JPH06295972A - Positioning structure for lead frame of hybrid ic and manufacture of hybrid ic - Google Patents

Abstract

PURPOSE:To prevent imperfect molding due to position deviation of a lead frame, and imperfect connection of a lead part due to heat at the time of resin molding. CONSTITUTION:Position alignment protrusions 28 formed on a metal substrate 21 are engaged with engaging holes of fixing segment parts 34 formed in a frame part 29 of a lead frame 31, and a lead frame 31 is positioned and fixed to the metal substrate 21 by caulking tips of the positioning protrusions 28. After that, a circuit element like an IC chip 25 is mounted on the metal substrate 21, and lead parts 29 are electrically connected with a wiring part 24 on the metal substrate 21 via bonding wires 35. After the whole part is resin- molded, leads and roots of the fixing segment parts 34 are cut off, and a tie bar 32 is cut and removed. Thus the manufacture of an hybrid IC is completed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid IC having improved lead frame positioning accuracy with respect to a metal substrate.
Lead frame positioning structure and hybrid IC
The present invention relates to a manufacturing method of.

[0002]

2. Description of the Related Art As an example of a conventional hybrid IC,
Toyota Loom Technical Report No. 25, APR. 1992 page 8 ~
There is a smart power module as shown on page 12. As shown in FIGS. 5 and 6, this device mounts a circuit element such as a drive IC 12 on a metal substrate 11 and solders a large number of lead portions 13 to a wiring portion 14 of the metal substrate 11, The entire structure is molded with the molding resin 15.

[0003]

By the way, a large number of lead portions 13 are formed in the frame portion 16 after the resin molding is completed.
Therefore, when the lead portions 13 are soldered to the metal substrate 11, a large number of lead portions 13 are
Are integrated as a lead frame 17 by the frame portion 16. Therefore, the lead portions 13 are soldered while the arrangement pitch of the lead portions 13 is accurately maintained, but the positioning accuracy of the lead frame 17 with respect to the metal substrate 11 is generally low, and the lead frame 1 with respect to the positioning jig is
7 and the fixed position of the metal substrate 11 overlap with each other, and the lead frame 17
However, the solder may be soldered in a state of being displaced by about 0.2 mm to 0.3 mm. For this reason, the setting state of the lead frame 17 in the mold may be incomplete during resin molding, which is a cause of defective molding.

Moreover, since the solder at the connecting portion of the lead portion 13 is softened by the influence of heat during resin molding, the lead portion 1 is applied by the force applied from the jig for clamping the lead frame 17.
The solder connection 3 may be incomplete or peeled off, which is also a cause of defective products.

The present invention has been made in view of the above circumstances, and a first object thereof is to provide a lead frame positioning structure for a hybrid IC capable of improving the positioning accuracy of the lead frame with respect to the metal substrate. ,
Further, it is possible to prevent a molding defect due to the displacement of the lead frame and prevent a lead part from being poorly connected due to heat at the time of resin molding, thereby providing a hybrid IC manufacturing method capable of improving a product yield. Second thing
The purpose of.

[0006]

To achieve the above object, a positioning structure for a lead frame of a hybrid IC according to the present invention comprises a positioning protrusion formed on a metal substrate and a frame portion of the lead frame. A fixed piece portion having a fitting hole to be fitted into the positioning projection, wherein the positioning projection is fitted into the fitting hole of the fixed piece portion, and by caulking the tip end portion of the positioning projection, The lead frame is positioned and fixed to the metal substrate.

When a hybrid IC is manufactured by utilizing this positioning structure, the positioning protrusion formed on the metal substrate is fitted into the fitting hole of the fixing piece formed on the frame portion of the lead frame, After the lead frame is positioned and fixed to the metal substrate by caulking the tip end of the positioning protrusion, the circuit element is mounted on the metal substrate, and the lead portion of the lead frame and the metal substrate are wired. After electrically connecting by bonding and then resin-molding the whole, the roots of the lead portion and the fixed piece portion of the lead frame may be cut to manufacture a hybrid IC.

[0008]

According to the positioning structure of the present invention, the positioning projection formed on the metal substrate is caulked at the tip of the positioning projection while being fitted into the fitting hole of the fixing piece formed on the frame portion of the lead frame. In addition, since both are positioned and fixed, it is possible to directly position and fix both without using a positioning jig, and it is possible to eliminate the cause of positional deviation due to the conventional positioning jig. In this case, the positioning accuracy of the lead frame with respect to the metal substrate is determined by the positioning accuracy of the fitting hole of the fixing piece, the positioning accuracy of the positioning protrusions, and the difference in radius between the two. The accuracy can be determined, and the radius difference between the two can be sufficiently fitted if it is, for example, 0.05 mm, so that high-accuracy positioning with an error of ± 0.05 mm or less is possible.

