1. Field of the Invention
The present invention is generally related to packaging of integrated circuit devices, and more specifically providing a thermal paste for cooling an integrated circuit device during operation.
2. Description of the Related Art
Since the invention of the transistor, dissipation of heat during operation has been an important consideration in semiconductor device package design. Heat can damage the delicate and tiny structures which allow transistors to function as intended in a semiconductor device. Power drawn by transistors and other electronic devices must be dissipated to avoid build up of heat and the development of high temperatures which can degrade the devices by such mechanisms as dopant diffusion, metal migration including solder softening and reflow, or the like.
As semiconductor devices become smaller and smaller, it has become more difficult to provide efficient heat dissipation mechanisms. Current designs provide thermal pastes in conjunction with heat sinks that facilitate internal cooling of the semiconductor devices. Thermal pastes are generally high thermal conductivity interface materials that fill the gaps between the back-side of integrated circuit chips and the inside surfaces of heat sinks. Generally, semiconductor device package components, like the back surface of the integrated circuit and the inside of the cap must be chemically compatible with the thermal paste, so that the paste can adhere to them. Furthermore, the package must be designed such that the thermal paste filled chip-to-heat sink gap has sufficient thickness that it will form a reliable and efficient heat dissipating structure.
The present invention is generally related to packaging of integrated circuit devices, and more specifically to the placement of thermal paste for cooling an integrated circuit device during operation.
One embodiment of the invention provides an integrated circuit package, generally comprising a substrate, an integrated circuit chip coupled with the substrate, and a cap configured as a heat dissipation element, wherein a thermal paste forms an interface between a top surface of the integrated circuit chip and a bottom surface of the cap. The integrated circuit package further comprises at least one barrier element formed proximate to at least one side of the integrated circuit chip, wherein a region between the barrier element and the at least one side of the integrated circuit chip defines a reservoir for excess thermal paste pumped from between the top surface of the integrated circuit chip and the bottom surface of the cap.
Another embodiment of the invention provides a method for fabricating an integrated circuit package. The method generally comprises providing an integrated circuit chip coupled with a substrate, placing a barrier element on the substrate proximate to at least one side of the substrate, depositing a thermal paste on a portion of a top surface of the integrated circuit chip, and pushing the thermal paste towards the integrated circuit chip with a surface of a cap, wherein the pushing spreads the thermal paste over the top surface of the integrated circuit chip and into a region between the barrier element and the at least one side of the substrate to form a reservoir of thermal paste.
Yet another embodiment of the invention provides an integrated circuit package, generally comprising a plurality of integrated circuit chips coupled with a substrate, a cap configured as a heat dissipation element, wherein a thermal paste forms an interface between top surfaces of the integrated circuit chips and a bottom surface of the cap, and at least one barrier element formed proximate to at least one side of at least one of the integrated circuit chips, wherein a region between the barrier element and the at least one side of the integrated circuit chip defines a reservoir for excess thermal paste pumped from between the top surface of the integrated circuit chip and the bottom surface of the cap.
So that the manner in which the above recited features, advantages and objects of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings.
It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.
Embodiments of the invention are generally related to packaging of integrated circuit devices, and more specifically to the placement of thermal paste for cooling an integrated circuit device during operation. A barrier element may be placed along at least one side of an integrated circuit chip. The barrier element may contain thermal paste pumped out during expansion and contraction of the package components to areas near the chip. The barrier element may also form a reservoir to replenish thermal paste that is lost during thermal pumping of the paste.
In the following, reference is made to embodiments of the invention. However, it should be understood that the invention is not limited to specific described embodiments. Instead, any combination of the following features and elements, whether related to different embodiments or not, is contemplated to implement and practice the invention. Furthermore, although embodiments of the invention may achieve advantages over other possible solutions and/or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the invention. Thus, the following aspects, features, embodiments and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s). Likewise, reference to “the invention” shall not be construed as a generalization of any inventive subject matter disclosed herein and shall not be considered to be an element or limitation of the appended claims except where explicitly recited in a claim(s).
As illustrated in
In one embodiment of the invention, the cap 110 may be mechanically coupled with the substrate 130. For example, in
While the cap 110 is shown as a single solid structure, in alternative embodiments, the cap may include a plurality of independent distinct solid structures that are coupled together to form the cap 110. For example, in one embodiment, the protrusion 112 may be a separate element that is detachable from the rest of the cap 110. In embodiments where the cap 110 comprises multiple distinct structures, each of the multiple distinct structures may be formed with similar or distinct materials, for example, the same or different types of metals, plastics, ceramic, or the like.
The chip 120 may be any type of integrated circuit including, for example, processors, memory controllers, memory devices, or the like. In general, the chip 120 may include a plurality of transistors, resistors, inductors, capacitors, or other like circuit components that consume power and dissipate heat during operation. As illustrated in
In one embodiment, the substrate 130 may be a wiring substrate configured to route signals from one location of the chip 120 to another location on the chip 120. The substrate 130 may also be configured to provide power and/or ground connections to the chip 120 via the solder bumps 121. In some embodiments, the substrate 130 may be configured to exchange one or more input and/or output signals with the chip 120 during operation. While not shown in
As illustrated in
The integrated circuit package 100 is commonly known in the industry as a flip-chip type package structure. Under this arrangement, most of the heat generated by integrated circuit chip 120 is expected to be transferred to the cap 110. First, the heat flows from the front side 122 of integrated circuit chip 120 (i.e., a circuit area) to the back side 123 of integrated circuit chip 120. Then, the heat flows from the back side 123 of integrated circuit chip 120 to the lower surface 113 of cap 110 through thermal paste layer 150. Finally, heat flows from the surface 113 of cap 110 to the protrusions 111 of cap 110.
