweat joints. (See Figure 4).
   
4. Probe each component lead to be sure that they are not soldered to the side of the plated hole and then remove component.
   
   NOTE If each lead is not completely free, resolder the joint and repeat steps 2 - 4.

PROCEDURE - Straight Leads, Auxiliary Heat Method Auxiliary heating may be required on solder joints with a large thermal mass. This is most common on multilayer circuit boards.

1. Figure 5: Place a soldering iron tip against the component lead and the desoldering tip over the lead end.

   Inspect the size of the solder joints on the component to be removed. If the size of the solder joint fillets are minimal, it may be desirable to add additional solder to form an "excess solder" joint. This will improve the thermal linkage.
   
2. Apply a small amount of liquid flux to the solder joints of the component to be removed.
   
3. Place a soldering iron tip against the lead of the component side of the circuit board. (See Figure 5).
   
4. Align the desolder tip with a component lead end and lightly make contact with the solder joint. Keep the desolder tip off the pad by allowing it to slide around on a film of solder.
   CAUTION
   Do not apply pressure with the solder extractor tip to the lands or other conductive patterns.
   
5. After the solder has melted, start a rotating or oscillating motion with the desolder tip. Continue the rotating motion until a change in the "feel" of the rotating motion occurs. At this instant the solder in the solder joint is completely molten. Immediately activate the vacuum, extracting the solder from the solder joint.
   
6. Maintain rotation of the desolder tip while continuous vacuum is being applied. This allows air to cool both the component lead and the plated-through hole preventing the component lead from resoldering to the side of the hole.
   
7. After the solder has been extracted from the solder joint, remove the desolder tip and the soldering iron tip from the component lead while maintaining continuous vacuum on the desoldering tip.
   
8. Maintain continuous vacuum for a few seconds to clear the desolder tip.
   
9. Turn off the vacuum.
   
10. Desolder each of the remaining component leads individually using a skipping method to reduce thermal buildup at adjacent hole locations.
    
11. Probe each component lead to be sure that they are not soldered to the side of the plated hole and then remove component.
    NOTEIf each lead is not completely free, resolder the joint and repeat steps 2 - 11.
    
12. Clean the area.
    

BGA Component Reballing, Fixture Method

BGA Component Reballing, Fixture Method

BGA Component Rework

BGA Component Rework

CAUTION - Operator Safety
A thorough review of the equipment manual and comprehensive training are mandatory. Daily maintenance is essential. Consult the equipment manual for more information.

CAUTION - Component Sensitivity
This method may subject the component to extreme temperatures. Evaluate the component's tolerance to heat prior to using this method.

CAUTION - Circuit Board Sensitivity
PC Boards are made from a great variety of materials. When subjected to the high temperatures they are susceptible to the following types of damage:
1. Layer delamination.
2. Copper delamination, separation of pads, barrels of inner layers.
3. Burns and solder mask chipping.
4. Warp.
Each circuit board must be treated individually and scrutinized carefully for its reaction to heat. If a series of circuit boards are to be reworked, the first several should be handled with extreme care until a reliable procedure is established.
TOOLS & MATERIALSBGA specific nozzle
Cleaner
Cleaning Wipes
Flux, Liquid
Hot Air rework Station
Hand held Digital Thermometer
Tape, Kapton
Microscope
Oven
Soldering Iron
Solder
Thermocouples
Vacuum Pen
RECEIVING AND PRICE QUOTING

1. Upon receipt, the customer supplied materials and products are logged into the Enterprise Resource Management System by the Shipper & Receiver. Customer supplied materials and product counts are verified.
   
2. The project is reviewed by the appropriate Sales Application Engineer to confirm the project requirements, determine the solder chemistry classification, and verify if a solder stencil is in stock or needs to be ordered. Repeat projects will have a previously created process sheet in the Hot Gas Rework System database. A copy should be printed out and included with the job Traveler.
   
3. New projects require a thermal profile for the circuit board. See the process step listed below and procedure 9.2.1. For profile development we request a scrap circuit board assembly and an extra component whenever possible.
   
