JPH03250653A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve heat radiation performance by connecting a radiation fin lead with a tab, installing the radiation fin lead to a cornered part of a package, and connecting it with an outer lead. CONSTITUTION:A low heat resistance type QFP.IC1 is continuously installed to a tab 2 formed in virtually squared board shape, a plurality of inner leads 3 laid out in a radiating manner near the four sides of the tab 2, and each inner lead 3 into one piece respectively. It is also provided with a plurality of outer leads 4 which project from the four sides of the tab 2 and bent in gull-wing shape. Four radiation fine leads 5 are continuously installed in a radiating manner from the four corners in one piece on the tab 2. When a pellet 9 gets exothermic during operation under a packaged state, the pellet 9 is directly bonded with the tab 2 incorporated into the fin lead 5 in one piece. Therefore, the heat is directly propagated to the radiation fin lead 5, thereby irradiating effectively the heat from the entire outer leads 5a by way of a printed wiring board 21.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a technique for improving the heat dissipation performance of a semiconductor device, particularly a semiconductor device equipped with a surface mount type pancage, and preventing defective bending of an outer lead. For example, the present invention relates to a device that can be effectively used in a low thermal resistance type semiconductor device equipped with a heat dissipation fin.

[Conventional technology]

As a low thermal resistance type semiconductor device equipped with a surface mount type package, for example, as described in Japanese Patent Laid-Open No. 61-152051, a plurality of heat dissipation fins are integrally formed on one tab. A semiconductor device in which a part of the heat dissipation fin is disposed outside the center of the resin-sealed package 2, and the protrusion of the heat dissipation fin is formed wide and has a gull wing shape. Some are bent.

In addition, Japanese Patent Application Laid-open No. 61-269345 discloses that by forming the width of the outer lead disposed in the package wider than the width of other outer leads, defective bending of the outer lead disposed on the outermost side is prevented. A semiconductor device configured to prevent this occurrence is disclosed.

[Problem to be solved by the invention]

However, in a low thermal resistance type semiconductor device such as that described in JP-A No. 61-152051, no consideration is given to preventing the occurrence of bending defects in the outer leads disposed at the outermost side. There is a problem in that the outer lead located at the outermost position tends to bend during handling.

In addition, the present inventor revealed that the semiconductor device described in Japanese Patent Application Laid-Open No. 61-269345 has a problem in that the heat dissipation performance is poor because no consideration is given to the heat dissipation performance. .

An object of the present invention is to provide a semiconductor device 1 that can improve heat dissipation performance and can prevent the outer leads disposed at the outermost positions from bending.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

An overview of typical inventions disclosed in this application is as follows.

That is, the heat dissipation fin lead is connected to the tab, this heat dissipation fin lead is arranged at the corner of the package, and the outer lead disposed at the corner of the package is connected to this heat dissipation fin lead. The outer lead connected to the heat dissipation fin lead has a cross-sectional area wider at least near its root than the other outer leads.

[Effect]

According to the above-mentioned means, the heat dissipation fin lead is connected to the tab, and the heat dissipation fin lead is disposed at the corner of the package, and the heat dissipation fin lead is disposed at the corner of the pan cage. Since the outer leads bonded to the tab are connected, the heat of the semiconductor pellet bonded to the tab is diffused from the tab to the heat dissipation fin lead, and is effectively radiated from the heat dissipation fin lead to the outer lead outside the pan cage. Therefore, heat dissipation performance is significantly improved.

In addition, the outer leads placed at the corners of the package have a wider cross-sectional area near their base than other outer leads, so the outer lead force applied to the corners (product assembly process In particular, it will not be bent even if external force is applied during delivery and mounting by the user.

〔Example〕

1st rj! J is a partially cutaway plan view showing a low thermal resistance type semiconductor device according to an embodiment of the present invention, FIG. 2 is an enlarged partial perspective view showing its mounting state, and FIG. 3 is a partially cutaway front view thereof.

In this embodiment, the low thermal resistance semiconductor device according to the present invention is a low thermal resistance semiconductor integrated circuit device (hereinafter referred to as a low thermal resistance QFP) equipped with a quad flat package.
It is called IC. ). This low thermal resistance type QFP/ICI includes a tab 2 formed in a substantially square plate shape, a plurality of inner leads 3 arranged radially close to each of the four edges of the tough 2, It is provided with a plurality of outer leads 4 which are integrally connected to each inner lead 3, project from each side of the tab 2, and are bent into a gull wing shape.
On the tab 2, four heat dissipating fin leads 5 are arranged radially from the four corners and are integrally connected.

