SOLDER SHORT DUE TO VOID IN BGA

#84992

SOLDER SHORT DUE TO VOID IN BGA | 16 June, 2020

Hello all,

I am randomly getting solder short due to voids in the BGA

Reference image attached.

Kindly provide your thoughts on this as how to approach to resolve this issue.

Attachments:

#84994

SOLDER SHORT DUE TO VOID IN BGA | 16 June, 2020

Your statement is interesting, but not necessarily correct. Are shorts in the same location? Is it one short or multiple? Are there any vias in the BGA pads on the PCB? Is part MSD and handled as ESD?

#84995

SOLDER SHORT DUE TO VOID IN BGA | 16 June, 2020

Thanks for your response.

Shorts are happening in different locations(Not same pad repeated) .kindly note these are happening one in 10kThat's the challenge to understand the exact issue. Only one short.

Vias - i will check and updated.

Yes it's msd level 3. Handling also been taken into account and I don't find any observations.

#84997

SOLDER SHORT DUE TO VOID IN BGA | 16 June, 2020

Voids form mainly two ways. 1. Contamination - due PCB pads/part leads oxidation, wetting on the pad is bad forming void(these are usually borders with SMT pad - peripheral) 2. Process formed. These are in the center of the solder joint - could not escape during soldering process

Can you tell with your X-ray where the void is?

#84998

SOLDER SHORT DUE TO VOID IN BGA | 16 June, 2020

Point one -; I am also having this concern but based on the DPM it's getting difficult to keep the track to understand what exactly happened with the particular PCBA (Attrition component placed or Cleaned PCBA due to some issue those components are placed). Trying to collect the data to match it.

Point two -; These voids are not creating at center pads only. These are creating randomly and corners also affected. (attached some more images for your reference)

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#85000

SOLDER SHORT DUE TO VOID IN BGA | 17 June, 2020

These are great pictures. I have never seen this kind of solder repelling from the pad. My number one suspect now is the PCB. Your focus should be on board plating and contamination. The easiest test is to have meaningful batches from another board house. I would also revisit the FAB drawing to see if the plating requirements are in spec.

#85001

SOLDER SHORT DUE TO VOID IN BGA | 17 June, 2020

Thank you for your valuable inputs.

Current two SMT line is running and I have initiated to use two different pcb suppliers in each line.

Do I need to check the plating details in issue pcba or random pcb. Kindly suggest.

#85005

SOLDER SHORT DUE TO VOID IN BGA | 18 June, 2020

I would say you check FAB drawing and see if there is any strange value on the stackup. Usually board house should inform you of these.

#85008

SOLDER SHORT DUE TO VOID IN BGA | 18 June, 2020

Usually board house should inform you of these.

Here supplier works differently. We generally don't get these updates. Only the ODM or customers get.

We only find when we are facing any issues.

Can you please enlight me on how to check the value on stackup.

#85015

SOLDER SHORT DUE TO VOID IN BGA | 19 June, 2020

We also don't inspect any things in incoming PCBs. We have CMM but will be used when we see any abnormality.

Kindly advise me on this.

CPH

#85123

SOLDER SHORT DUE TO VOID IN BGA | 30 June, 2020

Hi SRINI, Are you able to show X-ray of these 2 locations from other board w/o bridging? Void looks almost perfect circle which I never encountered before.

#85125

SOLDER SHORT DUE TO VOID IN BGA | 30 June, 2020

Hi CPH,

Thanks for your response. Sure I will share. But give me some time since we stopped SMT as of now. I will share you on 7/07/2020

#85165

SOLDER SHORT DUE TO VOID IN BGA | 7 July, 2020

Few more images attached.

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IMG-20200707-WA0017.jpg

#85167

SOLDER SHORT DUE TO VOID IN BGA | 7 July, 2020

Attachments:

DucHoang

#85170

SOLDER SHORT DUE TO VOID IN BGA | 8 July, 2020

Interesting!. They don't look like voids as usual meanings. The "voids" take the whole size of pads. We built millions of BGA, never seen those before. Look like the pads refused to connect with solder paste and pushed the paste away. Pads contaminated so bad (?) or the pads covered by foreign substances ( Solder Mask?). Are those pads connect to each other and the solder mask between them damaged. I wish I could see the board under microscope.

#85171

SOLDER SHORT DUE TO VOID IN BGA | 8 July, 2020

Hi DucHoang,

Thanks for the response.

I will share the images. We are using OSP boards and issue is not at particular BGA.

Can you suggest me any methods to identify the pad contamination.

DucHoang

#85173

SOLDER SHORT DUE TO VOID IN BGA | 8 July, 2020

OSP board finish is the issue. With OSP microBGA board, we need to have enough paste (enough flux) on pads (small pads on BGA), also we need to have strong, more activate flux to get rid of Preservative layer on top of pads. In this case, the OSP did not do good job on some BGA pads, randomly, leave the pads oxidized and causes poor solderability. Do not use OSP for microBGA.

#85174

SOLDER SHORT DUE TO VOID IN BGA | 8 July, 2020

Thanks for your input.

I do understand from this thread that OSP is the issue

We don't have options left. Need to use this.

Defect rate is just 0.002 still I am focusing on zero defect product since this will run for longer period.

Kindly provide your valuable suggestions on how to prove this issue with supplier.

#85188

SOLDER SHORT DUE TO VOID IN BGA | 10 July, 2020

Hi,

Image 1 - Solder short image Image 2 Same component X ray image Image 3 PCBA Solder short pad image (after removing the component) Image 4 Component pad image Image 5 PCBA pad image after tinning.

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researchmfg

#85191

SOLDER SHORT DUE TO VOID IN BGA | 11 July, 2020

The bubble inside BGA ball locate at via in pad and apply the resin plug hole.You shall check the cooper plating quality on PCB pad. If there is thin plating or broken on the pad then air will come from the resin plugged via and be trapped inside the BGA ball during reflow process.