CLIP-BONDED SEMICONDUCTOR CHIP PACKAGE USING METAL BUMPS AND METHOD FOR MANUFACTURING THE PACKAGE

Abstract

A clip-bonded semiconductor chip package comprises a lead frame having a pad and a lead; a semiconductor chip bonded onto the pad of the lead frame; a bonding pad on the semiconductor chip; metal bumps formed on the bonding pad; a clip having first and second portions coupled to each other wherein the first portion is bonded to the bonding pad via the metal bumps, wherein the second portion is bonded to the lead of the lead frame; and a package body made of a molding material around the lead frame, the semiconductor chip and the clip.

Claims

1. A clip-bonded semiconductor chip package comprising: a lead frame having a pad and a lead; a semiconductor chip bonded onto the pad of the lead frame; a bonding pad on the semiconductor chip; metal bumps formed on the bonding pad; a first conductive adhesive material on the bonding pad and the metal bumps; a clip having first and second portions coupled to each other wherein the first portion is bonded to the bonding pad via the metal bumps and the conductive adhesive material, wherein the second portion is bonded to the lead of the lead frame; and a package body made of a molding material around the lead frame, the semiconductor chip and the clip.

2. The clip-bonded semiconductor chip package of claim 1, wherein the metal bumps are made of a metal including copper or gold.

3. The clip-bonded semiconductor chip package of claim 1, wherein the conductive adhesive material includes a solder or a conductive epoxy-based adhesive material.

4. The clip-bonded semiconductor chip package of claim 1, wherein the second portion of the clip has a downset extending downwardly and inclinedly, wherein the downset has a distal end portion contacting the lead of the lead frame, wherein only an edge of the distal end portion contacts a surface of the lead of the lead frame, wherein a second conductive adhesive material is formed between the distal end portion and the lead of the lead frame.

5. The clip-bonded semiconductor chip package of claim 1, wherein the metal bumps are formed on the bonding pad using at least one of wire melting, sputtering, plating, and screen printing methods.

6. The clip-bonded semiconductor chip package of claim 1, wherein a top face of the clip is exposed to an outside of the package body.

7. The clip-bonded semiconductor chip package of claim 1, wherein a heat discharging slug is bonded to the clip on a top face thereof.

8. The clip-bonded semiconductor chip package of claim 7, wherein a top face of the heat discharging slug is exposed to an outside of the package body.

9. A clip-bonded semiconductor chip package comprising: a lead frame having first and second leads and a pad; a first semiconductor chip bonded onto the pad of the lead frame; a first bonding pad on the first semiconductor chip; first metal bumps formed on the first bonding pad; a first conductive adhesive material on the first bonding pad and the first metal bumps; a first clip having first and second portions coupled to each other wherein the first portion is bonded to the first bonding pad via the first metal bumps and the first conductive adhesive material, wherein the second portion is bonded to the first lead of the lead frame; a second semiconductor chip bonded onto a top face of the first clip; a second bonding pad on the second semiconductor chip; second metal bumps formed on the second bonding pad; a second conductive adhesive material on the second bonding pad and the second metal bumps; a second clip having third and fourth portions coupled to each other wherein the third portion is bonded to the second bonding pad via the second metal bumps and the second conductive adhesive material, wherein the fourth portion is bonded to the second lead of the lead frame; and a package body made of a molding material around the lead frame, the first and second semiconductor chips and the first and second clips.

10. The clip-bonded semiconductor chip package of claim 9, wherein the metal bumps are made of a metal including copper or gold.

11. The clip-bonded semiconductor chip package of claim 9, wherein the conductive adhesive material includes a solder or a conductive epoxy-based adhesive material.

12. A clip-bonded semiconductor chip package comprising: a lead frame having a pad and a lead; a semiconductor chip bonded onto the pad of the lead frame; a bonding pad on the semiconductor chip; metal bumps formed on the bonding pad; a clip having first and second portions coupled to each other wherein the first portion is bonded to the bonding pad via the metal bumps, wherein the second portion is bonded to the lead of the lead frame; and a package body made of a molding material around the lead frame, the semiconductor chip and the clip.

