JPH08139265A - Molded package for semiconductor device - Google Patents

Abstract

PURPOSE: To provide a package which enables matching of characteristic imped ance of an outside lead-out lead and is excellent in transmission characteristic of a high frequency signal, relating to a mold package for a semiconductor device which seals a semiconductor element by resin. CONSTITUTION: After a semiconductor element 1 and a first outside lead-out lead 2 whereto an electrode thereof is connected are sealed by first resin 3, a second outside lead-out lead 4 forming a metallic layer for forming a conductive layer is mounted on the first resin 3. Thereafter, the first resin 3 and the second outside lead-out lead 4 are sealed by second resin 5. A second outside lead-out lead is grounded, and a thickness of the first resin 3 and a signal line width of a first outside lead-out lead are optimized for enabling matching of impedance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold package for a semiconductor device.

[0002]

2. Description of the Related Art In a conventional mold package for a semiconductor device, as shown in FIG. 7, a semiconductor element (61) and an external lead (62) are molded with one resin (63). Since a semiconductor device mold package having such a structure can be mass-produced at low cost,
It is most commonly used as a mold package for consumer semiconductor devices.

On the other hand, semiconductor devices used at particularly high frequencies, such as communication semiconductor devices and industrial semiconductor devices, are provided with ceramic packages in consideration of the characteristic impedance of signal lines in order to make use of the high-frequency characteristics of the semiconductor elements. Is used. However, in recent years, consumer electronic devices such as satellite broadcasts and mobile phones have been developed to have several hundred MHz to several G
Since a very high frequency of Hz is used, semiconductor devices used in these electronic devices are required to be inexpensive and have excellent high frequency characteristics. There is.

On the other hand, in the conventional molded package, although the cost can be reduced, the impedance of the signal line is not matched, so that the transmission characteristic of a high frequency signal of several hundred MHz or more is poor and the high frequency characteristic of the semiconductor element is reduced. There is a disadvantage that it will. Further, the price of a ceramic package having excellent high-frequency signal transmission characteristics is several tens to several hundreds of times that of a molded package, and thus it is not suitable for consumer semiconductor devices.

[0005] In order to solve these drawbacks, a method for matching impedance in a mold package has been proposed. For example, Japanese Patent Laid-Open No. 1-2028
53 (hereinafter referred to as the conventional example 1), Sekikai 63-12475
9 (hereinafter referred to as Conventional Example 2), JP-A-2-119166.
(Hereinafter referred to as Conventional Example 3). Conventional examples 1 to 3 will be described with reference to FIGS.

FIG. 8 is a sectional view of a high-frequency mold package proposed in Conventional Example 1 as viewed from the top.
In the first conventional example, the signal lead (72) and the grounding lead (71) are formed by the characteristic impedance of the distributed constant line constituted by the respective exposed leads and the characteristic impedance of the distributed constant line constituted by the non-exposed leads. The width (a1, a2) of the signal lead and the mutual interval (w1, w2) between the signal lead and the ground lead are set so that the characteristic impedances match.

FIG. 9 is a sectional view of a mold package proposed in the conventional example 2. As shown in FIG. In the second conventional example, a ground layer (83) is juxtaposed with an external lead (82) connected to a semiconductor element via an insulating adhesive resin (82). FIG. 10 is a cross-sectional view of the mold package proposed in Conventional Example 3. In the third conventional example, one external lead-out lead (98) made of metal and integrated with an island on which a semiconductor element is mounted, and at least one other lead-out lead independent of this lead both surround and shield the semiconductor element. It has a metal shield member (91).

[0008]

The above-mentioned conventional techniques have the following problems. The high-frequency mold package of Conventional Example 1 attempts to match the impedance of signal leads by optimizing the width and spacing of adjacent leads, but usually requires impedance matching with signal leads. The width of the opposing ground lead must be at least three times the width of the signal lead, and the effect is not sufficient with a limited package size. Further, there is a drawback that the electrode arrangement of the semiconductor element is restricted because the signal lead and the grounding lead always have to be adjacent to each other.

