Browse Prior Art Database

THERMALLY ISOLATED REFLOW PALLlET

IP.com Disclosure Number: IPCOM000006666D
Original Publication Date: 1992-Dec-01
Included in the Prior Art Database: 2002-Jan-22
Document File: 2 page(s) / 68K

Publishing Venue

Motorola

Related People

Richard Mangold: AUTHOR [+3]

Abstract

In order to achieve a suitable reflow profde for high melting point (220-3OYC) solders in a standard SMT reflow furnace, the pallet design must be modified to reduce heat sinking from the product area without sac- riftcing support, positional accuracy, durability, or com- patibility with the existing manufacturing line tooling. A pallet of standard design, made of aluminum, will heat sink the circuit to the point where a special furnace is required for reflow of high temperature solders. Alter- native pallet materials, such as fiber composites, will not withstand the elevated temperatures required for such applications.

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MOTOROLA INC. Technical Developments Volume 17 December 1992

THERMALLY ISOLATED REFLOW PALLl3

by Richard Mangold, Chris Becher, and Reed George

  In order to achieve a suitable reflow profde for high melting point (220-3OYC) solders in a standard SMT reflow furnace, the pallet design must be modified to reduce heat sinking from the product area without sac- riftcing support, positional accuracy, durability, or com- patibility with the existing manufacturing line tooling. A pallet of standard design, made of aluminum, will heat sink the circuit to the point where a special furnace is required for reflow of high temperature solders. Alter- native pallet materials, such as fiber composites, will not withstand the elevated temperatures required for such applications.

  An alternative pallet design (see Figure) is described below. The pallet consists of two main components; an interior latticed section that provides support and

positioning guidance to the circuit, and an outer section that incorporates the standard tooling holes, barcodes, etc. of standard pallets. The two sections are machined from aluminum, and are separated and joined by stain- less steel pins. Stainless steel has a thermal conductivity of approximately l/10 that of aluminum, and serves to thermally isolate the interior and exterior sections. By isolating the low mass interior section from the high mass exterior section with stainless steel pins, a pallet with fast thermal response at the circuit i...