Packaged die for heat dissipation and method therefor

A heat spreader die holder that covers at least 50% of both major sides of a semiconductor die. The heat spreader die holder includes at least one opening. The heat spreader die holder is attached to a substrate. Electrically conductive structures of the die are electrically coupled to electrically conductive structures of the substrate.

BACKGROUND

This disclosure relates generally to packaged die, and more specifically, to packaged die with heat spreading capability.

2. Related Art

In the semiconductor industry in general, heat dissipation is an issue. Various heat spreading techniques have been used to aid in heat dissipation. High power transistors are particularly sensitive to this concern. The manufacturing of the die itself is tailored to address the issue of heat dissipation. Also the packaging of the die is important. The particular environment of the application can affect the ability to dissipate heat. Thus, one desirable feature is to have the ability to select the particular heat spreader, if one is necessary, to achieve the needed additional heat dissipation. Another important issue is the rate at which heat transfer can occur between the die and the package. Another issue the ability to reduce hot spots within the die.

Accordingly, there is a need to improve upon one or more of the issues discussed above.

DETAILED DESCRIPTION

A die is inserted in an opening of a die holder. The opening is slightly larger than the die so that the die is in close proximity to sides of the of the die holder. The die is held in place by thermal interface material that is either cured or of sufficient viscosity to maintain the position of the die in the opening. The die in this packaged condition is then easily mounted to a surface such as a surface of a printed circuit board (PCB). This is better understood by reference to the FIGs. and the following description. Die holder10, at least the top portion, should be a heat conductor such as a metal, which may be, for example, copper or aluminum.

Shown inFIG. 1is a die holder10for use in receiving a semiconductor die. As shown inFIG. 1, die holder10has a top side14, a first side16, a front side18, and an opening20. The opening is sized to have slightly greater width and thickness than the semiconductor intended to be placed in the opening.

Shown inFIG. 2is die holder10showing that die holder10has a back side22and an opening24in back side22that extends to opening20. There is a second side opposite side16of which an edge along top side14is shown.

Shown inFIG. 3is a die holder unit26that includes die holder10and a heat spreader28mounted on top side14of die holder10and that die holder10has a bottom side30. Instead of attaching heat spreader28to top side14, the top side could be formed with a heat spreader. Top side14and bottom side30are each considered a major surface of die holder10. The combination of heat spreader28and die holder10may be referenced as die holder unit26. Die holder10alone provides some heat spreading so that the expression heat spreader die holder may refer to just the die holder or the combination of the die holder and added heat spreading. The added heat spreading may be a separately added heat spreader or one manufactured as part of the die holder. Because die holder unit26includes both a die holder and a heat spreader it may be referenced as a heat spreader die holder.

Shown inFIG. 4is die holder unit26with a semiconductor die32in opening20. Opening20is slightly wider and slightly thicker than die32. Die32is inserted fully into opening20and is left protruding from opening20and exposing a plurality solder balls in a row including a solder ball34. The combination of die holder unit26and die32forms die holder assembly36.

Shown inFIG. 5is die holder assembly36mounted onto a printed circuit board38in which the solder balls, including solder ball34, are attached to printed circuit board38. The bottom side of die holder unit26is attached to printed circuit board38using an attaching material. Examples of an appropriate attaching material are epoxy and solder. This approach allows for a robust method for mounting die32to printed circuit board38in which there is excellent heat transfer from die32to heat spreader28through the die holder10. An alternative to this approach is to extend a top portion of front side18over a top side of die32. This would provide more protection to die32. Thus the protrusion of die32from front side18would be on the bottom side of die32. The sides of die32could be covered by extensions along the sides of die holder10as well. Printed circuit board38could be used just for mounting die holder assemblies or die in addition to die holder assemblies in which case printed circuit board38may be considered a package substrate.

Shown inFIG. 6is die holder unit26having a die42that is wire bonded to a printed circuit board50. An exemplary wire bonding connection is a bond wire44connected to a bond pad46on die42and connected to a bond pad48on printed circuit board50. This shows a single row of external connections analogous to the row of solder balls shown inFIGS. 4 and 5. In the case of wire bonds, bond pad46extends beyond the opening. An alternative is to extend the die holder to encompass die42but form an opening to expose the row of bond pads.

Shown inFIG. 7is a die holder unit52having a die holder54and a heat spreader56in which an opening57is formed in a major surface of die holder54. A die58is wire bonded through opening57to a printed circuit board62. An exemplary wire bond60shows an electrical connection between die58and printed circuit board62. A flange64extends from adjacent opening57to provide a convenient way to attach die holder unit52to printed circuit board62.

Shown inFIG. 8is a die holder assembly80that has die holder82and a die84inserted into an opening92of die holder82. Die holder82has an additional opening along each side, openings86and90, and a back side, opening88, of the top side so that a row of bond pads is exposed at each opening of which bond pad96is an exemplary bond pad. With openings along each side exposing bond pads on each side, nearly the whole perimeter of die84is available for bond pads that can be attached to a printed circuit board. Analogous to this, the openings can be along the bottom side and solder balls attached to solder pads in those openings. Thus, nearly the entire perimeter is available for attaching to a printed circuit board with solder balls in similar manner to attaching to a printed circuit board with wire bonds as shown for die holder assembly80. Opening92is greater laterally compared to openings86,88, and90to allow entry of die84into die holder82.

Each major surface preferably has at least 50 percent coverage by the die holder. Preferably the percent should be at least 75 percent. Thus it is shown that a die holder as described above provides a convenient way to connect to a printed circuit board in a manner that provides effective heat dissipation. With the close contact of the die to the die holder, heat is efficiently transferred to the die holder and potentially to bigger heat spreader. The result is an effective way to spread the heat to reduce the magnitude of hot spots on the die and dissipate the heat.

