| 摘要 |
<p>A printed circuit module (50) supports host processors and memories. The module permits easy upgrades and repairs of the semiconductor devices without requiring modification of the motherboard. The module (50) includes a multilayer printed circuit board with a symmetrical design, permitting integrated circuits to be placed on both sides of the board. Microvias (170) connect the contact points on a signal layer (88, 124) directly to a ground layer (92, 120) on the printed circuit board, thereby reducing the need for escape routing. This greatly simplifies the design layout of the module (50). The ground layer (92) is located between two signal layers (88, 96), thereby decreasing the crosstalk between the signal layers. The symmetrical design permits drilled vias (160) to extend from a quadrant of one integrated circuit and exit through a similar quadrant on the opposite side of the circuit board. The modular design also simplifies impedance matching. Testing of the module (50) may also be accomplished even when the module is not fully populated through the use of test bypass circuitry.</p> |
