Reflow soldering

In the early 1970s, the first companies to apply low cost, mass production techniques to photovoltaics, a technology that had previously been considered an exotic aerospace technology, emerged. These techniques included the use of electroplated and screen printed metal paste electrical conductors, reflow soldered ribbon interconnects, and by 1977, low cost, automobile windshield-style, laminated module constmction. Such processes benefitted from a substantial existing industrial infrastmcture, and have become virtually ubiquitous in the present PV industry. 

PCT may be used for the production of electronic and automotive components such as circuit board components, connectors, switches and relays, and alternator armatures and pressure sensors. The main application has been in the fabrication of surface-mount connectors that can withstand infrared reflow soldering operations. 

PCX withstands SMT (surface mount technology) reflow soldering. 

Y. S. Son, T. L. Bergman, and M. T. Hyun, Simulation of Heat Transfer in a Reflow Soldering Oven with Air and Nitrogen Injection, ASMEJ. Electronic Packaging, 117, pp. 317-322,1995. 

However, up to now, most flexible circuit boards have been based on either polyester or polyimide. While polyester (PET) is cheaper and offers lower thermal resistance (in most cases reflow soldering with standard alloys is not possible), polyimide (PI) is favored where assemblies have to be wave or reflow soldered (with standard alloys). On the other side, the relative costs for polyimide are 10 times higher than for polyester. Therefore, a wide gap between these two dominant materials has existed for a long time, prohibiting broad use of flexible circuits for extremely cost-sensitive, high-reliability applications like automotive electronics. Current developments in the field of flexible-base materials as well as the development of alternative solder alloys seem to offer a potential solution for this dilemma. 

High green strength to hold components in place during component placement and reflow soldering. 

Figure 5.1 Representation of SMT for (a) wave soldering and b) reflow soldering.

If the device is not designed to use a heat resistant material, a loss of its functionality during reflow soldering may occur. The lithium alloy may react with the electrolytic solution and other components of the battery to cause abrupt bulging or explosion. Therefore, materials resistant to the reflow temperature must be used for the electrolytic solution, separator, or gasket... 

As the separator, an insulating membrane having a large ion transmittance and a predetermined mechanical strength is used. As a material for use in the reflow soldering, glass fibers are the most stable. 

Finite absorption of water presents popcorn problem during reflow soldering... 

---