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Built-In Thermal Islands in Heat-Conducting Printed Circuit Cards

IP.com Disclosure Number: IPCOM000043488D
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Aakalu, NG: AUTHOR

Abstract

Metal core printed circuit cards, such as porcelain on steel, glass ceramic on steel, organic film on steel, etc., are good heat spreaders. In some instances it may be necessary to locate heat-sensitive components, such as an electrolytic capacitor, near high heat-dissipating components, such as thick-film resistors. A slot in the form of a partially closed loop in the metal core around the sensitive zone can block the heat from reaching the sensitive component. Fig. 1 shows an example; Fig. 2 shows a fragmentary cross section, enlarged. The slot 10 is punched in the sheet metal core 12 of the card 14 prior to the application of the porcelain coating 16. The island 18, thus formed, is mechanically attached to the rest of the card in one or more spots 20, 22.

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Built-In Thermal Islands in Heat-Conducting Printed Circuit Cards

Metal core printed circuit cards, such as porcelain on steel, glass ceramic on steel, organic film on steel, etc., are good heat spreaders. In some instances it may be necessary to locate heat-sensitive components, such as an electrolytic capacitor, near high heat-dissipating components, such as thick-film resistors. A slot in the form of a partially closed loop in the metal core around the sensitive zone can block the heat from reaching the sensitive component. Fig. 1 shows an example; Fig. 2 shows a fragmentary cross section, enlarged. The slot 10 is punched in the sheet metal core 12 of the card 14 prior to the application of the porcelain coating 16. The island 18, thus formed, is mechanically attached to the rest of the card in one or more spots 20, 22. If necessary, by making the slot narrow (about half the thickness of the metal), it is possible to flow the porcelain coating into the slot in the metal and thus provide a continuous surface for wiring with minimal loss of heat isolation. An example is shown at 24 (Fig. 2). Surface tension of the molten porcelain acts to form a continuous surface across such gaps in the thermally conductive core. In the case of cards having an organic film laminated onto the heat sink core, the gap in the slot in the core need not be narrow, as there is a continuous film across the slot.

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