Must I use expensive polyimide labels to identify my PCB’s?
Written by Oliver Stockton, Managing Director, CILS
Polyimide labels feature high-temperature resistant adhesives and may be unnecessarily expensive if they do not need to be applied until after the PCB manufacturing process.
You only need to use polyimide labels if they are applied at the beginning of the manufacturing process and need to resist the elevated temperatures the boards are exposed to during reflow and wave soldering. The polyimide material and adhesive elements of high-temperature resistant labels are expensive so they should only be used when resisting these environments to maximise economy.
If the labels are only needed for end-use identification and applied after the population and soldering of components, they may only need to resist a board wash and the end-use environment.
To ensure the adhesive doesn’t dry out, you will need labels with a good-quality solvent acrylic adhesive to stick permanently to PCB’s, especially if they are exposed to an ambient heat of between -20°C / -4°F to +60°C / +140°F.
Polyester labels are most common because they can be made with solvent acrylic adhesives and resist Isopropanol (IPA) cleaning solutions.
If the labels are applied after a board wash and durability is not required, paper labels may be sufficient, but bear in mind, that paper labels do not have solvent acrylic adhesives so may dry out and fall off in time.
PCBs labels are typically small and 10mm x 10mm labels are common due to the limited flat surface space available to apply the label to. Data is usually embedded in a 2D data matrix code and QR codes are becoming more common and supply links to web pages that can hold an endless amount of relevant data.