The present invention is related to methods for fabricating semiconductor packages, and more particularly, to a method for fabricating heat-dissipating packages and the heat-dissipating structure applicable thereto.
In order to make a semiconductor package slimmer in size and volume, it is essential to be capable of manufacturing the semiconductor package with a high density of electrical components and circuits. Yet, such kind of semiconductor package could also generate more heat during operation. Therefore, if the heat generated by a semiconductor chip is not dissipated fast enough, the heat accumulated in the semiconductor package could jeopardize the electrical performance of the semiconductor chip and the reliability of semiconductor package severely. Moreover, in order to prevent contamination and entry of humidity or dusts from external environment, surfaces of the semiconductor chip are covered and isolated by a packaging encapsulant. However, the packaging encapsulant is generally made of a resin that has poor thermal-conductivity, as the heat transfer coefficient of the resin is about 0.8 w/mK. Consequently, heat generated by electrical components and circuits deployed on an active surface of the semiconductor chip cannot be efficiently dissipated to external environment via the packaging encapsulant, and thus a large amount of heat will accumulate within the semiconductor package, thereby resulting in damages to the chip and a reliability issue of the semiconductor package. Accordingly, in order to improve efficiency of heat dissipation, a solution utilized by the industry is to employ a heat-dissipating member in the semiconductor package.
Still, because the heat-dissipating member is completely covered by the packaging encapsulant, the only heat-dissipating pathway for the heat generated by the semiconductor chip is to be dissipated through the packaging encapsulant, thereby limiting the improvements in heat dissipation and fails to meet the requirements for heat dissipation. Accordingly, in order to effectively dissipate heat generated by the chip, the heat-dissipating member has to be sufficiently exposed from the packaging encapsulant to directly dissipate the heat generated by the semiconductor chip to the ambience during operation.
As shown in
Yet, fabrication of such semiconductor package 1 has several drawbacks. For instance, after the heat-dissipating plate 11 is attached to the chip 10, a molding process is performed, and the heat-dissipating plate 11 attached to the chip 10 is placed into a mold cavity of a mold to form the encapsulant 12. During the molding process, the top surface 11a of the heat-dissipating plate 11 should abut against a top surface of the mold cavity, in order to prevent the encapsulant from flushing over the top surface 11a of the heat-dissipating plate 11. Flushing as such not only decreases efficiency of heat dissipation of the heat-dissipating plate 11, but also forms an undesired appearance of the package, which requires extra post-treatment processes, such as deflashing to remove the encapsulant flushed over the top surface of the heat-dissipating plate. However, deflashing is an elaborate and time-consuming process, which often increases the cost of production and damages the product quite easily. In addition, if the heat-dissipating plate is abutted against the top surface of the mold cavity with excessive force, the chip 10 is easily damaged due to excessive stress applied thereto.
Moreover, in order to match the depth of the mold cavity to the distance between the top surface 11a of the heat-dissipating plate 11 and the top surface of a substrate 13, the adhesive layer between the heat-dissipating plate 11 and the chip 10, the adhesive layer between the chip 10 and the substrate 13, and the thickness of the heat-dissipating plate 11 must be precisely calculated, controlled and fabricated. To meet the aforementioned precision requirements, the complexity of fabrication has to be increased to a certain level, with an increase in cost of production. Therefore, it is quite impractical and inefficient to use such a fabrication method due to the increase of fabrication complexity of and cost of production.
Referring to
Referring to
Moreover, if the space above the heat-dissipating plate is adjusted and modified to provide more room for the mold flow to flow through, the amount of the packaging encapsulant used above the heat-dissipating plate will be increased. However, as the packaging encapsulant above the heat-dissipating plate must be removed in subsequent processes, such an increase of packaging encapsulant above the heat-dissipating plate not only wastes fabrication materials but also increases fabrication cost.
Accordingly, there still remains a need for providing a method for fabricating a heat-dissipating package and a heat-dissipating structure applicable thereto, which is not merely capable of avoiding damaging the semiconductor chip and flushing during the molding process, but also preventing warpage of the heat-dissipating structure during the molding process, to prevent delamination of the heat-dissipating structure from the chip to ensure quality of electrical connection between the chip and the substrate, as well as avoiding wasting fabrication materials and increasing fabrication cost.
In light of the shortcomings of the above prior arts, the primary objective of the present invention is to provide a method for fabricating a heat-dissipating package and a heat-dissipating structure applicable thereto, which can prevent warpage of a heat-dissipating structure during molding processes, so as to avoid delamination of a heat-dissipating structure from a chip and to ensure quality of electrical connection between a chip and a chip carrier.
