H.‐J. Krokoszinski and H. Esrom
A novel technology for the interconnection of bare chips in power modules is presented which circumvents the drawbacks of multiple heavy‐wire bonding as well as of reflow…
Abstract
A novel technology for the interconnection of bare chips in power modules is presented which circumvents the drawbacks of multiple heavy‐wire bonding as well as of reflow soldering of many single copper clips inserted into solder preforms. A piece of structured copper‐clad polyimide foil, here called a foil‐clip, is used to provide all required connections, i.e., die‐to‐die and die‐to‐substrate. Hot‐bar soldering or glueing is used for the final joining after adjustment of the foil‐clip to its land areas. Depending on the complexity of the module only a few touch‐downs of the heated tool are required for full assembly. In contrast to the well‐known TAB technique, in foil‐clip technology a copper layer is the top layer (typical thickness: 60 µm). The polyimide (PI) foil (e.g., 25 µm) is used simultaneously as insulation and solder stop layer on the die side. The contact of the photo‐lithographically patterned copper layer with the pads on top of the die and the substrate is achieved by grooving holes into the PI layer which are then filled in a subsequent step with solder or screen‐printed conductive adhesive. Via‐hole formation is achieved by light‐induced ablation. In the first stage of process development a scanning line beam of a pulsed UV excimer laser is moved across the surface of a metal mask containing the pattern to be eroded in the polyimide layer. The present paper describes the optimisation of process parameters in terms of wavelength, pulse rate and fluence variation as well as speed of the substrate displacement during illumination. In future, the use of a novel UV excimer lamp is envisaged which enables large‐area exposure and selective photoetching by using contact metal masks. Furthermore, measurements of the current load capability of the copper interconnects produced by foil‐clips are presented. With an infrared imaging system, the hot‐spot temperature was determined for increasing load current on tracks of different widths and lengths on their way down from high current rectifier diodes to DCB‐module substrates. It is shown that tracks with many squares (N = length/width => ∞) can be loaded with at least I = 22 A. On the other hand, due to cooling through the solder joints, the shortest tracks (N = 1) carry up to 128 A.
Ramona Teuber and Jørgen Dejgård Jensen
Given the fact that local food as a tool to create value-added is a relatively new trend in Scandinavian countries with a strong emphasis on organic food, only limited – and…
Abstract
Purpose
Given the fact that local food as a tool to create value-added is a relatively new trend in Scandinavian countries with a strong emphasis on organic food, only limited – and mainly qualitative and case-based - empirical evidence on producers and processors involved in local food value chains (FVCs) has been available so far. Thus, the present paper contributes to the small but growing literature analyzing local FVCs by providing and analyzing quantitative survey data. More specifically, the authors aim at investigating (1) how agricultural producers and processors define and perceive local food, (2) which drivers are important for the decision to become involved in local FVC and (3) whether these drivers differ in a systematic way across producers and processors.
Design/methodology/approach
In order to address these research questions, empirical data from a quantitative stakeholder survey carried out in spring in 2017 is used. Data are analyzed via descriptive and inductive statistics including a cluster analysis.
Findings
The survey results concerning the definition and perceptions of local food are in line with previous studies showing that there is usually a strong emphasis on geographic proximity. Besides, local (organic) food producers and processors are diverse and heterogeneous with differing distribution and product differentiation strategies being implemented and pursued. In particular, businesses employing primarily a personified distribution strategy (e.g. direct sales via farmers markets) differ quite substantially from businesses employing mainly a standardized distribution strategy (e.g. via retail) in their economic characteristics. Moreover, differences in the perception of potential benefits of local food as well as in the underlying drivers to become part of local FVCs were detected across businesses with different distribution strategies.
Research limitations/implications
Although the employed data sample is considered adequate for analyzing heterogeneity in firms' business strategies, the sample is not representative for Denmark and cannot straight-forwardly be extrapolated to the population level.
Originality/value
One of the first quantitative study on producers' and processors' perceptions of local food and its interaction with organic farming. So far, there is a large literature on consumers' perceptions but empirical evidence for other stakeholders is scarce. Hence, the present study provides a complementary perspective on the topic of local food.