| | I must assume you are a pcb fabricator. Therefore, as I have been in this business for some time, I have never cleaned boards for the reason you describe. No criticism intended, but the only reason I have ever cleaned bare fabs is to meet normal and ionic cleanliness requirements. | | The melted "fiber glass" is, obviously epoxy resin that cannot be cleaned as you wish but can be prevented. I don't understand why you cannot either establish router start points as part of your tooling hole drilling operation. If, as you say, this is not cost effective, can't you start at the panel's edges and enter the route process from their? Failing this, I can only say that epoxy smear is caused by the wrong feeds and speeds. That is: If a router tool is not sharp and is introduced to the material to be routed at too high a speed or movement along a path (just as in drilling holes), excessive smear is effected. | | I recognize your problem, but I believe it must be prevented instead of being washed away. | | Wish you well, | | Earl Moon | We are a high volume pcb fabricator, where most of the boards we make require | complex profiling with numerous internal cuts. As such, to add "router start-points" | would require adding in some cases over 1,000 holes | to the drilling operation / drilling stack -- a costly proposition. | When cutting outlines, this entry-point defect is not a problem. | It is primarily troublesome in complex internal features and | short routed slots. | To clarify the problem a bit, what I am dealing with is in fact not | epoxy smear, as you suggested but rather caking | of the router dust in the interstitial spaces between the stack of panels. | This caked dust tends to stick to the board (perhaps due to a slight | melting- although I have observed little to no damage to the solder | mask at the entry points, as is characteristic when I do encounter smear.) | Below I will list the measures I have taken to reduce/eliminate this problem. | 1. Reduce the pressing force in the floating presssure foot. This problem | is most pervasive (ironically) on our new Hitachi Routers with a floating | pressure foot. I found excessive pressure inhibits air-flow between | panels, and is a primary cause of the problem. | 2. Drillpoint router bits. I have found the alternate tip geometry | to be effective with 3/32" --> 1/8" cutters, although they can only be used | with our newer height-controlled machines. | 3. Reduction of operating parameters. Reduced Z-axis plunge rates for the | larger cutter sizes. | 4. Addition of a 1/2 sec. dwell at the plunges. The small pause helps to | loosen the impacted debris and caked debris, so that it will flake off | easier | 5. Replaced backup material with "corrugated plastic" which has long | air channels to increase air flow through the panels. Big cost savings | too!! | 6. Modifications to the washing systems- looking at dry bursing, | agitation, air knives, and higher pressure washers. | And still looking for more! | Thanks, | Dave You guys do know what you're doing. Have you tried ultrasonic cleaning? Earl
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