13. The clip-bonded semiconductor chip package of claim 12, wherein the metal bumps are formed on the bonding pad using at least one of wire melting, sputtering, plating, and screen printing methods.

14. The clip-bonded semiconductor chip package of claim 12, further comprising a conductive bonding material on the bonding pad and the metal bumps, wherein the first portion is bonded to the bonding pad via the metal bumps and the conductive bonding material.

15. The clip-bonded semiconductor chip package of claim 12, wherein the metal bumps are arranged on the bonding pad, and are made of a solderable metal.

16. The clip-bonded semiconductor chip package of claim 12, wherein the second portion of the clip has a downset extending downwardly and inclinedly.

17. The clip-bonded semiconductor chip package of claim 16, wherein the downset has a distal end portion contacting the lead of the lead frame, wherein only an edge of the distal end portion contacts a surface of the lead of the lead frame, wherein a second conductive adhesive material is formed between the distal end portion and the lead of the lead frame.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings, which are incorporated in and form a part of this specification and in which like numerals depict like elements, illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the disclosure.

[0024] FIG. 1 is a cross-sectional view of a conventional clip-bonded semiconductor chip package.

[0025] FIG. 2 shows cross-sectional views of a clip-bonded semiconductor chip package in accordance with a preferred first embodiment of the present disclosure.

[0026] FIG. 3 shows enlarged views of combinations between a lead of a lead frame and a clip downset end for a clip-bonded semiconductor chip package in accordance with an embodiment of the present disclosure.

[0027] FIG. 4 shows a cross-sectional view of a clip-bonded semiconductor chip package in accordance with a preferred second embodiment of the present disclosure.

[0028] FIG. 5 shows a cross-sectional view of a clip-bonded semiconductor chip package in accordance with a preferred third embodiment of the present disclosure.

[0029] FIG. 6 is a flow chart of a method for manufacturing a clip-bonded semiconductor chip package in accordance with an embodiment of the present disclosure.

[0030] FIG. 7 illustrates a process for forming metal bumps for manufacturing a clip-bonded semiconductor chip package in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTIONS

[0031] Examples of various embodiments are illustrated and described further below. It will be understood that the description herein is not intended to limit the claims to the specific embodiments described. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the present disclosure as defined by the appended claims.

[0032] FIG. 2 shows cross-sectional views of a clip-bonded semiconductor chip package in accordance with a preferred first embodiment of the present disclosure. In the present clip-bonded semiconductor chip package, a semiconductor chip 130 is bonded to a pad 120a of a lead frame 120 by a solder or an electrically conductive adhesive of an epoxy type; a bonding pad 130a of aluminum material is formed on the semiconductor chip 130. The bonding pad 130a is bonded to one end of a clip 150. The other end of the clip 150 is bonded to a lead 120b of the lead frame 120 by a solder or an epoxy-based electrically conductive adhesive. A surrounding thereof is filled with a thermosetting molding material such as EMC to form a package body 170.

[0033] As already mentioned above, on the semiconductor chip 130, the bonding pad 130a for bonding the clip 150 is formed. Since the bonding pad 130a is made of an aluminum material, the soldering is not possible. Thus, a separate metal layer must be formed on the bonding pad 130a for soldering bonding with the clip 150. However, in accordance with the present disclosure, in order to directly solder the clip 150 to the bonding pad 130a without performing the metal layer forming process, metal bumps 140 are formed on the bonding pad 130a of the semiconductor chip 130, as shown in FIG. 2.

[0034] The metal bumps 140 refer to means for facilitating the bonding between the bonding pad 130a of the semiconductor chip 130 and the clip 150 to enable the transfer of electricity and heat between the semiconductor chip 130 and the clip 150. The metal bumps 140 are embodied as a protrusion bonded on the bonding pad 130a. The metal bumps 140 are made of a metal material capable of soldering, such as copper (Cu) or gold (Au). The metal bumps 140 may have various shapes such as a spherical shape, an elliptical shape, or a cylindrical shape.

