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Apparatus for Removing Insulating Material on Conductors

IP.com Disclosure Number: IPCOM000045219D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 3 page(s) / 48K

Publishing Venue

IBM

Related People

Chen, SH: AUTHOR [+2]

Abstract

This apparatus provides automatic inspection and removing of excess glass or insulator adhered to conductive through-holes or vias in sintered multilayer ceramic modules.

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Apparatus for Removing Insulating Material on Conductors

This apparatus provides automatic inspection and removing of excess glass or insulator adhered to conductive through-holes or vias in sintered multilayer ceramic modules.

A layer of excess glass insulator often found adhered to the conductors in vias can cause a subsequent plating problem when solder contact pads are joined to the vias. This apparatus provides automatic inspection and the removal of excess glass along with an "end point" cleaning detection.

In Fig. 1, a laser 1 is selected to have a high absorption rate in the insulator and a high reflection or transmission rate in the underlying conductor which is desired to be retained. The pulse width and repetition rate for the laser are selected according to the thermal properties of the material. Both pulse lasers and continuous-wave lasers are suitable for the apparatus according to the thermal properties of the material. The energy level of the laser is selected such that the insulating layer will be removed but the underlying metal layer will not be damaged. The laser need not be focused on a sample and may in certain instances be de-focused to have a homogeneous distribution of energy.

A sample, typically a multilayer ceramic substrate, is disposed on a stage 2. A control unit 3 is adapted to maneuver the stage in X, Y and Z directions.

An acoustic sensor 4 is suitably positioned with respect to the sample and stage. The sensor, e.g. , microphone, piezoelectric crystal, or phonograph cartridge, is adapted to transform an acoustical signal into an electrical signal within a range from DC to above one GHz. An acoustic coupler 5 may be an open air gap or enclosed chamber filled with a certain amount of gas or liquid, or a selected solid or liquid can serve as a coupling agent between the sample and the sensor 4.

Suitable electronics 6 are connected through appropr...