JPH0736429B2 - Method for manufacturing ceramic wiring board - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic wiring board, and more particularly to a method for manufacturing a ceramic wiring board on which electronic elements such as ICs and semiconductor devices are mounted.

[0002]

2. Description of the Related Art Conventionally, metal patterns such as leads connected to electronic elements such as ICs and semiconductor devices mounted on a mounting portion provided on a ceramic substrate are extended from the outer peripheral side to the inner peripheral side of the ceramic substrate. A ceramic wiring board provided so as to exist is known.

As the ceramic wiring board, for example, a mounting portion on which a semiconductor device is mounted is provided in the center of the ceramic substrate, and the mounting portion is provided on the ceramic substrate from the outer peripheral side toward the inner peripheral side. GaA in which a plurality of signal leads connected to the semiconductor device and grounding leads provided between the signal leads are further provided, and a grounding layer is provided on the entire back surface of the ceramic substrate.
There is a microstrip transmission line used for evaluating the characteristics of semiconductor devices such as s.

In the microstrip transmission line, a semiconductor device is mounted on the mounting portion, a lead terminal of the semiconductor device is directly connected to the signal lead, and a connector is connected to the other end of the signal lead. The characteristics of the semiconductor device are evaluated by connecting to the impedance analyzer, network analyzer, or the like with a coaxial cable via the via. The grounding leads are grounded on the outer peripheral side of the ceramic wiring board in order to prevent crosstalk between the signal leads.

The microstrip transmission line is manufactured by firing a ceramic substrate provided with a high-melting-point metal conductor paste such as tungsten or molybdenum printed in a predetermined pattern, and firing the signal lead and the ground. The lead and ground layers were formed of a metallized layer obtained by firing the high melting point metal conductor paste.

As the ceramic wiring board,
A general ceramic package for a semiconductor device is also known in which leads formed of a metallized layer are provided inside a ceramic substrate. In such a ceramic wiring substrate, the leads are provided to the ceramic package via a via hole provided in the outer ceramic layer. Take it out,
It is designed to be connected to an external device.

In the general ceramic package for semiconductor device, an opening is punched in advance on a ceramic substrate provided by printing the high melting point metal conductor paste in a predetermined pattern, and the high melting point metal is formed in the opening. The leads are manufactured by laminating ceramic substrates filled with printed conductor paste and firing the same. The leads are metallized layers like the signal leads and ground leads of the ceramic wiring substrate for semiconductor device characteristic evaluation. Was formed by.

However, since the high-melting-point metal conductor paste contains a binder and the like in addition to the metal powder, the metal powder does not exist in the traces of the removed binder in the metallized layer after firing. Since the metal powder is present in a very sparse state, the resistance of the lead formed of the metallized layer tends to increase.

Therefore, it is conceivable to reduce the resistance of the leads by punching out a lead frame formed by connecting a plurality of leads to a tie bar from a metal plate and joining the lead frame to a ceramic substrate.

However, when the leads are formed of a metal plate, the thickness of the metal plate must be extremely thin (for example, 80 to 150 μm), and the obtained lead frame is poor in self-supporting property. Become. For this reason,
When joining a lead frame having a complicated shape with the plurality of leads to a ceramic substrate, it is difficult to accurately arrange the leads at predetermined positions.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a method for easily manufacturing a ceramic wiring board having a reduced resistance of leads.

[0012]

In order to achieve such an object, the ceramics wiring board of the present invention comprises a metal plate made of C
The method comprises the steps of joining to a ceramics substrate via an active metal brazing material layer containing u, Sn and an Ag—Cu—Ti alloy as a metal material, and then etching the metal plate to form a metal pattern. It is characterized by

In this case, the active metal brazing material is C
u and Sn are 5 to 15 with respect to the total metal material, respectively.
It is preferable that the Ti in the Ag-Cu-Ti alloy is contained in an amount of 1 to 10% by weight based on the Ag-Cu-Ti alloy, in addition to the content of 1 wt%.

