Browse Prior Art Database

Chip on Board Device Registration Template

IP.com Disclosure Number: IPCOM000034682D
Original Publication Date: 1989-Apr-01
Included in the Prior Art Database: 2005-Jan-27
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Roody, AG: AUTHOR [+3]

Abstract

Disclosed is the utilization of a template to retain silicon device location during chip on board (COB) attachment via standard surface mount processes. Silicon devices with solderable metals on the back side are attached to thermal carriers using standard surface mount processes. Subsequently, they are wirebonded to the carrier circuitry and encapsulated. During the solder reflow process, the devices float on the liquified solder diebond pad, allowing them to move, tilt, and skew. When the solder cools and solidifies, the devices are no longer positioned properly. In order to wirebond the devices with an automated wirebonder, the device position must be within certain limits for the vision system to recognize the pattern. These limits may vary with the equipment manufacturer.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 90% of the total text.

Page 1 of 2

Chip on Board Device Registration Template

Disclosed is the utilization of a template to retain silicon device location during chip on board (COB) attachment via standard surface mount processes. Silicon devices with solderable metals on the back side are attached to thermal carriers using standard surface mount processes. Subsequently, they are wirebonded to the carrier circuitry and encapsulated. During the solder reflow process, the devices float on the liquified solder diebond pad, allowing them to move, tilt, and skew. When the solder cools and solidifies, the devices are no longer positioned properly. In order to wirebond the devices with an automated wirebonder, the device position must be within certain limits for the vision system to recognize the pattern. These limits may vary with the equipment manufacturer. This phenomena causes the devices to be reworked and decreases yields, adding cost to the product. A device registration template can be fabricated out of a material that is not solderable, such as carbon. This template is a flat, thin sheet that fits over the surface of the carrier. The template-to- carrier registration is controlled by placing the two dowel pins of the template into the existing panel tooling holes, as shown in the figure. The template has openings in it that correspond to the devices. The size of the opening is fixed so that the movement of the device during reflow is constrained to meet the requirements of the automatic wirebon...