JPH08274218A - Ceramic circuit board - Google Patents

Abstract

PURPOSE: To rigidly bring a viahole into contact with a board main body, and rigidly solder a metal part member to the board main body, in a ceramic circuit board provided with the board main body having a viahole in which Ag based conductor material is buried and a thin film wiring layer electrically connected with the viahole on the surface of the board main body. CONSTITUTION: In a ceramic circuit board provided with a board main body 11 having a viahole 12 in which Ag based conductor material is buried, and a thin film wiring layer electrically connected with the viahole 12 on the surface of the board main body 11, a metal layer 13 selected out of Cr, Pd and Ni is formed between the viahole 12 and the thin film wiring layer. The thickness of the metal layer 13 is 100-50000Å. A metal part member is soldered to the thin film wiring layer wherein the viahole 12 is covered with the metal layer 13. The gap between the outer peripheral end of the metal layer 13 and that of the viahole 12 is at most 0.1mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic circuit board having thin film wiring formed on a board body having an Ag-based circuit.

[0002]

2. Description of the Related Art Conventionally, a circuit board having an alumina ceramic as an insulating material has been used as a board for mounting a semiconductor element such as an LSI. However, since the firing temperature of the alumina-based ceramic material is high, and high-melting-point metals such as W and Mo are used as the conductor material capable of simultaneous firing,
There was a problem that the conduction resistance was as high as 10 to 20 Ω / □. Therefore, a circuit board using a low-resistance conductor material such as Au, Ag, and Cu and glass or glass ceramic as a low-temperature firing insulating material capable of firing at the same time has come to be used. However, since Au is expensive as a conductor material, and Cu needs to be fired in a reducing atmosphere in order to prevent oxidation.
Attention has been paid to system conductor materials.

Further, with the progress of high performance and miniaturization of computers, circuit boards are required to have high density and high precision, and thin film fine wiring applying photolithography technology is also applied to circuit boards. It is being used. In particular, a ceramic circuit board in which thin film wiring is formed on a substrate body using a low resistance conductor material and glass or glass ceramic which is a relatively low dielectric constant insulating material is a multi-chip module (MCM) board. It has been applied as such.

Several proposals have hitherto been made as techniques for forming thin film wiring on a substrate body. For example, in Japanese Unexamined Patent Publication (Kokai) No. 6-177494, a thin film layer made of a 4A group or 5A group element having excellent adhesion to a ceramic is formed on a substrate body as
A technique is disclosed in which the adhesion strength between the substrate body and the thin film wiring layer is improved by forming the film as a layer and further forming a multi-layered thin film layer for the purpose of stress relaxation or the like thereon.

On the other hand, when connecting a metal member such as a seal ring, a lead pin or a lead frame to the substrate body,
The brazing method is widely used. In particular,
A brazing base is formed of a metal that allows the brazing material to be brazed on the substrate body where the metal member is to be brazed, and the metal member is brazed to the base using an Ag—Cu based brazing material or the like. . As the base, a conductor material that is co-fired with the substrate body or a conductor material for secondary metallization can be used.
Further, in Japanese Patent Laid-Open No. 64-1268, 4A is used as the base.
It is disclosed to form a metal layer composed of a group 5A group, a group 6A group, a group 8A group, a group 1B metal, or a combination thereof.

[0006]