Further, the lead frame positioning and fixing structure by caulking allows the functions of fixing the lead portion and electrical connection to be shared, and the connection reliability of the lead portion is extremely high. "Wire bonding" that enables high-speed bonding and is inexpensive
Can be used. In addition, if wire bonding is used, there is no fear of deterioration of the strength or peeling of the connection portion in the subsequent heat treatment process such as the resin molding process. Further, the assembly by crimping and wire bonding also has an advantage that a flux cleaning such as the conventional soldering is unnecessary and the assembly process is clean.

In addition, the circuit element can be mounted and the wire bonding can be performed in advance in the state where the metal substrates are respectively crimped to the lead frames that are integrally connected in advance, and the soldering of the lead portions can be eliminated. It is possible to assemble the same as a mass-produced normal monolithic IC.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to SIP (Single In
line package) type hybrid IC
An embodiment applied to the present invention will be described with reference to FIGS. 1 and 2 are an enlarged plan view and a sectional view showing a state at the time of a wire bonding process (before resin molding) in the course of manufacturing the hybrid IC, and a completed form of the hybrid IC is an enlarged sectional view in FIG. 4 (f). It is shown.

First, the structure of the hybrid IC of this embodiment will be described. The metal substrate 21 has an insulating layer 23 on the metal plate 22.
The wiring portion 24 is formed via the. In this case, the metal plate 22 is made of, for example, alloy aluminum A having a thickness of 1.5 mm in consideration of press workability, strength, stress corrosion cracking resistance and the like.
5052-H34. If there is no problem in strength with the structure of the hybrid IC to be manufactured using metals other than the above, the metal plate 22 may be pure aluminum, or may be copper or a copper alloy plated with nickel. You may use. However, the thickness of the metal plate 22 is preferably 0.5 mm or more so as not to impair heat dissipation.

On the other hand, the insulating layer 23 is made of, for example, a polyimide resin having a thickness of about 20 μm or Si having improved thermal conductivity.
It is made of, for example, an epoxy resin having an O ₂ filler and a thickness of 80 μm. The insulating layer 23 is laminated on the entire upper surface of the metal plate 22 with a uniform thickness. This insulating layer 2
The wiring portion 24 formed on the metal layer 3 is, for example, a copper foil having a thickness of 80 μm plated with nickel of about 5 μm, and a gold film having a thickness of, for example, about 300 angstrom is electrolessly plated thereon.

An IC chip 25 such as a power IC or a monolithic IC is provided on the metal substrate 21 having the above structure.
Other circuit elements such as capacitors and capacitors are mounted.
The IC chip 25 is fixed on the metal substrate 21 with solder, silver paste, or the like, and the IC chip 25 and the wiring portion 24 are electrically connected by a bonding wire 26.
As the bonding wire 26, a gold wire or an aluminum wire having an appropriate thickness according to the current capacity may be used.

Positioning holes 27 (see FIG. 1) are formed on both sides of the metal substrate 21, respectively.
One positioning protrusion 28 is formed on each of the remaining three sides of the four sides of the metal substrate 21 except the one side on which the lead portion 29 is arranged. Each positioning protrusion 28 is
For example, it is formed to have a diameter of 1 mm and a height of 1 mm (before caulking), and is formed by punching from the back surface (surface on which the insulating layer 23 is not formed) side of the metal substrate 21.

On the other hand, the plurality of lead portions 29 are integrated as a lead frame 31 by the frame portion 30 until the resin molding process is completed. Further, each lead portion 29 is connected by a tie bar 32 at an intermediate portion in order to prevent deformation during the manufacturing process. Also, the frame part 3
At 0, three fixing pieces 34 having fitting holes 33 (see FIG. 2) are formed corresponding to the three positioning protrusions 28. Then, the fitting hole 3 of the fixing piece portion 34
3 is fitted in the positioning protrusion 28, the front end of the positioning protrusion 28 is caulked, whereby the metal substrate 21
The lead frame is positioned and fixed with respect to. In this positionally fixed state, the position of the pad 24a of each wiring portion 24 is set such that the position of the pad 24a of each wiring portion 24 is located on the extension line of each lead portion 29. The pads 24a of each wiring part 24 and each lead part 2
9 is electrically connected by a bonding wire 35. As the bonding wire 35, a gold wire or an aluminum wire having an appropriate thickness according to the current capacity may be used, as described above.