Another objective of the present invention is to provide a method for fabricating a heat-dissipating package and a heat-dissipating structure applicable thereto, which can prevent an increase in fabrication cost and the amount of material used.
A further objective of the present invention is to provide a method for fabricating a heat-dissipating package and a heat-dissipating structure applicable thereto, without damaging chip and flushing during a molding process, so as to improve yield of production.
To attain the above and other objectives, the present invention is to provide a method for fabricating heat-dissipating packages, and the method comprises the steps of: mounting and electrically connecting a semiconductor chip to a chip carrier; attaching a heat-dissipating structure to the semiconductor chip, wherein the heat-dissipating structure comprises a main body having a first surface that has a covering layer formed thereon, a second surface opposite to the first surface, and a plurality of protruding portions from and formed at edges of the main body, wherein a size of the heat-dissipating structure is larger than a predetermined size of the package, such that the edges of the main body of the heat-dissipating structure outwardly extend beyond corresponding sides of the semiconductor chip, after the heat-dissipating structure is attached to the semiconductor chip via the second surface of the main body thereof; performing a molding process to form an encapsulant covering the heat-dissipating structure and the semiconductor chip, wherein the molding process includes disposing the chip carrier mounted with the semiconductor chip and the heat-dissipating structure into a mold cavity of a mold, filling the mold cavity with an epoxy mold compound (EMC) material to form the encapsulant, and removing the mold; performing a singulation process to form the package with the predetermined size; and performing a removing process to remove a portion of the encapsulant formed on the covering layer. Furthermore, in one embodiment, the covering layer may be a metal layer made of gold or nickel, so as to make an adhesive force between the covering layer and the heat-dissipating structure greater than an adhesive force between the covering layer and the encapsulant, thereby allowing a portion of the encapsulant formed on the covering layer to be easily removed during a removing process to expose the covering layer to the ambience. Accordingly, the heat generated by the chip can be effectively dissipated to external environment via the heat-dissipating structure and the covering layer. In another embodiment, the covering layer may be selectively made of at least one of a film, an epoxy material, and an organic layer, so as to make the adhesive force between the covering layer and the encapsulant greater than the adhesive force between the covering layer and the heat-dissipating structure, as an alternative to the aforementioned, thereby allowing the covering layer and the portion of the encapsulant formed on the covering layer to be removed at once during the removing process. As a result, the first surface of the main body of the heat-dissipating structure is exposed to the ambience, and therefore the heat generated by the semiconductor chip can be effectively dissipated.
Accordingly, the present invention purposes a method for fabricating a heat-dissipating package and a heat-dissipating structure applicable thereto. The heat-dissipating structure is attached to a semiconductor chip, and is formed with a covering layer on a surface thereof. Moreover, edges of the heat-dissipating structure are formed with a plurality of protruding portions upwardly protruded from the main body, and a size of the heat-dissipating structure is larger than a predetermined size of a heat-dissipating package. Thus, if the heat-dissipating structure is to be upwardly pushed by the bottom mold flow when the bottom mold flow below the heat-dissipating structure flows faster than the top mold flow thereabove, the protruding portions formed at the edges of the main body of the heat-dissipating structure can be abutted against the top surface of the mold cavity to avoid warpage of the heat-dissipating structure, at the time the chip carrier mounted with the semiconductor chip and the heat-dissipating structure thereon is placed in a mold cavity of a mold to be filled with EMC during a molding process. Therefore, the present invention not only prevents warpage of the heat-dissipating structure and delamination of the heat-dissipating structure from the chip, but also improves the quality of electrical connection between the chip and the chip carrier without enlarging the mold cavity. Consequently, arrangement and design of the present invention also reduce the amount of material used and the cost of production. Once an encapsulant is formed, which covers the heat-dissipating structure and the chip, the mold is then removed and the packaged structure is singulated according to a predetermined size. Subsequently, the portion of the encapsulant formed on the covering layer is removed, to form the heat-dissipating package integrated with the heat-dissipating structure.
Certain embodiments of the invention have other aspects in addition to or in place of those mentioned above. The aspects will become apparent to those skilled in the art from the following detailed description when taken with reference to the accompanying drawings.
The present invention can be more fully comprehended by reading the detailed description of the preferred embodiments listed below, with reference made to the accompanying drawings, wherein:
The following embodiments are described in sufficient detail to enable those skilled in the art to make and use the invention. It is to be understood that other embodiments would be evident based on the present disclosure, and that proves or mechanical changes may be made without departing from the scope of the present invention.
In the following description, numerous specific details are given to provide a thorough understanding of the invention. However, it will be apparent that the invention may be practiced without these specific details. In order to avoid obscuring the present invention, some well-known configurations and process steps are not disclosed in detail.