4. Upon completion of the Sales Order, it is sent via email to the customer contact for confirmation of the process outlined and the charges listed. The schedule is confirmed, and the customer products and materials are transferred to the BGA rework area.

PROJECT PROCESS DEVELOPMENT

1. Prior to starting the project the Operator will review the following:
   
   A. Verify circuit board and component part numbers and quantities match the Traveler.
   
   B. Visually inspect the circuit boards for temperature sensitive components or parts. (Fiber optics, plastic connectors, batteries, etc.)
   
   C. Ensure the Hot Air Rework Station maintenance is current and the appropriate checks are done prior to operating the BGA machines.
   
2. All Circuit boards are baked for a minimum 12 hours at 125C unless otherwise instructed by the customer. In addition, all BGA components that are received in unsealed packaging are baked per the Moisture Sensitive Device Control Procedure, unless otherwise instructed by the customer.
   
3. Thermal Profile development is required for all projects. If available, the Operator will develop the thermal profile using a customer supplied scrap assembly that is the same as the circuit boards to be processed. If the customer is unable to supply a scrap board, the Thermal Profile is developed during the initial removal process. In both cases the Operator will identify the following board conditions and start with the most logical machine setting:
   
   A. Solder chemistry, leaded or lead-free.
   
   B. Board thickness.
   
   C. Board and component density and layout.
   
   D. Component ball count and design.
   
   E. Under-fill or conformal coating surrounding the site.
   
   The Thermal Profile is created by placing Thermocouples at various locations to monitor and adjust the heating source time and temperature from the bottom side heat plate and the top side nozzle. Multiple machine cycles may be required to achieve the desired results. Upon completion, the profile is stored in the machine and saved in the Hot Gas Rework System database for current and future applications. See procedure 9.2.1 for more detailed information.
   
4. Additional notes are added to the Hot Gas Rework System process sheet to identify special handling or other process steps that are needed in order to achieve an acceptable condition. These include adjacent components that need removal, specific masking or shielding requirements, and other conditions that may impact the process.

BGA REWORK PROCESS

1. Operators initially review the Traveler and additional paperwork to ensure the instructions are clear and match the circuit boards to be processed. Any questions are directed to the Sales Application Engineer or to the customer for clarification.
   
2. If circuit board disassembly is needed, all materials must labeled and noted on the Traveler.
   
3. The Operator will locate and load the removal profile specified on or with the Traveler for the component removal. The removal process is visually monitored through a microscope. When the BGA component solder balls reach a molten state, the vacuum pick-up of the component is initiated.
   
4. Site cleaning is done with a non-contact site cleaning tool, or by using solder wick. If under-fill or conformal coating is present at the site, additional steps are required to remove it. Typically heat, machining or chemical stripping of the site is needed. Refer to the Sales Application Engineer, customer instruction or the product data sheet for the appropriate process.
   
5. No-clean solder paste/flux is utilized for BGA assembly and rework unless otherwise instructed by the customer.
   
6. After the site cleaning process is complete, the circuit board is inspected to ensure the mask is undisturbed and the site is suitable for the installation process. If solder mask touch-up or other issues are identified, they are reviewed with the Sales Application Engineer for direction.
   
7. Solder stencils are used to deposit the solder paste onto the site. Care is taken to ensure the paste is deposited evenly and completely.
   
8. The installation of the BGA component is completed following the programmed profile specified on or with the Traveler. The installation process is visually monitored through a microscope and when the BGA component solder balls and solder paste reach a molten state, and ball collapse is confirmed, the placement process is complete. (Note: High temperature solder balls will not collapse and will rely on the paste wetting to the ball).
   

9. Figure 2: X-ray inspection verifies shorted spheres.

   Upon completion of the placement process, the circuit board is visually inspected at the BGA placement site and all adjacent areas. Touch-up of the circuit board is completed if needed.
   
10. X-ray inspection is completed at the BGA placement site and adjacent areas. See procedure 9.1.2 for additional information. Any potential workmanship or unacceptable conditions are reviewed with the Sales Application Engineer for direction.
    
