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Mechanical Delamination at de-panel

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Mechanical Delamination at de-panel | 2 June, 2014

Background on the PCB: Thickness: .032" Material: Standard Fr4 V-score: Leaves .016" (approx .008" cuts on either side)

We are having some issues on these boards where the edges are delaminating all the way to the copper during de-panel. Now, we are not simply breaking them out of their arrays, but using a CAB Maestro 3 de-panel station. (pizza-cutter wheel setup) While I have never witnessed mechanical delam due to this process, nor heard of it, I'm certainly not going to let that get in the way of my investigation. The board house is suggesting a few causes, but at risk of leading the witnesses, I'll hold those assumptions back for now. The boards are ran through reflow prior to de-panel. So far, that is the only pbservable problem area. We have noticed quite a bit more "transparency" on this run as well. As well as a clearly defined weave pattern of the prepreg that is visible through the board itself. Does anyone have any ideas/suggestions on this issue? Perhaps some first-hand experience?

Thank you



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Mechanical Delamination at de-panel | 3 June, 2014

Check out the set up of Depanelizer. Try to cut at slower speed & check the blades to make sure it is not time to resharp the blades. If all this parameters OK I would sustect lamination process of board house.

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Mechanical Delamination at de-panel | 3 June, 2014

Incoming inspection: Look for flaws and measure position of v-score as well as depth. If v-scored on both sides of panel, make sure v-scores are in alignment. Follow the PCB thru all processes inspecting after each stage of processing, especially reflow and/or wave. Put your best operator on the pizza cutter and inspect after depanel. It's easy to cut cross-eyed on those things and do damage.

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Mechanical Delamination at de-panel | 3 June, 2014

Yes, unfortunately I was alerted to this problem at QC. (which is a reoccurring issue)

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Mechanical Delamination at de-panel | 3 June, 2014

Maybe the V-Score is not deep enough?

I am used to seeing more like a 30% remaining web, you are closer to 50%


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Mechanical Delamination at de-panel | 4 June, 2014

Well, we cannot make the cuts any deeper as then we would incur a significant amount of "bowing" at SMT placement/reflow.

-Has anyone ever heard of changes in material/laminate makeup that causes this? A sort-of stronger, or more flexible tensile strength than in recent years? (sorry for my terrible description, but my business is manufacturing and not literature)The vendor is telling me that new changes to materials in recent years will cause this.

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Mechanical Delamination at de-panel | 4 June, 2014

> Well, we cannot make the cuts any deeper as then > we would incur a significant amount of "bowing" > at SMT placement/reflow.

Interesting. Could be a number of factors contributing. Here's a story.... In the beginning was the board design, and in the name of economy the design was panelized. After panelizing, there was discussion about how to depanel, V-Score or Routed Tabs with Rat Bites. Since the interest was economy, V-Score was chosen. The panel size combined with typical v-score depth created a bowing condition, the remaining web was increased to 50% by the board house to mitigate the bow. Of course it was a bit harder on the depaneling machine to singulate the increased web thickness, and the results were not consistent with prior experience. Just wondering if some of the above events are existing in your case. Mechanical singulation is pretty straightforward, but there are limitations, and panel size/material type relative to remaining web is a science all by itself.

Careful setup might be the key to get you loose, as others have mentioned. Or it might be a less than optimal PWB singulation method with regard to the use of scorelines for that size panel array. Good call having Incoming Inspection look for the scorelines to match up. Misaligned scorelines will give a similar result. Tough Spot. Been there. Good luck! 'hege

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Mechanical Delamination at de-panel | 5 June, 2014

Can you cut v-scores deeper to resolve the issue then build carriers to support the panel? I would say that we usually build carriers for anything that thin regarless of the depanel method.

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Mechanical Delamination at de-panel | 6 June, 2014

SWAG has it. Carriers for SMT are a great idea, especially to mitigate sag, and allow some savings in setup.

Fixturing setup advantage: You could fixture everything to a fixed width, and eliminate rail setups throughout your lines. Trade off the fixturing one time cost for repeated rail setup time in the future. Not all factories can run this way, it is heavy in tooling for fixtures, but a time saver in the end. 'hege

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Mechanical Delamination at de-panel | 9 June, 2014

Well, typically we put rails on a lot of the boards due to the absence of fids and/or tooling holes. We do have a fixture that is somewhat universal that I could try to introduce into the next run.

Unfortunately, the next run does not help my problem in the present. Is the consensus that the thickness of the material left in the V-score is the culprit? Even though we use this same thickness repeatedly on other assemblies without issue? (Both .062 & .032 thicknesses) Have we been getting lucky or is this an anomaly that sometimes occurs?

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Mechanical Delamination at de-panel | 10 June, 2014

We had a similar problem once, it was due to insufficient v-score depth. While waiting for remade PCBs we would run an exacto knife along the score lines prior to depanel to cut a little deeper. Not ideal for sure, and not fast, but it worked.

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Mechanical Delamination at de-panel | 12 June, 2014

I didn't even think of running a blade down those scores. I will give it a shot and see.

The laminate they're using is Nanya NP-140, if anyone has ever used it or has any info regarding it's issues around something like this.

We can see resin weave clearly and are thinking it may be a bonding issue as well. Improper heat cycle/bad preg maybe.

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Mechanical Delamination at de-panel | 12 June, 2014

Deepening the V-scores was in vain. No change. This board is on Rev R now, with no changes to material/array/v-score spec, and this is the first we've seen this problem. I just don't get it.

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Mechanical Delamination at de-panel | 13 June, 2014

I did not see any mention on the inner layer setback. We use 0.025" and have not had problems. Point loads with either a CAB or a FKN can sometimes be problematic. I would search out someone you know that has a fancort industries VDP5. This cuts the boards with a fixed bottom linear blade and a moveable upper linear blade that puts a constant pressure across the entire side to depanel. Maybe that might work for you. I have both the pizza cutting system and the fancort system

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