Insulation Resistance of Flat Flexible Circuit Boards
- Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
The insulation resistance (RI) between parallel copper traces embedded on flexible, polyimide-based circuit boards was measured as a function of temperature, substrate type, copper thickness, and feature size. The results show a strong dependency on temperature: the measured RI decreases nearly seven-orders of magnitude upon a 90degC change. Also measured was RI as a function of the trace and space of parallel copper circuits. This dependency is less obvious but a correlation showing narrower spacing leads to lower RI is evident. The thickness/width of the copper traces has less of an effect on the measured RI. The thickness of the polyimide-based substrate, or core of the circuit boards, was also varied. Measurements of the RI versus substrate thickness were inconclusive. The height of the copper traces was changed and shows that heavier (or taller traces) result in a lower measured RI. Lastly, it was shown that the adhesive found between the copper traces and the polyimide core on so-called "LF" Pyralux(R) boards significantly reduces the measured RI compared to "AP" Pyralux(R) boards of the same dimensions. The presences of this adhesive in all LF materials, including LF coverlays should be avoided if high RI is desired for narrowly spaced copper traces. Alternative materials like AP Pyralux(R) or HT Pyralux(R) available from DuPontTM should be investigated when designing copper-based flat-flex circuit boards that require a demanding environmental specifications.
- Research Organization:
- Sandia National Laboratories (SNL-CA), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE National Nuclear Security Administration (NNSA)
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 1561692
- Report Number(s):
- SAND--2016-6275; 642924
- Country of Publication:
- United States
- Language:
- English
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