The heat dissipation fin leads 5 are arranged so that their outer ends are located at the four corners of the square package and protrude outward, and their protruding ends substantially correspond to the outer leads 4. It is bent into a gull wing shape. The outer lead portion 5a as a protruding end portion of the heat dissipation fin lead 5 has a plurality of notches 6.
They are arranged at approximately equal intervals in the width direction, and are cut radially inward from the outer edge of the outer lead portion 5a, stopping near the end of the gull-wing shaped flat portion 5b of the outer lead portion 5a. , each notch 6 is formed so that the solid portion 5c in the flat portion 5b is approximately equal in width to the outer lead 4.

In addition, a plurality of grooves 7 as uneven surfaces are formed in the middle part of the heat dissipation fin lead 5 so as to cross the heat dissipation fin lead 5 at a substantially right angle by a suitable means such as coining (coining). ing.

A plurality of bonding pads 8 are arranged in groups of grooves 7 on the upper surface of the radiation fin lead 5, and are formed by coining so that the upper surface thereof becomes a flat surface.

This bonding ink hat 8 has a circular planar shape, and its area is set to the minimum area necessary for wire bonding work, which will be described later.

A pellet 9 on which an integrated circuit is built is bonded onto the tab 2 by appropriate means, and a plurality of electrode bands 10 are formed in a substantially annular shape on the outer peripheral edge of the upper surface of the pellet 9. There is. Of these electrode pads 10, those connected to the signal circuit etc. are arranged on the edge of the inner lead 3 group side of the pellet 9, and a wire 11 is bonded between these electrode pads 10 and each inner lead 3 to form a bridge. It is connected. Therefore, the signal circuit etc. in the integrated circuit of the pellet 9 are connected to the electrode pad lO and the wire 11.
, are electrically drawn out to the outside via the inner lead 3 and the outer lead 4.

On the other hand, among the electrode pads, the pad l that should be grounded
Oa is disposed at a corner of the pellet 9 facing the heat dissipation fin lead 5, and a wire 12 is bonded between these grounding pads 10a and the bonding pad 8 formed on the heat dissipation fin 5. It is bridged. That is, the wire 12 is connected to the ground pad 1
0a, and second bonding to the bonding hole 8 on the heat dissipation fin lead 5. Therefore, the ground circuit in the integrated circuit of the pellet 9 is electrically drawn out to the outside via the electrode pad 10a, the wire 12, the bonding pad 8, the radiation fin lead 5, and its outer lead portion 5a.

Here, the heat dissipation fin lead 5 has a bonded ink hat 8.
is specially formed and the area necessary for bonding is secured, so the second bonding of the wire 12 can be performed properly and easily without impairing the function of the heat dissipation fin lead 5. It turns out. Further, since the bonding ink hat 8 is formed in a circular shape, a substantially uniform bonding area is ensured from any position of the electrode pad 10a.

This low heat resistance type QFP-ICI is equipped with a pancage 13 integrally molded from resin into a substantially rectangular flat plate shape by transfer molding or the like. The radiation fin lead 5, the pellet 9, and the wires 11 and 12 are non-hermetically sealed. That is, the four groups of outer leads protrude from the four sides of the pan cage 13, and the outer lead portions 5a of the heat dissipation fin leads 5 are
The four corners of the package 13 protrude radially outward in the radial direction. The outer lead 4 and the outer lead portion 5a are bent downward outside the package 13 and then further bent horizontally outward, thereby forming a gull wing shape.

Next, the action will be explained.

The low thermal resistance type QFP/ICI according to the above structure is used by being surface mounted on a printed wiring board as shown in FIG.

That is, on the printed wiring board 21, a plurality of lands 22 for signal circuits are arranged in a square frame shape so as to correspond to the four groups of outer leads of the QFP/ICI, and a substantially rectangular shape is formed using solder material or the like. It is formed into a small flat plate shape, and lands 23 for grounding are arranged at the four corners of both land 22 group rows so as to correspond to the outer lead portions 5a of the heat dissipation fin leads 5 of the QFP/ICI. It is formed into a rectangular flat plate shape that substantially corresponds to the flat portion 5b of 5a.

