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The best solder paste height with screen priting on 6mil stencil

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Milroy

#36524

The best solder paste height with screen priting on 6mil stencil | 7 September, 2005

I am engaged with SMT production and we are going to have a brand new SMT line and I am studing about the screen printing and I have seen most commonly used stencil thickness is 6mil and I need to know what is the best solder paste height we can achieve with this type of stencil with better performance?

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#36546

The best solder paste height with screen priting on 6mil stencil | 8 September, 2005

Milroy, The nominal height you will achieve with a 6 mil stencil is 6 mil. Any more and you are using either a stencil or squeegee snap off > 0. Any less and you are scooping the paste from the aperture with the squeegee blades. I'm not saying that either of these situations is a good or a bad thing, it's just that if you buy a 6 mil stencil, you are trying to achieve 6 mil paste height.

I would go to 5 mil, less design and process headaches. You just have to get people used to the fact that they are not going to see great gobs of solder, you may not have toe fillets, and you may not have complete wetting of the pad. BUT you will have less solder balling and beading and less tombstoning and bridging. Enjoy your brand new SMT line.

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GS

#36548

The best solder paste height with screen priting on 6mil stencil | 8 September, 2005

do not forget also wich Type of paste used( granulometry) if Type-3 ? Type 4? etc, it could change in final metal on your pads/joints.

Regards

GS

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