11. Re-assembly of any removed components or hardware is performed.
    
12. Final inspection is completed by QC Inspection.

BGA Component Rework Profile Development, Smart Track Method

BGA Component Rework Profile Development, Smart Track Method

TOOLS & MATERIALS
Aluminum Foil
BGA Rework Nozzles
BGA Rework System (Air-Vac)
Cleaner
Cleaning Wipes
Microscope
Oven
Profile Development Circuit Board Assembly
Profile Development BGA Components
Tape, Kapton
Tape, High Temperature Masking
Thermal Adhesive (J-B Weld)
Thermometer, Digital

CAUTION - Operator Safety
A thorough review of the equipment manual and comprehensive training are mandatory. Daily maintenance is essential. Consult the equipment manual for more information.

CAUTION - Component Sensitivity
This method may subject the component to extreme temperatures. Evaluate the component's tolerance to heat prior to using this method. Plastic BGA's are especially sensitive to moisture absorption. Carefully evaluate pre bake requirements.

CAUTION - Circuit Board Sensitivity
Circuit boards are fabricated from a wide variety of materials. When subjected to the high temperatures they are susceptible to the following types of damage:
1. Layer delamination.
2. Copper delamination, separation of pads, barrels of inner layers.
3. Burns and solder mask chipping.
4. Warp.
Each circuit board must be treated individually and scrutinized carefully for its reaction to heat. If a series of circuit boards are to be reworked, the first several should be handled with extreme care until a reliable procedure is established.

1.0 OVERVIEW
This procedure automatically creates a thermal profile based on user-defined target parameters. These may include; board temperature, soak duration, BGA package temperature, BGA package ramp rate, solder joint temperature, and time over reflow. The Smart Track profile development method is non-destructive since drilling holes to embed Thermocouples is eliminated. However, profile development circuit boards may be subjected to multiple thermal cycles. The Smart Track method automatically adjustments heater temperature, gas flow rates, and duration on a real-time basis. The method uses an automatic repetition procedure, using information learned from previous runs to optimize the process. 

NOTE
Read and understand all instructions that accompany each project prior to starting.

NOTE
Prior to starting the profile development process both the BGA Rework machine and the circuit board should be at, or near, room temperature. Avoid the use of fans to cool the circuit board or BGA rework machine during Profile Development. Doing so may interfere with the software program. Allow the circuit board and BGA rework machine to cool naturally.

NOTE
Profiles developed on one Air-Vac machine are portable, and may be transferred to other Air-Vac machines.

NOTE
If the circuit board has multiple BGA component locations that require profiles, and all the BGA components are the same type and size, one rework profile may be used for all. The BGA component location to select for the profile should be the one that will generally be the most challenging to rework. The most difficult BGA components to rework will generally be:

1. Closest to the edge of the circuit board.
2. In the most densely populated area.
3. Near, or surrounded by, a ground plane.

2.0 INITIAL SETUP

1. Select the BGA Rework Nozzle that will be used to develop the BGA Rework Profile. Nozzle Part Number should correspond to BGA physical size. Test fit Nozzle. Nozzle should fit over BGA component with minimal gap.
   
   Record Nozzle Part Number, BGA Component Height, and Circuit Board Thickness on BGA Rework Process Worksheet.

EZ & DVG Style NozzlesNot package specific. Zero adjacent component clearance. Adjacent components within .300" may reflow

X & M Style Nozzles
Component-specific design. 4-sided exhaust ports minimize adjacent component temperatures. Anti-crushing feature. Adjacent component clearance X=.100", M=.032".

ACG Style Nozzles
Component-specific design. Oversized heating tube optimizes thermal performance. Torlon corner standoff eliminates placement height concerns. Adjacent component clearance=.200". Also available with .100" clearance.

NOTE
Depending on the BGA Nozzle type, the epoxy that secures the Thermocouple to the top of the BGA component to be profiled may prevent the BGA Nozzle from contacting the circuit board surface.

1. Test all Thermocouples prior to each use using a Digital Thermometer.
   

1. Test fit the the circuit board on the base of the BGA rework machine. Consider the following:
2. The need to remove components or other hardware to allow the the location to fit under the nozzle without interference. If component need to be removed see appropriate procedure. Properly label removed components so that they can be replaced.
3. Need to apply "heat shields" using Kapton tape or aluminum foil.
4. Location of placement of Thermocouples.

