Description of the advance in science or technology that was being sought
We sought to improve product longevity and viability by identifying components which would cause potential reduction in manufacturing yields and identify areas on the PCB design which could be improved to reduce the subsequent volume manufacture cost and build times.
List of the scientific or technological uncertainties faced
- How could we ensure the area inside of an RF shielding Can weren’t being ‘cooked’ due to over-heating?
- Could we eliminate components having mismatching footprints, to ensure fewer mean time failures during build?
- Could we overcome the difficulties faced releasing the paste through SMD printing due to miniscule sizes of pads?
- What could we do to eliminate paste bleeding onto nearby pads where it wasn’t required?
Description of work carried out in order to resolve the uncertainties
- We experimented with our SMD printer, which had to go through various test cycles using different squeegee pressure settings to try to get an acceptable paste release on the smallest pads. This would eliminate them bleeding onto neighbouring pads, which would otherwise result in rework in confined inaccessible spaces inside an RF can (which was simultaneously placed and soldered during the initial SMD reflow process).
- One of the more sensitive engineering challenges was to find ways of soldering specific components/RF can onto the PCB without damaging other neighbouring sensitive devices. We had to use special soldering irons with ultra-fine tips and special heat dissipating flux gels at elevated temperatures to carefully and gently get around this issue. This became extremely labour intensive and time consuming, which is precisely what we were trying to avoid. So, we made suggestions to the client on how to redesign the unit with DFM (Design For Manufacturability) characteristics built in.
- Where components were misaligned, we had to use hot air guns to remove and refit them in conjunction with hot plates to ensure heat sinking wasn’t an issue, whilst using special thermal insulating materials in different parts of the PCB’s to protect them from being subjected to unwanted thermal profiles.