Newsgroups: alt.cd-rom Path: cdrom.com!barrnet.net!decwrl!hookup!europa.eng.gtefsd.com!howland.reston.ans.net!swrinde!sdd.hp.com!col.hp.com!csn!csus.edu!netcom.com!park From: park@netcom.com (Bill Park) Subject: Pinholes and Quality Control? Message-ID: Followup-To: alt.cd-rom Summary: Pinholes -- how serious? Keywords: CD-ROM quality control QC pinholes Organization: Netcom Online Communications Services (408-241-9760 login: guest) Date: Fri, 3 Jun 1994 17:05:35 GMT Lines: 43 For the last couple of years, I have found multiple pinholes on about half of the CD-ROMs that I have received from a certain publisher. The pinholes are easily visible to the naked eye by holding the CD-ROM up to a bright light and looking at a portion of the disc that has no ink on the silk-screened side -- the pinholes look like very bright stars. They always send me a replacement, no questions asked, but it is annoying. My friends now check their CD-ROMs too, and request replacements when they find pinholes. I haven't had any problems accessing data from any of these CD-ROMs yet, but I don't use them very much, and I don't have any software that will read the entire CD-ROM looking for bad tracks. Actually, I just used a 10-power loupe to look at the CD-ROM I got this week, and I can see hundreds of pinholes in it. A single human hair (male, caucasian, brown, scalp) hides most of them, but some are a bit larger than the width of the hair, if that tells you anything about their size distribution. A similar inspection of a music CD that I have played without problems showed no such defects. I didn't find any pinholes on some other CD-ROMs I looked at either, so It is apparently practical to manufacture "perfect" metallization layers. Somebody is able to do it right. I know that CD-ROMs are encoded with various kinds of redundancy to correct certain kinds of errors, notably those caused by scratches. But are pinholes of this size large enough to defeat these schemes and make a file -- or worse, a directory! -- on a CR-ROM unreadable? People developing marketing and password-locked CD-ROMs take note! You don't want to throw a read error when a customer tries to order or unlock one of the products on your CD-ROM. I hear Japanese customers are really demanding of perfection in products they use. If anyone can recommend a CD-ROM "printer" that has better quality control, I'll pass your recommendations along to the publisher. Thanks, Bill Park ========= -- Grandpaw Bill's High Technology Consulting & Live Bait, Inc.