As an electronic device and an information communication device are down-scaled and integrated more highly, they are greatly affected by heat, static electricity and electromagnetic wave. For example, a microprocessor that is one of electronic components processes data at higher speed and a storage capacity of a semiconductor memory increases larger, it generates a large amount of heat and electromagnetic wave, such that it is greatly affected by heat, static electricity and electromagnetic wave.
According to the prior art, a metal shield case is used to shield an electromagnetic wave generated from an electronic component or an electronic component module mounted on a printed circuit board (PCB). In the manufacturing process of the metal shield case, a metal shield case is made by continuously pressing a metal sheet and is soldered on a PCB where electronic components or electronic component modules are mounted. In this manner, an electromagnetic wave is shielded.
When such a metal shield case is used, heat is generated from the electronic components or the electronic component modules. To solve this problem, a vent hole is formed in a predetermined portion of the shield case. That is, air inside the metal shield case is circulated by convection or is forcibly circulated by a fan through the vent hole, thereby emitting the heat to an outside.
However, if a large number of vent holes are formed in consideration of the heat emission, it is difficult to shield an electromagnetic wave. Meanwhile, if a small number of vent holes are formed, it is difficult to circulate an air. Accordingly, an optimum number of vent holes must be formed so as to rapidly transfer the heat to the outside and effectively shield the electromagnetic wave.
Meanwhile, the electronic components or the electronic component modules received in the metal shield case must be electrically insulated from the metal shield case. Therefore, the metal shield case must be made in a sufficient size.
However, if the metal shield case is made in a large size, a wide gap exists between the metal shield case and the electronic component, and an air space therein causes the heat conductivity to decrease. Also, due to the air space, there is a limit in protecting the electronic component from an external impact. Further, it is reverse to the down-scale and the high integration and a manufacturing cost also increases.
Regarding the electric insulation, a method for attaching an insulated tape to an inner side of a metal shield case has been proposed. However, this method has following problems. Since a heat conductivity of the insulated tape is low and an elastic force of the insulated tape is low, the electronic component cannot be protected from an external impact. Also, due to the additional process, a manufacturing cost may increase and the vent hole may be closed due to the insulated tape.
USPTO Backgrounds
USPTO Backgrounds