Further, the structure of the semiconductor device of the prior art example 2 has the effect of reducing the mutual interference (so-called crosstalk) of signal transmission between adjacent leads, and has the thickness of the insulating adhesive resin and the signal leads. By optimizing the width of the external lead, matching of the characteristic impedance becomes possible. However, in the manufacturing process, a piece of adhesive insulating resin is adhered to the lead frame, and furthermore, a positional shift is caused between the juxtaposed leads and the ground layer in order to attach the individual ground layer, that is, a metal plate. There is a disadvantage that it is easy to occur. Further, there is a drawback that the cost is high because the process is completely different from the usual process of manufacturing a resin-encapsulated semiconductor device in which an insulating resin is attached to a lead frame.

In the semiconductor device of Conventional Example 3, since the metal shield member is mounted on the lead frame and then molded, there is a disadvantage that the metal shield member is likely to be displaced. Further, this structure has a disadvantage that the cost is greatly increased because the shape of the metal shield member becomes complicated as the number of leads led out increases.

[0011]

According to the present invention, in a semiconductor device mold package for encapsulating a semiconductor element with a resin, a semiconductor element and a first external lead connected to an electrode of the semiconductor element are first. And a metal layer for forming a conductive layer on a portion of the first resin in which the first outer lead is encapsulated, the metal layer forming a second outer lead. A molded package for a semiconductor device, characterized in that the portion including the first resin and the metal layer is molded with the second resin as described above. According to the present invention, there is provided a mold package for a semiconductor device, wherein a first external lead is molded in a comb shape with a first resin, and a second external lead is formed in a cross-sectional structure close to coaxial. It is.

[0012]

In the present invention, the impedance of the signal lead can be matched. Specifically, the second external lead is grounded, and the thickness of the first resin and the first
The characteristic impedance can be matched by optimizing the signal line width of the external lead. Also, by devising the shape of the second external lead, crosstalk between adjacent leads can be almost eliminated. That is, as a double mold structure, after the primary molding, the second lead frame is overlaid and the secondary molding is performed, and the impedance matching is possible by optimizing the primary mold thickness and the secondary mold thickness.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view showing the structure of a mold package according to a first embodiment of the present invention.
FIG. 3 is a process chart showing a method for manufacturing a mold package according to the first embodiment of the present invention. As shown in FIG. 1, in the mold package of the present invention, a first external lead-out (2) connected to an electrode of a semiconductor element (1) is primarily molded with a first resin (3), and is formed on a first mold. A metal layer is placed on the second resin layer so as to form a second external lead (4), and the first and second external leads are secondarily molded with the first resin and the second resin (5).

Regarding the manufacturing method of this mold package,
This will be described with reference to FIGS. 2A and 2B and FIGS. 3C and 3D. As shown in FIG. 2A, also in the mold package of the present invention, as in the case of a normal resin-sealed semiconductor device, the first package is used.
The semiconductor element (1) is mounted on the island (22) of the lead frame, and the electrode of the semiconductor element (1) and the external lead (2) are connected by the thin metal wire (23). Next, as shown in FIG. 2B, a portion including the semiconductor element and the thin metal wire portion is sealed with a first resin (3).

Next, as shown in FIG.
A second external lead (4) forming a metal layer is placed on the resin (3). Next, as shown in FIG. 3D, the portion including the first resin and the second external lead (4) is sealed with the second resin (5). In the molded package of the present invention, by grounding the second external lead, it is easy to match the characteristic impedance of the first external lead.

In such a structure, the characteristic impedance (Z) of the signal lead is such that the width of the signal lead is (w) and the thickness of the resin (ie, the distance between the signal lead and the ground lead) is (h). ), When the relative dielectric constant of the resin is (ε _r ), it is expressed by [Equation 1]. For example, when it is desired to obtain a characteristic impedance of 50Ω, when ε _r = 4.0 of the resin, The ratio between the molding thickness and the signal line width of the first external lead may be 1: 2.

[Equation 1]

In the structure of the molded package of the present invention, impedance matching is performed by providing a ground layer constituting the second external lead, so that the width of the ground layer facing the signal line can be made sufficiently large. Therefore, there is an advantage that the effect of impedance matching is increased and the arrangement of electrodes of the semiconductor element is not restricted. Furthermore, the first resin sealing, the second external lead placement, the second
Since the steps up to the resin sealing are all performed with reference to the positioning holes of the first lead frame, there is no fear that the second lead-out leads are displaced. Also, there is an advantage that the cost does not increase even if the number of externally derived leads increases.

