EMI and a Small Heat Sink Lead
to a Unique Design

Problem:  A medical device manufacturer needed a unique heater design for incubating fluid samples during testing in a chemical analyzer. Requirements included the need to have high resistance in a
small area (high resistance density), to minimize electromagnetic interference (EMI), and to reliably mount the heater to the cylindrical, polished surface of a small (20 mm diam.) heat sink. All of these requirements had to be implemented while reducing assembly time and accommodating the need for an integrated thermistor and an in-series thermal cut-off.

Solution: The ability of a flexible heater to conform to curved surfaces and provide temperature uniformity made it the obvious choice. To achieve the required
high resistive density, a specialty foil alloy heater element was rolled to extremely thin specifications
with an element to spacing ratio of 60/40 percent - vs industry standards of 50/50 percent. To improve electromagnetic compatibility a grounded EMI shield was added to the entire backing of the heater. A section of clear heat shrink tubing was placed over the heater and heat sink to firmly encase them. This minimized assembly time as well as improved durability. A 50K ohm thermistor was surface mounted to a pad connection so that the operating temperature could be monitored within a range from 25 degrees C to 55 degrees C. The requirement for a thermal
cut-off led to the design of an extra connection tab which was positioned on the outside perimeter of the heater so that the effective area of the heating element could be maximized.

Engineering Tip: In applying heaters to smaller, unique geometry heat sinks, it is important to take into account the end product's appearance, function and the ease with which it can be manufactured. 

Now available in Webcast or Podcast:
"5 Tips on How to Avoid Thermal Design Constraints"
Includes case studies on what you should know about installation scope, operation/storage environmental conditions, and component integration.


Minco designs, manufactures and markets critical components for critical applications. We are unsurpassed in our ability to integrate and assemble  Thermofoil Heaters, Flex Circuits, Sensors and Instruments into a single component for greater efficiency. We will help you minimize the risk of product failure by providing highly reliable components and expert design services.