Temporary VS Permanent Solder Mask

What is the difference between permanent solder mask (or solder resist) and temporary solder mask, and when should you use them?  

The main difference between temporary solder mask and solder resist lies in their purposes and longevity.  

Solder resist is a permanent coating applied to the entire PCB surface to provide long-term protection and prevent solder bridges.  
Temporary solder mask is used for selective soldering and rework processes and is removed after its intended use.

Pros of using Permanent Solder Masks

• Preventing corrosion or oxidation of copper traces  
• Preventing bridging and short circuits by excessive solder 
• Preventing blockage of vias during automated soldering 
• Temporary adhesive in the soldering of two-sided PCBs 

Cons of using Permanent Solder Masks

• Impact on Signal Integrity 
• Impact on electrical fields 
• Delamination of solder masks exposes the board to fault connections 
• Overcuring of solder masks can cause the PCB to become brittle and crack 

How can temporary solder mask solve issues caused by permanent solder masks?

Unlike permanent masks, temporary ones can be easily removed after assembly, eliminating any adverse effects on signal quality. Temporary solder also offers improved signal integrity and flexibility. They have a lower dissipation factor, reducing insertion and return loss, which enhances signal performance in high-frequency circuits. 

They are applied using methods such as stencil or silkscreen printing and can be cured with controlled heating or UV light, ensuring they do not become brittle or difficult to remove. This makes temporary solder masks ideal for high-speed PCBs, where they address the need for both protection during assembly and optimal performance afterward. 

As such, temporary solder masks have begun its rise in popularity to combat the problems faced by traditional permanent solder resist.  

TECHSPRAY Temporary Solder Masks

With the use of Techspray’s Peelable and Washable Solder Mask, the PCB assembly process can be car ried out without the need for rework and the signal integrity issues associated with a permanent solder mask can be eliminated.

Check out our range of temporary solder masks