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Chip Joining Method and Apparatus for Flexible Thin Film Modules

IP.com Disclosure Number: IPCOM000035860D
Original Publication Date: 1989-Aug-01
Included in the Prior Art Database: 2005-Jan-28
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Gazdik, CE: AUTHOR

Abstract

A flexible, thin polyimide film decal is metallized and circuitized to serve as a substrate in an electronic packaging scheme. The decal requires attachment to a chip using controlled collapse chip connector (C4) technology. Due to the highly flexible nature of the decal, a wrinkling of the film often occurs during the C4 chip join operation (Image Omitted) which is performed in a nitrogen atmosphere belt furnace. This wrinkling creates a separation between some C4 solder balls on the chip and their respective circuit pads on the decal. This results in an open circuit in the finished module. A tool and technique that positions, holds, and applies the necessary heat to the film during chip join keeps the film planar until the C4 joining is complete. The apparatus and its use is described in the following.

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Chip Joining Method and Apparatus for Flexible Thin Film Modules

A flexible, thin polyimide film decal is metallized and circuitized to serve as a substrate in an electronic packaging scheme. The decal requires attachment to a chip using controlled collapse chip connector (C4) technology. Due to the highly flexible nature of the decal, a wrinkling of the film often occurs during the C4 chip join operation

(Image Omitted)

which is performed in a nitrogen atmosphere belt furnace. This wrinkling creates a separation between some C4 solder balls on the chip and their respective circuit pads on the decal. This results in an open circuit in the finished module. A tool and technique that positions, holds, and applies the necessary heat to the film during chip join keeps the film planar until the C4 joining is complete. The apparatus and its use is described in the following.

The chip join reflow oven is replaced by an aluminum reflow fixture 1 (Fig. 1) mounted on a thermally resistant plate 2. The reflow fixture has small electric heaters 3 mounted in its base capable of raising its temperature sufficiently to reflow C4 solder alloy.

The reflow fixture 1 also has a vacuum channel 4 extending through its plate 2 up through its upper post 5. The configuration of the vacuum channel 4 where it terminates at the surface upper post 5 can be circular as shown in the top view Fig. 1, square (Fig. 2), or it can be an array as shown in Fig. 3. The shape and size of the vacuum cha...