March, 2012
www.us-tech.com Really Managing PWB Supply Continued from previous page
liness, surface finish, laminates, stack-ups, impedance, etc. Management recognized the
weakness of their system and under- stood that it could either limit their growth or cause the growth to be unprofitable. This was very discon- certing because the company had grown by 25 percent in the past 12 months and was expecting this growth trend to continue for several years. The problem required an imme-
diate solution that capital dollars alone could not solve. The reason was that when they analyzed the prior twelve months of activity, they deter- mined that they had purchased over 350 different PWBs from 25 different suppliers, and generated over 1000 receipts. The time element required to develop the internal PWB assur- ance capability for this very high mix was unacceptable. Management decided to take a
different approach and formed a partnership with a broker that had a product assurance laboratory to assume total supply chain manage- ment for PWBs. Under the agree- ment, the PWB Supply Chain Manager (PWBSCM) immediately
A Certificate of Conformance is only as
good as the business ethics of the company making the actual PCB.
diverted all incoming shipments of PWBs to their assurance facility. At the program inception there
were 110 different PWB part number on order from twenty-five (25) differ- ent suppliers. The suppliers were all notified to change their “Ship to” address to the PWBSCM. The incom- ing product was subjected to laborato- ry analysis including: cross section, cleanliness testing, visual inspection, and complete Bare Board Testing. The criteria for acceptance was the IPC A 600 Rev H Acceptability Standard. The results were not good, but
they supported the opinion of man- agement that they were at risk due to their inability to fully evaluate the suppliers. Of the 110 part numbers, 79 were received in the first 4 weeks (Lot 1) of which 61 percent passed (48 passed, 31 failed). Lot 2 consisted of 33 boards, and 65 percent of them passed (20 passed and 11 failed). While 25 fabricators were “in
play” more than half had fewer than 4 part numbers, and 5 had only 1 part number. It was interesting to note that the five vendors with only one part number had no failures. These five were the only suppliers to have a 100 percent pass rate. It is reasonable to assume that these were customer-directed and there- fore were held to a higher standard by a customer other than the CM. The PWB Supply Chain Man -
agement program with the CM has now progressed to the point where all incoming PWBs are being ordered and received by the PWBSCM. The aggregate pass fail data will be more difficult to assess for some time as there is a consolidation of vendors underway to remove all those who had poor pass rates. While it is anticipated that the
pass rates for even the poor vendors would improve, they will not be given
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second chances. The reason is that their performance was evaluated when they were not anticipating that the product could (or would) be evalu- ated prior to assembly. While perhaps a harsh assessment, they have already demonstrated their business ethics.
PWBSCM Program Advantages Since the program began, the
CM has not experienced a single PWB related failure. This is extreme- ly important as the agreement with the CM includes a compensation for the value added to a defective PWB (normal warranties are limited to the value of the PWB). Additional met- rics are being collected by the CM
relative to first pass yields, process defects, and customer returns. Early and (unscientific) evidence shows significant improvements in all of these areas. Further, it is anticipated that total inventory dollars will be reduced by having a PWBSCM focused entirely on managing the flow of PWBs. Safety stocks become the problem of the PWBSCM which frees up working capital for items central to the CM’s core competency. Purchasing, receiving, and
inventory resources can be re-allocat- ed to other priorities as they no longer are required to handle the PWB process. Incoming inspection is eliminated as bar code labels and
vacuum sealing in standard lots go directly to stock with only a label scan. Freight costs are reduced as shipments are consolidated. Last, Business Development can access knowledgeable and trustworthy resources to assist with quoting and directing customers into the most suitable technology. In essence, the CM has recaptured all the advan- tages of the captive PWB facilities of long ago with none of the costs.
Elements Required A successful PWBSCM program
requires a number of key ingredi- ents. Offering only procurement
Continued on page 61
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