PCBs


fabricators have little incentive to undertake the task. The difficulty of certifying PWBs to UL 94 V-0 hasn’t


deterred designers fromincreasingly incorporating rigid flex designs intomedical and commercial applications. It’s viability as a robust packagingmediumensure continued popularity, but this presents problems for rigid flex board fabricators.


Running a risk Many rigid flex fabricators offer to submit their customer’s constructions to get UL recognition onematerial set at a time. Any change inmaterials however, even adding a sheet of prepreg, automatically disqualify the part fromUL recognition and the new build must be resubmitted. This approach is still expensive and lengthy, as well as being limited in scope.


After receiving the UL qualification, PCi also added


color coded travelers for all manufacturing lots that required UL certification. The color coded travelers allow the UL auditor to verify which lots require UL certification, and to quickly determine compliance to their qualification listing. PCi is also adding to its file to include additionalmaterial sets and technology.


Printed Circuits UL 94 V-0 recognition on rigid


Costs for rigid f lex board testing can be prohibitive


flex constructions eliminates the cost and time required to test individual boards.Most popular constructions can be certified immediately, at no cost to the board designer or buyer. PWB designers and buyers have a source for fully compliant UL 94 V-0 rated boards, and can be assured that their boards are


rated 94 V-0. www.printedcircuits.com Some fabricators work around the requirement by specifying


that the board be built withmaterials that are recognized by UL to 94 V-0. This eliminates sampling and testing costs, however, it does not represent UL certification and would not comply with insurance carrier agreements for product liability. It leaves the board buyer exposed to claims, should anything occur with their end product.


Finally, some board fabricators assume that if they have


recognition of flexible circuit constructions and separate rigid board constructions, then they are legitimately allowed tomix andmatch. This is erroneous. Also, some fabricators think that if they have UL recognition on a rigid flex submission, they are qualified to build all rigid flex boardswith thatmaterial set. This is also erroneous. The error, if discovered by an auditor leaves the board fabricator vulnerable to losing their UL recognition and leaves the board buyer exposed to product liability claims should something gowrong.


Plug and play approvals To address this issue and alleviate the costs associated with testing rigid flex boards for UL approval, Printed Circuits (PCi), undertook a two year project to build, submit and qualify a set of rigid flex samples that would represent over 90 per cent of the designs on the market. The project required 138 samples that took a year and a half to build, plus six months of testing, to create what is claimed to be the largest UL 94 V-0 qualification of rigid flex in the world. Interestingly, in the first round of testing a couple of the


samples failed, even though they were manufactured with UL 94 V-0 approved materials. This serves to validate UL’s requirement that each construction must be tested before UL certification is awarded and that specifying and using 94 V-0 materials alone is not enough.


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IMPACT COMPONENTS supplies quality electronic components.


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obsolete parts as well as a viable source of cost savings. In-house X-ray, De-Cap and XRF Services.


For more info: sales@impactcomponents.com or www.impactcomponents.com Call 858 634-4800 or 800 326-5139


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