Figure 1: Place the tip of Thermocouple #2 on the center of the BGA component. Secure with Thermal Adhesive.

1. Clean the top of the BGA component to be profiled. Place the tip of Thermocouple #2 on the center of the BGA component. Apply High Temperature Tape to temporarily hold the Thermocouple in position. Tape should not cover the tip of the Thermocouple. (See Figure 1).
   
2. Mix up a small amount of Thermal Adhesive. Stir for one minute to insure a complete mix. Apply a small dab, (approx. 1/4" in diameter) to secure Thermocouple tip to BGA top. Place the circuit board in an oven for 15 to 30 minutes at 160ฐ - 175ฐF ( ฐC) to cure the Adhesive. After Adhesive cures remove from oven and allow to cool. (See Figure 1).
   

3. Figure 2: Place Thermocouple #3, and #4 under opposite corners of the BGA Profile component. Place Thermocouple #5 under adjacent component. Secure Thermocouples the circuit board surface using High Temperature Tape.

   Place Thermocouple #3 under one corner of the BGA component. Place Thermocouple #4 under the opposite corner of the BGA component. Thermocouples should be inserted far enough so that the wire insulation is just under the BGA component. Optimum location for these Thermocouples is between the 2nd and 3rd row of BGA solder balls. If needed, check location of Thermocouples using a microscope. Secure Thermocouples the circuit board surface using High Temperature Tape. (See Figure 2).
   
   NOTE
   The corners selected should be those closest to adjacent components or ground plane areas.
   
4. Place Thermocouple #5 under corner of adjacent component. Secure Thermocouple the circuit board surface using High Temperature Tape. Apply High Temperature Tape to divert hot air from BGA Rework Nozzle from flowing directly onto Thermocouple. 
   
5. Place one Thermocouple (#6) directly under the center of the BGA component on the opposite side of the circuit board directly in contact with the circuit board surface. Secure Thermocouple the circuit board surface using High Temperature Masking Tape.
6. Masking Tape.

Table 1 - Thermocouple Locations

Number	Thermocouple Location
1	IR Sensor
2	Top center of BGA component to be profiled.
3	Corner location under BGA component to be profiled.
4	Opposite corner location under BGA component to be profiled.
5	Under adjacent component.
6	Bottom side of circuit board under center of BGA component to be profiled.

3.0 PROFILE DEVELOPMENT SETUP

1. Figure 3: Place supports under circuit board to support area around BGA Component to be profiled.

   Place the circuit board on the base of the BGA rework machine. Circuit board should be centered over the bottom heater. Clamp circuit board in place using built-in machine clamps.
   
2. If needed, remove tape previously placed on the top of the BGA component to be profiled.
   
3. Plug in the Thermocouples as shown in Table 1 - Thermocouple Locations.
   
4. Install BGA Rework Nozzle in BGA Rework Machine. Depending on the nozzle type, the epoxy securing the Thermocouple to the top of the BGA component may prevent the nozzle from contacting the circuit board surface.
   
5. Position circuit board so that BGA component to be profiled is aligned below nozzle. Fine adjust X, Y and theta positions and lock the machine base.
   
6. Lift Board Carrier and place supports under circuit board to support area around BGA Component to be profiled. Check to be sure supports contact circuit board surface, not components. Lower Board Carrier. (See Figure 3).
   

7. Figure 4: Position the IR Sensor Thermocouple #1 approx. 2" from edge of BGA component being profiled.

   Position the IR Sensor Thermocouple #1 approx. 2" from edge of BGA component being profiled. Sensor should be above a spot on circuit board surface free of components. IR Sensor averages the surface temperature over a 3" circle. (See Figure 4).
   
8. Power on the machine. Pass "operator registration" and "password log in" screens.
   
9. Select "Control" - "Thermal Smart Track" - "Auto Temperature Profiling". The Thermal Smart Track screen appears. The system will automatically initialize the process parameters (user-adjustable) to the default (standard) settings. These factory settings represent a good starting point to begin the profile. If needed, the system will make adjustments automatically during the "optimize" cycles.
   
