You would expect to see overall better quality, with consistent paste volume, and good definition, especially for fine-pitch parts. There should also be fewer rejects, with a reduced need to clean under the stencil, fewer problems with insufficient joints due to solder paste exhaustion, and no paste deterioration on the screen. However, there may be some problems, because pressure printing needs care in set-up. As a user, you might also expect an eventual price reduction, because pressure printing will reduce wastage and allow faster printing, although this is obviously a commercial issue and volume-dependent.
From the design point of view, there are few changes to actual designs, although the print may be thinner than with conventional squeegees and pad sizes may have to be changed marginally to compensate for this.
Potentially you will also be restricted in your choice of pastes, although increasingly solder pastes are being formulated to withstand the pressure printing conditions.
You should also be aware that your assembler may have some preferences for board and panel dimensions, based on the sizes of pressure printing head available.
Finally, just to check that you are going through these SAQs, there is the point not mentioned anywhere in the text that pressure printing has given some problems with large areas of solder paste, and it is recommended that small supporting bridges be built into such structures, in order to support the paste retention blades, and prevent scooping. The presence of these webs has relatively little impact on the overall solder paste deposit – you certainly don’t get separate islands of solder after reflow.
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