Browse Prior Art Database

MID POWER SURFACE MOUNT TRANSISTOR

IP.com Disclosure Number: IPCOM000007003D
Original Publication Date: 1993-Oct-01
Included in the Prior Art Database: 2002-Feb-15
Document File: 2 page(s) / 84K

Publishing Venue

Motorola

Related People

Michael Bartlett: AUTHOR [+3]

Abstract

Current mobile radio PA technology requires manual placement of power amplifier SOE packages, and hand soldering of device leads to the PC board. In addition, matching capacitors are often hand soldered on top of the device leads. Mis-placement of the capacitors is the number one defect in a mobile radio factory. Furthermore, heat dissipated by the capacitors results in a significant temperature rise of the PA board, which can accelerate solder joint fail- ure. This invention describes a surface mountable power transistor design which can be mass reflow soldered to the PA board. The matching capacitors are located very near the device heat spreader, resulting in excellent heat transfer to the radio chas- sis. The package also has compliant leads between the device and the board, which improves solder joint reliability. The process is completely automated, which will result in higher yields and reduced cost.

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INC. Technical Developments Volume 20 October 1993

MID POWER SURFACE MOUNT TRANSISTOR

by Michael Bartlett, Robert Darveaux and William A. Gilbert

  Current mobile radio PA technology requires manual placement of power amplifier SOE packages, and hand soldering of device leads to the PC board. In addition, matching capacitors are often hand soldered on top of the device leads. Mis-placement of the capacitors is the number one defect in a mobile radio factory. Furthermore, heat dissipated by the capacitors results in a significant temperature rise of the PA board, which can accelerate solder joint fail- ure. This invention describes a surface mountable power transistor design which can be mass reflow soldered to the PA board. The matching capacitors are located very near the device heat spreader, resulting in excellent heat transfer to the radio chas- sis. The package also has compliant leads between the device and the board, which improves solder joint reliability. The process is completely automated, which will result in higher yields and reduced cost.

One process for fabricating the power transistor device is as follows: Place power transistor device
(1) upside down in pallet (2). Dispense or screen print solder paste (3). Place leads (4) and copper heat spreader (5). The package is then reflowed in a conventional manner. At this point, the package can be cleaned and loaded in a tape-and-reel, or it can be left in the pallete for subsequent pick-and-plac...