Likewise, the drawings showing embodiments of the structure are semi-diagrammatic and not to scale and, particularly, some of the dimensions are for the clarity of presentation and are shown greatly exaggerated in the drawings. Similarly, although the views in the drawings for ease of description generally show similar orientations, this depiction in the drawings is arbitrary for the most part. Generally, the invention can be operated in any orientation.
For expository purposes, the term “horizontal” as used herein is defined as a plane parallel to the plane or surface of the substrate, regardless of its orientation. The term “vertical” refers to a direction perpendicular to the horizontal as just defined. Terms, such as “on”, “above”, “below”, “bottom”, “top”, “side” (as in “sidewall”), “higher”, “lower”, “upper”, “over”, and “under”, are defined with respect to the horizontal plane.
As shown in
The first surface 41a of the heat-dissipating structure 41 is further covered by a covering layer 45. And the size of the heat-dissipating structure 41 is larger than the predetermined size of the package, so that the edges of the main body 410 of the heat-dissipating structure are allowed to outwardly extend beyond the corresponding sides of the semiconductor chip 40. Thus, it allows the protruding portions 411 to be positioned at areas outside the predetermined size of the package. In addition, the heat-dissipating structure 41 is attached to the semiconductor chip 40 via the second surface 41b thereof by the use of a thermal adhesive. (The borders of the predetermined size of the package are shown in dot lines in
The chip carrier 43 may be at least one of a Ball Grid Array (BGA) substrate, a Land Grid Array (LGA) substrate and a lead frame. The semiconductor chip 40 may be a flip-chip type semiconductor chip, which is electrically connected to the chip carrier 43 via a plurality of conductive bumps 400.
The covering layer 45 may be made from any material as long as the adhesive force between the covering layer 45 and the heat-dissipating structure 41 is relatively greater than that between the covering layer 45 and the encapsulant used for encapsulating the heat-dissipating structure 41 and the semiconductor chip 40 (to be illustrated below). For example, the covering layer 45 may be a metal layer made of gold or nickel.
Referring to
Subsequently, the packaging mold 46 is removed and the encapsulant 44 formed on the chip carrier 43, allowing the encapsulant 44 to cover the heat-dissipating structure 41 and the semiconductor chip 40.
Then, as shown
In the last step, a removing process is performed to remove the portion of the encapsulant 44 formed on the covering layer 45. Moreover, in this particular embodiment, the covering layer 45 is a metal layer made of gold and/or nickel, so that the adhesive force between the covering layer 45 and the heat-dissipating structure 41 is relatively greater and stronger than the adhesive force between the covering layer 45 and the encapsulant 44, allowing the portion of the encapsulant 44 formed thereon to be easily removed in order to expose the covering layer 45. Therefore, the heat generated by the chip 40 can be effectively dissipated to external environment via the heat-dissipating structure 41 and the covering layer 45.
To be concluded, the present invention mainly features in having a heat-dissipating structure with a covering layer formed on a surface thereof to be attached to a semiconductor chip, and edges of the heat-dissipating structure are formed with a plurality of protruding portions upwardly protruded from the main body of the heat-dissipating structure, and the size of the heat-dissipating structure is larger than a predetermined size of the heat-dissipating package. Therefore, while the chip carrier mounted with the semiconductor chip and the heat-dissipating structure thereon is placed in a mold cavity of a mold to be filled with EMC materials during a molding process, the protruding portions formed at edges of the heat-dissipating structure can abut against the top surface of the mold cavity to avoid warpage of the heat-dissipating structure, if the heat-dissipating structure is lifted by the bottom mold flow when the bottom mold flow below the heat-dissipating structure runs faster than the top mold flow thereabove. Accordingly, the present invention not only prevents warpage of the heat-dissipating structure and delamination of the heat-dissipating structure from the chip, but also improves the quality of electrical connection between the chip and the chip carrier without enlarging the mold cavity, thereby reducing the amount of material used and the cost of production. Once an encapsulant is formed, which covers the heat-dissipating structure and the chip, the mold is then removed and the package is cut according to a predetermined size. Subsequently, the portion of the encapsulant formed on the covering layer is removed, so that the heat-dissipating package integrated with the heat-dissipating structure is formed. Thus, the present invention not only solves drawbacks of the prior art, but also provides processes and configurations for highly efficient and economical manufacturing, application, and utilization.
While the invention has been described in conjunction with exemplary preferred embodiments, it is to be understood that many alternative, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations that fall within the scope of the included claims. The scope of the claims, therefore, should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements. All matters hitherto fore set forth herein or shown in the accompanying drawings are to be interpreted in an illustrative and non-limiting sense.
Number | Date | Country | Kind |
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095149739 | Dec 2006 | TW | national |