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SMT electronics assembly manufacturing forum.


Kelly Morris

#11617

Tombstoning 0805s w/palladium/platinum/silver terminations | 29 April, 1999

Tombstoning 0805s w/palladium/platinum/silver terminations

We are experiencing tombstoning problems on 0805 packages that have paladium/platinum/silver terminations. It comes & goes......

I�ve checked the reflow profile, and paste deposition and all looks well. I suspect the problem relates to the paladium/platinum/silver terminations.

Is anyone else using such a part, and or experiencing issues with the paladium/platinum/silver terminations?

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JohnW

#11618

Re: Tombstoning 0805s w/palladium/platinum/silver terminations | 2 May, 1999

| Tombstoning 0805s w/palladium/platinum/silver terminations | | We are experiencing tombstoning problems on 0805 packages that have paladium/platinum/silver terminations. It comes & goes...... | | I�ve checked the reflow profile, and paste deposition and all looks well. I suspect the problem relates to the paladium/platinum/silver terminations. | | Is anyone else using such a part, and or experiencing issues with the paladium/platinum/silver terminations? | | Kelly,

There are a few thing's to check, 1. pad sizes..if they aint right you are really gonna find it hard, check out the IPC or component vedor dim's for the part, 2. what direction is it going thro the oven..(what type of oven are u using IR / convection) if it's heading short edge first you may want to look at using a slight soak time on it and reducing the ramp rate to about 1.5 instad of the 2degrees. another trick that I've discovered is to drop the bottom heat zones for the 7/8 zone are by about 5-10 degree's to create a slight miss match, sound's bizzare but it does work. the other thing is what paste are you using for you components and what is the board finish..these can have an impact. Palladilum/silver somtimes has a different spec for profiles that std tin /lead..but you can usually get away with it no trouble. compair the component reflow profile to the paste, try and find some common ground.

good luck

JohnW

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#11619

Re: Tombstoning 0805s w/palladium/platinum/silver terminations | 3 May, 1999

| Tombstoning 0805s w/palladium/platinum/silver terminations | | We are experiencing tombstoning problems on 0805 packages that have paladium/platinum/silver terminations. It comes & goes...... | | I�ve checked the reflow profile, and paste deposition and all looks well. I suspect the problem relates to the paladium/platinum/silver terminations. | | Is anyone else using such a part, and or experiencing issues with the paladium/platinum/silver terminations? | | Kelly, Make sure that you are using a paste with 2% silver when soldering these parts. The palladium does not wet well with regular 63/37 paste (your joints will look poor also). This poor wetting will encourage a 'tug of war' at the opposite ends of the part during reflow and increase tombstoning.

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