Injection Moulding Co., Ltd
No.16 xixiang baoan, Shenzhen, Guangdong, China

I work with a plastic injection moulding company so my answer below will be based around the availability of resins for thermoforming and not necessarily injection moulding. You mentioned this being for an electrical part. Are there any anti-stat or Electro Static Dissipative properties that need to be considered? Once you start getting into the 350F temp range, your choices get somewhat narrow and the moulding cost goes up tremendously...especially for ESD materials. Injection molded Nylon will be about the cheapest high temp plastic. Your PEI, PPS, Polysulfones and the like are going to be extremely expensive. Your best bet is to determine which properties are important and then go to the website and use their plastics moulding calculator. It will allow you to input your properties and then will suggest materials based on those properties.

It really depends on many factors. New mould tooling? Electrical requirements? Thermal properties? The classic application conversion back in the 60s was the thermoset automotive distributor housings. They went to 30% glass reinforced PBT. A vast majority of injection molded parts have been switched to 30-40% glass reinforced PBT, NY66 and PPS. More information can help me in determining what might work for you.

It would be a disservice to you to answer this question without asking several as it is impossible to do so without knowing info like: temp, dielectric constant, load, water/steam/humidity, etc. without knowing the variables one can't make a definitive decision. I work with stock shapes specking in and out products and there are many injection molded parts that could replace phenolics but more needs to be known.