Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.

Selective soldering pallets


Selective soldering pallets | 26 February, 2001

Anyone using selective soldering pallets to run boards with previously reflowed bottom side SMT through the wave?

Any comments, pro or con? Seems like a reasonable approach for someone that doesn't want to install a dispenser.

reply »



Selective soldering pallets | 26 February, 2001

Steve, Currently we are using selective pallets and the best piece of advice is to find a supplier that will be able to handle the requirements of the selective wave process, for example proximity of chips to PIH devices, and pallet thickness etc. We have just successfully ran selective wave on a double sided card 20in by 18in, with smt on both sides. Interaction with the card development team is also important to adjust the card design to accomodate the selective process if required to enable the glue dispence station to be bypassed. You will notice the improvement on quality by changing to the selective process rather than glue dispence and wave on an open apeture pallet, as the scope for voids, misplacements, missing components etc improves greatly. Good luck!

reply »


Selective soldering pallets | 26 February, 2001

As a design rule, provide 0.050" minimum between parts to be "masked" and areas that require wave contact. The more the better is the general rule to apply. Check:

I�m sorry, I missed the connection between dispensing and selective soldering. Why can�t you print glue for your second-side SMT components that would be wave soldered, instead of paste? Much smoother flow, less labor input, faster NRE turn, requires no investment in pallets, etc, etc

reply »



Selective soldering pallets | 27 February, 2001


I have to support the comments made by Dave F. Provided the surface mount parts on the second side are correctly orientated and not too close to any adjacent through hole leads then the best option has to be to print glue then wave solder.

The use of selective pallets requires minimum clearances between SM parts and through hole leads as has already been pointed out, You also have to pump up your solder wave to ensure solder gets into all the nooks and crannies, so there is another bunch of wave solder settings to control.

Also you have to maintain the pallets, removing encrusted flux etc...

Is there any particular reason why you favour selective pallets?

best regards,

Pete B.

reply »



Selective soldering pallets | 27 February, 2001

We use Selective Wave Pallets for the vast majority of our boards with great success. Many of our boards have BGA's and connectors on both sides, which for the most part then require the Selective Wave Pallet. We successfully use pallets up to 10mm thick X 482mm wide X 610mm long, and experimenting with thicker (of course you need a fairly large Wave Solder machine). We ask for a minium clearance of .2 inch around parts, but can do .1 with care (I do NOT reccommend this). Up-keep and cleaning is a pain, but not difficult if done on a regular basis. The big draw back, as many of you is cost and turn around time. The cost will always be there, but some shops building the pallets can do a week or less turn around.

reply »


Selective soldering pallets | 27 February, 2001

Simply trying to answer a management question: "Can we do bottom side w/o capital expenditures?" If we reflow top and bottom we eliminate the need for dispensing and another oven. Do more with nothing, sort of. Of course the cost in loss of throughput cancels any savings in capital. Pallets would also allow us to put more technology on the bottom side also. Not that I'll tell engineering that.

I want a line prioritizing bottom side (dispense, place, cure) and a magazine loader to feed our 3 high speed lines. We could also use it for low volume top side. Hard to do w/o capital spending though.

reply »

SMT Spare Parts and Feeders

Metcal soldering rework