solder paste height standard

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want to know the tolerance the paste height in the solder pa... - Jan 07, 2014 by m_imtiaz

To most of our boards I give 20-30% tolerance in both direct... - Jan 08, 2014 by Evtimov

m_imtiaz, Over the last 15 years or so I've found that us... - Jan 24, 2014 by DaveM

thank for good input, any documented standard available fro... - Jan 30, 2014 by m_imtiaz

m_imtiaz

#71551

solder paste height standard | 7 January, 2014

want to know the tolerance the paste height in the solder paste printing. for example if stencil thickness is 7 mil, what will the acceptance level of paste height ( upper and lower) kindly share if any guidelines or formula for the same

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Evtimov

#71553

solder paste height standard | 8 January, 2014

To most of our boards I give 20-30% tolerance in both directions. From experience if you have big aperture on your stencil, the squeegee will scoop certain amount of paste from this aperture and you will see lower height. Depending on your board supports, clean rate and you printer capabilities(repeatability) you will see some variations. What I would do is to physically examine the board after the oven and see if any defects, then I will go back to my SPI and redefine tolerances.

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DaveM

#71633

solder paste height standard | 24 January, 2014

m_imtiaz,

Over the last 15 years or so I've found that using the stencil foil thickness +2mils/-0mils has worked very well.

For example, if you have a 5mil stencil thickness your upper control limit would be 7mils and your lower control limit would be the 5mil foil thickness. The point a previous poster made about "scooping" is a good one. But typically, it's the smaller/fine feature components you'll need to worry about.

Hope this helped.

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m_imtiaz

#71654

solder paste height standard | 30 January, 2014

thank for good input, any documented standard available from any well known body (IPC standard)

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