[0014]

According to the method for manufacturing a ceramics wiring board of the present invention, first, the metal plate on which the metal pattern is formed is bonded to the ceramics board through the active metal brazing material layer.

At this time, the active metal brazing material is bonded to the ceramics substrate by diffusing Ti in the Ag-Cu-Ti alloy into the ceramics substrate during melting. Therefore, unlike the case of silver solder (Ag-Cu alloy), the metal plate and the ceramic substrate can be directly bonded without providing a metallization layer or nickel plating for bonding on the ceramic substrate. Since it is not necessary to provide a metallization layer or nickel plating for the above-mentioned joining, not only the steps for providing these can be omitted, but also the interval between the metal patterns can be reduced.

However, since the active metal brazing material is applied to the metal plate, a gap exists between the active metal brazing material and the ceramic substrate. This gap is eliminated to some extent by applying a load, but it is not sufficient. Therefore, if the metal material of the active metal brazing material is (Ag-
If only the (Cu-Ti) alloy is used and the temperature is raised in such a state, the temperature is raised while the (Ag-Cu-Ti) alloy is not sufficiently wet with the ceramic substrate.
Ti in the g-Cu-Ti) alloy unilaterally diffuses to the metal plate side. Usually, Ti easily diffuses into the metal, and if the diffusion proceeds, the composition of the metal becomes brittle. Furthermore, when the diffusion of Ti into the metal plate begins, (Ag-Cu-Ti)
The Ti concentration in the alloy becomes relatively smaller in the metal plate than in the ceramic substrate side, and Ti on the ceramic substrate side moves to the metal plate side. When this state progresses, (A
Even if the g-Cu-Ti) alloy gets wet with the ceramic substrate, the bonding strength cannot be secured because Ti is not sufficiently present on the ceramic substrate side. Also (A
Since high temperature is required for melting the g-Cu-Ti) alloy,
During cooling following melting, due to the difference in the coefficient of thermal expansion between the ceramic substrate and the metal plate, residual stress is generated at the joint interface between the ceramic substrate and the metal plate, and depending on the thickness of the ceramic substrate and the metal plate, residual stress may occur. Warp occurs to remove a part of, and when the residual stress is large,
Cracks are generated in the ceramic substrate, and as a result, the bonding strength is reduced.

As described above, although Ti is generally easily diffused into the metal plate, the active metal brazing material used in the present invention contains Sn. Ti diffusion is prevented. As a result, it is possible to prevent the metal plate from becoming brittle due to the diffusion of Ti, and also Ti is sufficiently diffused to the ceramic substrate, so that the metal plate surely and firmly adheres to the ceramic substrate through the active metal brazing material. To be joined to. The Cu contained in the active metal brazing material is for adjusting the melting point of the active metal brazing material.

In the active metal brazing material used in the present invention, since Sn and Cu are added to the Ag-Cu-Ti alloy, the melting point of the active metal brazing material is lowered, and the active metal brazing material is relatively low in temperature. The material melts. Therefore, Ti starts to diffuse to the ceramic substrate side at a relatively low temperature, and unilateral diffusion to the metal plate side can be prevented from this point as well.

Further, since the melting point of the active metal brazing material of the present invention is lowered as described above, the residual stress caused by the difference in thermal expansion coefficient between the ceramic substrate and the metal plate is also alleviated.

In this case, in order to effectively exhibit the action of the active metal brazing material, according to various experiments conducted by the present inventors, the Cu and Sn are added to the metal material in an amount of 5 to 5 respectively. In addition to containing 15% by weight, the above A
The Ti in the g-Cu-Ti alloy is replaced by the Ag-Cu-Ti alloy.
It was preferable to use an active metal brazing material containing 1 to 10% by weight based on the whole alloy. By setting the contents of Cu and Sn to 5 to 15% by weight, the brazing flow was good, the wettability was excellent, and no cavities were generated, so that uniform brazing could be performed. If the content of Ti in the Ag-Cu-Ti alloy is less than 1% by weight, the bondability with the ceramic substrate becomes poor, and if it exceeds 10% by weight, Ti is excessively diffused in the metal plate and the metal plate becomes brittle. It was Note that Ti is not a powder of Ti alone but Ag-Cu-Ti.
The reason why it is used in the form of alloy is as follows. That is, Ti
The powder has high activity, and when used in the form of TiH,
This is because at a temperature of 00 ° C. or higher, H ₂ is released and becomes active Ti, which reacts with C, H, N, etc. in the surroundings to form a stable compound, and can no longer react with the ceramic substrate.

