How Important Are Solder Masks and Silkscreens
Solder MaskSolder Mask (also known as Solder Resist, or Solder Stop Mask) is a thin polymer that is applied to the surface of a Printed Circuit Board (PCB) to seal the copper of a Printed Circuit Board from the environment. All colours of LPS solder masks are available at Bittele Electronics at no extra cost. Bittele Electronics also includes double-sided solder mask in its standard service.
There are two main purposes for this masking:
- Prevent Oxidation
- Prevent Solder bridges
Solder Bridges occur when an unintended short is created by solder bridging the gap between two electrical elements such as traces, pads, or leads. The solder mask acts as a barrier to prevent these shorts from forming. This is especially useful in the case of Integrated Circuits where the gap between pads can be as small as a few thousandths of an inch. At Bittele Electronics can apply solder mask dams to spaces as small as 8mils for a board with 1oz copper weight. An extra 2mils of space is needed for 2oz copper weights and an extra 1mil of space for any colour of solder mask that is not green.
A solder mask is also useful in the mass assembly of PCBs. With the solder mask protecting the copper traces a solder bath can be used to tin each exposed copper pad on a board in one application without allowing any solder to come into contact with sealed areas.
During reflow, the wicking effect of the solder and tinned pads combined with the solder mask will ensure that no solder bridges form while the components are properly soldered.
SilkscreenAt first glance, a silkscreen layer may mistakenly seem to be unimportant, after all, it has no direct impact on the electrical functionality of a PCB. However, due to the valuable information provided by the silkscreen it can be determined to be extremely important to the functionality of a PCB. A silkscreen can provide the following information:
- Polarity of Parts
- Location of parts through Reference Designators
- Identify Test Points
- Identification numbers unique to each board
- Warning Symbols
At the end of the day the silkscreen layer is another means of providing information about the PCB. Most importantly it is information that cannot be separated from the board, therefore all warning symbols, unique identification numbers, certification logos, and manufacturer logos will be on display when viewing a board.
For information on designing a legible silkscreen please see this article: Making Readable Silkscreen Layouts for your Printed Circuit Board (PCB) Design
- PCB Solder Mask, Mask Options, Colours & Impact of Mask Colour
- Liquid Photo-Imageable (LPI) Solder Mask
- What is a Peelable Solder Mask?
- Making Readable Silkscreen Layouts for your Printed Circuit Board (PCB) Design
- Marking Diode Poles on Silkscreen Layer