   NOTE
   Prior to starting the profile development process both the BGA Rework machine and the circuit board should be at, or near, room temperature. Avoid the use of fans to cool the circuit board or BGA rework machine during Profile Development. Doing so may interfere with the software program. Allow the circuit board and BGA rework machine to cool naturally.
   
10. Enter the following information onto the screen. Values may vary depending on the application.
    

Table 2 - Cycle Parameters

Parameter	Standard Value
Device Joint(s) Average - Target (ฐC)	200ฐC
Device Joint(s) Average - Cool Down (ฐC)	160ฐC
Device Joint(s) Average - Reflow (s)	060 seconds
Min. Soak (ฐC)	140ฐC
Max. Soak (ฐC)	170ฐC
Soak (s)	060 seconds
T/C - Highlight Thermocouples being used.
Device Top T/C #2 - Max (ฐC)	230ฐC
Device Top T/C #2 - f(x)	2
Board Control T/C #1 - Target (ฐC)	090ฐC
Board Control T/C #1 - Start (ฐC)	065ฐC
Board Control T/C #1 - Max (ฐC)	130ฐC
Adjacent Device(s) Independent - Max (ฐC)	180ฐC Normally T/C #5
Nozzle Control Flow (%)	Set by selecting Nozzle Part No.
Nozzle Control Preheat (ฐC)	125
Device Top Ramp (ฐC/s)	1.0

4.0 PROFILE DEVELOPMENT OPERATION

1. Recheck the values are entered into the "Automatic Temperature Profiling" screen.
   
2. In the Options section, Click the "Cycle Start/Stop" icon to start the Automatic Temperature Profiling cycle.
   
3. If Automatic Temperature Profiling cycle fails to start, follow the "Pop-Up" instructions.
   
4. Monitor the process and stop the system if the Board Control T/C #1 temperature exceeds 183ฐC.
   You can monitor various stages by observing the following indicators:
   Board - This stage ends when the Board Control Target temperature is reached.
   Preheat - This stage ends when the PCB Target temp. of the Board Control is reached.
   Soak - This stage ends when the Soak Seconds value of the Device Joints is reached.
   Reflow - This stage ends when the Reflow Seconds value of the Device Joints is reached.
   Cool Down - This stage ends when the solder joints are under 183ฐC.
   
5. If all of the Thermal Profile Parameters have been met on the first pass "Done" indicator will be illuminated. Proceed to section 5.0 PROFILE SAVING.
   
6. If all of the thermal profile parameters have not been met on the first pass the "Optimize" indicator will be illuminated.
   
   NOTE
   The system will automatically run up to 3 additional cycles. Do not Start or Stop the machine, nor make any parameter changes. System will restart another cycle once the circuit board has cooled down to the Board Control T/C #1 Start Temperature.
   
   The following Process Optimization Rules may be applied during the Optimize cycles. Only one rule can be applied per optimize cycle.
   001
   The targeted device joint average temperature was not achieved. Attempt to increase device top maximum temperature by 5ฐC. If the device top maximum temperature is currently implemented, the rule is skipped.
   002
   The actual reflow time was less than the target reflow time minus 10 seconds (the system provides a 10 second success window). To compensate, the system will consider the actual cool down time. Next, the system will compute the necessary time extension to achieve the targeted reflow seconds. This time extension is implemented using a device joint average temperature maintain mode. The heating and flow sub-systems will be pulsed on/off to maintain the current device joint average temperature rather than simply turned off when the joint temperature is reached as in the original cycle.
   003
   The target device joint average temperature was not achieved. If the targeted device joint average temperature is at the minimum, the rule is skipped.
7. If the system changes any values, record the values on the BGA Rework Process Worksheet.
   
8. After the additional Profile Cycles, the system will illuminate the "Done" light.
   
   NOTE
   If an optimized cycle can not be achieved, the system will report this condition to the user. Refer to Air-Vac manual for further information.

