JPH0629443A - Manufacture of hybrid integrated circuit - Google Patents

Abstract

PURPOSE:To decrease the lead pitch of a hybrid integrated circuit to achieve high mounting density by grasping a ceramic substrate between two lead frames and fixing the grasped part using high temperature melting solder. CONSTITUTION:A lead frame with a required lead pitch is produced by punching a metal sheet, which is thinner than one used for the conventional lead frame. The ends of the leads 18 and 19 of the lead frame are bent by 1/2 of the thickness of a ceramic substrate 1 so that they can grasp the substrate as shown in the Figure. The grasped part is fixed by high-melting solder and molded with resin 9. According to this method, it is possible to produce a lead frame with a lead pitch of 0.5mm and thus realize a hybrid integrated circuit that enables high-density mounting of surface mount devices.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a hybrid integrated circuit having a reduced lead pitch. In order to miniaturize the electronic equipment which constitutes the information processing apparatus, it is necessary to improve the degree of integration of the semiconductor integrated circuit, and to miniaturize the circuit components to be mounted and miniaturize and increase the density of the wiring board.

Therefore, chip parts are often used for semiconductor parts and circuit parts to be mounted on a wiring board.
In addition, the wiring board has been improved in integration degree from the initial single-layer printed board to a multilayer printed board and a surface-mounted printed board.

[0003]

2. Description of the Related Art As a method for mounting semiconductor integrated circuits such as LSI and VLSI, instead of the conventional lead insertion component mounting, chip components are fixed on a wiring board with an adhesive or a eutectic alloy, then solder or wire. Surface Mounting Technology for connecting circuits by bonding (SMT)
Has become the mainstream, and flat packages are often used.

By the way, the inventors of the present invention have proposed a hybrid integrated circuit (Hybrid I
With regard to (C) as well, there is an increasing demand for surface mount type
QFP (Quarter Flat Package) type surface mount hybrid integrated circuit (abbreviated as SMD-HYB) has been developed and used.

FIG. 3 is a schematic sectional view showing this structure.
That is, a wiring pattern such as a thick film resistor 2, a land, a bonding pad, a conductor line 3 and a through hole 4 is formed on the front and back surfaces of a ceramic substrate 1 made of alumina or the like by using a thick film HYB manufacturing technique, and a semiconductor chip 5 is formed. Then, the chip capacitor 6 and the like are mounted, the semiconductor chip 5 is connected to the bonding pad by using the wire 7, and the chip capacitor 6 is welded to the pad provided on the conductor line 3 by soldering. .

After the hybrid integrated circuits are formed on both surfaces of the ceramic substrate 1 by using the through holes 4 as described above, the lead terminals 8 and the land portions patterned on the end surface of the ceramic substrate 1 are subjected to high-temperature soldering or the like. Use to weld.

Finally, the resin exterior 9 is applied by the transfer molding method to complete the hybrid integrated circuit. Further, FIG. 4 is a plan view (A) and a side view (B) of the QFP type resin package formed in this way, which has a huge number of lead terminals 8 for high-density mounting. ing.

[0008] For example, regarding the SMD-HYB whose package size currently used is 32 mm in width, 28 in height, and 4.4 mm in height,
104 lead terminals, 44 mm wide, 40 vertical, height
With respect to the 4.4 mm SMD-HYB, the number of lead terminals reaches 168, but for the latter package size, there is a demand for the practical application of SMD-HYB with more than 200 (for example, 256) lead terminals. There is.

Here, as a measure for satisfying such requirements, it is necessary to miniaturize the conductor lines and chips formed on the ceramic circuit board by patterning.
In addition to this, it is necessary to change the structure of the lead terminal.

That is, the conventional lead terminal is joined to the ceramic circuit board 1 as shown in FIG. That is, a method is used in which a clip lead 12 having a sandwiching portion 11 at the tip is formed, the ceramic substrate 1 is inserted into the sandwiching portion 11, and welding is performed using high-temperature solder, a gold-tin eutectic alloy, or the like.

Here, conventionally, a copper alloy having a thickness of 0.2 to 0.3 mm is used as the material of the lead terminal, and a clip lead type structure is adopted as shown in FIG. 6, and the lead pitch 13 is 0.8 mm. However, in order to increase the number of pins, it is necessary to reduce the lead pitch to 0.5 mm.

However, in the case of the clip lead type structure, 0.1 mm is required as the gap 14 between the holding portions, and
The width of the lead pieces 15 must be 0.2 mm, and the mutual spacing 16 between the lead terminals must be at least 0.1 mm.

Therefore, the lead pitch in the case of the clip lead type structure is limited to 0.6 mm, and the above dimension is the processing limit even when a copper alloy having a plate thickness of 0.15 mm is actually used.

[0014]

The surface mount hybrid integrated circuit (SMD-HYB) developed by the inventor and the like needs to have a higher packing density because it is necessary to miniaturize the electronic equipment that constitutes the information processing apparatus. There is a demand for an increase in the number of lead terminals in the conventional package area.

Therefore, the conventional lead pitch of 0.8 mm is changed to 0.5 m
We would like to realize multiple pins with m, but there is a problem that it cannot be realized with the conventional clip lead type, and this solution is a problem.

