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Sn90Sb10 Solder Paste

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Sn90Sb10 Solder Paste | 22 March, 2013

We are trying to use this high-temp solder paste due to a very special process, but we run into tombstones on chip caps, 0402 and 0603. We don't have this problem if we use regular SAC305 solder paste. If you have experience with this type of solder paste, please share. Thank you.

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Sn90Sb10 Solder Paste | 1 April, 2013

First check the profile. I would go with linear profile and smoother increase of temperature. Usually you will get tombstones when you have too aggressive profile. My next step will be to redesign the stencil.

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Sn90Sb10 Solder Paste | 1 April, 2013

In thinking about troubleshooting tombstoning {TS} defects, seek balance: * Pads the same size * Same amount of paste on each pad * Component placed with the same amount of contact on each pad * Heating the same on each pad, no via connection to a ground plane on one side and not the other * Components with the same amount of solderable metal on each termination * ... stuff like that

Some alloys, like Sn62Pb36Ag2, are better at preventing TS because they have a wide pasty range.

Some pastes are formulated to reduce TS.

Sometimes too much paste will be the cause TS

If the gap between the pads is too large it can cause TS.

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