A ceramic having a substrate body having a via in which an Ag-based conductor material is embedded, and a thin film wiring layer electrically connected to the via on the surface of the substrate body. In a circuit board, when a thin film layer made of elements of Groups 4A and 5A of the Periodic Table is directly formed on the substrate body, heat treatment in the step of forming the thin film layer and subsequent thermal processing lead to a Ag-based conductor material. Since the adhesion strength with the thin film layer made of the 4A group and 5A group elements is insufficient, defects such as swelling and peeling may occur. On the other hand, when a thin film layer made of the 6A group, 8 group, and 1B group elements of the periodic table is formed on the substrate body, the adhesion between the thin film layer and the Ag-based conductor material is excellent, but the adhesion between the ceramic part is insufficient. Is.
Therefore, defects such as swelling and peeling may occur between the ceramic part and the thin film layer due to heat treatment in the step of forming the thin film layer and subsequent thermal processing. The present invention relates to a ceramic circuit board including a substrate body having a via in which an Ag-based conductor material is embedded, and a thin film wiring layer electrically connected to the via on the surface of the substrate body. An object is to provide a ceramic circuit board having a thin film wiring layer firmly adhered to a system via.

On the other hand, in order to braze a metal member onto a substrate body having an Ag-based circuit, a base for brazing may be formed on the surface of the substrate body with an Ag-based conductor material.
However, the adhesion strength between the ceramic and the Ag-based conductor material is not always sufficient. Therefore, even if the metal member is brazed to the base formed of the Ag-based conductor material, it may be separated at the interface between the ceramic portion and the base. Another object of the present invention is to provide a ceramic circuit board in which a metal member is brazed with sufficient adhesion strength to a board body having a via in which an Ag-based conductor material is embedded.

[0008]

In order to achieve this object, the invention of claim 1 has a substrate main body having a via in which an Ag-based conductor material is embedded, and the via on the surface of the substrate main body. In a ceramic circuit board having a thin film wiring layer electrically connected to, a metal layer selected from Cr, Pd and Ni is provided between the via and the thin film wiring layer. The main point is a ceramic circuit board.

According to a second aspect of the invention, the metal layer has a thickness of 100.
A ceramic circuit board according to claim 1, wherein the ceramic circuit board has a thickness of up to 50,000 angstroms.

The invention according to claim 3 is characterized in that the via is covered with a metal layer in which the distance between the outer peripheral edge of the metal layer and the outer peripheral edge of the via is 0.1 mm or less. The gist of the ceramic circuit board according to Item 2.

According to a fourth aspect of the present invention, there is provided the ceramic circuit board according to any one of the first to third aspects, wherein the metal member is brazed to the thin film wiring layer via the Ni plating layer. Use as a summary.

The term "Ag-based conductor material" as used herein refers to a low-resistance conductor material containing Ag as a main component, and in addition to Ag only, metal components such as Pd and Cu less than 20% in Ag, the metal oxide component such as cr ₂ O ₃ may be obtained by addition. Further, in order to match the shrinkage rate with the ceramic at the time of firing and further improve the adhesion with the ceramic, a component made of glass or glass ceramic or a glass-based component similar thereto may be contained.

The ceramic constituting the substrate body is Ag.
Simultaneous firing with the base conductor material, that is, 800 to 110
A glass or glass-ceramic material that can be fired at 0 ° C. For example, borosilicate glass and several kinds of oxides (MgO, CaO, SrO, BaO, Al ₂ O ₃ , K
₂ O, Na ₂ O, Li ₂ O, ZnO, ZrO ₂ , TiO ₂ )
Or a glass-ceramic material obtained by mixing such glass with ceramic particles such as alumina, quartz, mullite, or cordierite as an aggregate.

Any one metal layer selected from Cr, Pd and Ni can be formed by a vacuum deposition method, a sputtering method or a plating method. The reason why the thickness of the metal layer is 100 to 50000 angstroms is that if the thickness is less than 100 angstroms, the effect of forming the metal layer is not sufficiently exhibited. Again 500
If the thickness is greater than 00 angstroms, the effect of forming the metal layer is sufficiently exhibited, but C forming the metal layer is formed.
r, Pd, and Ni are electrically unsuitable because they have high resistance and increase wiring resistance. Further, the metal layer or the thin film wiring layer may be peeled off due to the thermal stress due to the difference in thermal expansion coefficient among the ceramic, the metal layer, and the thin film wiring layer. Furthermore, the process time becomes longer and the cost increases, which is not preferable. The thickness of the metal layer is 150 to 1000.
When it is 0 angstrom, the effect of any one metal layer selected from Cr, Pd and Ni is sufficiently exhibited, and it is more preferable in terms of cost.