The metal substrate 21 and the IC chip 2 described above
The circuit elements such as 5 and the bonding portion of the lead portion 29 are resin-molded with a molding resin 36, and after the resin molding, the roots of the lead portion 29 and the fixing piece portion 34 are cut, and the tie bar 32 is cut off. IC is completed. In this hybrid IC, the back side of the metal substrate 21 is exposed to the outside without resin molding in order to enhance heat dissipation.

Next, a method of manufacturing the hybrid IC having the above structure will be specifically described. In advance, when the lead frame 31 is punched and formed, at the same time, the fixing piece portion 34 having the fitting hole 33 is formed in the frame portion 30. Further, the metal substrate 21 on which the insulating layer 23 and the wiring portion 24 are formed in advance.
Then, the positioning protrusion 28 is formed by punching from the back surface (the surface on which the insulating layer 23 is not formed) side [FIG.
(See (a)]. At this time, punching is performed from the back surface side of the metal substrate 21 using the punch 37 so that the insulating layer 23 and the wiring portion 24 on the surface of the metal substrate 21 are not scratched.

After that, as shown in FIG. 4B, the positioning protrusion 28 of the metal substrate 21 is fitted into the fitting hole 33 of the lead frame 31, and the tip of the positioning protrusion 28 is caulked. Position and fix. At this time, as shown in FIGS. 1 and 3, the metal substrates 21 are respectively crimped to the lead frames 31 that are integrally connected in advance.
As a result, the subsequent steps can be efficiently performed in the same procedure as the manufacturing steps of a normal mass-produced monolithic IC.

Next, as shown in FIG. 4 (c), after fixing the circuit element such as the IC chip 25 on the metal substrate 21 with solder, silver paste or the like, as shown in FIG. 4 (d), I
Bonding wires 26 and 3 are provided between the C chip 25 and the wiring portion 24 and between the lead portion 29 and the wiring portion 24, respectively.
5 for electrical connection. Thereafter, this assembly is housed in a molding die, and as shown in FIG. 4E, the circuit element such as the metal substrate 21, the IC chip 25, and the lead portion 29.
4 (f) by cutting the roots of the lead portion 29 and the fixed piece portion 34 and cutting off the tie bar 32 after resin-molding the bonding portion of the above with the molding resin 36.
The manufacturing of the hybrid IC as shown in FIG.

According to this embodiment described above, the positioning protrusions 28 formed on the metal substrate 21 are attached to the lead frame 3
The fitting hole 3 of the fixed piece portion 34 formed in the frame portion 30 of No. 1
In the state in which the positioning projections 28 are fitted to each other, they are positioned and fixed by caulking the tip ends of the positioning projections 28. Therefore, both of them can be directly positioned and fixed without using a positioning jig. The shift factor can be removed. In this case, the positioning accuracy of the lead frame 31 with respect to the metal substrate 21 is determined by the positioning accuracy of the fitting hole 33, the positioning accuracy of the positioning protrusion 28, and the difference in radius between the two, but the positioning accuracy of both is highly accurate due to the processing accuracy of the press. And the radius difference between the two is, for example, 0.0
If the distance is 5 mm, the fitting can be sufficiently performed, so that the positioning can be performed with high accuracy, for example, an error of ± 0.05 mm or less. For this reason, the lead frame 31 is set in the mold accurately at all times during resin molding, and molding defects do not occur.

Further, the lead frame 3 by caulking as described above.
With the positioning and fixing structure of No. 1, it becomes possible to divide the roles of each function of fixing the lead portion 29 and electrical connection.
As the electrical connection method of No. 9, "wire bonding" which has extremely high connection reliability, high-speed bonding and low cost can be used. In addition, if wire bonding is used, at a temperature of about 170 ° C. in the subsequent resin molding process, there is no fear of the strength of the adhesive portion being peeled off or peeling, and the connection failure of the lead portion 29 will not occur, and the above-mentioned molding will be performed. Combined with the defect prevention effect, the product yield can be improved. Moreover, the assembly by caulking and wire bonding has an advantage that the flux cleaning unlike the conventional soldering is unnecessary and the assembly process is clean.

In addition, the circuit board such as the IC chip 25 can be mounted and the wire bonding can be performed while the metal substrate 21 is crimped to each of the lead frames 31 that are integrally connected in advance. Since the soldering of 29 can be eliminated, the same assembly as a normal monolithic IC having mass productivity can be performed, and the cost can be reduced by the mass production effect. On the other hand, in the conventional soldering method, it is necessary to solder the lead part lastly in consideration of the thermal effect at the time of wire bonding of the IC chip, and therefore, it is compatible with the manufacturing process of a general monolithic IC. However, it has the disadvantage of poor productivity and poor mass productivity.