By now it should be appreciated that there has been provided a method of packaging a semiconductor die. The method includes providing a heat spreader die holder, the heat spreader die holder including a first opening. The method further includes inserting a semiconductor die into the heat spreader die holder through the first opening to form a semiconductor die assembly, wherein the semiconductor die includes a plurality of electrically conductive connector structures, wherein for the semiconductor die assembly, at least a majority of a first major side and at least a majority of a second major side of the semiconductor die are covered by thermally conductive structures of the heat spreader die holder. The method further includes physically attaching the semiconductor die assembly to a substrate. The method further includes electrically coupling the plurality of electrically conductive connector structures to a plurality of conductive structures of the substrate. The method may have a further characterization by which for the semiconductor die assembly, at least a portion of the semiconductor die extends out from the first opening, wherein the plurality of electrically conductive connector structures are located on the at least a portion of the semiconductor die. The method may have a further characterization by which the plurality of electrically conductive connector structures are electrically coupled to the plurality of conductive structures of the substrate with a plurality of solder balls. The method may have a further characterization by which the plurality of solder balls are attached to the plurality of electrically conductive connector structures of the semiconductor die prior to inserting the semiconductor die into the heat spreader die holder. The method may have a further characterization by which the electrically coupling the plurality of electrically conductive connector structures to the plurality of conductive structures of the substrate includes wire bonding the plurality of electrically conductive connector structures to the plurality of conductive structures of the substrate. The method may have a further characterization by which wherein the electrically coupling the plurality of electrically conductive connector structures to the plurality of conductive structures of the substrate includes wire bonding the plurality of electrically conductive connector structures to the plurality of conductive structures of the substrate. The method may have a further characterization by which for the semiconductor die assembly, at least 50 percent of each of three minor sides of the semiconductor die are covered by thermally conductive structures of the heat spreader die holder. The method may have a further characterization by which the physically attaching the semiconductor die assembly to a substrate includes attaching the assembly to the substrate such that the first major side of the semiconductor die and the second major side of the semiconductor die are parallel to a major side of the substrate. The method may have a further characterization by which when the semiconductor die assembly is attached to the substrate, the heat spreader die holder includes a thermally conductive structure positioned between the semiconductor die and the substrate. The method may have a further characterization by which wherein the physically attaching the assembly to a substrate includes attaching the assembly to the substrate such that the first major side of the semiconductor die and the second major side of the semiconductor die are perpendicular to a major side of the substrate. The method may have a further characterization by which for the semiconductor die assembly, thermal interface material is located between the semiconductor die and the heat spreader die holder.

Also disclosed is a semiconductor die assembly. The semiconductor die assembly includes a heat spreader die holder. The semiconductor die assembly further includes a semiconductor die at least partially within the heat spreader die holder, wherein at least 50% of a first major side of the semiconductor die and at least 50% of a second major side of the die are covered by thermally conductive material of the heat spreader die holder; wherein the semiconductor die includes plurality of electrically conductive connector structures. The semiconductor die assembly further includes a substrate, the heat spreader die holder attached to the substrate, the substrate including a plurality of electrically conductive structures electrically coupled to the plurality of electrically conductive connector structures, wherein the first major side and the second major side of the semiconductor die are parallel to a major side of the substrate. The semiconductor die assembly may further include a plurality of solder balls, wherein the plurality of electrically conductive connector structures are electrically coupled to the plurality of electrically conductive structures of the substrate with the plurality of solder balls. The semiconductor die assembly may have a further characterization by which the plurality of electrically conductive connector structures are located on the first major side of the semiconductor die, the first major side of the semiconductor die facing the major side of the substrate, the plurality of solder balls are located between the first major side of the semiconductor die and the first major side of the substrate. The semiconductor die assembly may have a further characterization by which the heat spreader die holder includes a major side structure of a thermally conductive material, the major side structure is located between the first major side of the semiconductor die and the first major side of the substrate at a location adjacent to the plurality of solder balls. The semiconductor die assembly may further include a plurality of bond wires, wherein the plurality of electrically conductive connector structures are electrically coupled to the plurality of electrically conductive structures of the substrate with the plurality of bond wires. The semiconductor die assembly may have a further characterization by which the plurality of electrically conductive connector structures are located on the first major side of the semiconductor die, the first major side of the semiconductor die faces away from the major side of the substrate. The semiconductor die assembly may further include thermal interface material located between the semiconductor die and the heat spreader die holder. The semiconductor die assembly may have a further characterization by which the heat spreader die holder includes a major side structure generally parallel to the first major side and the second major side, wherein the major side structure includes an opening at an edge location, the plurality of electrically conductive connector structures are electrically coupled to the plurality of electrically conductive structures of the substrate through the opening. The semiconductor die assembly may have a further characterization by which the heat spreader die holder is characterized as a unitary structure of thermally conductive material.

Disclosed also is a semiconductor die assembly. The semiconductor die assembly includes a heat spreader die holder. The heat spreader die holder further includes a semiconductor die at least partially within the heat spreader die holder, wherein at least 50% of a first major side of the die, at least 50% of a second major side of the die, at least 50% of a first minor side of the semiconductor die, and at least 50% of a second minor side of the semiconductor die are covered by thermally conductive material of the heat spreader die holder, wherein the semiconductor die includes a plurality of electrically conductive connector structures. The semiconductor die assembly further includes a substrate, the heat spreader die holder attached to the substrate, the substrate including a plurality of electrically conductive structures electrically coupled to the plurality of electrically conductive connector structures.