An innovative "ChemicalVia" process for the production of high density interconnect printed circuit boards The ATLAS muon chamber quality control with the X-ray tomograph at CERN

The ChemicalVia process, patented by CERN, provides a new method of making microvias in high-density multilayer printed circuit boards of different types, such as sequential build-up (SBU), high density interconnected (HDI), or laminated multi-chip modules (MCM-L). The process uses chemical etching instead of laser, plasma or other etching techniques and can be implemented in a chain production line. This results in an overall reduced operation and maintenance cost and a much shorter hole production time as compared with other microvia processes. copy Emerald Group Publishing Limited. 4 Refs.4 An essential part of the Muon Spectrometer of the ATLAS experiment is based on the Monitored Drift Tube (MDT) technology. About 1200 muon drift chambers are being built at 13 institutes all over the world. The MDT chambers require an exceptional mechanical construction accuracy of better than 20 mu m. A dedicated X-ray tomograph has been developed at CERN since 1996 to control the mechanical quality of the chambers. The chamber wire positions are measured with a statistical error of 2 mu m and a systematic error of 2 mu m over a working area of 2.2 m * 0.6 m. During the construction phase of the MDT chambers, from middle 2000 to mid 2005, the X-ray tomograph is the key tool for ensuring consistent chamber production with a sampling rate of ~15%. To achieve this program efficiently, an effort for complete automation of the tomograph operation has been underway. Until September 2003, 79 chambers out of 739 chambers produced at 11 of the construction sites have been measured. The X-ray tomograph has proved to be an essential and powerful tool in assessing the validity of the various construction steps. (4 refs).