BGA Reballing Practice Kit

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BGA removal, reballing, soldering exercise

The kit contains (almost) everything you need to reball your first BGA chip! Includes the exact brands and tools used by Hacker Camp Shenzhen to teach BGA reballing at a mobile phone repair school. Accompanies the Hacker Camp Shenzhen 2014 BGA workshop video (available soon).

BGA kit

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What's in the box:

  1. Recycled mobile phone (chip donor)
  2. Solder paste
  3. Flux
  4. Spatula
  5. Tweezers right angle (ST-15)
  6. Tweezers sharp (ST-11)
  7. Knife and flat blade
  8. BGA stencil
  9. PCB holder
  10. Screw driver
  11. Phone opening tools
  12. Cotton sticks
  13. Dangerous Prototypes stickers

You will need to bring your own (B.Y.O.):

  1. Soldering iron (any will work)
  2. Hot air rework station
  3. Acetone (or nail polish remover)
  4. Tissues

Basic outline

1. Open phone: Starting along the side, pry the phone case open with the blue phone tool or guitar pick.

2. Unscrew phone cover: Remove screws found inside the phone.

3. Remove PCB and screen: Remove the circuit board from the phone case, remove the screen. Place the PCB in the PCB holder.

4. Remove RF shields: On some phones metal RF shields hide several chips. Remove with tweezers or hot air (250C, 55% flow). Circle one shield at a time slowly, spend about 0.5 seconds on corners to give a little extra heat. Lift gently with sharp tweezers (ST 11) until the shield comes off the PCB.

5. Remove BGA chips: In this phone the BGA chips are not glued in place. Heat BGA chips in center with hot air (320C, 55% flow), then around the edge. Use sharp tweezers (ST 11) as a lever to gently flip the chip off the PCB.

6. Clean PCB: Using hot air (300C, 55% flow) heat the PCB that was under the BGA chip. Use the knife with flat blade to clean the old solder from the BGA footprint. After cooling the board, use acetone (or nail polish remover) and a cotton stick to firmly scrub the PCB footprint clean.

7. Clean BGA chip: Clamp the BGA chip between the part of the PCB holder with a screw and the block that holds the long rail. Heat with hot air (300C, 55% flow) and use the knife with flat blade to scrape off any remaining solder. Let the chip cool. Scrub firmly with cotton stick and acetone (or nail polish remover) to remove any residue.

8. Tin BGA chip: Using a soldering iron heat solder and spread over the BGA chip. This should make each connection bright and shiny.

9. Dry solder paste: Place a small amount of “Mechanic” solder paste in a tissue and fold. Squeeze to dry the solder paste.

10. Place stencil over chip: Find a BGA stencil that matches the chip. Most chips in this phone will work with the “0.8 16x16” and “ST4904 CPU” stencils. Stencils are not an exact match, but are adequate for the job. Place the BGA chip on a tissue and place the stencil over the chip. Align so the shiny connections on the chip are all visible.

11. Apply solder paste: Hold the stencil firmly on either side of the chip with the right angle tweezers (ST 15). Use the spatula to spread the dried solder paste into the stencil holes. Don’t use too much, and remove any excess from the top of the stencil.

12. Create new BGA balls: Still holding the stencil in place, use hot air (280-300C, 20% flow) to melt the solder paste. When all the newly created balls are shiny, remove the heat and continue to hold the stencil firmly until cool. To remove the chip use sharp tweezers to push the chip through the stencil.

13. Inspect the BGA: Hold the chip at an angle and inspect the rows of balls. They should be fairly uniform and none should be missing. Repeat inspection on each side of the chip. If balls are missing, remove all the balls with hot air and the flat knife, repeat the process.

14. Reflow the BGA: Place the BGA chip back on a tissue and apply hot air (320C, 20% flow) quickly over the solder balls. This helps them snap into place and corrects any misalignment.

15. Resolder the chip to the PCB: Heat the cleaned PCB footprint with hot air (280-300C, 40% flow). Apply a tiny amount of solder flux using the sharp tweezers or a cotton stick. Place the BGA chip back on the board and continue to heat. When the balls melt the chip will ‘float’. Nudge it into place with the sharp tweezers, then remove the heat and allow to cool.

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