This application claims the priority benefit of Taiwan Patent Application Serial Number 097108438 filed Mar. 11, 2008, the full disclosure of which is incorporated herein by reference.
1. Field of the Invention
The invention relates to a heat sink structure, a semiconductor package and a method for configuring heat sinks on a semiconductor package and more particularly, to a heat sink structure pre-applied with a layer of solder, a semiconductor package with the above heat sink structure and a method for configuring the above heat sink structure on a semiconductor package.
2. Description of the Related Art
High-performance flip chip ball grid array (HFCBGA) package is one of the reinforced packages that has a metal ring to support a heat sink for covering the package. Referring to
However, the TIMs 132 and 134 are typically made of polymer material with a thermal conductivity of only about 4-5 W/mK. Therefore, when the package 100 consumes much power, said more than 100W, the conventional TIMs 132 and 134 cannot afford the requirement for heat dissipation.
Moreover, since the solder typically has a thermal conductivity of 30 W/mK, the solder made of pure indium, especially has a thermal conductivity of up to 80 W/mK, some manufactures have begun to offer such thermal interface material of solder. Referring to
Referring to
However, it is likely that there will be a lot of voids formed in the solder 206 on the heat sink 204 after the reflow process. This phenomenon frequently occurs in the solder made of indium. The voids in the solder 206 will have an adverse effect on heat dissipation.
Accordingly, there exists a need to provide a heat sink structure to solve the above-mentioned problems.
It is an object of the present invention to provide a heat sink structure that the heat sink has been applied with a solder.
In order to achieve the above object, the heat sink structure according to the present invention includes a first heat sink that has a through opening extending from the upper surface through to the lower surface. A solder made of such as indium is disposed in the through opening and on the upper and lower surfaces of the first heat sink, wherein the portion of the solder in the through opening is connected with the portions of the solder on the upper and lower surfaces.
It is another object of the present invention to provide a method for configuring heat sinks on a semiconductor package.
In order to achieve the above object, the method for configuring heat sinks on a semiconductor package according to the present invention is first to provide a substrate. A chip is disposed on the upper surface of the substrate. The active surface of the chip is faced down and electrically connected to the substrate by a plurality of first solder balls. The first solder balls are covered with an underfill encapsulant. A plurality of second solder balls is disposed on the lower surface of the substrate to enable the chip to be electrically connected to external circuitry. Furthermore, a metal ring is disposed on the upper surface of the substrate and surrounds the chip. Afterward, the heat sink structure with the solder on the first heat sink according to the present invention is disposed on the chip. A second heat sink is then disposed on the upper surface of the first heat sink. Finally, a reflow process is performed to have the portions of the solder on the upper and lower surfaces of the first heat sink firmly affixed to the second heat sink and the chip, respectively.
According to the method of the present invention for configuring heat sinks on a semiconductor package, the solder pre-applied on the heat sink acts as a thermal interface material. The heat sink with the solder can be attached to a chip and another heat sink by only a reflow process. The time for configuring the heat sinks on the package can be greatly reduced accordingly. Moreover, when there are voids formed in the portions of the solder between the heat sink and chip or between the heat sinks after the reflow process, the resulting package can be reflowed again to have the solder melted. The portion of the melted solder in the through opening will flow out to fill the voids. Therefore, the rework can be easily carried out without the need of detaching the heat sinks.
The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.
a illustrates the heat sink structure of the present invention, wherein a solder is disposed in the through opening and on the lower surface of the heat sink.
b illustrates the heat sink structure of the present invention, wherein a solder is disposed in the through opening and on the upper and lower surfaces of the heat sink.
c illustrates the heat sink structure of the present invention, wherein a solder is disposed in the through opening and on all of the upper surface and part of the lower surface of the heat sink.
a to 7b illustrate the method for configuring heat sinks on a semiconductor package according to the present invention.
Referring to
Referring to
Afterward, referring to
According to the method of the present invention for configuring heat sinks on a semiconductor package, the solder pre-applied on the heat sink acts as a thermal interface material. The heat sink with the solder can be attached to a chip and another heat sink by reflow process only once. The time for fixing the heat sinks on the package can be greatly reduced accordingly. Moreover, when there are voids formed in the portions of the solder between the heat sink and chip or between the heat sinks after the reflow process, the resulting package can be reflowed again to have the solder melted. The portion of the melted solder in the through opening will flow out to fill the voids. Therefore, the rework can be easily carried out without the need of detaching the heat sinks.
Although the preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
Number | Date | Country | Kind |
---|---|---|---|
097108438 | Mar 2008 | TW | national |