Since any one metal layer selected from Cr, Pd, and Ni is selectively formed on the via in which the Ag-based conductor material is buried, photolithography is performed.
Technology can be applied. For example, C on the substrate body
Any one metal layer selected from r, Pd and Ni is formed to a predetermined thickness by a vacuum vapor deposition method or a sputtering method, a photosensitive resist agent is applied onto the metal layer and dried to form a predetermined pattern. -Exposure and development are performed by using a mask of a mask so that the resist agent covers only the metal layer on the Ag-based via. Next, the exposed metal layer is removed by etching, and the resist agent is further removed, whereby the metal layer can be selectively formed on the Ag-based via.

The plating method is effective for selectively forming any one metal layer selected from Cr, Pd, and Ni on the via in which the Ag-based conductor material is buried. A by electrolytic plating method or electroless plating method
This is because the plating layer is selectively formed only on the via surface made of a g-based conductor material.

When the distance between the outer peripheral edge of the metal layer and the outer peripheral edge of the via is 0.1 mm or less, the shortest distance from one point on the outer peripheral edge of the via to the outer peripheral edge of the metal layer is the distance between both outer peripheral edges at that point. And that the distances at all points around the entire outer peripheral edge of the via are 0.1 mm or less. The reason for coating the via with a metal layer in which the distance between the outer peripheral edge of the metal layer and the outer peripheral edge of the via is 0.1 mm or less is as follows. The distance between the outer edge of the metal layer and the outer edge of the via is 0.1 m
When the via is covered with a metal layer larger than m, the adhesion between the ceramic portion and Cr, Pd, and Ni forming the metal layer is poor, and therefore peeling may occur at the interface between the two. Of course, the metal layer must at least completely cover the via,
It goes without saying that the effect of forming the metal layer is insufficient.

For the thin film wiring formed via any one metal layer selected from Cr, Pd and Ni, conventionally known materials or a combination thereof can be used. For example, as the first layer, 4A that has excellent adhesion to ceramics
A thin film layer composed of a group 5A group element or a compound thereof, on which a stress relaxation layer of Mo, Cu, Fe, Al or the like is formed as a second layer, and a thin film layer of Au or the like having an excellent corrosion prevention effect is formed as a surface layer. The formed multi-layered thin film layer can be formed.

When a metal member is joined to the ceramic circuit board, brazing using a brazing material such as Ag ₇₂ -Cu ₂₈ can be performed. In this case, it is preferable that the uppermost layer of the thin film wiring layer is made of a material such as Ni that is easily wetted by the brazing material. For example, the Ni layer can be formed by plating the thin film wiring layer with Ni. Similarly, the metal member or the brazed portion of the metal member is preferably made of a material that easily wets the brazing material.

[0020]

In the ceramic circuit board, the substrate main body has a via having an Ag-based conductor material embedded therein, and a thin film wiring layer electrically connected to the via on the surface of the substrate main body. And C between the thin film wiring layer and
By forming any one metal layer selected from r, Pd, and Ni, it is possible to prevent swelling and peeling between the Ag-based via and the thin film wiring layer due to heat treatment in the thin film forming process. This is because any one metal layer selected from Cr, Pd, and Ni has high adhesion strength to both Ag-based conductor material and thin-film wiring material, and firmly adheres the Ag-based via and the thin-film wiring layer. This is because it can be done. Further, by brazing the metal member on the thin film wiring layer formed on the substrate body having the via in which the Ag-based conductor material is embedded, the metal member is sufficiently adhered to the substrate body. It becomes possible to braze with strength.