[0035] A conductive solder or a conductive epoxy-based adhesive (hereinafter, referred to as conductive adhering film 145) is applied on a surface of the bonding pad 130a on which the metal bumps 140 are formed. One end of the clip 150 is bonded on the conductive adhering film 145. Accordingly, the clip 150 is electrically connected to the metal bumps 140 by the conductive adhering film 145. Further, since the metal bumps 140 are conductive, it is electrically connected to the bonding pad of the semiconductor chip 130, and, thus, the semiconductor chip 130 and the clip 150 are electrically connected to each other.

[0036] The other end of the clip 150 is connected to a lead 120b of the lead frame 120 via conductive adhering means (a solder or epoxy-based conductive adhesive) 155. To this end, the other end of the clip 150 has a downset 150a extending downwards and in an inclined manner. The downset 150a end is coupled to the lead 120b of the lead frame 120.

[0037] In this connection, the downset 150a end of the clip 150 and the lead 120b of the lead frame 120 may be coupled in a state where flat surfaces are mutually bonded, i.e., in a surface contact state. However, the present disclosure is not limited thereto. As shown in FIG. 2 and FIG. 3, it is preferable that one side edge portion of the downset 150a end of the clip 150 is coupled to the lead 120b so as to contact the surface of the lead 120b. This is to improve the adhesion between the clip 150 and the lead 120b of the lead frame 120. In this connection, when the edge of the downset 150a end of the clip 150 contacts the surface of the lead 120b of the lead frame 120, a predetermined angle space is defined between a bottom end face of the downset 150a end of the clip 150 and the surface of the lead 120b and the lead frame 120. Then, the space is filled with the conductive adhering means 155 to fix the clip 150 to the lead 120b. In this connection, the contact area of the clip 150 and the conductive adhering means 155 becomes larger. Further, as the conductive adhering means 155 are cured, the clip 150 is firmly secured by the cured conductive adhering means 155. Thus, the bonding between the clip 150 and the lead 120b of the lead frame 120 is improved.

[0038] The lower edge of the downset 150a end of the clip 150 edge is shown in FIG. 3a to be configured in a pointed shape. Alternatively, the lower edge of the downset 150a end of the clip 150 edge is shown in FIG. 3b to be configured into a blunt shape. A angle between an inner inclined side face of the downset 150a and the surface of the lead 120b of the leaf frame 120 may be in a range of about 30 to 90 degrees.

[0039] As shown in FIG. 2, another bonding pad on the semiconductor chip 130 may be connected to another lead of the lead frame via a wire BW. In an alternative, another bonding pad on the semiconductor chip 130 may be connected to another lead of the lead frame via another clip.

[0040] Moreover, as shown in FIG. 2 and as mentioned above, after the clip 150 is bonded to the semiconductor chip 130 and lead 120b of the lead frame 120, the surrounding thereof is sealed with a molding material such as EMC. In this connection, as shown in FIG. 2a, the clip 150 may be configured to be surrounded by the molding material and not exposed to the outside. Alternatively, as shown in FIG. 2b, in order to discharge the heat generated from the semiconductor chip 130 and clip 150 to the outside, 2, the package body 170 may be formed by filling the molding material such that the top surface of the clip 150 may be exposed to the outside. FIG. 4 shows a cross-sectional view of a clip-bonded semiconductor chip package in accordance with a preferred second embodiment of the present disclosure. In this embodiment, the metal bumps 140 are formed on the bonding pad of the semiconductor chip 130, and the clip 150 is bonded to the bonding bad by the conductive adhering film 145. In addition, a heat dissipating slug 160 for discharging heat generated from the semiconductor chip 130 and the clip 150 to the outside is bonded to the upper surface of the clip 150. The heat dissipation slug 160 is formed in a rectangular plate shape made of a metal material having excellent thermal conductivity. The heat dissipation slug 160 is bonded to the clip 150 on a top face thereof, for example, by a conductive adhesive or ultrasonic welding. The heat dissipation slug 160 is disposed such that a top surface thereof is exposed to the outside of the package body 170.

