As part of the process involved in the development of popular light, compact, portable, yet elaborate, electronic apparatuses, such as notebook versions of personal computers (PCS), the density of circuit boards employed for these devices has been increased.
A plurality of circuit boards mounted at a high component density are accumulated in a limited space, also, the depositing of signal lines at a higher component density, i.e., more electrodes at larger intervals, is required for connectors used for the electrical connection of circuit boards.
FIG. 1 is a diagram showing a conventional circuit board connector, and FIG. 2 is a cross-sectional view of the connector in FIG. 1 taken along the line A-A'.
In FIG. 1, connector 10 comprises a first housing unit 12 and a second housing unit 14. At a bottom portion 16 of the housing unit 12, a plurality of connector pins 22 are provided in an array with their ends ranged along two slots 18 and 20. The arms of the connector pins 22 extend outward parallel to the surface of the bottom portion 16 of the housing unit 12, and are bonded to a plurality of electrodes on a circuit board 26, such as by soldering. Similarly, as seen in FIG. 2, connector pins 28 are provided with their arms extending outward parallel to a bottom portion 24 of the second housing unit 14, and are bonded to a plurality of electrodes on a circuit board 30 by soldering.
Two projecting portions 32 formed inside the first housing unit 12 extend outward away from the bottom portion 16, with the connector pins 22 running downward along their enclosed side walls. And two opposing recessed portions 34, as best seen in FIG. 2, formed in the second housing unit 14 are located at the side opposite the bottom portion 24, with the connector pins 28 running upward along the interior of their side walls. Thus, when the two housing units 12 and 14 are coupled together in the direction indicated by the downward pointing arrows in FIG. 2, the projecting portions 32 engage the recessed portions 34, and the arms of the connector pins 22 contact arms of the connector pins 28 and establish an electrical connection.
Although the conventional circuit board connector, which has a higher signal line density, satisfies the need for increases in the number of electrodes and in the sizes of the intervals for circuit board connectors, it has the following deficiencies.
That is, since the interval "D" between the two slots in the bottom of the housing unit 12, as shown in FIG. 2, is narrow and the slots (recessed portions) defining the interval "D" is deep, in the soldering process (reflow process) for bonding the bottom of the housing unit 12 to the board, an infrared ray for heating that is provided upward from the surface of the board does not satisfactorily irradiate the connector pin terminals in the interval "D." As a result, the solder is not adequately heated (melted) and soldering failures can and do frequently occur.
Furthermore, when a soldering failure occurs at a connector pin terminal in the interval "D," it is difficult to insert the distal end of a soldering iron into the narrow and deep interval "D" between the two slots. As a result, considerable problems are encountered when attempting to correct a soldering failure. In some cases, correction is not possible.