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Housing Less High Voltage Fast Recovery Diode

IP.com Disclosure Number: IPCOM000247713D
Publication Date: 2016-Sep-29
Document File: 4 page(s) / 201K

Publishing Venue

The IP.com Prior Art Database

Related People

Jan Vobecky: AUTHOR [+3]

Abstract

Technology for packaging of high voltage Fast Recovery or Rectifier Diode is proposed. The new concept drops the expensive and bulky ceramic housing, which is replaced by Combined LTB-Molding process. As a result, the new Housing Less Diode slims down while staying hermetic and maintaining the original electrical performance

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This is the abbreviated version, containing approximately 52% of the total text.

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CH-1602801

TECHNICAL FIELD

The present disclosure describes a new technology for packaging of high voltage fast recovery or rectifier diode.

BACKGROUND OF THE DISCLOSURE

The state-of-the-art high-voltage (≥ 2.5 kV) discrete diode is packed in a ceramic housing with nickel plated copper pole pieces (see Fig.1). The silicon wafer itself is mounted between two molybdenum disks serving as strain buffers towards the "outside world" of dissimilar coefficient of thermal expansion in comparison with that of silicon and molybdenum. In application, they are inserted between coolers, which are part of a bulky stack (see Fig.2). Any reduction of space is in favour of cost efficient solution and increases competitiveness of resulting system.

Fig.1: FRD in ceramic housing.

Housing Less High Voltage Fast Recovery Diode 

Authors: J. Vobecky, D. Guillon, K. Stiegler


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Fig.2: Stack with devices in ceramic housing.

SUMMARY

New technology for packaging of high voltage Fast Recovery or Rectifier Diode is proposed. The new concept drops the expensive and bulky ceramic housing, which is replaced by Combined LTB- Molding process. As a result, the new Housing Less Diode slims down while staying hermetic and maintaining the original electrical performance.

DETAILED DESCRIPTION OF EMBODIMENTS

Fig.3 shows the existing concept of discrete device in ceramic housing with copper pole pieces (left) and new concept of Housing Less Fast Recovery Diode (HL-FRD). The copper pole pieces and ceramic housing are omitted in the HL-FRD, which is intended to be inserted directly between coolers within a stack. The original rubber protection of junction termination is replaced by mold compound polymer which serves as a hermetic protection of the surface passivation by Diamond Like Carbon (DLC).

The mold compound material has low shrinkage (~1%), low water absorption (<0.1%), good adhesion to DLC, Ni, Ru, Si surfaces, small elastic modulus (<10GPa), low CTE close to the Moly and Si CTE (~6E-6/K), which lead to achieve a low build-in stress after the manufacturing process that allows the encapsulation to survive under large temperature excursion (-40°C~125°C).


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Creepage distance of the original concept is maintained by adjusting the size of the molded part in lateral direction, where there is usually enough space. If it was necessary to increase the distance in lateral direction above that of the mechanical construction (stack width), the mold part may contain feed-through holes for the beams of a stack. Furt...