Q: What is the smallest UID label available? I need to put a UID on a circuit card faceplate that is approximately 8″ long x 0.787″ wide. Is it possible to put a label on a conformal coated printed wiring board, that is not flat, due to copper traces? – John P.
A: The label can be quite small. We just made a 0.25″ square UID label for a printed circuit board. The key issue is the number of characters that are encoded. The data matrix is scalable and “grows” with the number of characters encoded. So limiting the characters by using a Construct 1 UII will help. Although printing methods can accommodate very high resolution labels, Mil Std 130 dictates that the data matrix cell size shall not be less than 7.5 mil. This is to ensure readability with a “normal” 2D scanner. In addition to the printing, a quiet zone is required around the code. I would recommend staying at a 10 mil cell size on your application which will give you about 13 or so characters to encode. For your particular space, it may make sense to make a rectangular code as opposed to a square code an utilize the length of the area you have available and thus create a larger label.
Another practical consideration is the tolerance of the tooling used to cut the label. If the label is too small it may be hard to register for cutting with some print and cut processes.
As for attachment, a flat, smooth surface is desired for two reasons. First, to be sure the pressure sensitive adhesive touches the surface of the part. Second, to be sure the data matrix code will scan properly. The second point is a lesser concern as the data matrix code is very robust and scans quite well even when compromised.
I hope that helps. Please contact Camcode if you have any additional questions.