General Dynamics Corp., Pomona Division

General Dynamics Corporation

General Dynamics Corporation, Air Defense Systems Division

William P Dugan

Marvin R Johnson

Ramon D Vanderveer

Eugene Phillips

John A Muhr

Grace A Rivas

Rama P Samudrala

A method for manufacturing a probe test structure for microcircuits utilizes a multiple coating method in conjunction with a novel double-cell electroplating apparatus having a relatively high-resistance ion path between the cells. Photoresist is applied to both sides of a copper foil, copper posts are electroformed onto selected areas of one side of the foil through image hole patterns, the remaining photoresist is stripped away, polyimide prepreg is laminated to the post side of the foil, the copper posts are exposed by sanding, photoresist is reapplied to both sides of the sanded remainder, additional copper is electroformed on each post through image hole patterns in the post side of the photoresist, the foil on the side opposite the posts is chemically milled to provide leads integral with each post using appropriate masking techniques and, finally, all of the remaining photoresist is removed to leave the desired test probe set. In a second embodiment, nickel plating is added over the copper to achieve selective etching, permitting processing of both sides of the copper foil simultaneously.

Electroformed chemically milled probes for chip testing

An apparatus and method are described for electroplating surfaces. The apparatus reduces the anode effect on current density, and is therefore particularly suitable for copper or nickel plating of fine-line metal circuitry. Current density regulation is achieved by separating the anode and cathode into separate cells and achieving electrolyte communication between the cells by providing a relatively high-impedance ion path. The preferred embodiment includes a siphon tube as an ion path and a pump and filter in a separate path to maintain electrolyte circulation between the cells.

Double-cell electroplating apparatus and method

A process for producing a copper lead frame tape in which the individual fingers of the lead frame are provided with gold plated bumps. A copper foil is provided with dry film photoresist on both sides and is initially processed to provide openings in one side of the resist for electroforming of the end products directly on the copper foil. Further processing produces openings on the other resist side in locations other than opposite the first resist side bumps whereby a following chemical milling of the exposed opposite side copper yields a plurality of fingers, each consisting of an integral bump/copper foil arrangement. The electroforming step is made possible by a novel double-cell electroplating method in which a relatively high-impedance ion path connects the two cells. Bump heights of as much as 0.0013 inch or greater are produced by the disclosed process, with uniformly excellent quality.

Electroformed and chemical milled bumped tape process

A method for manufacturing a probe test structure for microcircuits utilizes a multiple coating method in conjunction with a novel double-cell electroplating apparatus having a relatively high-resistance ion path between the cells. Photoresist is applied to both sides of a copper foil, copper posts are electroformed onto selected areas of one side of the foil through image hole patterns, the remaining photoresist is stripped away, polyimide prepreg is laminated to the post side of the foil, the copper posts are exposed by sanding, photoresist is reapplied to both sides of the sanded remainder, additional copper is electroformed on each post through image hole patterns in the post side of the photoresist, the foil on the side opposite the posts is chemically milled to provide leads integral with each post using appropriate masking techniques and, finally, all of the remaining photoresist is removed to leave the desired test probe set. In a second embodiment, nickel plating is added over the copper to acheive selective etching, permitting processing of both sides of the copper foil simultaneously.

Probes for testing circuitry comprising plural oriented; circular cross-section; microcircuit probes positioned in a dielectric base and having connections on the opposite side of base to attach probe circuitry. A method of manufacture of such probes includes assembling a laminate of a dielectric base, and an aluminum mandrel, drilling holes in the laminate at positions corresponding to the eventual probe positions, electroless plating the entire package, passivating the electroless plated coating, plating the entire assemblage until the holes are substantially filled with plating, separating and shearing off the layers of plating from the laminate, applying a photoresist and developing it one the aluminum side corresponding to the holes for the probes, and on the opposite side corresponding to the desired circuitry, removing the material on the aluminum side to expose the aluminum, dissolving the aluminum to expose the probes, and soldering and reflowing the solder on the probes.

Fine line circuitry probes and method of manufacture

Probes for testing circuitry comprising plural oriented, circular cross-section, microcircuit probes positioned in a dielectric base and having connections on the opposite side of base to attach probe circuitry. A method of manufacture of such probes includes assembling a laminate of a dielectric base, and an aluminum mandrel, drilling holes in the laminate at positions corresponding to the eventual probe positions, electroless plating the entire package, passivating the electroless plated coating, plating the entire assemblage until the holes are substantially filled with plating, separating and shearing off the layers of plating from the laminate, applying a photoresist and developing it on the aluminum side corresponding to the holes for the probes, and on the opposite side corresponding to the desired circuitry, removing the material on the aluminum side to expose the aluminum, dissolving the aluminum to expose the probes, and soldering and reflowing the solder on the probes.

