Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

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v-scoring | 6 July, 2001

Question, on a pc board that is .060 thick what should my v-score depth be? WE are currently using a v-score that leaves a remaining web of 15 thousandths is this adequate, or should we be going deeper?? thanks in advance for any input, Jake

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v-scoring | 6 July, 2001

Groovy!!! [Sorry, I always wanted to say that.]

As background, look at: * SMTnet Archives * "Pocket Guide to Excellent V-Scoring" and "Scoring FAQ's" [] they cover all of the dimensions and give a short summary on the different methods, advantages, and costs.

As you say, this issue is not the depth of the V-score, but the thickness of the remaining material, because there�s lotsa room for variation in the overall thickness of the board. Your 15 thou for 62 thou thick FR4 boards sounds fine. What�s your concern?

Changing gears slightly, the second element of the defining your scoring requirement is keep-out. On 62 thou FR4, a web of 16 thou, a new 30� carbide blade; the width of the score line is approximately 14 thou. [Halp, he�s doin� math again.] However in the real world, the tip of that carbide blade goes away pretty fast. As the blade disappears, the cut needs to go a little deeper to compensate for that wear. The deeper the cut, the wider the cut. Compounding that, when using a re-sharpened blade that�s mid-way through its service life, that 14 thou easily becomes 24 thou . Of course, only half of the 24 thou is a keep-out area on one side of the cut. So, the accumulation of these working tolerances is important. 20 thou to 25 thou is a good number for keep-out. Any thing below this is asking for trouble in a production environment.

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