[0021]

EXAMPLES Examples of ceramic circuit boards within the scope of the present invention will be described below with reference to FIGS. 1 and 2, and those outside the scope of the present invention will also be described as comparative examples. Example _{1 CaO-MgO-Al 2 O} 3 -SiO 2 -B 2 O 3 based ceramic green fabricated from glass powder and alumina particles - Nshi - Doo, Ag-based conductor Bae - wiring pattern using strike - After printing, the sheets were laminated and thermocompression bonded. The connection of the conductors between the layers was performed by filling a 0.12 mmφ through hole formed by punching a green sheet with an Ag-based conductor paste. The laminated body was heat-treated in the air at 250 ° C. to remove the binder, and then fired in the air at 950 ° C. for 3 hours. Thus, a substrate body (11) having a 0.10 mmφ Ag-based via (12) was obtained. Further, on the side (11) where the thin film wiring layer of the substrate body (11) is formed.
The surface roughness (Ra) was adjusted to 0.2 μm or less by polishing a).

The obtained substrate body (11) is set in a vacuum vapor deposition apparatus, and the inside pressure is reduced to 10 ^-6 Torr or less, and then 2
After heating to 50 ° C., a Cr layer having a thickness of 150 Å was formed by a vacuum evaporation method. A photosensitive resist agent was applied onto the Cr layer, dried, exposed and developed with a mask having a predetermined pattern, and a state in which only the Cr layer on the Ag-based via (12) was covered with the resist agent having a diameter of 0.12 mm did. Next, the exposed Cr layer is removed by etching and the resist agent is further removed to obtain a substrate body (11) having a 0.12 mmφ Cr layer (13) formed on an Ag-based via (12). I was able to.

Next, the substrate body (11) is set in a vacuum vapor deposition apparatus, and the inside pressure is reduced to 10 ^-6 Torr or less, then 25
After heating to 0 ° C., a Ti layer (14) of 2000 angstrom is formed on the metal layer (13) of Cr by vacuum deposition.
And a Cu layer (15) having a thickness of 5000 angstrom was formed thereon. Next, a photosensitive resist agent was applied on the Cu layer (15), dried, and exposed and developed with a mask having a predetermined pattern. A Cu plating layer (16), a Ni plating layer (17), and then an Au plating layer (18) are formed in this order on a portion where the resist agent is not covered becomes a thin film wiring layer. Next, the resist agent was removed, and unnecessary Cu layer and Ti layer were removed by etching. Finally, the substrate body (11) was annealed at 250 ° C. in a nitrogen atmosphere to obtain a ceramic circuit substrate having a thin film wiring layer formed thereon. In the obtained ceramic circuit board, Ag
Adhesion between the system via (12) and the thin film wiring layer is sufficient,
No defects such as peeling occurred.

[0024]

[Table 1]

Examples 2 to 5 In Examples 2 to 5, the thickness of the Cr layer, which is a metal layer, is 100,
This is an example in which a ceramic circuit board was manufactured by the same method as in Example 1 except that the thickness was changed to 300, 1000 and 3000 angstroms. In all of the obtained ceramic circuit boards, the adhesion between the Ag-based via and the thin film wiring layer is sufficient, and the swelling,
No defects such as peeling occurred.

Examples 6 to 8 Examples 6 to 8 are the same as Example 1 except that the metal layer is made of Ni and the thickness thereof is changed to 150, 300 and 1000 angstroms, respectively. It is an example of producing a ceramic circuit board. In all of the obtained ceramic circuit boards, the adhesion between the Ag-based via and the thin film wiring layer is sufficient,
No defects such as swelling and peeling occurred.

Examples 9 to 11 In Examples 9 to 11, the metal layer was formed of Pd and the thickness thereof was 150, 300 and 1000 angstroms, respectively.
This is an example of producing a ceramic circuit board by the same method as in Example 1 except that the ceramic circuit board was changed. In each of the obtained ceramic circuit boards, the Ag-based via and the thin film wiring layer were sufficiently adhered to each other, and defects such as swelling and peeling did not occur.

