Patent Application
20100020505
1. Technical Field
The present invention relates to printed circuit boards in general, and more particularly, to a printed circuit board assembly having multiple land grid arrays for providing power distribution.
2. Description of Related Art
Generally, printed circuit boards are structures for distributing signals and power to components mounted thereon. Components, such as single-chip modules and multi-chip modules, can be mounted on printed circuit boards via land grid arrays.
Power connections for single-chip modules and multi-chip modules tend to be grouped directly under the modules where the heat dissipation capability is minimal. Meanwhile, the signal contacts tend to be arranged along the perimeters of the modules by using long traces. Having the signal contacts arranged along the perimeter of the modules requires perforations to be added to power planes surrounding the power connections because each signal contact requires a clearance hole (or anti-pad) to be placed in a power plane. Such addition of perforations will increase the resistance of the power planes and subsequently obstructs the current being delivered to the modules. On the other hand, the modules continue to demand more current, and the current requirement may exceed the capability of the power planes.
In accordance with a preferred embodiment of the present invention, a printed circuit board (PCB) assembly includes a first PCB, a second PCB and a land grid array (LGA). The first PCB includes signal interconnects for transmitting logic signals and power interconnects for transmitting power signals. In contrast, the second PCB includes only power interconnects for transmitting power signals exclusively. The second PCB also has significantly less vias than the first PCB. The second PCB is connected to the first PCB via the LGA.
All features and advantages of the present invention will become apparent in the following detailed written description.
The invention itself, as well as a preferred mode of use, further objects, and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein:
With reference now to the drawings, and in particular to
Power regulation circuits 160 can be mounted on second PCB 120 to provide power for module 130. Power regulation circuits 160 include voltage transformation module (VTM) capable of converting a relatively high DC voltage (e.g., 40 V) to a relatively low voltage (e.g., 1V), and multiplying the current where the VTM is remotely located from the voltage regulation portion of the power supply. Thus, power regulation circuits 160 can provide a relatively high current distribution to module 130.
First LGA 111 and second LGA 121 may share an LGA stiffener 150. LGA stiffener 150 may also include a thermal interface for thermal cooling and heat dissipation and an electrical insulator to isolate the plated through holes in PCB 120. In some cases, LGA stiffener 150 may be implemented by using a heat sink or cold plate.
First PCB 110 is similar to second PCB 120 in construction. However, first PCB 110 includes signal interconnects for carrying logic signals as well as power interconnects for carry power signals, and second PCB 120 primarily includes power interconnects to carry current to chip(s) and may include some control circuits for voltage regulation. For example, PCB 110 includes signal interconnects 220a-220b for carrying logic signals as well as power interconnects 210a-210b for carry power signals. In contrast, PCB 120 includes only power interconnects 230a-230b with limited VTM or similar control circuit for carrying chip current. Using two separate PCBs 110 and 120 allows them to be tailored to applications where PCB 110 can have a high percentage of signals leads for high-speed communications, and PCB 120 can have a high percentage of power distribution structure.
As shown in
With reference now to
As has been described, the present invention provides a printed circuit board assembly having multiple land grid arrays for providing power distribution.
While the invention has been particularly shown and described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention.
