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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


BGA cracking

Views: 3376

#56513

BGA cracking | 15 September, 2008

Hi

Has anyone experienced laminateand BGA cracking on ENIG finish boards built using a lead free process? The laminate is cracked directly underneath the pad where the solder joint has cracked. We have confirmed the cracking via Microsectioning. We have also confirmed the cracking is not happening after the reflow process,again via microsectioning. There is no ICT involved but the card is fitted with PCI bracket and then fitted into a chassis assembly.

Thanks in advance Adam

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#56516

BGA cracking | 15 September, 2008

Hi Adam,

Since you don't see any cracking right after re-flow, then the most probable cause is the board flexture during handling/assembly. I bet you see cracking in the outer row(s) and mainly in the corner balls.

Regards,

Vlad

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#56549

BGA cracking | 16 September, 2008

Would you attach pix of the sections?

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#56567

BGA cracking | 17 September, 2008

Adam,

Most leadfree components can handle only 260C. When you doing the profile, you should put thermocouple on the of the BGA package and to ensure the temp is not go over 260C.

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#56570

BGA cracking | 18 September, 2008

Hi

Please see attachment

Adam

Attachments:

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#56573

BGA cracking | 18 September, 2008

It looks "normal" for that type of failure

Vlad

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#56575

BGA cracking | 18 September, 2008

Hi Vlad

Please explain "Normal" ?

Adam

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#56580

BGA cracking | 18 September, 2008

Any crack in laminate caused by excessive flexure would look exactly like the one in the image.

Vlad

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#56581

BGA cracking | 18 September, 2008

Ditto, we just went through this with a customer "fitting" our boards into a card cage. Mechanical stress/flexing.

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#56698

BGA cracking | 25 September, 2008

Ditto here, also.

This is generally referred to as �cratering,� and is associated with stress on boards from operations such as ICT, installation of compliant pin connectors, and depanelization.

It is more common on PCBs designed for Lead-free processes since these often incorporate more brittle laminates.

Glenn Robertson

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