Help understanding something about stencil orientation when printing

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Hi, I am struggling to interpret correctly the following... - Nov 03, 2016 by lachrymal

Lachrymal, Where are you getting that from. Let me keep this... - Nov 08, 2016 by MPMENG

Hi MPMENG, Thanks for you reply. I must say I am printin... - Nov 09, 2016 by lachrymal

lachrymal

#76540

Help understanding something about stencil orientation when printing | 3 November, 2016

Hi,

I am struggling to interpret correctly the following statement:

"An aperture oriented with its long axis in the same direction as the blade stroke does not fill as well as an aperture oriented with its short axis to the blade stroke."

If I am printing a rectangular aperture, is it generally ideal that the long side of the rectangle is horizontal to the printing direction or vertical to the printing direction?

Thanks in advance,

Kind Regards

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MPMENG

#76581

Help understanding something about stencil orientation when printing | 8 November, 2016

Lachrymal, Where are you getting that from. Let me keep this simple because there can be so many variables in modern printing, some you can control and some you can't. Unless you are designing your own PCB's where you can decide how to orient the components, there are always going to be difficult pads to print especially if you are printing fine pitch. If you go back to old school printing the statement would be backwards, but the reality is that with modern component packages sometimes starving the aperture yields a better printing result; for example you may reduce bridging by going the short way. A properly set up printing profile, a good quality well managed solder paste, good squeegees, a quality stencil with appropriate aperture design and what most people forget, proper clamping and board support for the PCB, will give you the results you need.

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lachrymal

#76582

Help understanding something about stencil orientation when printing | 9 November, 2016

Hi MPMENG,

Thanks for you reply. I must say I am printing onto wafers& I'm still somewhat new to the process but much of the theory is the same as for PCB. I trialled it in the mean time and I did find that printing into the long side of the pad was causing bridging issues, probably the distance between those two long apertures is too close on the stencil anyway. I'm considering increasing the stencil thickness so I can reduce the aperture size but it needs a lot more work before I make any real decision.

Anyway, thanks for your kind reply.

Regards.

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