Ryszard Kisiel, Marek Guziewicz, Andrzej Taube, Maciej Kaminski and Mariusz Sochacki
This paper aims to investigate the sintering and solid liquid interdiffusion bonding (SLID) techniques to attach AlGaN/GaN-on-Si chips to direct bond copper (DBC) substrate. The…
Abstract
Purpose
This paper aims to investigate the sintering and solid liquid interdiffusion bonding (SLID) techniques to attach AlGaN/GaN-on-Si chips to direct bond copper (DBC) substrate. The influence of metal layers deposited on the backside of AlGaN/GaN-on-Si dies on the assembly process is also investigated.
Design/methodology/approach
The authors assumed the value of the shear strength to be a basic parameter for evaluation of mechanical properties. Additionally, the surface condition after shearing was assessed by SEM photographs and the shear surface was studied by X-ray diffraction method. The SLID requires Sn-plated DBC substrate and can be carried out at temperature slightly higher than 250°C and pressure reduced to 4 MPa, while the sintering requires process temperature of 350°C and the pressure at least 7.5 MPa.
Findings
Ag-, Au-backside covered high electron mobility transistor (HEMT) chips can be assembled on Sn-plated DBC substrates by SLID technology. In case of sintering technology, Cu- or Ag-backside covered HEMT chips can be assembled on Ag- or Ni/Au-plated DBC substrates. The SLID process can be realized at lower temperature and decreased pressure than sintering process.
Research limitations/implications
For SLID technology, the adhesion between Cu-backside covered HEMT die and DBC with Sn layer loses its operational properties after short-term ageing in air at temperature of 300°C.
Originality/value
In the SLID process, Sn-Cu and Sn-Ag intermetallic compounds and alloys are responsible for creation of the joint between Sn-plated DBC and micropowder Ag layer, while the sintered joint between the chip and Ag-based micropowder is formed in diffusion process.
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POLAND: Opposition’s combative tactics may cost votes
Details
DOI: 10.1108/OXAN-ES284980
ISSN: 2633-304X
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Geographic
Topical
This chapter deals with the progressive political mobilisation of peasantry in Poland, its institutionalisation, mainly in inter-war period, and its political appropriation by the…
Abstract
This chapter deals with the progressive political mobilisation of peasantry in Poland, its institutionalisation, mainly in inter-war period, and its political appropriation by the Communist regime after 1945, when State socialism needed to ground itself in Polish national history and political traditions. These various mobilisations could be labelled as ‘populist’ because of their peasantist components and ideological trends, but the chapter considers them rather as a political form of representation, which political uses by actors fluctuate according historical contexts. The first part analyses the emergence of peasant movement and the success of peasant political parties in pre-1939 Poland. The second part shows how formers activists of these parties tried to produce themselves as the only historical heirs of the peasant movement, in opposition to the new, Leninist, peasant party of the Communist Poland. In the third and last part, the chapter analyses how the Communist official peasant party, the ZSL, invented new political traditions, mainly by historicising strategies, in the aim to encapsulate the peasant form of representation in its identity.
In the article, the author presents the results of biographical research on one of the activists of the Independent Self-Governing Trade Union “Solidarity” during the period of…
Abstract
In the article, the author presents the results of biographical research on one of the activists of the Independent Self-Governing Trade Union “Solidarity” during the period of martial law in Poland (1981–1983). The heroine of this story is Ewa Zydorek, one of many women, trade union activities, whose no less than men led to the victory of democratic opposition and sociopolitical transformation in Poland after 1989. At the same time, the roles of women and men in the prodemocratic trade union and political movement in Poland at the end of communism were different. Many women involved in this movement acted as guards and intermediaries for the interned men. When the internees were released, women moved into the background. Only some women, such as Ewa Zydorek, played an increasingly important role in the social and trade union life of independent Poland after 1989.
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POLAND: President and new government fall out
Details
DOI: 10.1108/OXAN-ES284486
ISSN: 2633-304X
Keywords
Geographic
Topical
Wos can now be prosecuted for his alleged role in mishandling a justice ministry fund when he was a member of previous governments led by the right-wing Law and Justice (PiS…
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DOI: 10.1108/OXAN-DB288148
ISSN: 2633-304X
Keywords
Geographic
Topical
Jaroslaw Krzywanski, Marta Wesolowska, Artur Blaszczuk, Anna Majchrzak, Maciej Komorowski and Wojciech Nowak
The purpose of this paper is to first present the key features of the fuzzy logic (FL) approach as a cost-effective technique in simulations of complex systems and then…
Abstract
Purpose
The purpose of this paper is to first present the key features of the fuzzy logic (FL) approach as a cost-effective technique in simulations of complex systems and then demonstrate the formulation and application of the method.
Design/methodology/approach
The FL approach is used as an alternative method of data handling, considering the complexity of analytical and numerical procedures and high costs of empirical experiments. The distance from gas distributor, the temperature and the voidage of the bed, flue gas velocity and the load of the boiler are the input parameters, whereas the overall heat transfer coefficient for the membrane walls constitutes the output. Five overlapping sigmoid and constant linguistic terms are used to describe the input and the output data, respectively. The Takagi–Sugeno inference engine and the weighted average defuzzification methods are applied to determine the fuzzy and crisp output value, respectively.
Findings
The performed FL model allows predicting the bed-to-wall heat transfer coefficient in a large-scale 670 t/h circulating fluidized bed (CFB) boiler. The local heat transfer coefficients evaluated using the developed model are in very good agreement with the data obtained in complementary investigations.
Originality/value
The performed model constitutes an easy-to-use and functional tool. The new approach can be helpful for further research on the bed-to-wall heat transfer coefficient in the CFB units.