How to Mechanically Plate and Solder to Inkjet-printed Traces

A Guide for your PCB Rivet Toolpress

BotFactory Inc., JF Brandon (BF)

PCB Rivet Plating is a mechanical process of compress-fitting a copper through-hole rivet onto a hole, lining the edges and inside and connected with traces on the substrate. Unlike your traditional PCB plating methods, we are offering a non-chemical (and therefore safe!) method of plating. This tutorial will provide a guide to design with PCB rivets in mind, the plating process and tips on soldering. The scope of this piece is concerned with providing a solution for solder and through-hole part placement on FR-4 substrates and not creating double-sided boards or plating flexible, semi-flexible or rigid-flex PCBs.

Needed Tools

  • BotFactory Rivet Press 
  • PCB Rivets with matching Toolhead set
  • Drill Press
  • Appropriately-sized Drillbits

Please note that the User must provide their own drill press - Our PCB Printers do not include a drill-head or tool for creating holes in the substrate. We used this particular model in this guide, providing a low-cost solution without sacrificing precision. We do not recommend using handheld powertools. 

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Design Guidelines

Before printing or any plating happens, it is important that you follow our design guidelines so that each rivet is well-connected to the Squink-printed traces. Here are some essential tips

  • Design your PCB like any other, respecting Squink's trace tolerances. Spec each plated through-hole with drill holes and annular ring (or Pad diameter) that match the rivet's dimensions. Rivet specs can be found in the tool press manual.
  • Each Rivet's head diameter ought to match the pad diameter of the plated through hole in your layout. 
     
We use 40 mil rivets in this example, which were large enough for this particular component. For 100 mil pitch (0.254 cm) headers, 30 mil (0.8 mm) rivets would be a better choice in comparison to 40 mil (1 mm) rivets as there would be sufficient space between the plated through holes.  
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Print Traces

Once you are satisfied with your design, turn on your PCB Printer and place a piece of FR4 or another material. No special settings for printing are needed.

We used the 1mm thick FR-4 sheets  provided with each machine - you are welcome to use another material but a certain thickness is needed. For example, 100 micron polyamide may not be thick enough for a rivet to clamp onto. The reverse is true as well - the material may be too thick to properly rivet. Therefore we recommend you use materials thicker than 0.5 mm and thinner than 2 mm. 

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Drilling

Using the correctly sized drillbits and a drill press, place your completed board and mill out the pads. High rotational speeds reduce the chance that the laminate will leave burred and damaged hole-edges. While the silver is well connected to the substrate (in our case, FR-4), sanding and de-burring should be avoided to avert doing unnecessary damage to the pads. 

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Plating

Take out your rivet-press and begin plating the holes. Consult with your manual that comes with each machine to ensure you are plating them correctly.

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Soldering

After plating the holes and placing your part, take out your iron and favorite solder and begin to solder everything together. A few things you should keep in mind before you start. Soldering directly to the traces tends to damage them. The copper rivet mitigates this by wicking away heat and solder, providing a connection point between the part and the trace. Therefore,

  • use the lowest possible heat-setting. We used 315C in this example.
  • solder to the back of the substrate, opposite to the printed-side.
  • avoid placing too much solder as it may overflow onto the traces
  • avoid repeatedly soldering, desoldering and resoldering. Copper rivets may expand and contract and could potentially become loose and fall out.
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Plate and Solder - no Sweat

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