That’s one I can’t answer as I know nothing about our pricing. Maybe a sales guy could answer that. My opinion would be that if it does it would be a trivial amount. We drill an awful lot of holes.
I just watched the video on your factory tour page – did I mishear when I thought it said that drill bits have to be changed after 300 hits, and you do it after 200? Is that automated with cheap bits, or do you just move to laser drilling for via stitching, or …?
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Hit count is primarily dependent on tool diameter and the type of material being drilled. A 6mil bit drilling ceramic filled PTFE may only last 200 hits while a 20mil bit drilling FR4 may go 1500 hits. Sierra has a software system that automatically assigns the correct diameter page – includes hit count, infeed rate, spindle speed, etc. for every diameter – for each type of material/construction. Panel thickness, layer count and total copper is also taken into consideration. All of this becomes part of the drill program and the machine will automatically adjust parameters, track hit counts and change tools based on this information. The bits aren’t cheap but they usually don’t affect the overall cost much unless you have lots of 6 mil holes in ceramic filled PTFE. Laser is really only good for blind vias – no through holes.
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According to our Chief Drilling Officer, a typical bit is pulled after about 1200 hits with many other shops pushing to 1500. Most bits are resharpened once or twice before discarding.
Laser wouldn’t work well for stitching vias as it is too depth limited.
Best,
Allan
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That sounds much better.
Has “hits” become sort of a abstract virtual measurement, the way CPU seconds did a while ago? (When machine time was charged by how much time a particular long-obsolete CPU would have spent, rather than anything tied to actual time or even the actual CPU.)
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Hit count/hits has been used for a really long time. The letter H – for hits – is a command in the diameter page that tells the machine how many holes to drill before expiring the tool.
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I recall listening to one of your Youtube presentations on DFM and vias, but not sure exactly which one. Sierra mentioned that you should not define the plating thickness of the via barrel, but I cannot recall the specifics. I was hoping you could explain what the cons might be for defining the plating thickness of vias? Also, if we have a high current hole, should we define additional plating, are their any cons to doing this? What verbiage should be used? We are building to class 3 so there is also that specification.
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Standard for Class 2 is a minimum of .0008” in the hole, Class 3 is .001”mil and our standard is .002” thick for thermal vias but you can define whatever plating thickness in the holes you want up to 6mills. No big downside for adding extra copper but whatever is plated in the hole is going to be added to the surface copper and the drilled hole size needs to be increased to maintain the finished hole size. All the holes along with the surface/pattern copper get plated at the same time so selecting specific holes for additional plating isn’t really particle. As far as verbiage goes just add what you want to your specifications/fab notes. Also good to discuss any special instructions/needs with your sales rep as well.
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