Many everyday labeling applications such as on printed circuit boards require printed bar codes, safety and warning labels with legibility and adhesive bonds that must survive high temperatures – upwards of 500 degrees F. Labels that fail are visible by your customers and can mean costly interruptions in production or shipping.
(Shown here are the effects of time and temperature (315oC / 600oF for 50 minutes) on a “standard” polyimide label from a competitor, compared to a new generation, lead free polyimide label TT407. These new polyimide labels are designed for the higher temperatures required for lead free soldering processes.)
What do you need to know to avoid this?
Labels exposed to higher temperatures are subject to shrinkage, discoloration, peeling, lifting, and cracking. Shrinkage can distort bar codes and produce an adhesive halo on the substrate. Bar codes may not scan correctly, information is lost. The adhesive bleed may interfere with how labels come off the liner, apply to the product or attract dust/dirt.
Resistance to discoloration is another important feature of high temperature label materials to protect the clarity of printed information, product identification, and bar code scanning. High temperature labels are matched with adhesives that perform without lifting, peeling or drop-off.
Having the right balance between “shear”, “tack” and “peel” assures proper adhesion when applied, during expected use, and at removal for best performance of the adhesive at high temperatures.
Assessing The Variables
One of the key factors to consider is the maximum temperature and duration of that temperature in which the label will be expected to perform. These two factors are key to determining the correct label material for your application and will assure excellent performance.
Will the label face the high temperature when the labeled product is in the manufacturing process? If your label faces a combination of heat, abrasion and chemical exposure you may need an overlaminate to protect the label performance.
What about labels subject to both high and low temperatures? Certain durable label materials are designed to go from one extreme to another. It’s always best to know this up front.
Will variable information be added to the label? This may impact the selection of label material, overlaminate areas or ribbon choice. In some instances, a topcoat is added to the label surface for best printability and durability.
Making the Right Choice
Working with your label converter up front will address key questions to determine the right pressure-sensitive labeling product for your [WincoID_pcb_2D] application.
Often, a simple polyester will provide the performance required. Polyester has very good thermal resistance, along with excellent clarity, chemical resistance, and durability.
White polyester is a popular choice for material tracking labels, safety/hazard/instructional labels, and product identification labels, and clear polyester is often used as an overlaminate.