A company who supplies and repairs processing equipment for the semiconductor industry approached Tempco with a mica insulated strip heater that was supplied to them by another heater manufacturer. The customer was experiencing issues with the thickness of the strip heater and having difficulties with the lead wires breaking off during operation and handling. Upon inspecting the original sample, Tempco engineers observed several internal design flaws. Several special internal and external features were considered to improve the design.

The sample given to Tempco had noticeable bulk around the lead exits due to the type of connection used between the heating element inside and the leads. This caused an inconsistent width and contributed to the lead wires breaking off. To help maintain a nominal thickness of 3/16” Tempco used different internal wiring methods with the lead wire to insure a flat finish at the lead exits. We designed the new heater to have a slimmer yet durable internal connection for the leads. Additional internal connections were made between the heating elements in such a way to maintain the thin profile needed for the application. The finished heater uses a Tempco Type L2 termination with a central common lead. This is a typical choice where space is limited and when a low-profile termination is required.

This mica strip heater was designed with a weld-on butt case to help keep the thickness uniform across the whole heater. Tempco uses two styles of butt cases. One style has a separate top plate that is spot welded into place. The other method has a larger case fold that is used to envelop the plate and internal components. In this instance, a separate top plate was chosen due to the strip heater size. The butt case helps to maintain a uniform surface on the top side of the heater while also providing extra protection. The plate is spot welded evenly on top to secure it and cut outs are put at the lead wire exits to provide relief from pressure applied on the surface of the heater.

The new Tempco heater was well received by the customer. An improvement in craftsmanship and durability was noted from the previous design. Additional similar mica insulated strip heaters were designed based on this first design and they met the requirements of the end user. With the combination of some standard features and attention to detail, Tempco was able to provide a mica insulated strip heater to satisfy all the customer’s requirements.