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Solder Paste Testing

Mark D. Milward


Solder Paste Testing | 19 January, 2000

Does anyone consider the use of a Cyberoptics LSM solder paste thickness measurement system to be a valid test in determining the viscosity of solder paste. This procedure was proposed as an alternative to using the Malcolm gage for viscosity testing. I don't agree. The thinking is that the height and thickness of the paste measured after screen print can corelate with the viscosity of the paste. Without having performed an experiment I would think that solder paste with a high viscosity (above acceptable limits) would not not have a bearing on height and thickness and a low viscosity would merely slump. Has anyone performed this experiment. Please give me your input. It would be greatly appreciated,


Mark Milward

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Re: Solder Paste Testing | 19 January, 2000

I'm with you Mark. Haven't done the experiment, lemme know ...

Dave F

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Scott S. Snider


Re: Solder Paste Testing | 20 January, 2000

I ran this test back in '92 or '93 when Alpha was first pushing to change from Brookfield to Malcolm readings. The correlation between Malcolm readings to solder paste height is good. I could always look at the viscosity reading and know at least a day ahead whether we would have high defects or not. We used both the big fancy Malcolm and the small handheld. At the same time we implemented the LSM (second generation). We measured solderpast on the stencil using the handheld and then measured solder paste height with he LSM. The correlation was strong. We did encounter a couple problems. First the variation from operator to operator using the LSM was large. Second it was a pain to measure the viscosity and have to clean the tool. In the end we just measured with the LSM and were content.

Scott Snider Anything worth doing is worth doing badly. Chesterton

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Charley Qin


Re: Solder Paste Testing | 25 January, 2000

Hi, Mark

Acturally, solder paste viscosity reading is very closely related to eviroment such as temperature and relative humidity. So I'm afraid it is hard to tell the diffrence between measurements without enviroment control. Regarding to LSM, we've ever done a Gauge R & R study to this equipment and the value is bigger than 70%.

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