Apparatus and method for creating detachable solder connections

Claim 2

A process for creating a temporary and detachable connection between one surface which is partially non-wettable by solder and a second surface having a source of solder, comprising the steps of: (a) preparing a first surface having solder non-wettable material to adhere a film of solder wettable material; (b) depositing a film of solder wettable material onto said first surface; (c) heating said solder wettable material such that at least a portion of said solder wettable material combines with said solder non-wettable material of said first surface; (d) removing excess solder wettable material from said first surface and creating a third surface, wherein said third surface has areas of solder wettable material and solder non-wettable materials; (e) overlaying said second surface having said source of solder onto said third surface having said regions of solder wettable material and solder non-wettable material; and (f) reflowing said solder of said second surface to thereby form a temporary and detachable connection between said third surface which is partially non-wettable by solder and said second surface.

Claim 3

The process of claim 1, wherein said first surface is a contact pad on a carrier for mounting a semiconductor chip and said second surface consists of solder balls on a semiconductor chip.

Claim 4

The process of claim 1, wherein said solder wettable and solder non-wettable areas are formed on selected portions only of said first surface.

Claim 5

The process of claim 1, wherein the step of depositing a film of solder wettable material consists of plating said film on said first surface, and wherein said step of heating said solder wettable material into said first surface consists of diffusing said solder wettable material into said first surface.

Claim 6

The process of claim 1, wherein said solder non-wettable material is selected from the group consisting of molybdenum, tungsten, chrome and alumina/molybdenum and said solder wettable material is selected from the group consisting of nickel, copper and gold.

Claim 7

The process of claim 1, wherein said third surface consists of about 10% to about 45% of solder wettable material, and preferably about 20% to about 35% of solder wettable material.

Claim 8

A process for creating a temporary and detachable connection between one surface which is partially non-wettable by solder and a second surface having a source of solder, comprising the steps of: (a) preparing a first surface having solder wettable material to adhere a film of solder non-wettable material; (b) depositing a film of solder non-wettable material onto said first surface; (c) heating said solder non-wettable material such that at least a portion of said solder non-wettable material combines with said solder wettable material of said first surface; (d) removing excess solder non-wettable material from said first surface and creating a third surface, wherein said third surface has areas of solder wettable material and solder non-wettable materials; (e) overlaying said second surface having said source of solder onto said third surface having said regions of solder wettable material and solder non-wettable material; and (f) reflowing said solder of said second surface to thereby form a temporary and detachable connection between said third surface which is partially non-wettable by solder and said second surface.

Claim 9

A process for creating a temporary and detachable connection between one surface which is partially non-wettable by solder and a second surface having a source of solder, comprising the steps of: (a) preparing a first surface having solder wettable material to adhere a film of solder non-wettable material; (b) depositing a film of solder non-wettable material onto said first surface; (c) heating said solder non-wettable material such that at least a portion of said solder non-wettable material combines with said solder wettable material of said first surface; (d) removing excess solder non-wettable material from said first surface and creating a third surface, wherein said third surface has areas of solder wettable material and solder non-wettable materials; (e) overlaying said second surface having said source of solder onto said third surface having said regions of solder wettable material and solder non-wettable material; and (f) reflowing said solder of said second surface to thereby form a temporary and detachable connection between said third surface which is partially non-wettable by solder and said second surface.

Claim 10

The process of claim 1, wherein said first surface is a contact pad on a carrier for mounting a semiconductor chip and said second surface consists of solder balls on a semiconductor chip.

Claim 11

The process of claim 1, wherein said solder wettable and solder non-wettable areas are formed on selected portions only of said first surface.

Claim 12

The process of claim 1, wherein the step of depositing a film of solder non-wettable material consists of plating said film on said first surface, and wherein said step of heating said solder non-wettable material into said first surface consists of diffusing said solder non-wettable material into said first surface.

Claim 13

The process of claim 1, wherein said solder non-wettable material is selected from the group consisting of molybdenum, tungsten, chrome and alumina/molybdenum and said solder wettable material is selected from the group consisting of nickel, copper and gold.

Claim 14

The process of claim 1, wherein said third surface consists of about 10% to about 45% of solder wettable material, and preferably about 20% to about 35% of solder wettable material.

Claim 15

A process for creating detachable electrical connections between solder balls of a semiconductor chip and connecting pads of a carrier wherein the pads consist of a material which is solder non-wettable, by forming areas on the pads which consist of a matrix of solder wettable and solder non-wettable materials such that the chip can be readily removed from the carrier with minimal damage to the chip and carrier, comprising the steps of: (a) treating each pad in order to create a roughened surface; (b) plating a film of solder wettable material onto said treated pads; (c) diffusing said film of solder wettable material into said solder non-wettable material of said pads; (d) removing excess portion of said solder wettable material which has not diffused into said pad from said pad; (e) plating at least one additional film of at least one solder wettable material onto the diffused surface of step (c); (f) removing excess portion of said additional film of said solder wettable material; (g) mounting said chip on said carrier such that said solder balls of said chip coincide and overlay said treated contact pads of said carrier; and (h) reflowing said solder of said solder balls in order to make electrical connections between said chip and said carrier.

Claim 16

A process for creating detachable electrical connections between solder balls of a semiconductor chip and connecting pads of a carrier wherein the pads consist of a material which is solder non-wettable, by forming areas on the pads which consist of a matrix of solder wettable and solder non-wettable materials such that the chip can be readily removed from the carrier with minimal damage to the chip and carrier, comprising the steps of: (a) treating each pad in order to create a roughened surface; (b) plating a film of solder wettable material onto said treated pads; (c) diffusing said film of solder wettable material into said solder non-wettable material of said pads; (d) removing excess portion of said solder wettable material which has not diffused into said pad from said pad; (e) plating at least one additional film of at least one solder wettable material onto the diffused surface of step (c); (f) removing excess portion of said additional film of said solder wettable material; (g) mounting said chip on said carrier such that said solder balls of said chip coincide and overlay said treated contact pads of said carrier; and (h) reflowing said solder of said solder balls in order to make electrical connections between said chip and said carrier.

Claim 17

The process of claim 13, wherein said pads of said carrier are levelled to ensure that they are substantially flush with the surface of said carrier.

Claim 18

The process of claim 13, wherein the steps of removing wettable material includes the use of a vapor-blast etch.

Claim 19

The process of claim 13, wherein said solder non-wettable material is selected from the group consisting of molybdenum, tungsten, chrome and alumina/molybdenum, and said solder wettable material is selected from the group consisting of nickel, copper and gold.

Claim 20

The process of claim 13, further including the steps of: conducting burn-in tests on said chip while it is attached to said carrier; and removing said chip from said carrier upon completion of said burn-in tests.

Claim 21

The process of claim 17, wherein the step of removing said chip from said carrier includes shearing the connections between said solder balls and said pads on said carrier.

Claim 22

The process of claim 13, wherein the step of removing excess portion of said solder wettable material includes the use of an iodine etch.

Claim 23

The process of claim 13, wherein the step of plating a film of solder wettable material consists of plating a film of solder wettable material to approximately 0.5 microns in thickness.

Claim 24

The process of claim 13, wherein said step of treating the pads includes grinding said pads to make them flush with the surface of said carrier and creating a roughened surface with at least one vapor blast etch.

Claim 25

The process of claim 13, wherein after said diffusion step, said pad consists of about 10% to about 45% of solder wettable material, and preferably about 20% to about 35% of solder wettable material.