Hi Brad,
Being that I work for a board house here is my take on this issue.
In the past it used to be 1 scrap per palt up to 10% of the total order. scrap is supposed to be sepperated to location and packaged sepertaly. Then it turned into No Scrap due to Assembly houses loosing two much time dealing with x-outs. and The feeling was that it was cheeper to have the board house increase the price of the product then to assemble boards with X-outs. True or not? I'm sure some one has done the math.
The majority of our Customers do not allow X'outs. Which means that we up the price of their product by 10 % to cover the increase in material we need to send to the floor to cover this requirment.
For Custormers that allow x-outs we release around 5 -10% overage to the floor to cover manufacturing and any snafu that can happen. if a No x-out is required that overage goes up to 10-15 % based on what technology and layer count. And of course someone needs to pay for this extra material being released.
Major things that have change in the last couple of years that can be a reason for this increase in X-outs your seeing.
As stated earlier, line width and spacings being reduced to 4 mils and lower. Average used to be 6 mils. Drill sizes dropping under 8 mil. with Pad sizes decreasing so the manufactures are not able to get desired Annual Ring. BGA Pitches and amount of BGA Components- which cause Solder-Mask Registation issues.
and the main reason is that this Industry has been Devistated by Beancounters trying to save a Penny for their companies and moving the PCB every chance they can save a nickel. The unfortuniate draw back to this is the OEM & the Assembly House suffers because you do not get the same product from shop to shop. It's been forgoten over the last couple of years that the PCB is a Custom product and not Punch and Crunch like a Component.
and last but not least but a major one, Overseas compatition forcing our profits down to next to nil, which take away the ability to Buy New equiptment to keep up with the above technologies. So most US shops are building today's technology product with yesterday's equiptment. I'm sure the Assembly houses are dealing with this same issue. I just like to vent about it.
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