Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Cleaning Reworked BGA's.

Views: 1061

Sandy B

#35846

Cleaning Reworked BGA's. | 2 August, 2005

I am looking for a method (Automated preferably) to clean any residue and or debris from a BGA after rework.

Is it possible to clean them using an inline wash process, as long as the devices are intact and held correctly. What woudl be the correct method to hold trhem during this process.

reply »

#35848

Cleaning Reworked BGA's. | 2 August, 2005

Are we talking: * BGA that you've reballed and want to clean prior to attachment to a circuit board? * BGA that you've attached to a circuit board after correcting something or other?

... and we're talking a water soluble flux or what?

reply »

#35920

Cleaning Reworked BGA's. | 4 August, 2005

Hi Sandy B,

You certainly can clean the BGA's using an inline or batch process. The correct method to hold them during this process, is the method that provides the desired outcome. I'm familiar with the desired outcome for cleaning singulated BGA's to primarily be:

(1) free of flux residues (especially around the fillets of the solder balls/bumps and around perimeter of any NSMD pads) (2) free of solder splatter/balls on the surface of the substrate (3) cosmetically appealling solder spheres, (4) unmarred solder spheres (5) no missing solder spheres (unless you are just cleaning the substrate/pads, having removed the spheres as part of the rework) (6) acceptable flatness of BGA (7) free of wash solution (meaning completely rinsed) (8) free of ionic contamination (meaning rinsed with good quality DI water and dried without reintroducing ionics) (9) free of rinse solution (meaning totally dry) (10) exit with acceptable handling temperatures

Cleaning the BGA's while they are held in JEDEC trays or AUER boats would likely provide the desired transport method and presentation of the BGA's to the cleaning process to maximize potential for achieving the desired outcome. A fixture can be fabricated that provides the charactoristics of the trays/boats while providing flexibility for a range of BGA sizes.

If your inline blast the BGA's out of the fixture, several methods can be considered to retain the parts in the fixture. Clamps that hold the BGA in the fixture, or, stacking an empty fixture over the loaded fixture is possible in some applications. Avoid dynamic top hold down belts, as these have a great potential to damage the soft solder, and/or, rip the solder from the pad. If no solder is present on the pad, observe if the top hold down conveyor scars the pad.

Hope this helps! and Have a Great Week!!

Shean Dalton Austin American Technology Your Global Cleaning Experts www.aat-corp.com (512) 335-6400

reply »

#35935

Cleaning Reworked BGA's. | 5 August, 2005

Hi Sandy, Here are some suggestions for an optimum cleaning process for cleaning under BGAs if they are assembled to the board to add to the great tips Shean already listed:

- Use a good saponifier w/ DI water - an effective saponifier will be able to get under the BGA and clean the area without living any residue. - Maintain a wash temperature of 140 F. - Run with lower pressures in the pre-wash and wash sections at a slower belt speed - Pre-wash and Wash pressures should be set at 35 and 30 psi top and bottom respectively, and belt speeds of 3.0 ft/min

We have always found in our cleaning facility that when using an in-line or batch cleaning process, the most effective cleaning method for the best ionic cleanliness is to use a low pressure, high flood protocol with a good saponifier and slow belt speed. This is an effective protocol to use with cleaning BGAs.

Regards, Sara Gorcos Foresite Inc. www.residues.com

reply »

PCB Soldering Tools

PCB Cleaning