摘要:

Applications of silicone materials for potting and encapsulation are discussed. After introductory notes on general requirements and alternative materials, a description is given of the good dielectric characteristics and thermal endurance of the silicones. Reference is made to their comparatively high cost and, for some applications, limited physical strength.Silicone fluids are then described, with a note on their chemical structure. Graphs illustrate the variation of permittivity and vapour pressure with viscosity, and the effects of frequency and temperature on power factor and permittivity.Following a section on compounds, an account is given of silicone rubbers, especially of the cold-curing types. The lengthening of pot life for the catalyzed materials by adding solvent or silicone fluid is illustrated graphically.A newly developed silicone gel with novel self-healing characteristics is then described. After describing the use of silicone resin-based cements to encapsulate wire-wound resistors, and solventless silicone resins for encapsulating and potting other components, the paper concludes by referring to present and future requirements. It is considered that improved physical properties which are expected to arise from current research are the most important requirement.

DOI:10.1049/pi-b-2.1962.0048

出版商:IEE    

年代:1962

数据来源: IET

摘要:

The paper reviews the development of epoxide-resin casting systems for the potting of electronic components and gives the results of some long-term investigations of the effect of various resin formulations on component values.The first part of the paper deals with the chemical aspects of the reliability of resin-cast components, together with an assessment of the results of some long-term chemical immersion tests. The second part covers the drift of component values during temperature cycling and storage, with particular reference to grade I high-stability resistors.

DOI:10.1049/pi-b-2.1962.0049

出版商:IEE    

年代:1962

数据来源: IET

摘要:

Various means of modifying liquid epoxide-resin systems to adapt them for specific uses are illustrated. The use of coal tar as a cheap diluent is described and its effects on some electrical properties of two typical epoxide-resin compositions are shown.Some mechanical and electrical properties of systems containing a new flexible diepoxide resin are indicated. Such systems are of potential interest for the encapsulation of components where good resistance to moderate temperatures and thermal shock is required.The results of the formulation of doughs and powders from liquid epoxide-resin systems are shown by reference to dough moulding compositions, moulding powders and powders for application by the fluidized-bed technique.

DOI:10.1049/pi-b-2.1962.0050

出版商:IEE    

年代:1962

数据来源: IET

摘要:

A brief résumé of the printed-circuit techniques in use and an outline of the preparation of the metal-clad insulating board are given. A detailed description of the types of material available is included and the performances of these materials in varying conditions are compared. Comparative costs and an outline of the fields of applications of the varying types of materials are discussed. The paper concludes with an outline of possible future trends in the production of printed-circuit materials.

DOI:10.1049/pi-b-2.1962.0051

出版商:IEE    

年代:1962

数据来源: IET