Issue link: https://iconnect007.uberflip.com/i/565949
44 The PCB Magazine • September 2015 float tests; one material has been basically incin- erated—obviously not the laminate you want used with your PCBs. There are many laminate manufacturers in Asia. How well known, reli- able, well-tested, etc. is the one being used? It is best to conduct such tests yourself or have them done by a reliable test lab. While you're at it, a few tests on the pre-preg would also be a good idea. Multilayer Lamination From what I've seen, most small- to medi- um-sized PCB fabricators in China don't actu- ally run their own multilayer presses. Rather, they contract this out to a mass laminator. Ev- ery time I've asked what type of audits they do on those suppliers, I just end up getting copies of certs. That's not very reassuring since mass laminators don't just press the panels. They ac- tually take responsibility for the entire inner- layer production process, including: • Materials selection • Image • Develop, etch, and strip • AOI • Oxide • Multilayer lamination These are all critical steps. Questions you can ask would include: 1. How often are thermocouples run with the panels to validate press recipes? 2. How do operators validate that min/max line widths are being met? 3. How often does the PCB fabricator visit the mass laminator for spot audits? 4. What types of validation are being performed by the PCB fabricator on the mass laminator's products? (e.g., delta Tg/Td testing to validate cure; registration tests to confirm scale factors; layer-to-layer registration, etc.) Drilling Most China PCB shops re-point their drill bits in-house, and they usually have a manual operation set up to do this. The setup would include bit grinding/re-point stations and then at least one inspection station for every two re-point stations. This is an area where I bust almost every board house. During one visit I had, the management folks were walking with us. I made a comment that I would bet they barely ever reject drill bits after inspecting, and they all proudly concurred. It figure 2: sample press cycle. BECOMING AN AuTOMOTIVE SuPPLIER—PROCEED WITH CAuTION continues FEAturE