Browse Prior Art Database

Ceramic Primary Winding for Planar Transformers

IP.com Disclosure Number: IPCOM000120205D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Gordon, JC: AUTHOR [+4]

Abstract

Disclosed is a high power, 130 degree temperature rated primary winding for use with planar transformers. The construction provides a low thermal resistance from the mounting surface to the primary coil and also provides high reliability by reducing thermal stresses.

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Ceramic Primary Winding for Planar Transformers

      Disclosed is a high power, 130 degree temperature rated
primary winding for use with planar transformers.  The construction
provides a low thermal resistance from the mounting surface to the
primary coil and also provides high reliability by reducing thermal
stresses.

      This new approach is constructing primary windings for planar
transformers used in switching regulators is designed for optimum
thermal performance which far exceeds previous methods (see U.S.
Patent 4,754,390).  A special alumina bobbin 1 is used to provide
high thermal conduction from the primary coil 3 and excellent
electrical isolation.  As shown in the drawing, a  preform 2 made
from a thermally conductive epoxy adhesive film and the primary coil
3 are placed in the bobbin 1. The coil 3 is then pressed against the
bobbin base while the epoxy cures to ensure a good bond and thermal
interface. Then a plastic insulating cap 4 is adhered to the top of
the coil to meet UL and CSA safety requirements.  A plastic cap 4 is
used over the primary winding instead of an epoxy potting compound
for manufacturing ease and also to eliminate the stresses induced
from the potting compound curing and those incurred during thermal
cycling due to the high thermal expansion properties of the potting
compound, thus greatly increasing the reliability.