[0041] FIG. 5 shows cross-sectional views of a clip-bonded semiconductor chip package in accordance with a preferred third embodiment of the present disclosure. In this embodiment, two semiconductor chips are stacked on top of each other, and each clip is bonded to each bonding pad of each semiconductor chip via each metal bump and each conductive adhering means.

[0042] More specifically, as shown in FIG. 5, a first semiconductor chip 130 is bonded by an adhesive AD on a pad 120a of the lead frame 120. First metal bumps 140 are formed on a first bonding pad 130a on the first semiconductor chip 130 . A first conductive adhesive film 145 is applied to the first bonding pad 130a with the first metal bumps 140 formed thereon. A first clip 150 is bonded onto the first metal bumps 140. Next, a second semiconductor chip 130 is bonded onto the first clip 150 by a second adhesive AD. Second metal bumps 140 are formed on a second bonding pad 130a. A second conductive adhesive film 145 is applied to the second bonding pad 130a with the second metal bumps 140 formed thereon. The second clip 150 is bonded onto the second metal bumps 140 and onto the second bonding pad 130. The other ends of the first clip 150 and the second clip 150 are coupled respectively via the first and second conductive adhering means 155 and 155 to the first lead 120b and the second lead 120b on the right and left sides of the lead frame 120 respectively. In this embodiment as well, as shown in FIG. 5a, the second clip 150 can be configured to be sealed within the package body 170. As shown in FIG. 5b, the top face of the second clip 150 can be configured to be exposed to the outside of the package body 170 in order to discharge the heat to the outside.

[0043] Until now, the structures of the clip-bonded semiconductor packages using metal bumps in accordance with various embodiments of the present disclosure have been described. Hereinafter, with reference to FIG. 6, a method for manufacturing the clip-bonded semiconductor package using metal bumps in accordance with an embodiment of the present disclosure will be described. FIG. 6 is a flow chart of a method for manufacturing a clip-bonded semiconductor chip package in accordance with an embodiment of the present disclosure.

[0044] As shown in FIG. 6, a method for manufacturing a clip-bonded semiconductor chip package in accordance with an embodiment of the present disclosure may include a semiconductor chip bonding operation S100, a metal bumps forming operation S200, a clip bonding operation S300, a bonding operation between a clip and a lead of a lead frame S400, and a molding operation S500.

[0045] As a first operation, in the semiconductor chip bonding operation S100, the semiconductor chip 130 is bonded to the pad 120a of the prepared lead frame 120 using an adhesive. In this connection, an aluminum bonding pad 130a is formed on the semiconductor chip 130 in advance. It is acceptable that a separate metal layer such as Ni/Ti/Au is not formed on the bonding pad 130a surface.

[0046] Subsequently, as a second operation, in the metal bumps forming operation S200, on the surface of the bonding pad 130a on the semiconductor chip 130, metal bumps 140 of a solderable metal such as copper or gold are formed.

[0047] FIG. 7 illustrates a process for forming the metal bumps 140 for manufacturing a clip-bonded semiconductor chip package in accordance with an embodiment of the present disclosure. As shown, the metal bumps 140 may be formed using a wire melting method. This is a method of applying a general wire bonding method. Specifically, as shown in FIG. 7, a capillary CP having a copper or gold wire W disposed therein is spaced from a bonding pad 130a formed on a semiconductor chip 13. An electrical spark is applied to a tip end of the wire W to melt the wire W to form a metal ball on the bonding pad 130a surface. Subsequently, a portion of the wire W connected to the metal ball is cut using the cutter C while slightly lifting up the capillary CP. The metal balls are then cooled and solidly bonded to the bonding pad surface to complete the metal bumps 140.

[0048] Alternatively, the metal bumps 140 may be formed using electrical plating, sputtering, screen printing, etc. In this connection, while the bonding pad 130a is masked with a mask with metal bumps pattern, the electrical plating, sputtering, screen printing, etc. may be applied to form the metal bumps 140.