Reusable mandrels for fabricating bumped circuit base sheets may be formed by alternative methods. One method involves the selective etching of a copper sheet to develop pits or cavities at predetermined locations. A thin plating layer is deposited on the base sheet, covering the surface including the depressions to form the mandrel. After passivation of the plated surface, copper is plated thereon to form the sheet with the bumps in place. This sheet is then peeled off the mandrel so that the mandrel may be reused for making subsequent bumped sheets. An alternative method of forming the reusable mandrel involves the selected build-up of a base metal sheet by plating with a compatible material about islands of photoresist. Thereafter, the photoresist is removed, leaving cavities where the islands had been. This surface is then plated with a thin layer of nickel to form the permanent mandrel.

Permanent mandrel for making bumped tapes and methods of forming

An electroforming process in which parts of complex configurations can be formed more effectively than with the processes available in the prior art. In particular, a heat shrinkable tube is positioned on a mandrel, the mandrel being of a shape different from the ultimate part to be formed but which will develop the desired shape for the part when shrink tubing is shrunk onto the mandrel. A layer of metal is then deposited over the tube and the mandrel is then removed. The tube is heated again, shrinking to a smaller size which enables it to be removed from the finished part.

Method and device for providing shaped electroformed parts using

Probes for testing circuitry comprising plural oriented, circular cross-section, microcircuit probes positioned in a dielectric base and having connections on the opposite side of base to attach probe circuitry. A method of manufacture of such probes includes assembling a laminate of a dielectric base, and an aluminum mandrel, drilling holes in the laminate at positions corresponding to the eventual probe positions, electroless plating the entire package, passivating the electroless plated coating, plating the entire assemblage until the holes are substantially filled with plating, separting and shearing off the layers of plating from the laminate, applying a photoresist and developing it on the aluminum side corresponding to the holes for the probes, and on the opposite side corresponding to the desired circuitry, removing the material on the aluminum side to expose the aluminum, dissolving the aluminum to expose the probes, and soldering and reflowing the solder on the probes.

A method of electroforming a part comprising the steps of electroless depositing a coat of metal on a mandrel of heat shrinkable material, electrodepositing a second coating of metal over the first coat, heating to a temperature which will shrink the mandrel, and removing the shrunken mandrel from the electroformed part.

Method of electroforming

Method for producing fine line circuit boards utilizing both sides thereof, with through-hole plating wherein the board is drilled and conductive metal clad, the surface is passivated and the holes and the surfaces are electroplated to a desired thickness. Thereafter the surface electroplate is peeled off the board, leaving the plating in the holes. Subsequently the board is masked in a desired pattern, etched to remove the cladding and form a circuit, and then the mask is removed and solder is applied to the plated holes.

Plug plating

Carriers forming strips for semiconductor integrated circuit chips. The carrier consists basically of a flexible tape, such as a polyimide. A conductive sheet, such as a copper sheet, is initially prepared to form a lead circuit on one surface and a bump circuit on the other. This metal sheet may be gold plated. Subsequently, a layer of polyimide is applied to the lead circuit side and both the polyimide sheet and the opposite bump circuit are covered with a metal sheet, such as copper. A photoresist layer is put over the copper and is suitably illuminated and developed to provide apertures through which the copper can be etched to expose the polyimide sheet. This takes place over the windows or openings adjacent the bumps for the application of a heat ram as well as for the sprocket holes used for precisely aligning the carrier with the to-be-associated semiconductor chips. Finally, openings may also be provided to separate adjacent carrier strips from each other. The exposed polyimide layer is now removed by chemical milling. Subsequently the previously applied outer copper sheets are removed as by etching.

Bump circuits on tape utilizing chemical milling

A process for manufacturing a carrier for semiconductor devices such as integrated chips. The carrier conventionally comprises, on one surface, a lead circuit providing leads to the conduction pads of the semiconductor devices. The other side may be called a bump circuit and includes bonding pads or bumps to contact corresponding elements of the semiconductor devices. Small size bumps are made by applying the etching solution only to the lead circuit which has previously been coated with photoresist as well as the bump circuit. Eventually, the etching solution will run over the bump circuit, thereby to create bumps or pads without reducing the thickness of the lead circuit to less than about 2 mils thickness. The resulting carrier may then be polished and covered with a layer of nickel and a layer of gold.

Method of making circuitry with bump contacts

A process for manufacturing printed circuit boards having plated through-holes. An epoxy glass substrate is laminated on opposite surfaces by a thin copper foil and subsequently apertures are drilled through the laminated substrate where the plated through-holes are desired. The exposed surfaces of the apertures are electroless copper plated. Then by means of a photoresist, the desired circuit images and the apertures are exposed and the initial electroless copper plating is removed again. The apertures and the desired circuit images are again plated by electroless copper plating to establish an initial copper thickness. The apertures in the desired circuit images are then electro-copper plated to the approximate thickness of the photoresist and preferably so that their thickness is less than the thickness of the photoresist. The copper plating is then electro-solder plated. The remaining photoresist is removed and the now exposed laminated copper foil is chemically removed to provide the finished printed circuit board.

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Pomona, CA, United States of America

William P Dugan