Printed Board Type: R/F/W/C
Skill Level: Advanced
Conformance Level: High
Revision: Pending
Revision Date: Pending

OUTLINE

Plastic Ball Grid Array Component

This procedure covers the most commonly used methods for replacing Plastic Ball Grid Array (PBGA) components and Ceramic Ball Grid Array (CBGA) components. These packages are typically referred to as Plastic Ball Grid Array (PBGA) or Tape Ball Grid Array (TBGA) or Chip Scale Package (CSP) components.

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.
   

REFERENCES
1.0	Foreword
2.1	Handling Electronic Assemblies
2.2	Cleaning
2.5	Baking and Preheating
7.1.1	Soldering Basics
7.1.2	Preparation For Soldering And Component Removal

Figure 1: Commercially available BGA Rework Station.

TOOLS & MATERIALS
BGA 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


GENERAL NOTES

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

   Profiles for both removal and replacement of the selected component must be developed prior to rework. (See section 8.5.2 for instruction)
   
   
2. Check the board for any heat sensitive components that may be damaged by the process, especially near the location of rework.
   
   
3. Profiles are board and site specific. Profiles that are successful on one board type are not necessarily effective on other assemblies.

1. Select the appropriate nozzle and install into the rework station.
   
   
2. The nozzle should hold the component securely yet allow for expansion during the process.
   
   

   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 °C to 100 °C is recommended.
   
   NOTE
   To remove moisture from components, it is recommended that all parts are baked per the component manufactures suggestion. Generally, a 24 hour bake at 125°C will remove most moisture. This will prevent pop-corning or delamination of the component.
   
   

3. Place a pre baked board into the fixture.
   
   
4. Attach monitoring and trigger thermocouples
   
   
5. Establish a bottom side, under part threshold temperature from which to begin the reflow ramp. 140°C underneath the part should correspond to approximately 90°C 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 at BGA ball reflow temperature.
   
   
6. Align the device and nozzle.
   
   

   NOTE
   If the bottom temperature exceeds 210°C, terminate the replacement and check the process parameters.
   
   

7. Lift the nozzle when well below reflow temperatures.
   
   
8. Ion fans may be used to cool the components and the board.
   
   
9. Clean the area . Remove all flux residue from the site.

1. Visual examination of the perimeter spheres for joint shape, alignment and condition.
   
   
2. Visual examination for part planarity and condition.
   
   
3. X-ray examination as required for shorting or joint deformities. 
   See (Figure 2).
   
   
4. Electrical tests as applicable
   
   
5. On removed part, visual evaluation of post reflow condition.