Examples 12 and 13 In Examples 12 and 13, ceramic circuit boards were produced in the same manner as in Example 1 except that the size of the metal layer made of Cr was 0.20 mmφ and 0.30 mmφ, respectively. Here is an example. In each of the obtained ceramic circuit boards, the Ag-based via and the thin film wiring layer were sufficiently adhered to each other, and defects such as swelling and peeling did not occur.

Examples 14 to 16 Examples 14, 15 and 16 are examples in which a Ni layer which is a metal layer is formed by a plating method. First, a polished substrate body having Ag-based vias is obtained in the same manner as in Example 1.
In the obtained substrate body, the thin film wiring layer is not connected A
A g-type via and other circuit parts are covered with a masking agent to form a plating mask. Next, a Ni plating layer is applied to each of the Ag-based vias not covered by the mask by plating by 500
0, 10,000, and 50,000 angstroms were formed. Then, the masking agent is removed using an organic solvent,
After cleaning, a substrate body was obtained in which a metal layer made of Ni was formed on the Ag-based via.

Next, the substrate main body is set in a vacuum vapor deposition apparatus, the inside pressure is reduced to 10 ^-6 Torr or less, then heated to 250 ° C., and a Ti layer of 2000 angstrom is formed on the metal layer made of Ni by the vacuum vapor deposition method. And a Cu layer on top of it
It was formed to a thickness of 000 angstroms. Next, a photosensitive resist agent was applied onto the Cu layer, dried, and exposed and developed with a mask having a predetermined pattern. A place where the resist agent is not covered becomes a thin film wiring layer, and a Cu plating layer, a Ni plating layer, and an Au layer are sequentially formed there by an electrolytic plating method.
Form a plating layer. Then, the resist agent was removed, and unnecessary Ti layer and Cu layer were removed by etching. Finally, the substrate body was annealed by heat treatment at 250 ° C. in a nitrogen atmosphere to obtain a ceramic circuit substrate on which a thin film wiring layer was formed. In the obtained ceramic circuit board, the Ag-based via and the thin film wiring layer were sufficiently adhered to each other, and defects such as swelling and peeling did not occur.

Example 17 Example 17 is an example in which a metal member is brazed onto a substrate body through a thin film wiring layer formed by the method of the present invention. As shown in FIG. 2, in the same manner as in Example 1, the metal layer (23) made of Cr was 0.12 mmφ and the thickness was 150 angstrom on the substrate body (21) having the Ag-based vias (22). To form. Next, a metal layer made of Cr (2
3) a Ti layer (24) of 2000 angstroms, a Mo layer (25) of 3000 angstroms thereon, and a Cu layer (26) of 50 thereon by a vacuum deposition method.
It was formed to a thickness of 00 angstrom. Next, a photosensitive resist agent is applied on the Cu layer (26), dried, and exposed and developed with a mask having a predetermined pattern. A Cu plating layer (27) is formed thereon by electrolytic plating, and a Ni plating layer (28) is formed on the area where the resist agent is not covered becomes a base for brazing. Then, the resist agent was removed, and unnecessary Cu layer, Mo layer, and Ti layer were removed by etching. Next, the substrate body (21) was annealed by heat treatment at 500 ° C. in a nitrogen atmosphere to 2 mm.
A substrate body (21) on which a φ brazing substrate was formed was obtained. A lead pin (3) in which a brazing material (29) made of Ag ₇₂ -Cu ₂₈ is melted and adhered to a brim (31) to be brazed.
0) is prepared as a metal member. The lead pin (30) was made of Kovar, the shaft diameter was 0.45 mm, and the collar-shaped portion (31) was 0.7 mmφ. The lead pin (30) and the substrate body (21) were set on a carbon brazing jig, and brazing was performed by heat treatment at 840 ° C. in a nitrogen atmosphere. Then, a coating layer (not shown) of a Ni-Au plating layer is formed on the entire surface of the circuit portion including the lead pin (30) exposed on the surface by electrolytic plating, and heat treatment is performed at 250 ° C. to anneal. did. The brazing strength is the lead pin (30)
Was tested by pulling it 45 ° above the brazing surface.
Any of the lead pins (30) was cut by the shaft portion (32), and the substrate body (21) and the lead pin (30) were brazed with sufficient strength.

