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The Microelectronics Division of the Radio Measurement Engineering Research Institute of Lithuania has developed a unique photoimageable thick film chemistry and process technology which has been in use since the mid‐1980s. The main application of the technology was for complex thick film microwave integrated circuits at lower cost than equivalent thin film devices. The paper describes the photoimageable materials and processing used at the Institute and also gives examples of suitable application in the microwave, high density interconnect, sensor and component fields.

Temperature humidity acceleration factors for surface conductance are obtained to relate the reliability of film conductors formed by different processes. Analytical expressions for acceleration factor are evolved for both screen‐printed and laser micromachined conductor samples. The rapid solidification of metal conductors due to laser micromachining and its effect on surface conductance are also studied. An analytical expression for the most common accelerated test condition (85°C, 85% relative humidity) is also derived for both screen‐printed and laser micromachined samples.

Thick film screen printing technology is able to reach a pitch of 250 μm. In an attempt to achieve lower values, two approaches have been developed so far. Both are based on the combination of screen printing as a deposition technique and photolithography for the patterning. The first approach uses photoimageable conductor and dielectric pastes; the second is based on photoimageable dielectric and etching of the fired conductor. In order to obtain a full characterisation of both processes, a test module was designed and manufactured by using the first process and identical test modules were provided by the supplier using the second technology. The design of the test module is based on a two‐layer interconnection pattern including structures for testing cross‐overs, via interconnections with various resolutions (down to 50 μm via size), in order to investigate the limits of these technologies. This paper gives a comparison of these two approaches based on the results of electrical and mechanical measurements performed on both sets of the test modules. Electrical parameters and resolution data are discussed for both processes. The chip and wire assembly method is evaluated to prequalify the technology as an advanced MCM‐C technology for telecoms applications. Finally, the results of reliability tests (humidity ageing and burn‐in) are presented.