1. Technical Field
The present invention relates to a plurality of solder bumps each of which joins electrodes together, an electronic component including the plurality of solder bumps and a method for manufacturing the electronic component. In particular, the present invention relates to an electronic component in which a chip or the like is installed by using of flip chip or BGA (Ball Grid Array), and a method for manufacturing the electronic component.
2. Background Art
As an electronic component, there is a semiconductor component including a substrate on which an LSI chip is mounted. FIG. 13A is a plan view of a general semiconductor component and FIG. 13B is a side view of the general semiconductor component. In FIG. 13A and FIG. 13B, a semiconductor component 100 has a structure that an LSI (Large Scale Integrated circuit) chip 102 having a plurality of electrode pads 101 is mounted over a resin substrate 104 having a plurality of electrode pads 103. In FIG. 13B, each of the electrode pads 101 and each of the electrode pads 103 are joined together via one of solder bumps 105.
When the LSI chip 102 or an apparatus including the semiconductor component 100 is heated, the LSI chip 102 and the resin substrate 104 expand. Since linear expansion coefficient of the resin substrate 104 is generally smaller than that of the LSI chip 102, thermal stress is generated at a joining area of the solder bump 105. Then, exfoliation of the joining area and destruction of the solder bump 105 occur in some cases.
A related art 1 (Japanese Patent Application Laid-Open No. 1998-223693) and a related art 2 (Japanese Patent Application Laid-Open No. 2005-340674) disclose a technology which suppresses exfoliation of the joining area and destruction of the solder bump due to the thermal stress.
The related art 1 discloses a technology that an LSI chip is arranged over a resin substrate, and the LSI chip is lifted from the resin substrate during a heating process. When the LSI chip is lifted while solder bumps are melting, the solder bumps are stretched and become into hourglass-shaped. Here, a contact angle between a peripheral surface of a solder bump and an electrode pad at the joining area (hereinafter, referred simply to as contact angle of joining area) of the hourglass-shaped solder bump is smaller than that of an usual solder bump. When the contact angle of joining area becomes small, the thermal stress which is applied to the joining area is reduced. Accordingly, it is possible to suppress exfoliation of the joining area and destruction of the solder bump.
Meanwhile, the related art 2 discloses a technology that four electrode pads of a LSI chip which are the nearest to corners of the LSI chip are arranged at positions which come off from a aligning position of others on the LSI chip, and all of electrode pads of a resin substrate are arranged at aligning positions on the resin substrate. Accordingly, four solder bumps which are the nearest to corners of an LSI chip slant toward nearby one of the four electrode pads of the LSI chip and solidify into hourglass-shape. When the LSI chip expands larger than the resin substrate during a heating process, the hourglass-shape solder bumps become into upright state. Accordingly, it is possible to suppress exfoliation of the joining area and destruction of the solder bump.