Integration of SMD components in an IC housing

This nonprovisional application claims priority under 35 U.S.C. §119(a) to Euorpean Patent Application No. EP 09012018.9, which was filed on Sep. 22, 2009, and which is herein incorporated by reference.

1. Field of the Invention

The invention relates to an electronic component.

2. Description of the Background Art

An electronic component of this type is disclosed in JP2004241579 A. This electronic component comprises a semiconductor chip, mounted on a support platform of a lead frame, and a capacitor formed as an SMD component, which is arranged between the support platform, used as the ground terminal, and a connecting lead for supplying an operating voltage. To form a housing, the semiconductor chip and the SMD component as well are molded with a molding compound.

The mounting of such an SMD component on the lead frame occurs by means of an adhesive bond with an epoxy base, whereby an electrically conducting connection is produced by means of additives. It is a disadvantage here, however, that bleeding (epoxy bleeding) of the adhesive occurs, so that as a result the adhesive can spread uncontrolled to the bond fingers and bondability is therefore no longer assured.

To resolve this problem, DE 197 14 385 A1 proposes a method for limiting the bleeding of the adhesive, particularly during mounting of electronic components in a COB (chip on board) design, according to which by a method-related application of an obstacle, a self-contained barrier is formed by the use of suitable lacquers, e.g., of a solder resist. In this prior-art method, this barrier is placed as a closed ring in the gap between the mounting surface of a semiconductor chip and the associated bond pad.

The disadvantage of this prior-art method is not only the additional cost of producing an appropriate solder resist mask but also the additional process steps. Depending on the type of solder resist used, after application to the chip carrier it must be cured or dried, exposed to light, and developed.

It is therefore an object of the present invention to provide an electronic component of the aforementioned type, in which bleeding of the adhesive is effectively prevented by means of simple measures, without the disadvantages of the prior-art method.

In an electronic component of this type, according to the invention, in the area of the SMD component, the support platform and the connecting lead to create barriers are profiled in such a way that flowing of a free-flowing material from the contact surfaces, connected to the SMD structural element, of the chip carrier onto the support platform and onto the connecting lead is prevented.

These barriers represent an effective separator for the free-flowing material from the chip carrier contact surfaces contacted by the SMD component. Further, the electronic component of the invention is notable particularly in that the fabrication process in the backend need not be changed, rather the chip carrier (metal grid, lead frame) used in the backend process already has the mechanical barriers, which are formed preferably as trenches or elevations and can be produced by simple embossing on the chip carrier or the lead frame during the manufacturing process thereof, as a result of which particularly the area requirement for this type of barriers is very low. Overall, compared with the prior-art method, these advantages result in cost saving, both with respect to material and tool costs and with respect to shorter process times.

In an embodiment of the invention, the barriers are arranged transverse to the flow direction of the free-flowing material, as a result of which optimal orientation with respect to their function is assured.

It is advantageously, when according to an embodiment of the invention, the barriers run linearly between opposing edge areas of the support platform or the connecting leads in such a way that the contact surfaces are separated from the other area of the support platform or the connecting lead. No curvilinear barriers are therefore needed, as a result of which simple tools can be used, for example, for the creation of the barriers by embossing processes.

According to an embodiment of the invention, to form the contact surface connected to the SMD component, the support platform has at least one nose element, whereby the barrier is profiled in such a way in the support platform that the nose element in the transition region to the support platform is separated from the same. In this way, this nose element, which is the contact surface for the SMD component, can be separated in an especially simple way from the other area of the support platform by a linear barrier.

The support platform can be formed with a number of such nose elements, each of which has a contact surface and is connected via an SMD component to a connecting lead, the associated barriers on the support platform being produced as a continuous structure. A barrier, which extends linearly along the transition region of these nose elements on the support platform and serves simultaneously as a barrier for all contact surfaces on the nose elements, can thereby be produced with one tool.

A connecting lead can be formed on the support platform between two such nose elements, having contact surfaces for SMD components, in such a way that in the area of the nose elements a predefined distance to the nose elements is maintained. The barriers assigned to the contact surfaces of the two nose elements are thereby connected linearly via said connecting lead, so that it can be advantageously produced as a single barrier. This type of connecting lead generally has the same potential as the semiconductor component and is used as the ground terminal. This results in large degrees of freedom with respect to the design of the chip carrier or the lead frame with the associated barriers.

An embodiment of the invention results from the formation of at least one connecting lead with a contact surface, connected to the SMD component, and with a bond finger in such a way that the bond finger extends in the direction of the connecting lead and the contact surface for this is formed substantially at right angles to the connecting lead. As a result, the area on the connecting lead, which is in contact with at least one bond wire, is separated geometrically from the area on the connecting lead forming the contact surface for the SMD component, so that this also prevents free-flowing material, for example, the adhesive, from flowing under the SMD component into the bond finger.

In another embodiment of the invention, the connecting leads within the housing are profiled in the edge area thereof to create additional barriers, to prevent the entry of moisture from outside over these connecting leads. Preferably, the additional barriers on the connecting leads extend parallel to the lateral surface of the housing from which the connecting leads emerge from the housing.

