Receiver module and device

1. A receiver module, comprising:

a semiconductor light receiving element comprising an electrode; and

a sub-mount comprising:

an electrical wiring;

a barrier metal disposed on a joining surface of the electrical wiring facing the electrode; and

solder disposed on a surface of the barrier metal, and the electrical wiring is joined to the electrode by the solder with the barrier metal disposed therebetween,

wherein the electrical wiring has a trap region disposed around the barrier metal, and the trap region retains melted solder by solder wetting on the electrical wiring,

wherein a surface area of the electrode joined to the electrical wiring is smaller than a surface area of the barrier metal.

2. The receiver module according to claim 1 ,

wherein the trap region contains a metal to be reacted with the solder to be alloyed.

3. The receiver module according to claim 2 ,

wherein the electrode has a surface containing Au as a main component,

wherein the solder comprises AuSn-based solder, and

wherein the trap region has a surface containing Au.

4. The receiver module according to claim 1 ,

wherein the barrier metal has a surface containing one of Pt and Pd.

5. The receiver module according to claim 1 ,

wherein the semiconductor light receiving element comprises a plurality of electrodes,

wherein the sub-mount comprises a plurality of electrical wirings,

wherein each of the plurality of electrodes is joined to a corresponding one of the plurality of electrical wirings with solder, and

wherein the trap region is respectively arranged around each of the plurality of electrical wirings to retain melted solder when the plurality of electrodes and the plurality of electrical wirings are joined to each other, thereby preventing the melted solder from joining between the plurality of electrodes and joining between the plurality of electrical wirings.

6. The receiver module according to claim 1 ,

wherein the barrier metal prevents segregation of the solder which occurs when the electrode and the electrical wiring are joined to each other.

7. The receiver module according to claim 1 ,

wherein the electrode of the semiconductor light receiving element has a surface layer containing Au,

wherein the electrical wiring of the sub-mount is joined to the electrode with AuSn-based solder, and

wherein the trap region of the sub-mount has a surface layer containing Au.

8. The receiver module according to claim 7 , wherein the barrier metal has a surface layer containing one of Pt and Pd.

9. The receiver module according to claim 1 , further comprising:

an optical fiber for passing light from outside;

a lens for causing the light that has passed through the optical fiber to enter the receiver module; and

a lead pin for outputting a signal that has been photoelectrically converted by the receiver module.

10. The receiver module according to claim 1 , wherein the joining surface of the electrical wiring does not contact the solder.