I wonder if it's possible to use certain screws/spacers in a wave soldering machine, so that it will be possible to screw a screw to the spacer attached to the PCB afterwards?

My intial thought is that maybe a titanium screw/spacer might work due to poor Solder-ability but I have no clue if that works.

To understand the problem; I've a heatsink that has to be screwed to the PCB before soldering the TO-220 packages to the PCB. The reason to this is to minimize stress on the legs due to the stiff fitting till the heatsink (only available solution for my application). So I would like to find a solution where it's not necessary to hand solder this specific part, which is the case right now.

Best regards


That kind of thing is usually handled by a peelable solder mask applied before the board goes through the machine.

enter image description here

  • \$\begingroup\$ If not my question was misunderstood. The answear is that a solder mask can be applied on a spacer that is mounted on the PCB which will be in the wave solder? I'm going to use a spacers that looks like this: link \$\endgroup\$ – Anton Ingemarson Mar 7 '17 at 16:46
  • \$\begingroup\$ Yes @AntonIngemarson, The mask is applied as a preparation step to places you do not want soldered and removed after soldering and cleaning. It can be to holes you want left open, as in the image, or on top of screws or other parts that would be damaged by the heat. \$\endgroup\$ – Trevor_G Mar 7 '17 at 16:48
  • \$\begingroup\$ Though I am a little confused why you would want the spacer pre-mounted on the underside of the board. \$\endgroup\$ – Trevor_G Mar 7 '17 at 16:51
  • \$\begingroup\$ Perhaps you need to add a mechanical drawing / sketch to the question to clarify. \$\endgroup\$ – Trevor_G Mar 7 '17 at 16:52
  • 1
    \$\begingroup\$ @AntonIngemarson Generally it's not the best idea to get "random brass spacer" and put it through any soldering process if you want to rely on it. There are actual components that can be soldered onto a board in both wave and reflow systems that allow screws to be connected, designed for the purpose, allowing you to use well tested solder openings and profiles in the board design. An example of what I have recently reflowed onto a PCB in large quantities: katalog.we-online.com/en/em/WP-SMBU_THROUGH-HOLE?sid=a9d2ec293f \$\endgroup\$ – Asmyldof Mar 7 '17 at 17:23

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