Requirements
The higher the voltage, the higher the requirements. The Semix® 5 housing bonding frame is a power module that is installed in numerous power converters, e.g. in air conditioning, drive systems or solar inverters worldwide. Areas of application with often extreme thermal and dynamic loads. We successfully put the hybrid assembly into series production with all the necessary development, manufacturing and assembly services on behalf of a leading manufacturer of power electronics components.
In addition to the metal parts’ bonding capability and the positioning accuracy of the metal inserts in the tool, our planning focused on the assembly’s insulation and high-voltage resistance. Despite the more than 20 metal parts, the power module was to be designed to be compact and at the same time as flexible as possible for further developments. To guarantee reliable sealing during encapsulation, it was also necessary to ensure the housing components have uniform flatness and dimensional accuracy. And with extremely fast insertion and cycle times.
Process
As a system supplier, our customers benefit from a comprehensive range of industrialization services, the corresponding manufacturing technologies and assembly facilities at the production site. This is also the case with the Semix® 5, which we developed a special insertion hand to place the metal parts in the cavity for its production. In addition to the complete process development and tool design, all the stampings and overmoldings are also produced in-house. Only the Pressfit pins on a continuous strip are purchased externally.
Immediately after the cutting and bending process, the Pressfits are fed to the rotary table machine for the injection molding process using a specially developed pneumatic insertion device. A clear advantage, as this shortens the cycle time and significantly increases both the process stability and production capacity. Since the thermoplastic warps slightly during the cooling phase, we had to plan for correction loops from the beginning to achieve the required flatness for the printed circuit board support. In some cases, areas were even adjusted empirically.
The injection molded housing’s material is made of a robust PPS GF40, which has high temperature resistance and exceptional CTI (insulation capability) value. All power connections including the base plate are made of copper with selective nickel plating of the connection lugs. The purchased control contacts have a bondable ALSi range and the required Pressfit geometry.
Following assembly and the application of two laserable stickers, the parts undergo one hundred percent high voltage testing. It is only finally packed in the pendulum packaging provided by the customer after this final quality inspection.
Result
Today, we produce over 200,000 Semix® 5 bonding frames in a year in 3-shift operation. Process efficiency increases significantly thanks to the implementation of all processes in-house. Costs, time and energy consumption can be reduced accordingly, as unnecessary transport routes and external work steps are eliminated. The production of the housings on the vertical rotary table machine with two ejector sides also saves time and costs, as the next inserts can already be preloaded during the injection cycles.
Each process step is permanently monitored using measuring machines, gages, dial gages and calipers, and documented in the CAQ system. This is also an important success factor when it comes to reproducibility and tolerances in the micro range.
3
tool sets
4
overmolded inserts per year
16
kg of material throughput
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