This procedure covers the reballing of BGA components.
Minimum Skill Level - Expert
Recommended for technicians with advanced soldering and component rework skills and extensive experience in most repair/rework procedures.
Conformance Level - High
This procedure most closely duplicates the physical characteristics of the original, and most probably complies with all the functional, environmental and serviceability factors.
Disposable brushes for solvent cleaning and application of coatings.
Disposable, puncture-resistant gloves designed for handling mild chemicals.
Additional Items and Supplies
General purpose cleaner for removing contamination.
Batch or inline cleaning system for removing fluxes and contamination.
Woven copper wire designed to wick solder from surfaces and holes.
Precision microscope with stand and lighting for work and inspection.
General purpose oven for drying, baking and curing epoxies.
Reflow oven with multiple zones for controlled solder reflow.
Protect your eyes and your vision with proper safety glasses.
Used to prepare solder surfaces and to prevent formation of oxides during soldering.
Solder paste for component soldering and rework.
Solder balls or spheres for BGA component reballing and rework.
Properly maintained soldering iron and properly sized soldering iron tips.
Nonabrasive, low-linting wipes for cleanup.
Images and Figures
BGA component prior to reballing.
Figure 1. Remove existing solder spheres on BGA components using desolder braid.
Figure 2. Apply tacky flux to flat BGA component pads using a brush.
Figure 3. Place the BGA component(s) into a fixture and cover with the appropriate stencil.
Figure 4. Reflow oven used for controlled reflow of solder balls.
Procedure - Braid Ball Removal
Ensure all BGA components to be processed meet the requirements for acceptable moisture levels.
Note: For information on baking and moisture level control see 2.5 Baking and Preheating
Remove existing solder spheres on BGA components using desolder braid. Place the desolder braid on the balls to be removed, and gently place the soldering iron on the desoldering braid. Apply very light pressure to melt the solder balls. As the solder melts, it will be drawn onto the copper desoldering braid by capillary action. Repeat as needed to remove all the solder balls. See Figure 1.
Clean the BGA components with an approved cleaning solution. Some cleaning solutions may be specified by the customer or contract. The typical cleaning process uses a cleaning brush and cleaner. Gently brush the surface until all evidence of flux and debris has been removed. Dry with a clean wipe or blow dry using an air gun.
Procedure - Reflow Oven Attachment
Apply tacky flux to the flat BGA component pads using a brush. Flux should be evenly applied across the entire BGA pad surface. Use minimal flux needed to fully cover the surface. Remove any excess flux. See Figure 2.
Place the BGA components into a fixture and cover with a matching stencil. Check to ensure the alignment is correct. See Figure 3.
Place a quantity of the appropriate size solder spheres onto the fixture and use a clean cleaning brush to distribute the solder spheres, so they fill all the open apertures in the BGA component stencil. Check to be sure all the apertures are filled with only one solder sphere. Tilt the fixture and pour the excess solder spheres into a collection container for reuse.
Note: Avoid overloading the solder stencil with excess solder spheres as they may wedge under the stencil. This will make lifting the stencil to remove any excess solder spheres difficult.
Set up the reflow oven with the proper profile and run the oven for 5 minutes to ensure the reflow zone temperatures are stable. See Figure 4.
Note: If a profile has not been defined, a profile will need to be created.
Place the BGA fixture and BGA components into the reflow oven. As the fixture moves through the oven, the fixture and components will go through the required preheat, reflow, and cooling cycles.
When the fixture and components emerge from the reflow oven, use gloves to remove the fixture and place it on a flat surface. Allow the fixture and components to cool for one minute to ensure package thermal stability prior to removing the BGA components from the fixture.
Visually inspect the BGA component balls for proper alignment and appearance.
Clean the BGA components in an approved cleaning solution.
Inspect the body of the BGA components for abnormalities.