Method and composition for mounting an electronic component and device formed therewith

• US 6,589,376 B1
• Filed: 04/28/1998
• Issued: 07/08/2003
• Est. Priority Date: 04/28/1998
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Davis, John G., Poole, Joseph D., Weller, Michael C., Slesinger, Kris A.
• Primary Examiner(s): Ball, Michael W.
• Assistant Examiner(s): Haran, John T.
• Application Number:
  US09/067,940
• Time in Patent Office: 1,897 Days
• Field of Search: 156/64, 156/152, 156/247, 156/249, 156/299, 156/307.1, 438/14, 438/17, 438/108, 438/119, 438/106, 438/107, 295/93, 298/32, 298/34, 298/42, 297/40, 297/41
• US Class Current: 156/64
• CPC Class Codes: H05K 2201/10689 Leaded Integrated Circuit [IC] package, e.g. dual-in-line [DIL]
• CPC Class Codes: H05K 2201/10734 Ball grid array [BGA]; Bump grid array
• CPC Class Codes: H05K 2203/0191 Using tape or non-metallic foil in a process, e.g. during filling of a hole with conductive paste
• CPC Class Codes: H05K 2203/0278 Flat pressure, e.g. for connecting terminals with anisotropic conductive adhesive
• CPC Class Codes: H05K 2203/1476 Same or similar kind of process performed in phases, e.g. coarse patterning followed by fine patterning
• CPC Class Codes: H05K 2203/162 Testing a finished product, e.g. heat cycle testing of solder joints patterns for electrical inspection or testing H05K1/0268
• CPC Class Codes: H05K 2203/176 Removing, replacing or disconnecting component; Easily removable component thermal arrangements, e.g. to prevent overheating H05K1/0201
• CPC Class Codes: H05K 3/305 Affixing by adhesive
• CPC Class Codes: H05K 3/321 by conductive adhesives
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product
• CPC Class Codes: Y10T 156/1092 All laminae planar and face to face
• CPC Class Codes: Y10T 29/49133 with component orienting
• CPC Class Codes: Y10T 29/53178 Chip component
• CPC Class Codes: Y10T 29/53183 Multilead component

Abstract

A method of mounting a component on a substrate includes applying a conductive adhesive on a contact pad joined to a substrate, aligning a component with the substrate such that at least one lead of the component is juxtaposed with the conductive adhesive, performing a partial cure of the conductive adhesive, testing performance of the component, and performing a full cure of the conductive adhesive. Another method includes the additional steps of applying a tacky film to the substrate and juxtaposing the component with the tacky film. When the testing in either embodiment shows a defective or misaligned component, the component may be replaced or repositioned by cold separation of the at least one component lead from the partially cured conductive adhesive. Optionally, additional conductive adhesive may be applied, when needed, before replacement or repositioning of a component. A composition for mounting a component on a circuit board includes a conductive adhesive screened on a contact pad, the conductive adhesive being partially cured, wherein the composition allows cold separation of the component from the substrate and may be fully cured by heat exposure. An apparatus is also provided including a component, a substrate, and a means for temporarily mounting and electrically connecting the component on the substrate.

Claims

1. A method for mounting a component including a plurality of leads on a circuit board including a plurality of contact pads such that each contact pad corresponds to at least one of the plurality of leads, the method comprising the following steps performed in the indicated order:

a) applying a plurality of conductive adhesive elements such that each conductive adhesive element is on each contact pad;

b) aligning the component with the circuit board such that each lead is juxtaposed with its corresponding conductive adhesive element and each conductive adhesive element is located between one of the plurality of contact pads and its corresponding at least one lead;

c) performing a partial cure of the conductive adhesive elements, the partial cure of the conductive adhesive elements providing temporary mechanical connections that affix the plurality of contact pads to their corresponding leads while allowing for adjustment in relative positions of the plurality of contact pads and their corresponding leads such that electrical connections suitable for testing are provided between the plurality of contact pads and their corresponding leads;

d) testing the component and determining whether the component is defective or misaligned;

e) replacing the component, if defective, with a new component and adjusting the position of or repositioning the component, if misaligned; and

f) performing a full cure of the conductive adhesive elements, the full cure of the conductive adhesive elements providing permanent fixed mechanical and electrical connections between the plurality of contact pads and their corresponding leads, wherein the method additionally comprises the step of applying a tacky film to at least one of the circuit board and the component, and wherein the step of aligning the component with the circuit board additionally comprises interfacing the tacky film between the circuit board and the component.

