The Use of Silkscreen in PCB Assembly

PCB assembly is a complex process that involves multiple steps, components, and planning. It’s important that care goes into each PCB board as important electronic equipment such as computers in aerospace, automotive, and the medical industry rely on the boards being put together correctly. One crucial aspect of PCB assembly involves silkscreen, but what exactly is silkscreen and why is it an important part of quick turn PCB assembly?

What is Silkscreen?

Silkscreen is the layer of ink that identifies various PCB components and is usually white, but can also be other colors such as yellow, black, red, or blue depending on the designer’s preference.

Why is silkscreen so important?

PCB assembly requires communication and an understanding of what each component is and where it needs to go. Silkscreen is important because it is used to inform the assembly team where components need to be placed. It’s more for the manufacturing process than it is for the customer, although customers can also benefit from silkscreen as it allows them to see all of the components, what they are, and the location of each piece. After all, the person ordering the boards should be able to know the ins and outs of their board.

What Does Silkscreen identify?

As we noted above, silkscreens identify the location of components on the circuit board so the assemblers know where to place everything. However, they serve even more purposes:

  • Test points
  • Logos
  • Date codes
  • Part numbers
  • Manufacturer marks
  • Warning symbols

It’s important that any print is easily legible since many people will view said print during the assembly process. The font, size, and color of the silkscreens all matter in order to make the custom quick turn PCB assembly process as painless as possible.

How are Silkscreens Applied?

Silkscreens can be applied in a variety of ways: liquid photo imagine, direct legend printing, or manual screen printing.

The cheapest option is manual screen printing. Ink is pushed through a stencil onto the laminate before being cured or “baked” on in an oven.

Liquid photo imaging involves a photo-imageable epoxy liquid that is put on the circuit board and gets “baked” on with an UV light.

Direct legend printing involves acrylic ink derived from CAD data.

Whichever method is used will depend on the budget, goals, and time constraints of the manufacturer. As we mentioned above, manual screen printing is the least expensive option which makes it a popular choice for quick turn pcb assembly services USA. If the goal is just to ensure that the labels are easily legible for the assemblers then it is a great option. The other methods might be better for certain layouts or sizes, but that is completely up to the company’s discretion.

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