In the method for manufacturing a ceramics wiring board of the present invention, next, by etching the metal plate firmly bonded to the ceramics board as described above,
Form a metal pattern. Since the metal plate is strongly bonded to the ceramic substrate beforehand, the metal pattern is accurately formed at a predetermined position by the etching,
The labor for joining the lead frame having a complicated shape to the ceramic substrate so that the metal plate is accurately arranged at a predetermined position is omitted.

[0022]

The ceramic wiring board of the present invention will now be described in more detail with reference to the accompanying drawings. 1 is a plan view showing the structure of a ceramic wiring board obtained by a first embodiment of the manufacturing method according to the present invention, and FIG. 2 is a schematic sectional view taken along the line II-II of FIG. 1 showing the manufacturing method according to the present invention. FIG. 3 is an explanatory sectional view showing the ceramic wiring board obtained by the second embodiment, and FIG.

The ceramic wiring board obtained by the first embodiment of the manufacturing method of the present invention is a microstrip transmission line used for evaluating the characteristics of a semiconductor device, and its surface has a central portion as shown in FIG. A plurality of signal leads 2 connected to the semiconductor device mounted on the portion 1 are provided so as to extend from the outer peripheral side to the inner peripheral side, and the signal leads 2 are connected to each other at the central portion 1. A grounding lead 3 is provided.

At the outer peripheral side end of the grounding lead 3, there are four screw holes 4 used for fixing the ceramic wiring board to the jig when the semiconductor device is evaluated. Screw holes 5 used for fixing the semiconductor device at the time of evaluating the semiconductor device are opened at four positions on the inner peripheral side end of the use lead 3.

The microstrip transmission line 11 is
As shown in FIG. 2D, a thin plate 7 made of Cu or the like is bonded to both upper and lower surfaces of a ceramic substrate 6 made of aluminum nitride or the like via an active metal brazing material 8, and a Cu-made thin plate bonded to the upper surface. 7, the signal lead 2 and the ground lead 3 are provided. In addition,
Although not shown, the Cu thin plate 7 joined to the lower surface of the ceramic substrate 6 has four screw holes 4 and four screw holes 5, respectively.

In manufacturing the microstrip transmission line, first, as shown in FIG.
A paste of the active metal brazing material 8 is applied to the bonding surface of the Cu thin plate 7 of m by printing or the like. In the present example, the coating thickness of the active metal brazing material was 4 to 20 μm, and the thickness after joining was 2 to 14 μm.

Here, the paste-like active metal brazing material 8 contains Cu, Sn and Ag-Cu-Ti alloys as metal materials, and further, an organic binder, a plasticizer and a volatile solvent are mixed. It was done. And more specifically, the composition of Cu and Sn in the metal material is 5 to 15% by weight based on the total weight of the metal material,
The composition of Ti in the Ag-Cu-Ti alloy is 1 to 10% by weight based on the total weight of the Ag-Cu-Ti alloy.
And the Ag / Cu ratio is 72/28 or 85/15, acrylic resin is used as the organic binder, and DOP (di-2-ethylhexyl phthalate) is used as the plasticizer.
Is used and terpineol is used as the volatile solvent.

Next, after the volatile solvent in the paste-like active metal brazing material 8 is volatilized and removed, the Cu thin plate 7 is fixed by pressure contact with the upper and lower surfaces of the ceramic substrate 6 via the active metal brazing material 8. . In this state, in a vacuum furnace (not shown) (10 ⁻⁵ mmHg) at a predetermined temperature (1 from the melting point of the brazing material).
The temperature is raised to 0 to 100 ° C., preferably 20 to 40 ° C.), and then cooled.

