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DC-DC Converter with solder ball package

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DC-DC Converter with solder ball package | 26 May, 2006

Due to spacing issue, we are considering using power bricks with tin/lead solder ball instead of PTH package. The solder ball is 40 mil diameter. Our CM suggested they do hand place since the pick and place nozzle cannot pick up and hold the part due to the non balance shape of the device. The size of the brick is 1.495"x0.87". Has anyone ever experienced using this kind of part package? Does the reflow temperature need to be adjusted higher? Any concerns at all? Thanks for your inputs.

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DC-DC Converter with solder ball package | 26 May, 2006

Yes we do place "big and heavy" SMT DC/DC:s on most of our board's. Please tell us what brand it is or at least what the package look like?!? For instance we place a different numbers of "heavy" DC/DC converters (40x20mm & 45x25mm) that has the pick-up area (that is the flat surface the nozzle use) position off center by up to much as 16mm. This is interesting, because the of center pick-up area is well within the center of gravity. That means that there should not be any problem to pick it up, rotate and place the component. What is your smt-machine brand and what nozzle size does it use? That is for the placement question.

As for the soldering question; You must attach the temp. solder probes in a proper place on 2 places: one on top of the component body or if it is an open frame, just put it in top on the surface of the component body that you will use for pick-up and one on the power lead/bump since the heavy mass of the DC/DC converter will affect the delta T of the component and more off, the delta T of the PCBA. Make sure that the terminal is used, not all terminals is used on every DC/DC.s The manufactory of the DC/DC:s usually have an example of how and where to attache the temp. probes.

You will need to go up in temp to be able to solder the DC/DC's solder bumps, but in the same time you don't like to over heat the small chips around. Right? That is the tricky part! The DC/DC:s I think You are talking about req. the same treatment as a big CCGA.

BTW. We have adjusted our profiles according to the IPC:s and our custumer req. Big and heavy DC/DC converters:s could be a problem once in a while, but we have not any problem with soldering these nor delta -T at the moment, even in a lead free environment...

Sorry for my poor english and gramma. /Sincerly

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