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HIP defect in BGA

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#84959

HIP defect in BGA | 9 June, 2020

Hi Team,

Please help in suggesting stencil aperture opening for the 0.4 mm pitch BGA. PAD Diameter is 0.24mm.

we have 0201 components also in same board.

We have HIP in this BGA.

Solder paste : Alpha Om5300 ( PB+ solder paste ) type 4

We have tried with electroform stencil with 0.2 mm opening. 3.5 mil stencil thickness. RSS profile was used.

Ramp rate : 1.3 deg / c Soak ( 140 - 170 ) = 100 sec Reflow ( Above 183 deg C ) = 85 sec Peak : 233 Deg C

planning to move to :

3.5 mil stencil with 0.22 mm aperture opening.

Shoulder profile :

Ramp rate : 1.3 deg / c Soak ( 140 - 170 ) = 60 sec Reflow ( Above 183 deg C ) = 85 sec Peak : 230 Deg C soak 1 ( 170 - 180 deg C ) - 22 sec.

Please provide valuable feedback on the same.

Regards, Ameen.

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#84960

HIP defect in BGA | 9 June, 2020

Any reason you're doing a RSS profile rather than a RTS?

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#84963

HIP defect in BGA | 10 June, 2020

Hi Phil,

we used RSS profile initially , because of tombstone issue at 0201 package.

We are planning to reduce soak a now to have flux till the end of reflow to avoid HIP now.

and to support that . we are increasing over aperture opening also.

Regards, Ameen

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#84970

HIP defect in BGA | 12 June, 2020

I cannot see the logic connection between HIP and RSS or RTS, or between HIP and solder paste volume because volume is ok. Did you measured the BGA solder profile?

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#84976

HIP defect in BGA | 14 June, 2020

Where are HIP connections located?

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#84981

HIP defect in BGA | 15 June, 2020

Hi Team,

Main reason for HIP are; 1. Warpage in component or PCB : Verified the part and PCB 1.6 mm thickness no warpage found. 2. Hip was at different locations : center as well as corner : So not because of warpage of component. 3.Solder paste equal deposition : Old stencil area ratio was 0.57 for electroform stencil. felt not good enough for BGA for good transfer efficiency. Even though studies says 0.5 area ration is good enough with electroform stencil. We have increased the stencil area ratio to 0.64.

4. Exaustion of Flux : Might be because we had used high soak for thermal equilibrium to avoid tombstone at 0201 parts in same board.

So going with Shoulder profile. To save the flux exhaustion and at same time to provide thermal equilibrium.

Shoulder profile concept by Dr. Ning Ching Lee - indium.

HIP is found at different BGA solder ball location at different BGA. we have 4 BGA on board with 0.4mm pitch.

Regards, Ameen

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#85045

HIP defect in BGA | 23 June, 2020

If you swear in having consistent print, I bet you it is the part. Some of these BGAs probably have missing or inconsistent balls.

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lead free wave solder

Capillary Underfill process