[0049] After the metal bumps 140 are formed on the bonding pad 130a of the semiconductor chip 130, a clip bonding operation S300 is performed as a third operation. In this operation, a conductive adhering film 145 is applied to a bonding pad 130a having metal bumps 140 formed thereon. Then, the clip 150 is bonded on the conductive adhering film 145 on the bonding pad 130a.

[0050] Subsequently, as a fourth operation, the clip 150 and a lead 120b of the lead frame 120 are boned to each other S400. In this operation, the other end of the clip 150, specifically, the downset 150a end of the clip 150, is bonded to the lead 120b of the lead frame 120 with the conductive adhering means 155. In this connection, as shown in FIG. 2 and FIG. 3, it is preferable that one side edge portion of the downset 150a end of the clip 150 is coupled to the lead 120b so as to contact the surface of the lead 120b. This is to improve the adhesion between the clip 150 and the lead 120b of the lead frame 120. In this connection, when the edge of the downset 150a end of the clip 150 contacts the surface of the lead 120b of the lead frame 120, a predetermined angle space is defined between a bottom end face of the downset 150a end of the clip 150 and the surface of the lead 120b and the lead frame 120. Then, the space is filled with the conductive adhering means 155 to fix the clip 150 to the lead 120b. In this connection, the contact area of the clip 150 and the conductive adhering means 155 becomes larger. Further, as the conductive adhering means 155 are cured, the clip 150 is firmly secured by the cured conductive adhering means 155. Thus, the bonding between the clip 150 and the lead 120b of the lead frame 120 is improved.

[0051] Subsequently, as a fifth operation, in the molding operation S160, a surrounding around the lead frame 120, and the semiconductor chip 130, and the clip 150 is filled with a thermosetting molding material such as EMC to form a package body 170. In this way, the semiconductor chip package as shown in FIG. 2 is completed.

[0052] It will be understood that, although the terms first, second, third, and so on may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. Thus, a first element, component, region, layer or section described below could be termed a second element, component, region, layer or section, without departing from the spirit and scope of the present disclosure.

[0053] It will be understood that when an element or layer is referred to as being connected to, or coupled to another element or layer, it can be directly on, connected to, or coupled to the other element or layer, or one or more intervening elements or layers may be present. In addition, it will also be understood that when an element or layer is referred to as being between two elements or layers, it can be the only element or layer between the two elements or layers, or one or more intervening elements or layers may also be present.

[0054] Spatially relative terms, such as beneath, below, lower, under, above, upper, and the like, may be used herein for ease of explanation to describe one element or feature's relationship to another element s or feature s as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or in operation, in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as below or beneath or under other elements or features would then be oriented above the other elements or features. Thus, the example terms below and under can encompass both an orientation of above and below. The device may be otherwise oriented for example, rotated 90 degrees or at other orientations, and the spatially relative descriptors used herein should be interpreted accordingly.

[0055] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. As used herein, the singular forms a and an are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms comprises, comprising, includes, and including when used in this specification, specify the presence of the stated features, integers, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, operations, elements, components, and/or portions thereof. As used herein, the term and/or includes any and all combinations of one or more of the associated listed items. Expression such as at least one of when preceding a list of elements may modify the entire list of elements and may not modify the individual elements of the list.

[0056] Unless otherwise defined, all terms including technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this inventive concept belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0057] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure. The present disclosure may be practiced without some or all of these specific details. In other instances, well-known process structures and/or processes have not been described in detail in order not to unnecessarily obscure the present disclosure.

[0058] The above description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of exemplary embodiments, and many additional embodiments of this disclosure are possible. It is understood that no limitation of the scope of the disclosure is thereby intended. The scope of the disclosure should be determined with reference to the Claims. Reference throughout this specification to one embodiment, an embodiment, or similar language means that a particular feature, structure, or characteristic that is described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases in one embodiment, in an embodiment, and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.