This printed wiring board 21 is a low thermal resistance type QFP/ICI.
QFP-ICI outer lead 4 when surface mounted on
The group and heat radiation fin lead connecting outer leads 5a are brought into contact with lands 22 and 23 on the printed wiring board 21, respectively, with cream solder material (not shown) sandwiched between them. Subsequently, when the cream solder material is melted and solidified by an appropriate means such as reflow soldering, solder is formed between the outer lead 4 groups and the heat dissipation fin lead connecting outer lead 5a and the lands 22 and 23. Since the attached parts 24 and 25 are respectively formed,
The QFP/TCI is electrically and mechanically connected to the printed wiring board 21 and is surface mounted.

By the way, if the cutout part 6 is not formed in the gull-wing shaped flat part 5b of the heat dissipation fin lead connection outer lead 5a, a soldering part 25 is formed between the heat dissipation fin lead connection outer lead 5a and the land 23. When the heat dissipation fin lead connection outer lead 5a and the land 23 have a large contact area especially in the width direction,
Gas generated from volatile components contained in the cream solder material may remain in the soldering section 25, and voids may be formed within the soldering section 25.

However, in this embodiment, the gull-wing shaped flat portion 5 of the heat dissipation fin lead connecting outer lead 5a is
Since the notch 6 is formed in the portion b, even if gas is generated from the cream solder material sandwiched between the radiation fin lead connecting outer lead 5a and the land 23, voids will be formed in the portion 25 during soldering. It won't happen.

That is, even if gas is generated from the cream solder material sandwiched between the heat dissipation fin lead connection outer lead 5a and the land 23, the gas is generated in the gull-wing shaped flat portion 5b of the heat dissipation fin lead connection outer lead 5a. Since the soldered heat is immediately and sufficiently discharged to the outside from the cutout 6, no voids are formed in the soldered portion 25 formed between the heat dissipating fin lead connecting outer lead 5a and the land 23. .

When the pellet 9 generates heat during operation in the mounted state, since the pellet 9 is directly bonded to the tab 2 integrated with the heat dissipation fin lead 5, the heat is directly propagated to the heat dissipation fin lead 5, and the heat is transferred to the heat dissipation fin lead 5. Heat dissipation fin lead 5
Heat is effectively radiated from the entire outer lead 5a connected to the printed wiring board 21.

Here, the heat propagated from the bullet 9 to the radiation fin lead 5 is radiated from the outer lead portion 5a of the radiation fin lead 5 to the printed wiring board 21 via the land 25. At this time, since the notch 6 is cut only in the gull-wing shaped flat part 5b of the heat dissipating fin lead connecting outer lead 5a, the heat dissipation effect of the heat dissipating fin lead connecting outer lead 5a is reduced by the presence of the notch 6. Never.

That is, since the cross-sectional area of the rising portion 5d of the outer lead portion 5a, which serves as a heat transfer path in the heat dissipation fin lead 5, is not reduced by the cutout portion 6, heat is propagated without any obstruction in the outer lead portion 5a of the heat dissipation fin lead 5. The heat is radiated to the printed wiring board 21.

In addition, when this low thermal resistance type QFP/ICI is mounted on a printed wiring board, the outer lead portion 5a of the heat dissipation fin lead 5 is electrically connected to the ground terminal, so the circuit of the bellet 9 is connected to the ground pad 1. Oa,
It is grounded to the printed wiring board 21 through the wire 12, the bonding pad 8, the radiation fin 5, and the outer lead portion 6.

On the other hand, since the heat dissipation fin lead 5 protrudes to the outside of the package 13 with a large opening, the interface between the heat dissipation fin lead 5 and the package 13 becomes large, which increases the possibility of moisture infiltration from that interface, resulting in poor moisture resistance. It is possible that this will decrease.

However, in this embodiment, since the heat dissipation fin lead 5 has a groove 7 formed inside the package 3 so as to cross the fin 5, the deterioration in moisture resistance is effectively suppressed. . That is, this is because the groove 7 lengthens the leak path from the heat dissipation fin lead 5 to the pellet 9.

In addition, since the outer lead portion 5a disposed at the corner portion of the package 13 has a wider cross-sectional area near its root than the other outer leads 4, the outer lead portion 5a disposed at the corner portion of the package 13 is Even if an external force acts on the outer leads disposed at the corner portions during mounting, the outer lead portions 5a will not be accidentally bent.

