Soldering method and solder joint member

1. A method for soldering an electronic component including a palladium or palladium alloy layer formed on a surface of the electronic component and also including a soldering lead terminal onto a printed wiring board including a soldering land and plated through hole, comprising the steps of:

forming a solder layer containing tin and zinc as main components on surfaces of the land and the through hole by a HAL treatment;

inserting and mounting the lead terminal in the through hole; and

supplying the solder to the land and through hole by bringing the printed wiring board into contact with a jet flow of a solder containing tin and zinc as main components; and

wherein a flux for use in soldering the lead terminal to the solder contains an acrylic acid adduct of rosin and an activator including a sarcosine framework.

2. The method according to claim 1 , wherein:

the solder allows to wet the lead terminal while the solder wets up to reach an upper surface of the land via the through hole by bringing the printed wiring board in contact with the jet flow of the solder.

3. A method for soldering an electronic component including a soldering lead plated terminal onto a printed wiring board having a soldered through hole, comprising the steps of:

forming a solder layer containing tin and zinc as main components on a surface of the through hole by a HAL treatment;

inserting and mounting the lead terminal in the through hole;

bringing the printed wiring board into contact with a jet flow of a solder containing tin and zinc as main components, and

supplying the solder to the through hole so as to reduce or prevent lift-off; and

wherein a flux for use in soldering the lead terminal to the solder contains an acrylic acid adduct of rosin and an activator including a sarcosine framework.

4. The method according to claim 3 , wherein:

the solder allows to wet the lead terminal while the solder wets up via the through hole by bringing the printed wiring board in contact with the jet flow of the solder.

5. A flow soldering method for bringing a printed wiring board on which an electronic component is mounted into contact with a jet flow of a solder containing tin and zinc as main components to perform soldering, comprising the steps of:

forming a layer of a solder rich in tin not containing bismuth and lead and containing tin, silver, and copper as main components, a solder containing tin and silver as the main components, or a solder containing tin and copper as the main components, content of tin being 90 weight % or more, or a layer of tin on an surface of a land to be soldered and plated through hole of the printed wiring board beforehand;

mounting the electronic component; and

bringing the printed wiring board into contact with the jet flow of the solder containing tin and zinc as the main components to solder the board; and

wherein a flux for use in the flow soldering contains an acrylic acid adduct of rosin and an activator including a sarcosine framework.

6. The flow soldering method according to claim 5 , wherein:

a palladium or palladium alloy layer is formed on a surface of a soldering terminal of the electronic component to be mounted on the printed wiring board.

7. The flow soldering method according to claim 5 , wherein:

the electronic component mounted on the printed wiring board includes a lead terminal,

a palladium or palladium alloy layer is formed on the surface of the lead terminal, and the lead terminal is inserted and mounted in the plated through hole.

8. The flow soldering method according to claim 5 , wherein:

temperature of the jet flow of the solder containing tin and zinc as the main components falls within a range of 220° C. to 250° C.