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SMT electronics assembly manufacturing forum.


RF BOARD + SOLDER PASTE TYPE PROBLEM

Views: 1459

#52291

RF BOARD + SOLDER PASTE TYPE PROBLEM | 4 November, 2007

we are manufacturing some rf boards that works on a high frequency margins now our boards doesn't pass in impedance test and we concluded that the problem might cause by the solder paste that we are using . our solder alloy is sn62/pb36/ag2 and we think that it might be form the AG2 that is used in this solder paste does anybody have the same problem or can help us in this matter ?

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#52316

RF BOARD + SOLDER PASTE TYPE PROBLEM | 5 November, 2007

As unlikely that this may be, if the RF circuit is sensitive enough, and the minor change in alloy is the only thing that changed, this MAY be the cause.

The circuit was probably tuned to Sn63/Pb37.

The reason I'm not surprised? I once had a customer ask me to increase solder volume on perfectly good solder fillets on MELF components. The reason? RF. Anyway I did what he asked. I overprinted the pad by a mil on each side, and it worked. He got his soldering attenaes.

Good luck!

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#52323

RF BOARD + SOLDER PASTE TYPE PROBLEM | 5 November, 2007

You weren't specific about the frequency band were you're operating. So, let's pound a couple of stakes in the ground. * Conventional tin-lead plating of 200-300 �m is quite satisfactory for lower frequencies in the range of 2GHz. * At frequencies higher that 2Ghz the skin effect phenomenon severely affects the circuit performance. Most of the electrical conductivity takes place on the top layer of the circuit, called the skin depth. * Though tin-lead satisfies the corrosion and assembly considerations it is over 10 times less conductive than copper. * Silver and OSP are the preferred solderability protection of circuity operating in the frequency band 10-15 GHz.

Some of the above points above are: * Repeated from Gold Plating Considerations for Microwave Circuits; K Ramachandran, Filtran Microcircuits * Made without attribution

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#52328

RF BOARD + SOLDER PASTE TYPE PROBLEM | 6 November, 2007

Run a board with regular solder paste and put your worries to rest. Total cost about $0.50 American. Total Time about 3 minutes placement - 6 minutes oven. Looks like it might be worth a cup of coffe and 9 minutes of your time to try.

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#52381

RF BOARD + SOLDER PASTE TYPE PROBLEM | 8 November, 2007

don`t we have any article about the manufacturing of high frequency board . and precautions that we should use ?

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#52387

RF BOARD + SOLDER PASTE TYPE PROBLEM | 8 November, 2007

No. Leave your desk. Go get your hands dirty.

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