Is paste mask layer, both top and bottom layer, necessary for THT components?

I know the paste mask layer is also called the stencil layer. It's only used for assembly. I want to know if the paste mask layer (both top and bottom layer) is necessary for through hole components. For SMD components I know the paste mask layer is required to solder the components. Is it necessary for through hole components?

No. Paste mask is normally used only for reflowing surface mount components, while the through hole components are soldered either manually or by wave solder bath at a later stage.

If you have through hole parts and the surface mount components on the bottom side, the paste mask stencil is not required, as the parts will all be soldered at once in a wave solder bath. This process requires you to generate a glue dot coordinates file, which will be used to place a dot of glue under the surface mount component and that will keep the part in place during the soldering process.

If the only through hole parts in the PCB were the connectors, it is also possible to reflow through hole components with solder paste. That requires some tweaking to get the right pad size and stencil opening. All we need to do is to have a larger pad on the top side, so that there was enough paste on the pad to wick down the hole and ensure a solid solder joint.

Read More: THT PCB Assembly

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Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.
Picture of Oliver Smith

Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.

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