At this time, in the active metal brazing material 8, first, the acrylic resin as the organic binder is decomposed and removed. If the organic binder remains in the form of carbon without being sufficiently decomposed and evaporated during heating, it reacts with Ti in an active state to form a compound TiC. Since this TiC is a stable compound, the activity of Ti becomes low and it can no longer react with the substrate. Therefore, as the organic binder, it is preferable to use an acrylic resin that decomposes into a monomer having a high vapor pressure as in the present embodiment.

Then, the temperature is 500 to 900 ° C., preferably 70.
The active metal brazing material 8 starts melting at 0 to 840 ° C, for example, 760 ° C. Then, when the active metal brazing material 8 starts melting in this way, Ti in the Ag-Cu-Ti alloy is
Diffuse into the ceramic substrate 6 and are bonded to the ceramic substrate 6. At this time, Sn prevents unidirectional diffusion of Ti into the Cu thin plate 7. Therefore, Ag-Cu
Ti in the —Ti alloy is sufficiently diffused also in the ceramic substrate 6, and as a result, after heating and cooling after melting, C
The thin plate 7 made of u is securely and firmly bonded and fixed to the ceramic substrate 6 by the active metal brazing material 8.

Next, as shown in FIG. 2B, a photoresist is applied in a predetermined pattern on the Cu thin plate 7 firmly fixed to the ceramics substrate 6, dried, exposed and developed to a predetermined amount. A photoresist layer 9 having the pattern of is provided. Although the photoresist layer 9 is only schematically shown in FIG. 2B, it is actually formed on the upper surface in the shape of the signal lead 2 and the ground lead 3 shown in FIG. There is.

Next, the photoresist layer 9 of the Cu thin plate 7 is formed.
The exposed portion which is not covered with the above is etched using an etching solution containing ferric chloride as a main component. As a result, the exposed portion of the Cu thin plate 7 and the active metal brazing material 8 thereunder are etched to form the Cu thin plate 7 in a predetermined pattern 10 as shown in FIG. . Although the pattern 10 is only schematically shown in FIG. 2C, it is actually formed on the upper surface in the shape of the signal lead 2 and the ground lead 3 shown in FIG.

Next, honing is performed, and abrasive grains such as alumina powder are wiped off to remove the photoresist layer 9 and the etching residue on the pattern 10, and FIG.
As shown in (d), the pattern 10 having the signal lead 2 and the ground lead 3 is obtained.

The screw holes 4 and 5 provided in the Cu thin plate 7 bonded to the lower surface of the ceramics substrate 6 may be provided by etching, but the screw holes 4 and 5 may be provided.
Since the shape provided with is relatively simple, the Cu thin plate 7 provided with the screw holes 4 and the screw holes 5 in advance may be joined to the lower surface of the ceramic substrate 6 by punching or the like. In addition, it is possible to establish continuity between the upper and lower adhesive surfaces by previously forming via holes in which the ceramic substrate 6 is filled with a refractory metal such as molybdenum or tungsten.

The ceramic wiring board obtained by the second embodiment of the manufacturing method of the present invention is a general ceramic package for semiconductor devices, and a part thereof is cut away to show a 1/4 cross section in FIG. Further, the semiconductor device 43 is mounted in the recess 42 at the center of the ceramic substrate 41, and the leads 44 connected to the semiconductor device 43 are provided so as to extend from the outer peripheral side to the inner peripheral side of the ceramic substrate 41. A metallization layer 45 is provided on the central recess 42, and the semiconductor device 43 is mounted on the metallization layer 45. The semiconductor device 43 is the bonding wire 4
It is connected to each lead 44 by 6. Further, on the ceramic substrate 41, an outer layer ceramic substrate 47 having a square shape in plan view is laminated.