Further, in this embodiment, since the position of the pad 24a of each wiring portion 24 is located on the extension line of each lead portion 29, the work or the bonding head is not rotated during wire bonding. The lead portion 29 can be wire-bonded, and the wire bonding can be efficiently performed. However, the present invention is not limited to the above configuration, and the position of the pad 24a of each wiring portion 24 is set to the position of each lead portion 2 due to restrictions on the wiring space.
The configuration may be shifted from the extension line of 9, and even in this case, the intended purpose of the present invention can be sufficiently achieved.

In the present invention, the number of the positioning projections 28 (fitting holes 33) is not limited to three, and may be two or four or more, and, like the lead frame 31, a metal substrate. 21 are also connected, and 1 after resin molding
The metal substrate 21 may be divided into individual pieces. Further, in this embodiment, in order to improve the heat dissipation of the hybrid IC, the back surface side of the metal substrate 21 is exposed to the outside without being resin-molded.
As for C, the back side of the metal substrate may be resin-molded.

In addition, in the present invention, S as in the above embodiment is used.
Not only IP type hybrid ICs, but also DIP (Du
It goes without saying that various modifications can be made without departing from the scope of the invention, such as application to a hybrid IC of an al Inline Package) type.

[0027]

As is apparent from the above description, according to the present invention, the positioning protrusion formed on the metal substrate is fitted in the fitting hole of the fixing piece formed on the frame portion of the lead frame. , Caulk the tip of the positioning protrusion,
Since both are positioned and fixed, they can be directly positioned and fixed without a positioning jig, and the positioning accuracy can be improved, and the lead frame set in the mold is always aligned during resin molding. Accurately performed, no defective molding occurs.

Moreover, since the caulking structure allows the functions of fixing the lead portion and the electrical connection to be shared, the connection reliability of the lead portion is extremely high and high-speed bonding is possible. Since "wire bonding", which is low in cost, can be used, there is no fear of strength deterioration or peeling of the connection portion during the heat treatment process such as the resin molding process, and the connection failure of the lead portion does not occur. Moreover, the assembly by caulking and wire bonding has an advantage that the flux cleaning unlike the conventional soldering is unnecessary and the assembly process is clean.

In addition, the circuit element can be mounted and the wire bonding can be performed in advance in the state where the metal substrates are respectively caulked to the lead frames that are integrally connected in advance, and the soldering of the lead portions can be eliminated. It is possible to assemble in the same manner as a mass-produced normal monolithic IC, and it is possible to reduce the cost due to the mass-production effect.

[Brief description of drawings]

FIG. 1 is an enlarged plan view showing a state during a wire bonding process (before resin molding) according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line II-II in FIG.

FIG. 3 is an enlarged side view showing a state in which a large number of metal substrates are caulked to a large number of connected lead frames.

FIG. 4A to FIG. 4F are process diagrams for explaining a hybrid IC manufacturing procedure.

FIG. 5 is a view corresponding to FIG. 1 for explaining a conventional example.

6 is an enlarged cross-sectional view taken along line VI-VI in FIG.

[Explanation of symbols]

21 ... Metal substrate, 22 ... Metal plate, 23 ... Insulating layer, 24 ...
Wiring portion, 25 ... IC chip (circuit element), 26 ... Bonding wire, 28 ... Positioning protrusion, 29 ... Lead portion,
30 ... Frame part, 31 ... Lead frame, 32 ... Diver, 33 ... Fitting hole, 34 ... Fixing piece part, 35 ... Bonding wire, 36 ... Mold resin.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hatsuko Kato 1-1-1, Showamachi, Kariya city, Aichi Nihon Denso Co., Ltd.

Claims (2)

[Claims] 1. A positioning means for fixing a lead frame to a metal substrate of a hybrid IC in a positioning state, wherein the positioning protrusion is formed on the metal substrate, and the positioning protrusion is formed on a frame portion of the lead frame. And a fixed piece portion having a fitting hole to be fitted to the metal substrate, wherein the positioning projection is fitted into the fitting hole of the fixed piece portion, and by caulking the tip of the positioning projection, A lead IC positioning structure for a hybrid IC, wherein the lead frame is positioned and fixed to the lead frame. 2. The metal substrate by fitting a positioning protrusion formed on a metal substrate into a fitting hole of a fixing piece portion formed on a frame portion of a lead frame, and caulking a tip portion of the positioning protrusion. After positioning and fixing the lead frame with respect to, while mounting the circuit element on the metal substrate, electrically connecting the lead portion of the lead frame and the metal substrate by wire bonding, after this,
A method of manufacturing a hybrid IC, comprising manufacturing the hybrid IC by resin-molding the whole and then cutting the lead portions of the lead frame and the roots of the fixing pieces.