Browse Prior Art Database

Holographic Selective Heating System

IP.com Disclosure Number: IPCOM000090168D
Original Publication Date: 1969-Feb-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

O'Hara, DJ: AUTHOR [+2]

Abstract

Simultaneous soldering of a number of surface and buried connection points is effected by this device. Laser 1, preferably operating in the infrared spectrum, is positioned to illuminate phase hologram 2. The latter has recorded in it a spatially redundant diffraction pattern of the interconnection points on carrier 3 for a plurality of modules 4. These normally include the locations at which the leads from modules 4 are to be fixed to conductors on carrier 3. In addition, certain carriers require the connection of certain buried conductors in the event that carrier 3 contains more than one plane of interconnections.

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Holographic Selective Heating System

Simultaneous soldering of a number of surface and buried connection points is effected by this device. Laser 1, preferably operating in the infrared spectrum, is positioned to illuminate phase hologram 2. The latter has recorded in it a spatially redundant diffraction pattern of the interconnection points on carrier 3 for a plurality of modules 4. These normally include the locations at which the leads from modules 4 are to be fixed to conductors on carrier 3. In addition, certain carriers require the connection of certain buried conductors in the event that carrier 3 contains more than one plane of interconnections.

The energy from laser 1 is concentrated at the interconnection points by hologram 2. This concentration of energy causes localized heating in the area of the interconnection to effect a bonding by solder reflow. The use of a substrate such as LUCALOX* allows buried interconnection points to be soldered since this material allows roughly 40% at 1.06 mu, 85% at 5.5 mu and 90% in the visible spectrum infrared transmission through a 1.0 mm, 40 mils, thickness.

The use of phase holograms, which are transparent, reduces the laser energy dissipated in the hologram and permits high diffraction efficiencies. The phase hologram therefore allows the use of high power lasers and minimizes the laser energy lost in the zero-order beam. The three-dimensional nature of the holographic image permits concentration of the energy at...