1. Field of the Invention
The present invention relates to a lead pin for a package substrate, and more particularly, to a lead pin for a package substrate, which connects the package substrate, on which an integrated circuit (IC) is mounted, to a main board.
2. Description of the Related Art
As the electronics industry has developed, various types of semiconductor packages have been manufactured. As interconnections for semiconductor packages have become highly dense, a Pin Grid Array (PGA) semiconductor package substrate on which a plurality of T-type lead pins are installed is widely used as a substrate which connects a package substrate, on which an IC is mounted, to a main board.
A typical package substrate generally uses an insertion-type pin, which is inserted into a through-hole, and a T-type lead pin, which is attached to a package substrate by soldering. Compared with the insertion-type pin, the T-type lead pin is commonly used because there is less limitation on the circuit configuration of the package substrate.
Since the use of Pb has recently been restricted due to the consideration of environmental impact of soldering, a Pb-free solder such as Sn—Ag—Cu or Sn—Sb is used. Thus, a solder melting temperature is high.
As the solder melting temperature increases, a solder which supports a lead pin may be melted by reflow heat during a reflow process for mounting an IC chip on a package substrate, causing the lead pin to be inclined.
Furthermore, a solder often flows over the top surface of the lead pin and then flows toward the coupling pin during the reflow process. Therefore, there is a need for technologies which can solve these problems.