[0016]

SUMMARY OF THE INVENTION The above-mentioned problems are solved by providing a lead having a required lead pitch by punching a metal plate having a thickness smaller than that of a metal plate used for a lead frame. The step of forming the frame and the tip of this lead frame should be at least 1 / of the ceramic substrate.
Bending process so that there is a difference in thickness of 2 and using two lead frames, using high melting point solder with the ceramic substrate sandwiched between the tips, the land of the ceramic substrate and the tip of the lead frame It can be solved by forming a method for manufacturing a hybrid integrated circuit, characterized by including at least a step of welding and fixing.

[0017]

In the present invention, since it is impossible to set the lead pitch to 0.5 mm in the conventional clip lead, as shown in FIG. 2, the ceramic substrate is not sandwiched by one lead terminal as in the conventional case. Lead piece with bent tip 1
Prepare a leadframe with 8,19 and this lead piece 1
The land of the ceramic substrate is sandwiched by 8,19.

FIG. 1 is a sectional view showing the structure of an SMD-HYB to which the present invention is applied. The ceramic substrate 1 is sandwiched by lead pieces 18 and 19, and the sandwiched portion is welded and fixed by using high temperature solder. The figure shows a state where a resin sheath 9 is applied.

By adopting such a method, it is possible to clear the lead pitch limit of 0.6 mm when the conventional clip lead structure is adopted, and it is possible to realize a lead pitch of 0.5 mm.

Here, as a method of mounting the lead terminals on the ceramic substrate, two sets of lead frames are fixed and integrated to the lands of the ceramic substrate which are patterned by screen printing of conductive paste. Insert it and weld it using high temperature solder or gold-tin (Au-Sn) eutectic solder as before.

Then, after the resin molding, a plating process is performed on the lead terminals to improve solderability. At this time, the two lead terminals are completely integrated by performing a thick plating. You can

For this reason, the thickness of the lead frame used in the manufacturing process according to the present invention is at least 1 / the conventional thickness.
2 is enough. The other manufacturing steps are exactly the same as the conventional one.

[0023]

[Example] A conventional lead frame has a thickness of 0.25 mm of Cu.
Alloy is used, but in the practice of the present invention 0.1 mm
A Cu alloy having a thickness of 1 was used to prepare a lead frame in which the tip end was bent in the opposite direction as shown in FIG. 2 by punching.

The SMD-HYD was formed by the same process as the conventional process. That is, a thick film paste is printed on the front and back surfaces of a ceramic substrate having through holes at predetermined positions to form wiring patterns such as lands, bonding pads, conductor lines, and through holes, and then at predetermined positions on this substrate surface. After the semiconductor chip and a chip component such as a chip capacitor were bonded and fixed, the semiconductor chip was connected by the wire bonding method, and the capacitor was connected by soldering.

Next, two lead frames were used, and the land of the ceramic substrate and the leading end of the lead frame were welded and fixed to each other by using high melting point solder with the leading end sandwiching the ceramic substrate.

Next, transfer molding of epoxy resin is performed on the ceramic substrate with the tip end of the lead frame welded and fixed, and then the lead portion of the resin-molded lead frame is solder-plated to a thickness of 10 μm. After the application, the leads are bent and subsequently cut from the lead frame to complete the hybrid integrated circuit element.

[0027]

As described above, according to the present invention, a QFP having a small lead pitch of about 0.5 mm and a large mounting density is provided.
A type of SMD-HYB can be put to practical use.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of SMD-HYB to which the present invention is applied.

FIG. 2 is a perspective view showing a configuration of a lead terminal according to the present invention.

FIG. 3 is a schematic cross-sectional view showing a configuration of a surface mount hybrid integrated circuit (SMD-HYB).

FIG. 4 is a plan view (A) and a side view (B) of a surface mount hybrid integrated circuit (SMD-HYB).

FIG. 5 is a plan view (A) and a side view (B) showing a structure of a conventional lead terminal.

FIG. 6 is a plan view of a lead terminal of a clip lead type.

[Explanation of symbols]

 1 Ceramic substrate 8 Lead terminals 12 Clip leads 13 Lead pitch 14 Gap 15,18,19 Lead pieces 16 Mutual spacing

Claims (1)

[Claims] 1. A step of printing a thick film paste on the front and back surfaces of a ceramic substrate having through holes at predetermined positions to form wiring patterns such as lands, bonding pads, conductor lines, and through holes, and the substrate surface. After the chip parts are bonded and fixed to the prescribed positions, the circuit connection is performed, and the required lead pitch is obtained by punching a metal plate that is thinner than the metal plate used conventionally for lead frames. And a tip of the lead frame is formed on the ceramic substrate.
Bending process so that there is a step with a thickness of 1/2, using two lead frames, using a high melting point solder with the ceramic substrate clamped at the tip, the land of the ceramic substrate and the lead frame Of the lead frame is welded and fixed, the ceramic substrate with the tip of the lead frame is welded and fixed, is resin-molded by resin transfer molding, and the lead part of the resin-molded lead frame is plated. A method for manufacturing a hybrid integrated circuit, comprising the following steps: bending the leads after applying the leads, and subsequently cutting the leads from the lead frame.