According to the embodiment described above, the following effects can be obtained.

(1) A heat dissipation fin lead is connected to the tab, and this heat dissipation fin lead is arranged at the corner of the package, and an outer lead disposed at the corner of the pan cage is connected to this heat dissipation fin lead. Therefore, the heat of the semiconductor pellet bonded to the tab is diffused from the tab to the heat dissipation fin lead, and is effectively dissipated from the heat dissipation fin lead to the outer lead outside the package. Therefore, heat dissipation performance is significantly improved.

(2) Since the outer leads located at the corners of the package have a wider cross-sectional area near their base than other outer leads, it is difficult to easily implement them during the product assembly process, at the time of delivery to the user, and when the user mounts them. Sometimes, even if an external force acts on the outer lead located at the corner,
This outer lead is never bent.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, the outer lead connected to the heat dissipation fin lead is not limited to the configuration as in the above embodiment, but may be configured as shown in FIGS. 4, 5, and 6.

FIG. 4 shows an embodiment in which the radiation fin lead connection 5e is formed wide overall.

FIG. 5 shows an embodiment in which a part of the heat dissipating fin lead connecting outer lead 5f is formed wide, and the rest is formed to have the same width as the normal outer lead 4.

FIG. 6 shows an embodiment in which the radiation fin lead connecting outer lead 5g is formed to have the same width as the normal outer lead 4, and the dam member 5h is left uncut.

The above explanation will mainly focus on the low thermal resistance type QFP-
Although the case where the present invention is applied to an IC has been described, the present invention is not limited thereto, and can also be applied to a low thermal resistance type IC having a quad flat I-lid package (QFl).

[Effects of the Invention] The effects obtained by typical inventions disclosed in this application are briefly explained as follows.

By connecting the heat dissipation fin lead to the tab, placing this heat dissipation fin lead at the corner of the package, and connecting the outer lead disposed at the corner of the pan cage to this heat dissipation fin lead, bonding to the tab is achieved. The heat of the semiconductor pellet is radiated from the tab,
Since the heat is diffused into the inner leads and effectively dissipated from the heat dissipation fin leads to the outer leads outside the package, heat dissipation performance can be greatly improved.

In addition, by forming the outer leads arranged at the corners of the package so that the width of the cross-sectional area near the root of the outer leads is wider than that of other outer leads, it is possible to When implementing
Even if an external force acts on the outer leads disposed at the corner portions, they will not be bent.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway plan view showing a low thermal resistance type semiconductor device which is an embodiment of the present invention, FIG. 2 is an enlarged partial perspective view showing its mounting state, and FIG. 3 is a partially cutaway front view thereof. be. FIGS. 4, 5, and 6 are partial plan sectional views showing other embodiments of the present invention, respectively. 1...Low thermal resistance type QFP-IC (semiconductor device), 2.
...Tab, 3...Inner lead, 4...Outer lead, 5...Radiation fin lead, 5a...Outer lead part, 5e, 5f, 5g, 5 b-...Flat part, 5c
=-Solid ridge 5d...rising portion, 6...notch (gas venting space), 7...groove, 8...ponding pad, 9...bellet, 10.10a... - Electrode pad, 11.12... Wire, 13... Package, 21... Printed wiring board, 22... Land, 2
3...Land for outer lead connecting heat dissipation fin lead,
24.25...Soldering is part. Figure 4 Figure 6 Figure 5

Claims (1)

[Claims] 1. A heat dissipation fin lead is connected to the tab, and the heat dissipation fin lead is disposed at the corner of the package, and further, the heat dissipation fin lead is provided with a heat dissipation fin lead disposed at the corner of the package. A semiconductor device characterized in that the outer leads connected to the heat dissipation fin lead are connected to each other, and the outer lead connected to the heat dissipation fin lead has a cross-sectional area wider at least in the vicinity of its root portion than the other outer leads. . 2. The semiconductor device according to claim 1, wherein a plurality of outer leads are connected to the heat dissipation fin lead, and the base portions of these outer leads are formed in series. 3. The semiconductor device according to claim 1, wherein a plurality of outer leads are connected to the heat radiation fin lead, and dams of these outer leads are left uncut.