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The present paper describes a relaxation technique to calculate the two dimensional temperature distribution of a hybrid circuit made on a ceramic substrate. The method calculates the potential and power density distribution in the resistors before the temperature is evaluated so that special effects due to trimming cuts can be analysed.

A finite difference method is presented to calculate the potential distribution in a trimmed resistor. The numerical results are used to study the influence of trimming on the power density distribution and the noise performance.

In this paper the temperature distribution in hybrid circuits will be studied in two different ways. First of all the results of numerical simulations obtained with the programs PROMETHEE and HYBRITHERM will be shown. Secondly, experimental temperature plots obtained with infra‐red thermography will be compared with the theoretical results. The influence of the substrate material (epoxy, glass, Al2O3, AlN and BeO) on the temperature distribution will be demonstrated. Various ways of cooling will also be considered. It will be shown that using high quality substrates such as AlN or BeO is not always useful from a thermal point of view.

A review is given of the several heat transfer phenomena occurring in hybrid circuits. Most attention is devoted to the non‐linear properties. Some theoretical simulations and experimental results are discussed.

In this contribution a short review is given on thermal analysis of hybrid circuits using 2‐D, 3‐D and time‐dependent models. It will be shown which models are necessary to be included in a CAD system for hybrid circuit design.

In this contribution a linear thermal model for hybrid circuits is presented. Both the heat dissipated in screen printed resistors and in mounted components such as transistors and integrated circuits is taken into account.

Computer algebra or symbolic manipulation is nothing else than performing analytical calculations with the help of a computer. This offers the advantage that lengthy and complicated calculations can be carried out without errors in a very short time. Computer algebra techniques have also been applied to solve electrical networks. This offers particular advantages for hybrid circuit design, as will be outlined extensively in this paper.

The paper presents a two‐dimensional and three‐dimensional thermal model of the power hybrid circuit. Measurement of the accuracy of temperature computation using the two‐dimensional model is carried out. Based on both models, the AUTO_T program for thermal analysis is created. This program chooses the proper model according to the required accuracy of computation. The reduction of the computational time is evident.

This paper describes a simple test configuration which allows an analytical solution for thermal analysis. Comparison with experimental measurements has been undertaken and complete agreement has been found.

The purpose of this paper is to simultaneously test the association between three different sources of knowledge (internal, collaborative and regional) and innovation. This study aims to expand the insights by assessing these associations in the context of a rapidly developing and liberalizing economy; Vietnam. By conducting this study with Vietnamese data, the authors can assess whether the association between different sources of knowledge and innovation shows systematic differences to those in advanced economies.

In this study, the authors utilize data from two main sources: The World Bank Enterprise Survey and the Innovation Capabilities Survey. These firm-level surveys comprise non-agricultural formal and private sector firms. For Vietnam, 300 manufacturing firms have been included in the sample. The authors use a series of binary logistic regression models to analyze the data.

The analyses reveal that internal R&D has a strong positive association with product innovation. In contrast to findings in Western economies, not all kinds of collaborative knowledge sources have a significant association with innovation. Only collaborative knowledge gained from inside the supply chain is positively related to product innovation. Unexpectedly, negative effects from using too much external knowledge were also found.

Due to the cross-sectional nature of the data causality could not be inferred from the study. Moreover, a relatively large number of the measures were dichotomous due the large number of missing observations for more detailed measurements of the variables.

When developing their innovation strategy firms in developing countries should take into account that collaborating with partners useful, but only if they collaborate within the supply chain. As such, firms should increase their interaction with suppliers and customers and put their efforts on the development of customized solutions for them.

The Vietnamese Government could implement policies that help to enhance the quality of universities and research institutes. In most developed countries, universities and research institutes are vital sources of knowledge for innovation whereas they are not in Vietnam.

This paper contributes to the growing body of literature on firm-level innovation in developing countries. It identifies several core differences between the drivers of innovation in developed and developing contexts. Surprisingly, a feature that was expected to differ, the negative effect of over-search of external knowledge on innovation, was also found in Vietnam.