Text measuring only 0.61mm high was marked on this ceramic capacitor using 7 watts of power.

The change from discrete electronic components to Surface Mount Technology (SMT) devices was a revolution for device and board manufacturers alike. In many cases, SMT devices are several times smaller than their discrete counterparts and their leadless package design helps to reduce, if not eliminate, lead trimming and thru-hole drilling operations.

The problem for manufacturers is how to mark or label individual components when they typically measure only a few millimeters in length and/or width. As a case in point, the surface mount capacitor in the accompanying photograph measures only 2.6 mm by 3.2 mm (0.102” × 0.125”). The solution to miniature part identification is CO₂ laser marking. Because the laser’s output can be precisely controlled, heat input into the part is limited to just enough energy to affect a visible change in the part surface and the laser’s small beam diameter creates legible characters with Text Height values only four to six times the focused spot size.

To create this CO₂ mark on a ceramic SMT capacitor, we fitted an 80 mm lens to an FH Index marking head. The 80 mm lens provides a 116-micron (0.005”) focused spot with a 0.8 mm (0.032”) depth of focus. Using one of WinMark Pro’s twelve built-in stroke fonts, we created a four-digit part code that measures only 0.61 mm (0.024”) high. In WinMark Pro, we set a Power value corresponding to 7 watts and a Velocity of 9 inches per second. With these settings, the resulting cycle time for each part mark is 0.07 seconds.