Active thermography application for solder thickness measurement in surface mounted device technology
✍ Scribed by Boguslaw Wiecek; Erwin De Baetselier; Gilbert De Mey
- Book ID
- 104157840
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 421 KB
- Volume
- 29
- Category
- Article
- ISSN
- 0026-2692
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✦ Synopsis
In this paper we discuss an active thermography application measuring solder (Sn/Pb) thickness on printed circuit boards (PCBs). We use an infrared thermographic camera to measure the transient thermal response on the PCB during back side irradiation of the latter with an infrared light source. Different solder thickness yields a different thermal behaviour on the solder surface. This because of the difference in parameters such as the capacity and the conductivity.
Using basic parameter extraction procedures, we were able to measure solder thickness. The resolution of the method depends on the properties of the camera. With the available camera (sensitivity 0.2K, 16 gray scales) this resolution is estimated to be 20/~m. Of course other measurement methods exist. However, the method used by us allows fast measurements during the production cycle. Also, numerical simulations for a complex layered structure (epoxy-solder) have been done in order to obtain the temperature decay after irradiation with the infrared source, and it's dependency upon the solder thickness.