The lead 44 is joined to the ceramic substrate 41 via the active metal brazing material 48, and the outer ceramic substrate 47 is joined to the ceramic substrate 41 from above the lead 44 via the low melting point glass 49. .

In manufacturing the ceramic package for a semiconductor device, first, a thin plate 50 made of Cu or the like shown in phantom in FIG. 3 is formed on the upper surface of the ceramic substrate 41 having a concave portion 42 formed in the center thereof as an active metal brazing material 48. The ceramic substrate 4 is bonded in the same manner as in the first embodiment, except that the Cu thin plate 50 is etched into the shape of the lead 44 shown in FIG.
44 joined to the No. 1 via an active metal brazing material 48
Is formed. In addition, the ceramic substrate 41,
A metallization layer 45 is previously formed on the recess 42.

Next, the semiconductor device 43 is mounted on the metallized layer 45 formed in the recess 42 and connected to the lead 44 by the bonding wire 46. Next, the outer layer ceramics substrate 47 is bonded to the ceramics substrate 41 from above the leads 44 by the low melting point glass 49. In the bonding, the low melting point glass 49 is applied to the peripheral portion of the outer layer ceramic substrate 47, and then the outer layer ceramic substrate 47.
The outer layer ceramics substrate 47 is mounted on the ceramics substrate 41 via the low melting point glass 49 while the peripheral edge of the ceramics substrate 41 is pressed against the periphery of the ceramics substrate 41. At this time, each of the leads 44 fixed to the ceramic substrate 41 is exposed in the recess 42 at the end portion on the inner peripheral side and is wire-bonded 46.
Is connected to the outer peripheral side ceramic substrate 47 and the ceramic substrate 41, and the outer peripheral side end portion is connected to the concave portion 4
It is extended outward from 2.

In this state, these are, for example, 38
Low melting point glass 49 heated in an atmosphere of 0 to 400 ° C.
Are melted and then cooled. As a result, as shown in FIG. 4, the outer ceramic substrate 47 is fixed on the ceramic substrate 41. Since the heating temperature for melting the low melting point glass 49 is sufficiently lower than the melting point of the active metal brazing material 48 bonded to the lead 44 and the ceramic substrate 41, the active metal brazing material 4 is heated by the heating.
8 does not melt, so that the bonding state between the lead 44 and the ceramic substrate 41 is reliably maintained,
The lead 44 will not be displaced.

[0040]

As is apparent from the above, according to the method for manufacturing a ceramic wiring board of the present invention, a metal plate is previously bonded to the ceramic substrate via the active metal brazing material layer, and the metal plate is attached. By etching, it is possible to easily manufacture a ceramics wiring board having a metal pattern having a desired shape and a reduced resistance.

[Brief description of drawings]

FIG. 1 is a plan view showing the structure of a ceramic wiring board obtained by a first embodiment of a manufacturing method according to the present invention.

2 is an explanatory cross-sectional view schematically showing the manufacturing method according to the present invention by the cross section along the line II-II of FIG.

FIG. 3 is a perspective view showing a ceramic wiring board obtained by another embodiment of the manufacturing method according to the present invention with a part of the structure cut away.

[Explanation of symbols]

2 ... Signal lead, 6 ... Ceramics substrate, 7 ... C
u thin plate, 8 ... Active metal brazing material.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical indication location H01L 23/15 H01P 3/08 11/00 G H01L 21/88 R 23/14 C

Claims (2)

[Claims] 1. A metal plate made of Cu, Sn and Ag-Cu-Ti.
Manufacture of a ceramic wiring board comprising: a step of joining to a ceramics substrate through an active metal brazing material containing an alloy as a metal material; and a step of subsequently etching the metal plate to form a metal pattern. Method. 2. The active metal brazing material is Cu or Sn.
5 to 15% by weight based on the total metal material, and 1 to 10% by weight of the Ti in the Ag-Cu-Ti alloy based on the Ag-Cu-Ti alloy. The method for manufacturing a ceramic wiring board according to claim 1.