Copper-filled through-hole electrode of a ZnS window material for sealing a thermal infrared sensor

Takafumi Fukumoto, Naoki Okamoto, Yoshimi Ohta, Yasuhiro Fukuyama, Masaki Hirota, Kazuo Kondo

Research output: Contribution to journalArticle

Abstract

The through-hole electrode for the wafer level package (WLP) was formed with the aim of lowering the cost of infrared sensors. It has been difficult to plate a ZnS substrate for use as the window material of WLPs because of low adhesion. However, through-hole filling was successfully accomplished in this work by applying a newly developed method of direct nonelectrolyte plating. Concretely, a blast cleaning process was performed on a ZnS substrate of 1 mm thickness. Then, a through-hole with both sides tapered was formed with an aspect ratio of 7. A compound process of Cu substitution plating and Ni nonelectrolyte plating was applied to the through-hole, forming a uniform plating film with high adhesion in the hole. Finally, the through-hole was completely filled by Cu electroplating. A He leak test confirmed that the sample had high sealing properties, with a measured leak rate of 1.0 × 10 -10 Pa·m3/sec or less. The results showed that a ZnS substrate can be used effectively for IR window material, making it possible to reduce the cost of infrared cameras.

Original languageEnglish
JournalIEEJ Transactions on Sensors and Micromachines
Volume130
Issue number9
DOIs
Publication statusPublished - Nov 9 2010
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Mechanical Engineering
  • Electrical and Electronic Engineering

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