5.0 PROFILE SAVING

1. Save the new Profile by clicking on the "Save" button in the upper left corner of the screen.
   
2. Enter the "Long Name" of the profile. (Example: ley 15 IC 907)
   
3. Click on the "Thumbs Up" icon, the OK, then Click on the "Thumbs Up" icon again.
   
4. Using "Print Options" print a copy of the graph page, and run a Data Point Summary Report.
   
5. Click on the "Thumbs Up" icon to display a new screen.
   
6. Check the "Build Profile" box.
   
7. Check the "Component Removal" box.
   
8. Check the "Removal Retry" box.
   
9. Check the "Component Placement" box.
   
10. Record the Nozzle Length: Click on the "Asterisk" (*) and select the nozzle size.
    
11. Record the Device Height: Click on the "Asterisk" (*) and select the BGA type.
    
12. Record the circuit board thickness: Enter the value.
    
13. Save the profile using the profile "Long Name" as follows:
    1. Customer Name
    2. Circuit Board Type
    3. BGA Ball Count and Part Type
    4. BGA Location
    5. Nozzle Part Number
    6. Operator Initials
14. Send the file to: Profile Library 1/99.
    
15. Click on the "Thumbs Up" icon.
    
16. Click on Save = OK.
    
17. If needed, the new Profile can be tested. It is suggested that the Removal cycle be performed using this new profile.
    
18. When complete, remove all Thermocouples except the #6 Bottom Side. Remove the circuit board from the machine, and store for further use.

BGA Component Rework Profile Development, Standard Method

BGA Component Rework Profile Development, Standard Method

TOOLS & MATERIALS Ball Mills
BGA Specific nozzle
Cleaner
Cleaning Wipes
Flux, Liquid
Microscope
Hot Air Rework Station
Hand held Digital Thermometer
Oven
Precision Drill Press
Scrap development Assembly
Scrap BGA Components
Tape, Kapton
Temperature recorder, and Analysis Software
Thermal Adhesive


CAUTION - Operator Safety A thorough review of the equipment manual and comprehensive training are mandatory. Daily maintenance is essential. Consult the equipment manual for more information.

CAUTION - Component SensitivityThis method may subject the component to extreme temperatures. Evaluate the component's tolerance to heat prior to using this method. Plastic BGA's are especially sensitive to moisture absorption. Carefully evaluate pre bake requirements.

CAUTION - Circuit Board SensitivityPC Boards are made from a great variety of materials. When subjected to the high temperatures they are susceptible to the following types of damage:
1. Layer delamination.
2. Copper delamination, separation of pads, barrels of inner layers.
3. Burns and solder mask chipping.
4. Warp.
Each circuit board must be treated individually and scrutinized carefully for its reaction to heat. If a series of circuit boards are to be reworked, the first several should be handled with extreme care until a reliable procedure is established.
PROCEDURE
GENERAL INSTRUCTIONS

1. Figure 1: Flux manufacturers reflow profile.

   NOTEYour solder paste manufacturer will have a recommended time/temperature curve for these applications. It is recommended as guidance for profile development. (See Figure 1)
   
2. One fully assembled development board is required.
   
3. 4 to 6 sample BGA components for development may be required.
   
4. A steady state operating temperature or threshold must be established prior to launching the reflow cycle. A consistent temperature starting point is necessary for repeatable results. Between 110ฐ C and 140ฐ C is recommended.
   BGA SOLDERING PROFILE INSTRUCTIONS
   NOTE The BGA replacement profile may require more time and even more heat (usually not more than 20 seconds time) to not only reflow all joints but to properly evacuate flux gases and create uniform joints across the package.

   1. Figure 2: Precision drill press.

      Using a precision drill press (See figure 2), drill through the bottom of the board as follows: One hole in the center of the part, preferably into one of the center balls, if available. One hole into the corner of the part, preferably into one of the balls in the outside row. One hole through the opposite corner of the part into one of the balls. Another hole may be also drilled or substituted for this last one, this being one drilled on the side of the component in an outside row. (See Figure 3).
      
      NOTE
      If the BGA component is susceptible to high temperatures, additional thermocouples may be placed into the device itself to measure the vertical temperature differential (Z- axis).
      

