1. Field of the Invention
The invention relates to a membrane circuit board and, more particularly, to a membrane circuit board with high error tolerance and better quality control efficiency.
2. Description of the Prior Art
Recently, various integrated circuits (ICs) are widely applied in all kinds of applications, e.g. computer, PDA or smart phone, etc. The membrane circuit board is one of the common integrated circuit structures. One membrane circuit board may consist of substrate, active components and passive components. The substrate is usually made of insulation material, e.g. glass or porcelain. The active components (e.g. transistor or diode) and the passive components (e.g. resistor or capacitor) are formed onto the substrate by various processes, for example, vacuum evaporation process, sputtering process, silk screening process and metallization process.
A traditional membrane keyboard in prior art includes a substrate, an upper cover attached on the substrate and a membrane circuit board. The membrane circuit board is disposed between the upper cover and the substrate for sensing the electronic signals while users are typing on the keyboard.
Please refer to FIG. 1. FIG. 1 is a schematic diagram illustrating a membrane circuit board 1 in prior art. As shown in FIG. 1, the membrane circuit board 1 includes a substrate 10 and a plurality of signal pins 12. The signal pins 12 have terminals 120 with one identical width. The terminals of the signal pins 12 are coupled with an external electronic device (e.g. personal computer, laptop computer, mobile phone or PDA) for transmitting the electronic signals (typing input) to the external electronic device.
However, the signal pins of the membrane circuit board may have some mismatch or defect problem because mold injection process in forming the signal pins. Besides, the signal pins are arranged in a compact space, such that a defective product can not be distinguished from normal ones by human eyes of an Input Quality Control (IQC) person. Especially, when the defects happens on the power-controlling signal pin (which is usually the first or the last pin of these signal pins) of the membrane circuit board, it might cause the external electronic device not response to the turn-on request from users. In this case, it is hard for users or producers to confirm or examine the real bug or fault cause on the electronic device, which is not even power-on.
The invention discloses a membrane circuit board with high error tolerance and better quality control efficiency, so as to solve aforesaid problems.