High-strength solder joint
AssigneeNEC Corporation
InventorsKazuyuki Kawashima, Yasunori Tanaka
Life of this patent
Estimating the term…
Abstract
A soldering method achieving a high-strength joint between a solder and an nickel/gold electroless plated surface is disclosed. The nickel/gold electroless plated layer is soldered using a solder including tin (Sn), silver (Ag), and copper (Cu). At a solder joint, a layer sturcture of nickel layer/intermetallic compound layer/solder layer is formed. The intermetallic compound layer is composed mainly of tin (Sn) and copper (Cu), and further including nickel (Ni). The intermetallic compound layer has cauliflower-shaped surfaces formed in a solder-layer's side thereof.
Claims12
A soldering method comprising the steps of:
- preparing a nickel/gold electroless plated layer composed of a nickel layer formed by nickel-phosphorus electroless plating and a gold layer formed on the nickel layer;
- and
- soldering the nickel/gold electroless plated layer using a solder so that an intermetallic compound is formed at an interface surface between the nickel layer and the solder, wherein the intermetallic compound is shaped like a cauliflower as seen under magnification.
A method for forming a wiring structure having a plurality of conductor terminals formed thereon, comprising the steps of:
- forming a nickel/gold electroless plated layer on each of the conductor terminals, wherein the nickel/gold electroless plated layer is composed of a nickel layer formed by nickel-phosphorus electroless plating and a gold layer formed on the nickel layer soldered;
- and
- soldering the nickel/gold electroless plated layer using a solder so that an intermetallic compound is formed at an interface surface between the nickel layer and the solder, wherein the intermetallic compound is shaped like a cauliflower as seen under magnification.
A method for forming a device comprising:
- a wiring substrate having a plurality of substrate terminals formed thereon;
- and
- a functional circuit having a plurality of circuit terminals, wherein the substrate terminals are connected to respective ones of the circuit terminals,
- the method comprising the steps of:
- forming a nickel/gold electroless plated layer on each of the substrate terminals, wherein the nickel/gold electroless plated layer is composed of a nickel layer formed by nickel- phosphorus electroless plating and a gold layer formed on the nickel layer soldered;
- and
- soldering the nickel/gold electroless plated layers on the substrate terminals to respective ones of the circuit terminals using a solder so that an intermetallic compound is formed at an interface surface between the nickel layer and the solder, wherein the intermetallic compound is shaped like a cauliflower as seen under magnification.
A method for forming a device comprising:
- a printed circuit substrate having a plurality of substrate terminals formed thereon;
- and
- a semiconductor chip package having a plurality of package terminals, wherein the substrate terminals are connected to respective ones of the package terminals,
- the method comprising the steps of:
- forming a nickel/gold electroless plated layer on each of the corresponding substrate terminal and a corresponding package terminal, wherein the nickel/gold electroless plated layer is composed of a nickel layer formed by nickel-phosphorus electroless plating and a gold layer formed on the nickel layer;
- and
- soldering the nickel/gold electroless plated layers on each of a corresponding substrate terminal and a corresponding package terminal to connect them, using a solder so that an intermetallic compound is formed at an interface surface between the nickel layer and the solder, wherein the intermetallic compound is shaped like a cauliflower as seen under magnification.
Dependencies are inferred from the claim text.