While a flip chip package is described herein, it should be understood that embodiments of the invention may be advantageously utilized in other chip configurations such as, for example, wire bonding configurations. In general, embodiments of the invention may be used in any type of integrated circuit package wherein transfer of heat from an integrated circuit chip to a heat sink is desired.
During operation of the chip 120, transistors and other circuit components of the integrated circuit may be turned off and on several times. The switching of transistors may result in cyclical generation of heat from the integrated circuit chip 120. Such thermal cycling may result in the expansion and contraction of the cap 110, the chip 120, and the substrate 130. The expansion and contraction, particularly expansion and contraction along the y axis (see
The removal of thermal paste from the interface between the cap 110 and the chip 120 may be detrimental to the efficient dissipation of heat from the chip 120. For example, in prior art systems, loss of thermal paste in the interface between the chip and the cap may generate voids and/or air pockets at the interface that result in poor and uneven thermal conductivity across the interface. Such uneven and poor heat dissipation may result in damage to the chip, or to electrical components of the chip due to overheating.
Furthermore, pumped out thermal paste may be deposited at undesired locations on a substrate, thereby damaging the integrated circuit package. For example, pumped out thermal paste may interact with adhesive material used to affix the cap to the substrate, thereby loosening or even detaching the cap from the substrate.
Embodiments of the invention provide at least one barrier element 140 (two exemplary barrier elements 140 shown in
In one embodiment, the barrier element 140 may be formed in a void region 170 formed between an outer leg 116 of the cap 110, and side wall portions of the chip 120 and the protrusion 112 of the cap 110, as is illustrated in
As illustrated in
The barrier element 140 may be made with any suitable material such as, for example, a ceramic, a plastic, metallic, or a composite material. In one embodiment, the barrier element 140 may be made sufficiently thin so as not to take up too much space in the package 100. For example, in one embodiment, the thickness w of the barrier element 140 may be between around 0.025 and 4.0 mm.
In one embodiment of the invention, the barrier element 140 may be coupled with both, the cap 110 and the substrate 130. For example, referring to
In one embodiment of the invention, a region 151 between the barrier element 140 and a side of the chip 120 may be used to store excess thermal paste that may act as a reservoir to replenish pumped out thermal paste from the interface between the chip 120 and the cap 110. For example, referring to
In one embodiment of the invention, a barrier element 140 may be provided along each side of a chip in an integrated circuit package.
While the barrier elements are shown encompassing all sides of each chip in the integrated circuit package of
In one embodiment of the invention a plurality of capacitors 360 may be placed in close proximity to the chips 310, 320, 330, and 340. The capacitors 360, in conjunction with the solid barrier element 350 may contain the thermal paste near the respective chips 310, 320, 330, and 340 and provide a thermal paste reservoir. For example, the shaded portions in
In one embodiment, the capacitors 360 may have a thickness that is greater than a thickness of the solid barrier element 350. In other words, as a barrier element, the solid barrier element 350 may take up less space on the integrated circuit chip in comparison to the capacitors 360. In one embodiment, the capacitors 360 may have one or more electrical functions such as, for example, providing for decoupling of the chips 310, 320, 330, and 340 from other package components. Furthermore, in some embodiments, the capacitors 360 may provide an additional source of power to the chips 310, 320, 330, and 340 during spikes in current requirements in any one of the chips 310, 320, 330, and 340.
While the elements 360 are described as capacitors hereinabove, in alternative embodiments, the elements 360 illustrated in
While the barrier elements illustrated in
In one embodiment, a barrier element 430 may be affixed to the substrate 420, as illustrated in
After coupling the chip 410 and the barrier element 430 to the substrate, thermal material may be placed on an exposed surface of the chip 410. In one embodiment of the invention, thermal material 440 may be placed on the chip 410 such that the thermal material 440 covers less than the total exposed surface area of the chip 410, as is illustrated in
In one embodiment of the invention, the volume of thermal material 440 deposited over the chip 410 may be greater than a desired volume of thermal material 440 at an interface of a cap and the chip 410. In one embodiment, the volume of thermal material 440 deposited may be sufficiently large to fill a reservoir region between the barrier element 430 and the chip 410 in addition to the interface between the chip 410 and a cap.
In one embodiment, after depositing the thermal material 440 on the chip 410, the thermal material may be pushed towards the chip 410 using a surface 451 of a cap 450, as illustrated in
Advantageously, by providing a barrier element configured to contain thermal paste material near an integrated circuit chip and store excess thermal paste to replenish thermal paste lost during thermal paste pumping, embodiments of the invention provide an efficient and reliable heat dissipation system.
While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
Number | Date | Country | Kind |
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2676495 | Aug 2009 | CA | national |