9.4.4 BGA Component Reballing, Robotic Ball Removal Reflow, Reflow Oven Attachment Method

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 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.
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. (See Figure 3)
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 - Reflow Oven Attachment

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 the BGA components into a fixture and cover with a matching sphere-capture stencil. Check that alignment is correct. (See Figure 5 and 6)
3. 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 4)
   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.
4. Set up the reflow oven with the proper profile and run the oven for 5 minutes to ensure the reflow zone temperatures are stable.
   Note: If a profile has not been defined, a profile will need to be created.
5. Place the BGA fixture and BGA components into the reflow oven. As the fixture moves through the oven, the fixture and components will undergo the required preheat, reflow, and cooling cycles. (See Figure 7)
6. 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 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.