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October 27, 2008

Adhesive for Sensor Attachment

I need to attach a pressure sensor to the PCB with adhesive and then solder the pins. The adhesive is needed to provide mechanical support. The pressure sensor has a ceramic substrate and plastic body.

Can you suggest an adhesive or epoxy that would work and also not too difficult to remove in case we need to replace the pressure sensor?



V. P.

Experts Comments

There are a number of adhesives that can be used to provide support to the sensor. You want to make sure they are compatible with the electronics, in other words, a material that won't outgass or leech corrosive products.

In most cases an epoxy system would be ideal - providing good adhesion and good chemical resistance. There are systems available that cure during the SMT reflow process, therefore you could save a step by curing the same time as reflow. There are some other systems that are quick cure thermal, or even UV - depending on your process needs.

If you want reworkability, that narrows down the available materials. It depends on how you describe "reworkable" some of the epoxies may work, it just depends how much effort you are willing to use to remove the adhesive.

There are some silicone materials (RTV or room temperature curing) or UV cure materials that may work in the application. Once again be careful to choose a material that is compatible with electronics.

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Dr. Brian Toleno
Application Engineering
Henkel Electronics
Dr. Brian Toleno is the Application Engineering Team leader for Henkel Technologies. He is responsible for the technical service and application engineering for Henkel's electronics assembly materials, including solder paste, underfills, PCB protection materials, and underfills.

NF-260 is a reworkable no-flow underfill which could do the job.

See Indium Corporations rework video.

A no-flow underfill is an epoxy & flux combined:

  • Products that require underfill are typically reflow soldered and then underfilled
  • A no-flow underfill combines these 2 steps into 1 step with both reflow & underfilling happening in 1 step

In this application, NF260 can be used as the reworkable epoxy/adhesive and soldering can also be done simultaneously.

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Karthik Vijay
Technical Manager - Europe
Indium Corp.
Currently with Indium Corporation and responsible for technology programs and technical support for customers in Europe. Over 15 yrs experience in SMT, Power, Thermal & Semiconductor Applications. Masters Degree in Industrial Engg, State University of New York-Binghamton.
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