Considerations to make when selecting labels for electronic devices
There are as many reasons why labels need to adhere through temperature extremes as there are industries in which labels are used. Ranging from everyday use on air conditioners, home appliances and outdoor power tools and equipment to heavy industrial applications in the automotive market and computer assembly areas, labels need to serve a variety of functions throughout the life of the product.
Often taken for granted, labels perform a critical function for the products they are adhered to. Important warning and safety information as well as proper operating instructions need to remain noticeable and legible.
An important first step is selecting the correct combination of label film along with the proper adhesive and topcoat. Industry regulations, such as meeting UL and cUL standards, and the end-use application for which the label is intended play a vital role in that decision process.
If your application temperature needs are less that 250F, polyester (PET) films would be the choice. Household appliances, outdoor power and garden equipment use PET films for bar coded identification labels for wires and hoses. Automotive uses include the inside-the-door labels that list the correct tire pressure, as well as labels for under the hood and other critical applications like wire diagrams and warning labels.
Durable polyester film labels are ideal for use where prolonged exposure to the sun, elevated heat generated by engines or moving parts can reach more than 100F (as an example, a lawn mower engine can reach 150F during operation). Important safety instructions on farm equipment and even everyday consumer lawn and garden machinery require labels that retain integrity and readability.
PEN (polyethylene naphthalate) films possess a higher-temperature resistance than PET films. The automotive industry uses PEN films for some under-hood applications such as wire harness labeling. Battery information can also be contained on PEN films, used again because of their higher heat resistance. PEN films have a general service temperature range from -40F to 302F (-40C to 150C) and intermittent up to 500F (260C). A PEN construction with a permanent acrylic adhesive with a temperature range from -40F (-40C) to 302F (150C), topcoat designed for smooth print surfaces to allow for alphanumeric bar code printing, and an overlaminate to protect from the elements will, if applied properly, last for the intended life of the product.
Polyimide films (PI) are designed to meet the most challenging temperature extremes. One of the most demanding processes that high-temperature resistant films can be exposed to occurs during the manufacture of circuit boards. Exposed not only to extreme temperatures, but a variety of caustic chemicals and reflux washes, these labels have to not only adhere to the boards, but retain their readability for pre-printed alphanumeric bar coding. PI films generally can endure temperatures up to 750F (398C) on an intermittent basis and up to 500F (260C) for a five minute steady duration without any loss of performance. The correct topcoat makes sure the surface is exceptionally smooth which is critical for accurate bar code printing and alphanumeric scannability. In addition to surviving the circuit board manufacturing process, circuit board labeling must remain adhered during the high operating temperatures of many consumer electronics. These labels act as viable asset tracking all through the manufacturing process and during consumer use.
Choosing the right combination means success
There are many label stocks to choose from to meet both the performance and aesthetic needs of today’s OEMs. In order to select the right combination of film, adhesive and topcoat, as well as outside agency requirements it is vital to understand the end use requirements and the temperature extremes the label will endure. Taking all these factors into the decision making process will ensure that the labels will meet all expectations.