Patent Application
20140146479
This invention relates generally to the dissipation of thermal energy generated by semiconductor devices, such as memory chips.
Some systems that include single chip or multi-chip integrated circuit assemblies where the devices are mounted on a substrate with solder bonds, and a cap mounted in close proximity to the backsides of the devices require cooling.
The high circuit densities in modern integrated circuit semiconductor devices require that the heat generated by their operation be efficiently removed in order to maintain the temperature of the devices within limits that will keep the operating parameters of the devices within predetermined ranges, and also prevent destruction of the device by overheating.
The problems of heat removal are increased when the device is connected to the supporting substrate with solder terminals that electrically connect the device to appropriate terminals on the substrate. In such solder-bonded devices, the heat transfer that can be accomplished through the solder bonds is limited, as compared to back-bonded devices. Cooling of semiconductor devices can be achieved by immersing the devices in a suitable liquid coolant. However, these cooling techniques can result in corrosion of the device and substrate metallurgy, and also present rework problems. Cooling can also be achieved by using a fan to create forced air convection. However, system level requirements sometimes prohibit fan usage due to reliability. Cooling can also be achieved by providing a conducting link of material between the device and the cap or cold plate.
According to a non-limiting embodiment described herein, a system for use between a heat generating electronic device having a die having a shape placed thereon and a heat sink, includes a thermally conductive slug having a plurality of edges; a plurality of discrete strips each of the strips having a proximal end attaching to one of the edges of the thermally conductive slug, a distal end wherein the distal end is rigid for attachment to the heat sink, a flexible portion between the distal end and the thermally conductive slug wherein the slug may move as the electronic device moves and wherein the strips are comprised of two of more discrete layers, or strands that create a braid.
As disclosed in any previous claim the strips include strands only.
As disclosed in any previous claim, the strands include two or more strands made of copper, silver, aluminum, or graphite.
As disclosed in any previous claim, the strips include layers only.
As disclosed in any previous claim, the layers include two or more layers made of copper, silver, aluminum, or graphite.
As disclosed in any previous claim, the system further comprises a spring biasing the slug for urging the slug against the die.
As disclosed in any previous claim, the system further comprises a frame for disposal between the discrete strips and the slug, the frame having a plurality of sides corresponding to the same number of strips, each of the distal ends of the strips attaching to a side of the frame.
As disclosed in any previous claim, the frame, the strips, and the slug comprise a preform.
As disclosed in any previous claim, the system further comprises a spring abutting the slug.
According to a further non-limiting embodiment described herein, a system for dissipating heat, the system includes a heat generating electronic device; a heat sink; and an assembly disposed between the heat sink and the electronic device, the assembly including: a thermally conductive slug abutting the heat generating electronic device and having a plurality of edges; a plurality of discrete strips each of the strips having a proximal end attaching to one of the edges of the thermally conductive slug, a distal end wherein the distal end is rigid for attachment to the heat sink, and a flexible portion between the distal end and the thermally conductive slug wherein the slug may move as the electronic device moves and wherein the strips are comprised of two of more discrete layers, or strands that create a braid.
As disclosed in any previous claim, the strips include strands only.
As disclosed in any previous claim, the strands include two or more strands made of copper, silver, aluminum, or graphite.
As disclosed in any previous claim, the strips include layers only wherein the layers include two or more layers made of copper, silver, aluminum, or graphite.
As disclosed in any previous claim, the system further comprises a spring biasing the slug for urging the slug against the die.
As disclosed in any previous claim, the system further comprises a die disposed atop the heat generating electronic device between the heat generating electronic device and the slug.
As disclosed in any previous claim, the system further comprises a thermal layer disposed between the heat generating electronic device and the slug.
As disclosed in any previous claim, the system further comprises a frame for disposal between for disposal between the discrete strips and the slug, the frame having a plurality of sides corresponding to the same number of strips, each of the distal ends of the strips attaching to a side of the frame.
As disclosed in any previous claim, the frame, the strips, and the slug comprise a preform.
As disclosed in any previous claim, the system further comprises a spring abutting the slug.
As disclosed in any previous claim, the preform is preattached to either of the heat generating electronic device or the heat sink
These and other features may be best understood from the following drawings and specification.
Referring to
Referring now to
Each strip 70 may have a particular composition so that each strip acts as a spring to urge the slug 55 against the compressive die 20 to ensure contact between the slug 55 and the die 20. If the electronic heat sink system 10 is to be used in an environment where grease that may be used would not be expected to withstand the vibration experienced in the electronic heat sink system 10, a spring 95, such as a leaf or other spring, may be utilized to ensure that the slug 55 is maintained (i.e., abutting or attaching) against the die 20 in all instances to ensure that thermal transfer is carried out in every instance. It is also possible that the flexible strips 70 do not act as springs, but are flexible/bendable to enable installation where manufacturing and installation tolerances, which may not always be ideal, have to be accounted for during assembly.
To install the attachment system between the microprocessor 15 and the heat sink 45, the slug 55 abuts the die 20 with either a thermal layer 90 of adhesive or grease therebetween. The strips 70 are bent or flexed inwardly or outwardly relative to the slug 55 to the desired length L so that the distal edge portions 73 abut the flat body 47 at a desired location on the heat sink 45. The portions 85 may be attached to the flat body 47 by using a thermal layer 90 such as adhesive therebetween, by mechanical attachment 105 by rivets or nuts and bolts, or both to ensure continued contact with the heat sink 45. The distal edge portion 73 may also be connected to the radial edge 49 and to the inner surface 51 to maximize heat transfer to the heat sink 45.
In another embodiment referring to
In another embodiment referring to
Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this invention. For that reason, the following claims should be studied to determine the true scope and content of this invention.