2. The method of claim 1, wherein the step of performing a partial cure comprises heat curing the conductive adhesive elements at 50 to 105°

C. for 10 minutes to 1 hour.

3. The method of claim 1, wherein the step of performing a full cure comprises heat curing the conductive adhesive elements at 50 to 200°

C. for 15 seconds to 12 hours.

4. The method of claim 1, wherein the tacky film is pressure sensitive tape, silicon-based adhesive tape, acrylic-based adhesive tape, partially cured polymer resin, thermoset or thermoplastic adhesive, or pressure sensitive, thermoset, or thermoplastic preform films.

5. The method of claim 3, wherein the step of performing a full cure comprises heat curing the conductive adhesive elements at 125 to 150°

C. for approximately 1.5 hours.

6. The method of claim 1, wherein additional conductive adhesive elements are applied before replacing the new component on the circuit board and before repositioning the misaligned component to its correct position such that each additional conductive adhesive element is on each contact pad.

13. The method of claim 2, wherein 50°

C. corresponds to a partial cure time of 1 hour and 105°

C. corresponds to a partial cure time of 10 minutes.

14. The method of claim 3, wherein 50°

C. corresponds to a full cure time of 12 hours and 200°

C. corresponds to a full cure time of 15 seconds.

7. A method for mounting a component including a plurality of leads on a circuit board including a plurality of contact pads such that each contact pad corresponds to at least one of the plurality of leads, the method comprising the following steps performed in the indicated order:

a) applying a plurality of conductive adhesive elements such that each conductive adhesive element is on each contact pad;

b) applying a tacky film to the circuit board;

c) aligning the component with the circuit board such that the component is juxtaposed with the tacky film and each lead is juxtaposed with its corresponding conductive adhesive element and each conductive adhesive element is located between one of the plurality of contact pads and its corresponding at least one lead;

d) performing a partial heat cure of the conductive adhesive elements, the partial heat cure of the conductive adhesive elements providing temporary mechanical connections that affix the plurality of contact pads to their corresponding leads while allowing for adjustment in relative positions of the plurality of contact pads and their corresponding leads such that electrical connections suitable for testing are provided between the plurality of contact pads and their corresponding leads;

e) testing the component and determining whether the component is defective or misaligned;

f) replacing the component, if defective, with a new component and adjusting the position of or repositioning the component, if misaligned; and

g) performing a full heat cure of the conductive adhesive elements, the full heat cure of the conductive adhesive elements providing permanent fixed mechanical and electrical connections between the plurality of contact pads and their corresponding leads.

8. The method of claim 7, wherein the step of performing a partial cure comprises heat curing the conductive adhesive elements at 50 to 105°

C. for 10 minutes to 1 hour.

9. The method of claim 7, wherein the step of performing a full cure comprises heat curing the conductive adhesive elements at 50 to 200°

C. for 15 seconds to 12 hours.

10. The method of claim 7, wherein the tacky film is pressure sensitive tape, silicon-based adhesive tape, acrylic-based adhesive tape, partially cured polymer resin, thermoset or thermoplastic adhesive, or pressure sensitive, thermoset, or thermoplastic preform films.

11. The method of claim 9, wherein the step of performing a full cure comprises heat curing the conductive adhesive elements at 125 to 150°

C. for approximately 1.5 hours.

12. The method of claim 7, wherein additional conductive adhesive elements are applied before replacing the new component on the circuit board and before repositioning the misaligned component to its correct position such that each additional conductive adhesive element is on each contact pad.

15. The method of claim 8, wherein 50°

C. corresponds to a partial cure time of 1 hour and 105°

C. corresponds to a partial cure time of 10 minutes.

16. The method of claim 9, wherein 50°

C. corresponds to a full cure time of 12 hours and 200°

C. corresponds to a full cure time of 15 seconds.