Furthermore, according to an embodiment of the invention, it is advantageous when the support platform has at least one formed nose element, projecting from a housing surface of the housing, and this nose element is profiled to create a barrier running within the housing, whereby this barrier extends parallel to the housing surface from which the nose element projects. This nose element is used to support the support platform during the housing manufacturing process.

Finally, according to an embodiment of the invention, it is cost-effective to produce the barriers formed as trenches and/or as elevations by embossing the support platform and the connecting leads by means of an embossing tool during the production of the chip carrier or of the lead frame, whereby preferably the trenches are formed with a V-shaped cross section.

Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:

FIG. 1 shows a schematic illustration in a top plan view of an exemplary embodiment of an electronic component of the invention;

FIG. 2 shows a schematic illustration in a top plan view of another exemplary embodiment of an electronic component of the invention; and

FIG. 3 shows a perspective illustration of the electronic component of the invention according to FIG. 2 .

The electronic component 1 according to FIG. 1 comprises a semiconductor chip 2 , mounted on a support platform 4 a of a chip carrier (lead frame) 4 , and two passive SMD components 3 , for example, two capacitors.

The rectangular support platform 4 a has on one side of the rectangle two rectangular nose elements 9 , which are formed on support platform 4 a and in each case form a contact surface 7 for a connecting end of one of the SMD components 3 . The other connecting ends of the SMD components 3 in each case contact a connecting surface 6 , which is formed as a rectangular part of a connecting lead (lead finger) 4 b of chip carrier 4 . The end of a connecting lead 4 b , adjacent to support platform 4 a , forms a bond finger 5 , whereby connecting surface 6 and said bond finger 5 are at right angles to one another. Semiconductor chip 2 is connected via bond wires 13 to bond fingers 5 of both connecting leads 4 b.

The two SMD components 3 are connected electrically by means of a conductive adhesive with an epoxy resin base to the two contact surfaces 6 and 7 . To prevent bleeding of this adhesive from said contact surfaces 6 and 7 in the direction of support platform 4 a and in the direction of connecting leads 4 b , particularly in the direction of bond fingers 5 , barriers 10 are embossed in the material of connecting leads 4 b and support platform 4 a.

Said barriers 10 are formed as trenches or channels with a V-shaped cross section and separate contact surfaces 6 and 7 from the other areas of connecting lead 4 b or support platform 4 a , in that these barriers connect the opposite edges of contact surfaces 6 or nose elements 9 linearly. These barriers 10 thereby represent an effective separator for the free-flowing material from contact surfaces 6 and 7 of chip carrier 4 contacted by the two SMD components 3 .

In addition, the risk of bleeding (epoxy bleeding) is reduced also in that bond fingers 5 of connecting leads 4 b and contact surfaces 6 thereof are geometrically offset to one another, therefore are placed “diagonally,” as is evident from FIG. 1 and has already been described above.

According to FIG. 1 , between the two nose elements 9 another connecting lead 4 d is provided, which is formed via a nose element 15 as a transition part on support platform 4 a and serves as a bond finger for the ground terminal, whereby this bond finger is connected via a bond wire 13 to semiconductor chip 2 . The ground connection between nose element 15 and semiconductor chip 2 , however, instead of via bond wire 13 , can occur equally well by an electrical back connection of semiconductor chip 2 via a conductive adhesive; i.e., semiconductor chip 2 is then glued with its back onto chip carrier 4 . Hereby barriers 10 , separating nose elements 9 from support platform 4 a , are connected linearly via this transition part 15 , so that this nose element 15 as well is separated from support platform 4 a . The gap between nose elements 7 and 15 are formed as slits and end in a semicircle in the area of barrier 10 . Thereby, the bond finger of nose element 15 associated with connecting lead 4 d is also protected from a bleeding adhesive from contact surfaces 7 .

Finally, FIG. 1 shows another connecting lead 4 c , which within housing 8 has a bond finger, which is connected via a bond wire to semiconductor chip 2 .

The housing 8 fabricated by means of a molding compound in a molding process integrates both the active semiconductor component 2 and the passive SMD component 3 in a THD housing, as is shown, for example, in principle in FIG. 3 .

Electronic component 1 according to FIG. 2 differs from that according to FIG. 1 only in that on support platform 4 a on opposite sides in each case additional nose elements 12 are formed, which project from housing 8 and serve to support the support platform 4 a by a molding tool during the molding process of housing 8 , in order to prevent tipping of support platform 4 a during the molding process.

Another difference in regard to the embodiment of FIG. 1 is that the chip carrier (lead frame) 4 according to FIG. 2 has additional barriers 11 and 14 , which are impressed as trenches with a V-shaped cross section into the material of chip carrier 4 .

Thus, barriers 11 are arranged in the edge area within housing 8 on connecting leads (lead fingers) 4 b , 4 c , and 4 d transverse to the longitudinal direction thereof, therefore parallel to the edge of housing 8 . Barriers 14 are also arranged within housing 8 such that they separate nose elements 12 from support platform 4 a . Said barriers 11 and 14 function to prevent the penetration of moisture into housing 8 .

FIG. 3 shows in a perspective view the molded electronic component 1 , which integrates both active semiconductor component 2 and SMD component 3 in housing 8 . In particular, the two nose elements 12 projecting from housing 8 can be seen in this FIG. 3 .

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.