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Component Registration Using Photosensitive Dielectric

IP.com Disclosure Number: IPCOM000038546D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Baldauf, LM: AUTHOR [+3]

Abstract

Figs. 1 and 2 illustrate the use of Photosensitive Dielectric, to provide Surface-Mounted Component (SMC) registration-orientation and restriction of movement during solder reflow. First, dielectric layer 1 acts as solder mask. After solder deposition on the pads, a second layer 2 of photosensitive dielectric is deposited and developed, providing a cavity for component placement. The cavity also acts as orientation guide due to the notched corner 3. The arrangement has several advantages: 1. The "pick-n-place" tolerance can be relaxed since the cavity acts as guide and the component has a self-centering action. 2. The component is restricted in the x and y directions, thereby movement due to mechanical vibration is eliminated.

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Component Registration Using Photosensitive Dielectric

Figs. 1 and 2 illustrate the use of Photosensitive Dielectric, to provide Surface-Mounted Component (SMC) registration-orientation and restriction of movement during solder reflow. First, dielectric layer 1 acts as solder mask. After solder deposition on the pads, a second layer 2 of photosensitive dielectric is deposited and developed, providing a cavity for component placement. The cavity also acts as orientation guide due to the notched corner 3. The arrangement has several advantages: 1. The "pick-n-place" tolerance can be relaxed since the cavity

acts as guide and the component has a self-centering action.

2. The component is restricted in the x and y directions, thereby

movement due to mechanical vibration is eliminated. This

feature eliminates use of an EPOXY-DOT for component hold

down.

3. The notch in layer 2 allows easy component orientation. This

feature can be used for auto-visual inspection to align the

component before placement. The method is applicable to both leadless and leaded components (i.e., J-leads, Gullwing, etc.). The process involves the following steps: After the first layer of Photosensitive Dielectric is applied, it is exposed and developed using the pad pattern. Solder is then deposited on pads, reflowed and leveled. The second layer is then applied, exposed and developed to component outline pattern, thus providing a cavity to match the component outline.

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