Comparative Example 1 Comparative Example 1 is an example in which a thin film wiring layer is directly formed on an Ag-based via. Except for omitting the step of forming the metal layer, a Ti-Cu thin film layer is directly formed on the Ag-based via in the same manner as in Example 1, and a Cu plating layer and N
The i-plated layer and the Au-plated layer were formed in this order. However, when annealed by heat treatment at 250 ° C., swelling occurred at the interface between the Ag-based via and the thin film wiring layer, and the adhesion strength was insufficient.

Comparative Example 2 Comparative Example 2 is an example in which a ceramic circuit board is manufactured by the same method as in Example 1 except that the thickness of the Cr layer which is the metal layer is changed to 50 Å. However, when annealed in the last step, that is, by heat treatment at 250 ° C., swelling occurred at the interface between the Ag-based via and the thin film wiring layer, and the adhesion strength was insufficient.

Comparative Example 3 In Comparative Example 3, the size of the metal layer made of Cr was 0.50 m.
This is an example of manufacturing a ceramic circuit board with lead pins brazed in the same manner as in Example 17 except that mφ was changed. However, when a lead pin tensile test was conducted, peeling occurred between the ceramic portion and the metal layer made of Cr.

Comparative Example 4 In Comparative Example 4, the thickness of the metal layer made of the Ni layer was 10,000.
This is an example of producing a ceramic circuit board by the same method as in Example 14 except that the thickness was changed to 0 angstrom. However, when annealed in the last step, that is, at a heat treatment of 250 ° C., swelling occurs between the Ag-based via and the thin film wiring layer,
The adhesion strength was insufficient.

[0036]

According to the present invention, a ceramic including a substrate body having a via in which an Ag-based conductor material is embedded, and a thin film wiring layer electrically connected to the via on the surface of the substrate body. In the circuit board, the adhesion between the via and the thin film wiring layer can be made strong. Further, the metal member can be firmly brazed to the substrate body through the thin film wiring layer formed according to the present invention.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a ceramic circuit board of the present invention.

FIG. 2 is a cross-sectional view showing the configuration of the circuit board of the present invention in which a metal member is brazed.

[Explanation of symbols]

(11), (21): Substrate body (11a): Side of the substrate body (11) on which the thin film wiring layer is formed (12), (22): Ag-based vias (13), (23): Cr Metal layer (14), (24): Ti layer (15), (26): Cu layer (16), (27): Cu plating layer (17), (28): Ni plating layer (18): Au plating Layer (25): Mo layer (29): Ag-Cu brazing filler metal (30): Lead pin (31): Lead pin collar portion (32): Lead pin shaft portion

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H05K 3/24 H01L 21/88 J 3/38 23/14 C

Claims (4)

[Claims] 1. A ceramic circuit board comprising: a substrate body having a via in which an Ag-based conductor material is embedded; and a thin film wiring layer electrically connected to the via on the surface of the substrate body. A ceramic circuit board having any one metal layer selected from Cr, Pd, and Ni between the via and the thin film wiring layer. 2. The ceramic circuit board according to claim 1, wherein the metal layer has a thickness of 100 to 50,000 angstroms. 3. The via according to claim 1, wherein the via is covered with a metal layer in which a distance between an outer peripheral edge of the metal layer and an outer peripheral edge of the via is 0.1 mm or less. Ceramic circuit board. 4. The metal member is brazed to the thin film wiring layer via a Ni plating layer.
3. The ceramic circuit board according to any one of 3 above.