   2. Figure 3: Thermocouple locations.

      Insert thermocouples into the holes. Ideally the thermocouple is secured in place by the solder of the pad that the thermocouple is placed in. (See Figure 4) Otherwise secure in place with Kapton tape, and thermal adhesive. Additional thermocouples will also be placed on the top of the circuit board, about two inches from the site and on the bottom side under the site. These thermocouples may be merely taped in place.
      
   3. Select an appropriate nozzle and install. Be mindful of the component height and clearance area around the component.
      
   4. Secure the board in place with appropriate tooling, clamps, and pins. The board should be secure but allowed to move with thermal expansion. Antistatic solder wave fixtures may be used to prevent warp.
      

   5. Figure 4: Ideal thermocouple placement.

      Connect the thermocouples (drilled locations) to a temperature recorder. Connect other monitoring thermocouples to hand held digital thermometers as required. Temperature recorder should present graphic display as per Figure 5.
      
   6. Select soldering process parameters from similar existing profiles. If none are available, contact the manufacturer of the rework station.
      
      NOTE
      It may be advisable to shut off all vacuum commands when developing a removal profile to prevent inadvertent component removal.
      
      NOTE
      Pre bake the board to drive out accumulated moisture. The length of pre bake will be affected by the board's environmental exposure. A pre bake temperature of 75 ฐC to 100 ฐC is recommended.
      
   7. Place a pre baked board onto the fixture.
      

   8. Figure 5: Temperature data using analysis software.

      Establish a bottom side, under part threshold temperature from which to begin the reflow ramp. 140ฐC underneath the part should correspond to approximately 90ฐC at 2" from the nozzle on the board's top side. Choosing a starting point in this approximate temperature range will help to reduce localized warping during BGA ball reflow.
      
   9. Run the process and monitor the temperature of the bottom and top of the board, next to and under the component.
   10. Disconnect the thermocouples and download recorded data.
       
   11. Analyze the data and optimize parameters for reliable rework as follows:
       1. Maximum temperature at the solder ball / board pad interface should be 205ฐC.
       2. Minimize temperature differential to less than 15ฐC for internal thermocouples measuring the various solder ball / board pad interface.
       3. Time above 183ฐC should be between 30ฐ and 60ฐ seconds
       4. Temperature rise and fall should not exceed 3ฐC/ Sec ramp
       
       
   12. Make changes to process settings as applicable.
       
   13. Run the process and return to step 13.
       
       
   14. Examine the surface under the component for warp.
       
       NOTE
       Excessive localized warp may be reduced by increasing the pre ramp temperature threshold. A convection oven can be used to decrease the thermally induced stress caused by the process. Even heating across the whole board may be required.
   DEVELOP REMOVAL PROCESS
   
   NOTE The component will typically release from its pads when two of the thermocouples measuring joint locations pass the 183ฐ C mark. In order to reduce mask, part or board damage due to excessive heat, the removal cycle is typically shorter than the replacement cycle. Reflow the joints just enough to effect removal.
   1. Copy the parameters of the soldering profile to develop the removal profile.
      
   2. Change process parameters as needed.
      
   3. Connect the thermocouples (drilled locations) to the temperature recorder. Connect monitoring thermocouples to the hand held digital thermometers.
      
   4. Run the process and monitor externally connected thermocouples.
      
   5. Disconnect the thermocouples and download recorded data.
      
   6. Analyze the data and optimize parameters for reliable rework as follows:
      1. Maximum temperature at any location should be 210ฐC.
      2. Minimize temperature differential to less than 15ฐC for internal thermocouples.
      3. Time above 183ฐ C should be between 30 - 60 seconds.
      
   7. Adjust process parameters as needed.
      
   8. Determine the time in the process when all ball locations reach 183ฐC. Note the bottom side monitoring thermocouple temperature.
   9. Reconnect thermocouples.
      
   10. Inject flux under the component.
       
   11. Run process and lift nozzle three seconds after reflow has been reached.
       
   12. Remove the component using vacuum tool.
       
       NOTE
       If software controls the vacuum, select the vacuum on command for all events. This will lift the component as soon as reflow temperatures have been reached.
       
   13. If the component can not be removed, analyze the temperature data and adjust the parameters. Return to step 10.
       
   14. Inspect the BGA footprint area for signs of unexpected overheating, solder mask or pad damage.