Board House Pcb Question

Hi Brad,

I don't know if this helps, but we had a policy of not accepting x-outs on rigids, and of max 10% per panel on Flexy boards (as long as the local fiducial was blacked out for the bad board) I'm always suspicious of x-outs as it points to processing problems at the board house.

On rigid boards where we had a higher proportion of x-outs in the past, we generally saw more quality issues with the bare boards - bad etching (under & over)mouse bites on tracks, bad connections to pads, poor barrel lining etc. So we canned those suppliers. Regarding flexy boards, thats another matter....

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Brad

We agree with Rob. Even if the fab marks the fids [on both sides] to reduce component attrition, you'd be surprised in the amount of paste that 'disappears' on x-out boards. Do the numbers [follow the money].

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Not aware of any published standard for this. Usually we take care of this upfront with the supplier. No more than X amount of panels with one or more Xouts in any lot, No more than X number of Xouts per panel, so on and so on.

Not defending board shops but could the increase in X-Outs be due to the miniturization of everything? Tighter trace widths, spacings, blind vias, etc...?

Of course a lot of PCB houses are just bad

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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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