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Pump Stencil

Views: 5137

AR

#46821

Pump Stencil | 19 January, 2007

Hi

I know that pump stencil technology can be used to print adhesive on boards with TH components already placed and clinched, but what about solder paste? The production sequence goes like this: First the jumper wires are placed and clinched with an odd-form assembly cell, then the boards are inverted and run through an SMT line consisting of a dispenser, SMD mounters and reflow oven. With a dispenser we are able to deposit a sufficient amount of solder paste on the pads so that the clinched leads do get soldered, but it is slooow. The whole business of dispensing solder paste on a panel with lots of components really slows the line down. So I was wondering if the pump stencil technology could be applied to solder paste as well, in order to get a large lump of paste on the TH joints but without getting too much of it on the SMD pads.

Thanks in advance.

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#46826

Pump Stencil | 19 January, 2007

I believe you are describing a pin in paste process. Not sure where a stencil is involved.

Depending on you machine/pump, you can do damage to it by running paste thru it. Paste is a metal and will wear out internal parts.

Also, most pastes used in this situation will have a lot of voids in the barrel. Also it takes a lot of paste to accomplish an acceptable solder joint.

But over all it is do-able. Try dispensing by hand and see how much paste you need on the thru-hole and how your older joints look.

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#46827

Pump Stencil | 19 January, 2007

Good afternoon,

DEK�s Pump Print is used for solder paste printing as well. Send your design to DEK and they will design the Pump Print stencil for your needs. Please note that price for pump print stencils is five times higher compared with conventional ones.

BR, Pavel

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Simon C

#46828

Pump Stencil | 19 January, 2007

Hi,

We have at DEK printed paste through a Pumprint stencil onto clinched leads, but there will be limitations depending on the product. If you can send a sample loaded board to me indicating where you want paste deposits then I can certainly take a look and let you know if it is do-able. Email me at sclasper@dek.com for further info.

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AR

#46865

Pump Stencil | 22 January, 2007

Thanks for the info everybody.

As Real Chunks stated, a lot of paste is needed in order to solder the clinched part of the lead on to the pad. It can be done with a dispenser but it takes a lot of time. The good part is that the result looks surprisingly good after reflow. The only benefit of printing would be the substantial saving in tact time. BTW, dispensing paste is no problem to our Camalot pump mechanicals.

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RDR

#46878

Pump Stencil | 22 January, 2007

Volume req'd for pih is 2.2 x the hole volume after lead has been inserted.

Stencils work quite well in PIH applications too if you can make aperture large enough. Slow squeegee speeds also aid in filling hole with paste.

Russ

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