# US 9,883,586 B2 · Wiring substrate for bonding using solder having a low melting point and method for manufacturing same

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- Number: US 9,883,586 B2
- Document ID: US9883586B2
- Status: Granted
- Kind: B2
- Application number: 14/808,275
- Filed: 2015-07-24
- Published: 2015-11-19
- Granted: 2018-01-30
- Earliest claimed: 2013-01-28
- Assignees: Toppan Printing Co., Ltd.; National University Corporation Gunma University
- Applicants: Toppan Printing Co. Ltd.; National University Corporation Gunma University
- Inventors: Tetsuyuki Tsuchida; Toshikazu Okubo; Ikuo Shohji; Akihiro Hirata
- Web page: https://patentgrep.com/patent/US9883586B2

## CPC

- H05K 1/09: Use of materials for the {conductive, e.g. } metallic pattern
- B23K 1/0008: {specially adapted for particular articles or work}
- B23K 1/0016: {Soldering of electronic components}
- B23K 1/008: Soldering within a furnace (B23K1/012 takes precedence)
- B23K 1/19: taking account of the properties of the materials to be soldered
- B23K 35/262: {Sn as the principal constituent}
- C22C 13/02: with antimony or bismuth as the next major constituent
- C25D 7/00: Electroplating characterised by the article coated
- H05K 3/10: in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
- H05K 3/244: {Finish plating of conductors, especially of copper conductors, e.g. for pads or lands (selective plating methods H05K3/243; finish plating of conductors made by printing techniques H05K3/246; solder as finish H05K3/3465)}
- H05K 2201/0341: Intermediate metal, e.g. before reinforcing of conductors by plating
- H05K 2203/043: Reflowing of solder coated conductors, not during connection of components, e.g. reflowing solder paste
- H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- 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
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- C25D: PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR

## Abstract

There is provided a wiring substrate including an electrode including Cu or a Cu alloy, a plating film having a film including at least Pd, formed on the electrode, and a solder which is bonded onto the plating film by heating, has a melting point of lower than 140° C., and includes Pd dissolved therein, a Pd concentrated layer being absent between the solder and the electrode.

## Claims

### Claim 1

A method for manufacturing a wiring substrate comprising:
forming a plating film comprising a film comprising at least Pd on an electrode comprising Cu or a Cu alloy;
forming a solder resist layer protecting a portion of the electrode outside of a bonding site of a solder, the solder resist fully covering all side surfaces of the electrode; and
bonding, onto the plating film, the solder having a melting point of lower than 140° C. onto the plating film by heating, to uniformly dissolve the Pd in the solder and remove the Pd from the plating film, the bonding the solder onto the plating film by heating being performed under one of the following predetermined thermal conditions:
(1) reflow treatment at a time of bonding the solder is performed one to five times under a condition where a peak temperature is 139° C. or higher and 169° C. or lower, a time of maintaining a temperature at 139° C. or higher and 169° C. or lower is shorter than 90 seconds, and a total time of heating treatment including reflow is 300 seconds or shorter,
(2) after bonding the solder, a heating treatment of maintaining the temperature at 139° C. or higher and 169° C. or lower for 90 seconds or longer is performed, and
(3) reflow treatment at the time of bonding the solder is performed one to five times under a condition where a peak temperature is 139° C. or higher and 169° C. or lower, a total time of heating treatment including reflow is 300 seconds or shorter, and the time of maintaining the temperature at 139° C. or higher and 169° C. or lower is 90seconds or longer.

### Claim 2 (depends on 1)

The method for manufacturing a wiring substrate according to claim 1,
wherein when the plating film is formed, a thickness of the film comprising Pd is 0.01 μm or more and 5 μm or less.