[Embodiment 2] Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is a diagram showing the shape of the first resin of the mold package according to the second embodiment of the present invention, and FIG. 5 is a diagram showing the shape of the external lead-out lead of the second embodiment. FIG. 6B is a top view showing the structure of the mold package according to the second embodiment of the present invention, and FIG.
FIG. 7 is a sectional view taken along line XX ′ in FIG. In the mold package of this embodiment, as shown in FIG. 4, a first external lead (32) connected to an electrode of a semiconductor element has a first configuration.
The first molding is performed by using the resin (33).
Are lead-out leads (32) are sealed with a first resin (33) having the shape shown in FIG. That is, the first external lead (32) is sealed in a comb shape with the first resin (33).

A metal layer is placed on a first resin (33), which is a primary mold, so as to form a second lead-out lead. 5 (a) and 5 (b). That is, the second external lead A (3) shown in FIG.
4) is formed in a U-shape so as to correspond to the first resin which is in the shape of a comb at the first external lead, and the second external lead B (35) is shown in FIG. b). The lead frame serving as the second external lead (ground) is connected to the second external lead A (34) in FIG. 5A and the second external lead B (35) in FIG. 5B. Is mounted and sealed with a second resin (36) as shown in FIG.

FIG. 6 (b) is a sectional view taken along line XX 'of FIG. 6 (a). The first external lead A (34) is formed by sealing the first external lead (32) with the first resin (33) and forming a U-shape on the first resin (33).
And a second external lead B (35), which is sealed with a second resin (36). By adopting such a structure, a structure close to coaxial as a cross-sectional structure around the signal lead can be realized, so that the characteristic impedance of the first external lead can be easily matched and crosstalk between adjacent leads can be almost eliminated. can do.

[0021]

As described above, according to the mold package for a semiconductor device of the present invention, the impedance of the signal leads can be matched and the cost can be increased even if the number of external leads is increased. There is an advantage that there is no. Further, by devising the shape of the second external lead, it is possible to substantially eliminate the crosstalk between adjacent leads.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a mold package according to a first embodiment of the present invention.

FIG. 2 is a view showing steps (a) and (b) of the method for manufacturing a mold package of FIG. 1;

FIG. 3 is a diagram showing steps (c) and (d) of the manufacturing method of the mold package of FIG.

FIG. 4 is a diagram showing a shape of a first resin of a mold package according to a second embodiment of the present invention.

FIG. 5 is a view showing a shape of an external lead-out according to a second embodiment of the present invention.

6A is a top view showing the structure of the mold package of the second embodiment of the present invention, and FIG. 6B is the same as FIG. 6A.
XX ′ sectional view of

FIG. 7 is a sectional view showing the structure of a conventional semiconductor device mold package.

FIG. 8 is a sectional view of the mold package of Conventional Example 1 as seen from a plane.

FIG. 9 is a cross-sectional view of a mold package of Conventional Example 2.

FIG. 10 is a sectional view of a mold package of Conventional Example 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor element 2, 32 First external lead 3, 33 First resin 4 Second external lead 5, 36 Second resin 22 Island 23 Fine metal wire 34 Second external lead A 35 Second Outer lead B 62, 82, 92 Outer lead 63 Resin 71 Ground lead 72 Signal lead 81 Insulating adhesive resin 83 Ground layer 91 Metal shield member

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 23/31

Claims (2)

[Claims] 1. A semiconductor device mold package for sealing a semiconductor element with a resin, wherein the semiconductor element and a first external lead connected to an electrode of the semiconductor element are molded with a first resin, There is a metal layer for forming a conductive layer on a portion of the first resin in which the first external lead is enclosed, and the metal layer forms a second external lead so that the first resin is formed. And a mold package for a semiconductor device, wherein a portion including the metal layer is molded with the second resin. 2. The first external lead-out is molded in a comb shape with the first resin, and the second external lead-out is formed to have a cross-sectional structure close to a coaxial shape. Molded package for semiconductor devices.