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IC Solder Voiding

Views: 6245

#83793

IC Solder Voiding | 21 November, 2019

Ok, Question for all of you quality inspectors out there. Would you consider the IC image here to have excessive voiding given the amount of vias ? I only see an IPC voiding spec on BGA balls but nothing for IC's. I'd appreciate all your thoughts ?

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#83795

IC Solder Voiding | 21 November, 2019

Do you mean the void over the vias? That's normal phenomenon due to air or solder go into the vias causes void.

You can check the IC datasheet to see if any requirement for solder connecting on the central body grounding area, suggest you have >=50% area soldered.

If you need less void the the grounding area, you can increase solder paste area/volume.

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DWL

#83800

IC Solder Voiding | 22 November, 2019

I'm worried about the voids that you have on the heel fillet of the leads. Off the top of my head, I don't recall if/what the IPC spec is for voids in gull lead fillets is but my gut instinct is that you're compromising the mechanical strength of the solder joint. The heel fillet provides the bulk of the mechanical strength of the joint, and from the image much of that fillet is missing.

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#83812

IC Solder Voiding | 26 November, 2019

Thank you for the response. Nothing in the datasheet referring to a percentage of thermal pad coverage. I am thinking along the same lines. We are not failing any thermal or functional testing as is so am thinking there is no problem here except maybe for the voids in the functional pads.

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#83813

IC Solder Voiding | 26 November, 2019

I am more worried about those voids also instead of the voids in the thermal pads. I still can't find any IPC spec that calls out a min. void percentage other than on BGA packages.

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#83817

IC Solder Voiding | 26 November, 2019

It's hard to tell from the image but it looks like there isn't much room for a heel fillet.

Seems like that could contribute to your voiding (or poor wetting) if there isn't enough paste volume there.

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#83826

IC Solder Voiding | 27 November, 2019

OK, if has concern on void in the function pin area, you need cross section of the pins solder joints, to see how much area ratio of the void to solder joint area. Of course you need make sure solder joint (the toe and heel, height)meet IPC requirement. And also you can use X-ray image to calculate the void to solder area ratio, suggest the ratio is within 25% is better, the void could reduce solder connecting between the function pin and the solder pad, that's main concern.

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SMTA-Norah

#83916

IC Solder Voiding | 10 December, 2019

The short answer is people are still arguing about what the standard should be. A max voiding between 25-30% depending on who you ask.

Also if those are capped vias they can still cause voids because bubbles are attracted to the irregularities in the plating.

That is a really nice x-ray image BTW, and I agree that the heel voids are really fascinating and more worrisome. I have never seen that covered by the IPC either, I don't even know how one would begin.

This message was posted via the Electronics Forum @ SMTASMTA

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#83921

IC Solder Voiding | 11 December, 2019

Hi,

Below may help you out.

per IPC 7093 ( Design and assembly Process Implementation for Bottom Termination Components ),Clause 6.1.5.3 voids on thermal pad up to 50% does not result in loss of thermal performance. Since the void criteria is meeting IPC ,we are following IPC 7093 which is specific for BTC components.

Regards, Ameen

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#83922

IC Solder Voiding | 11 December, 2019

Although this is not technically a bottom termination component, the method of attachment of the thermal pad is a bottom termination attachment. For bottom termination components IPC states that "thermal pad void criteria shall be established between the manufacturer and user". IPC-A-610G page 8-96.

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#83923

IC Solder Voiding | 11 December, 2019

Thank you all for the comments. They have been helpful to reinforce my first thoughts.

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#84001

IC Solder Voiding | 20 December, 2019

I agree with you in this case. The voids on ground pad of IC <=50%

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#84058

IC Solder Voiding | 30 December, 2019

Steve Thomas pointed the right question. Go and verify the design for this part. I thing it might be causing the void.

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SMTA-Davandran

#84102

IC Solder Voiding | 4 January, 2020

I do faced this problem and and not solve. Fortunately, did not seeing any functional failure from this voiding which approx 50%.

This message was posted via the Electronics Forum @ SMTASMTA

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