Scanning the Edge Thickness of a Circuit Board Posted in: Thickness Measurement – Tags: ,

In this application, we’re going to be using the Acuity AP820-5 laser line sensor for scanning edge thickness of a circuit board. The AP820 laser profiler has a five millimeter depth of field in the Z direction, and a four millimeter wide laser line sensor. With this model, we should have a linearity of about plus or minus 3.5 microns of accuracy, which equates to about a pixel roughly every seven microns.

In our demo video, we have our circuit board held up with a little dam of modeling clay and we’re looking across it with the red laser line. This fixturing isn’t the best but we’re just trying to get it as straight as possible. Looking at the profile provided by the laser, interestingly enough, we can see the printed circuit board epoxy material and where it appears to have been routed, as well as part of the gold contact area. So we are seeing some of the offset in our data and this is probably a little trace here that we’re picking up as it’s coming straight.

The main thing to show in this demo of scanning edge thickness of a circuit board is that we can make our thickness measurement and we can use our Acuityview software to measure the thickness, picking up our left edge and using feature 2 in our software picking up the right edge. It’s showing at about 1.1 millimeters, and we did hand measure it, and that is approximately within probably 10 microns of what we’re getting. As we move we see our measurements real time on the part, and we’re not having any problem with the epoxy glass or the gold surfaces.

Now we go back to our profile view. With this software we do have the capability of doing some 3D scans, so we can collect more data doing that by running the encoder over it. Using our encoder we get a lot of data. If we look at this in static points, there’s the edge of our part, and we can see the notch that’s been cut out. Now we’ll zoom this up enough to where we can see some of the small features of the material on the gold contact that’s been beveled or routed out.

So with this sort of laser sensor technology, we should be able to scan as shown in our demo video. To give an idea of speed for this type of measurement, we would say 10, 15 seconds easily we can scan the whole part and give a 3D model of that edge.

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AccuProfile 820 Laser Scanner

The AP820 2D laser scanner series offer a large selection of case sizes, measuring ranges, and diode/accessory options to be used in a wide range of measurement applications. The 2D/3D sensor performs very well on shiny or jagged targets and in environments with high ambient light. The sensor’s auto gain and high dynamic range allow for measurement in complex applications, even edge scanning on sharp targets.