# US 6,719,188 B2 · Rework methods for lead BGA/CGA

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- Number: US 6,719,188 B2
- Document ID: US6719188B2
- Status: Granted
- Kind: B2
- Application number: 09/912,192
- Filed: 2001-07-24
- Published: 2003-01-30
- Granted: 2004-04-13
- Earliest claimed: 2001-07-24
- Assignees: International Business Machines Corporation
- Inventors: Mukta G. Farooq; Raymond A. Jackson; David C. Linnell
- Web page: https://patentgrep.com/patent/US6719188B2

## CPC

- B23K 1/018: Unsoldering; Removal of melted solder or other residues
- H10W 72/071: {Connecting or disconnecting}
- B23K 2101/40: Semiconductor devices
- Y10T 29/49815: Disassembling
- Y10T 29/53274: Means to disassemble electrical device
- Y10T 29/53283: Means comprising hand-manipulatable implement
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A method and apparatus are provided for reworking electronic component assemblies where the components are joined by solder interconnections. A cutting device employing a heated wire, blade or other cutting element is forced against and through the solder interconnections to sever the interconnections. A preferred cutting device employs moving the cutting element transverse to the solder interconnections to also provide a sawing action to the solder interconnections. Another cutting device employs a water jet to provide a high pressure stream of water that cuts and severs the solder interconnections.

## Claims

### Claim 1

A method for separating electronic components joined by a row-by-row array of solder interconnections comprising the steps of:
supplying an electronic component assembly having at least two components joined by a plurality of solder interconnections in a row-by-row array and having a first thickness;
providing a water jet cutting element having a thickness less than the first thickness of the solder interconnections and which element has a front edge which extends across a row of solder interconnections and which has a plurality of water let openings spaced along the front edge of the element;
positioning the water jet cutting element adjacent one of the rows of the solder interconnections;
applying a force to advance the water jet cutting element through the row of solder interconnections whereby water jets from the openings in the water jet cutting element engage and simultaneously cuts through each solder interconnection in the row of solder interconnections and severs the row of solder interconnections;
continuing the above steps for the remaining rows of solder interconnections to cut and sever all the rows of solder interconnections; and
separating the two components.

### Claim 2

An apparatus for separating electronic components joined by a row-by-row array of solder interconnections comprising:
securing means to hold an electronic assembly having at least two components joined by a plurality of solder interconnections in a row-by-row array and having a first thickness;
a water jet cutting element having a thickness less than the thickness of the solder interconnections and which element has a front edge which extends across a row of solder interconnections and which has a plurality of water jet openings spaced along the front edge of the element;
positioning means to position the front edge of the water jet cutting element adjacent one of the rows of solder interconnections;
advancing means to force the water jet cutting element against the row of solder interconnections and through the solder interconnections whereby water jets from the openings in the water jet cutting element simultaneously cut and sever each solder interconnection in the row of solder interconnections; and
separating means to separate the two components when all the rows of solder interconnections have been cut and severed row-by-row by the water jet cutting element.

### Claim 3 (depends on 1)

The method of claim 1 wherein the water jet has a fluid pressure of about 20,000-60,000 psi.

### Claim 4 (depends on 3)

The method of claim 3 wherein the water jet has a thickness of about 0.002-0.040 inch.

### Claim 5 (depends on 2)

The apparatus of claim 2 wherein the water jet from the water jet cutting element has a pressure of about 20,000-60,000 psi.

### Claim 6 (depends on 5)

The apparatus of claim 5 wherein the water jet from the water jet cutting element has a thickness of about 0.002-0.040 inch.