9.4.3 BGA Component Reballing, Robotic Ball Removal, Mini-Oven Attachment Method

Outline

This procedure covers reballing of BGA components.

Minimum Skill Level - Expert

Conformance Level - High

Tools and Materials

Cleaner General purpose cleaner for removing contamination.

Cleaning Brushes Disposable brushes for solvent cleaning and application of coatings.

Cleaning System Batch or inline cleaning system for removing fluxes and contamination.

Gloves Disposable, puncture-resistant gloves designed for handling mild chemicals.

High Temp Tape Discs High temperature polyimide tape discs, .50" diameter.

Microscope Precision microscope with stand and lighting for work and inspection.

Oven General purpose oven for drying, baking and curing epoxies.

Safety Glasses Protect your eyes and your vision with proper safety glasses.

Solder Flux Used to prepare solder surfaces and to prevent formation of oxides during soldering.

Solder Spheres Solder balls or spheres for BGA component reballing and rework.

Wipes Nonabrasive, low-linting wipes for cleanup.

Procedure

Procedure - Touchless Ball Removal

This BGA component de-ball process dissolves and flushes away the existing solder balls, leaving a flat surface on each BGA component solder pad.

1. Ensure the BGA components are processed to meet the requirements for acceptable moisture levels.
   Note: For information on baking and moisture level control, see 2.5 Baking and Preheating.
2. A matrix tray or custom holding fixture will be required if the BGA components are supplied on tape and reel.
3. Set up the robotic hot solder dip de-ball system with the proper process parameters, including solder immersion depth, dwell times, insertion and extraction speeds, solder temperature, and other settings. (See Figure 1)
   Note: Refer to the component data sheet for guidelines regarding component peak temperature specifications and other process parameters.
4. Load the BGA components onto the fixture or matrix tray and place in the robotic hot solder dip de-ball system. (See Figure 2)
5. Activate the robotic machine process cycle.
6. The system will pick up a row of components from the matrix tray using a multi-head vacuum pickup.
7. The system will apply flux to the existing solder balls.
8. The system will remove the excess flux using an air knife.
9. The system will run the components through a programmed preheat stage to activate the flux.
10. The system will remove the unwanted solder balls using a dynamic solder wave.
11. The system will run the components through a filtered hot water rinse to remove the flux residues.
12. The system will dry the components using an air knife.
13. The system will return the de-balled BGA components to their original position in the matrix tray.
14. Visually inspect the BGA component's appearance, cleanliness, and condition. Check the solder pads for flatness and inspect the body of the BGA component for abnormalities.

Procedure - Mini-Oven Attachment Method

1. 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 cover the surface fully. Remove any excess flux. (See Figure 4)
2. Place a quantity of the appropriate size solder spheres into the fixture and use a clean brush to distribute the solder spheres so they fill all the open apertures in the BGA component stencil. Ensure 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. (See Figure 5 and 6)
   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.
3. Place the component and fixture into the mini BGA reflow oven. (See Figure 7)
4. Turn the Mini BGA Reflow Oven on and select the proper profile.
   Note: If a profile has not been defined, a profile will need to be created.
5. Close the cover of the mini BGA reflow oven and press the start button. The oven will undergo the required preheat, reflow, and cooling cycles.
6. When the temperature has cooled below 100° C, use gloves and remove the reball fixture from the mini BGA reball oven. Allow the fixture and components to cool for one minute to ensure package thermal stability before removing the BGA components from the fixture.
7. Inspect the BGA component balls for proper alignment and appearance.
8. Clean the BGA components in an approved cleaning solution.
9. Inspect the body of the BGA component for abnormalities and cleanliness.

Images

BGA Component Reballing, Robotic Ball Removal, Mini-Oven Attachment Method

Set up the robotic hot solder dip de-ball system.

Load the BGA components onto the fixture or matrix tray.

Remove the unwanted solder balls using the robotic system's dynamic solder wave.

Apply tacky flux to flat BGA component pads using a brush.

Place the BGA component into a fixture.

Place the proper stencil on the fixture and fill the stencil apertures with the proper size solder balls.

Place the component and fixture into the mini BGA reflow oven.