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BGA Bowing on the corners.

Mike Snider

#25568

BGA Bowing on the corners. | 22 August, 2003

I am placing a plastic Cypress, 256 pin BGA on a small assembly, and I cannot stop the corners from bowing. I've moved my profile up and down with no results. Any suggestions?

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RDR

#25574

BGA Bowing on the corners. | 22 August, 2003

Please search the archives, there is a ton of stuff on this.

Russ

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Hoss

#25577

BGA Bowing on the corners. | 22 August, 2003

Mike,

Any chance these parts have been sitting around esposed to your factory's ambient conditions, not in a vacuum sealed bag or dry box? If they haven't, you may have parts with a high moisture content which could cause "potato chipping" you describe upon reflow.

Try using some parts that have been properly stored with your normal profile and see if there is a difference. If there is, you'll need to bake the bad boys per JEDEC standards.

Good Luck.

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#25578

BGA Bowing on the corners. | 23 August, 2003

Handsome zhang

#25579

| 24 August, 2003

> I am placing a plastic Cypress, 256 pin BGA on a > small assembly, and I cannot stop the corners > from bowing. I've moved my profile up and down > with no results. Any suggestions?

Hi mike I am a staff of smt in ASUS(TAIWAN),I have a large intresting in SMT,in another way you can call me SMT FANS, I hope we can exchang questions by e-mail. wait your reply best wishes! Handsome zhang

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Dennis O'Donnelll

#25580

BGA Bowing on the corners. | 25 August, 2003

It could be moisture in the BGA. You should always bake the BGA before installation of course. But most likely you are usingf too much heat or too fast of a ramp speed. Make sure your top heater temp is below 230C. Set top heater to 220C, then adjust you bottom heat and ramp to achieve best results. I prefer a ramp of 2 degrees C. per 3 seconds. Check out: http://www.pcb-repair.com/

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#25582

BGA Bowing on the corners. | 25 August, 2003

For further discussion on the "being hosed by the physics": http://www.cooksonsemi.com/tech_art/pdfs/Controlling%20Warpage.pdf

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#25583

Welcome | 25 August, 2003

Handsome: Welcome. There is always room for another balding, fat, aging SMT smooth-talker here on SMTnet.

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#25587

BGA Bowing on the corners. | 26 August, 2003

For more information on moisture-induced BGA warpage, I suggest you read the following paper that was recently presented at ECTC :

"Impact of Ingressed Moisture and High Temperature Warpage Behavior on the Robust Assembly Capability for Large Body PBGAs", by Shook and Al.

You can download this document from the MSD Knowledge Base at http://www.cogiscan.com, click on the MSD logo, click on List of publications and other references, it is the first paper in the list.

Regards, Francois Monette Cogiscan Inc.

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