JP2001068813A - Ceramic wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ceramic wiring board by simultaneous baking a board which has a resistor showing a resistance of high precision without passing a process like trimming on a surface layer and/or an inner layer, in a ceramic based wiring board. SOLUTION: In this ceramic wiring board, a wiring circuit layer 12 is formed on a green sheet 10 composed of ceramic based insulating material, and a transfer film 13 on which a resistor layer 16 constituted of a metal plate or a metal foil 14 of high resistivity metal of at least 20 μΩcm is formed is pressure welded to the surface of the green sheet 10. By peeling the transfer film 13, the resistor layer 16 is transferred and formed on the surface of the green sheet 10. The green sheet 10 on which the wiring circuit layer 12 and the resistor layer 16 are formed is baked while restraining contraction especially in the X-Y direction, at a temperature lower than the melting point of the metal forming the layers 12 and 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic wiring board suitable for a hybrid integrated circuit board having a wiring circuit layer and a resistor layer on a ceramic insulating substrate and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a wiring board for a hybrid IC which forms a part of an electronic circuit by mounting a passive component or an active component, for example, a ceramic-based resistor mounting wiring capable of relatively high-density wiring. Substrates are frequently used.

[0003] This ceramic resistor mounted wiring board is
By mounting a resistor on the surface of the substrate, it is possible to reduce the size and increase the density of the circuit. An insulating substrate such as alumina or glass ceramic and W, Mo, Cu or Ag formed on the surface In addition to the wiring circuit layer consisting of, a resistor such as LaB ₆ or SnO ₂ is formed by a thick film method.

According to the thick film method, such a ceramic-resistor-mounted wiring board has, as a main component, an oxide powder such as LaB ₆ or SnO ₂ or a high-resistance metal powder such as a Cu—Ni alloy. A general method is to use a thick film resistor paste to print and form a predetermined shape on a fired ceramic substrate by a screen printing method or the like, and then to bake.

[0005]

However, in the above method, when a resistor paste prepared by adding an organic binder or the like to a resistor powder by a thick film method is screen-printed and formed by firing, the precision of the resistance value is poor. There was a problem. This is mainly due to the fact that the shape of the resistor cannot be accurately formed due to the printing accuracy of printing or the like and shrinkage variation during firing. Therefore, in order to form an accurate resistor by the thick film method, it is necessary to perform trimming after firing, and the number of steps is increased, resulting in an increase in cost and an increase in tact time.

Further, when a resistor element is to be formed inside a ceramic insulating substrate, trimming such as a thick film resistor cannot be performed. Therefore, a more accurate resistor is formed by simultaneous firing with an insulating substrate. However, it is almost impossible to form such a highly accurate resistor element without trimming. As a result, the formation of the resistor is always limited to the surface of the substrate, which is a great constraint on circuit design, and it has not been possible to meet the demand for further downsizing and higher density of the circuit.

Therefore, according to the present invention, in a ceramic wiring board having a resistor, a highly accurate resistor can be formed on a surface layer and / or an inner layer by simultaneous firing without increasing the number of steps such as trimming. It is an object of the present invention to provide a wiring board which can be reduced in size and density and a method of manufacturing the same.

[0008]

Means for Solving the Problems As a result of intensive studies on the above-mentioned problems, the present inventor has formed on a transfer film a resistor which has been previously adjusted to a predetermined resistance value as a resistor, and has formed this on a ceramic. It has been found that a resistor having high resistance accuracy can be easily produced by transfer-forming the green sheet surface and simultaneous firing, and the present invention has been accomplished.

That is, the ceramic wiring board of the present invention is a ceramic wiring board in which a wiring circuit layer is formed on the surface and / or inside of a ceramic insulating substrate.
A resistor layer made of a metal plate or a metal foil of the above high-resistance metal is formed by firing simultaneously with the insulating substrate. In particular, the resistor layer is formed of the ceramic-based insulating substrate. It is desirable to be formed inside.

Further, according to the method for manufacturing a ceramic wiring board of the present invention, (a) a step of producing a green sheet made of a ceramic insulating material, and (b) a step of forming a wiring circuit layer on the surface of the green sheet. (C) forming a resistor layer made of a metal plate or a metal foil of a high-resistance metal of 20 μΩcm or more on the surface of the transfer film;
(D) pressing the transfer film on which the resistor layer is formed on the surface of the green sheet and then peeling off the transfer film to transfer and form the resistor layer on the surface of the green sheet; e) firing the green sheet on which the wiring circuit layer and the resistor layer are formed at a temperature lower than the melting point of the metal forming the wiring circuit layer and the resistor layer. The step of laminating the green sheet with another green sheet produced through the steps (a), (b) or (a) to (c) before firing in the step (e). A substrate can be made.

In this case, it is preferable that the step (a) includes a step of forming a via hole in the green sheet and filling the via hole with a conductive paste. In firing, the green sheet X
It is desirable to perform while suppressing shrinkage in the −Y direction.

In the above structure, the resistor layer is made of Cu, Ni, Cr, Mn, Fe, Ag, P
t, Pd, Sn, Al, Si, Rh, Ir, Ru, R
e, made of at least one metal selected from Au, and the ceramic-based insulating substrate is preferably made of glass powder or a mixture obtained by firing a mixture of glass powder and ceramic filler powder.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a ceramic wiring board according to the present invention will be described with reference to the drawings. In the drawing,
The structure of the wiring board will be described with reference to an example of a multi-layer wiring board with a built-in resistor using a plurality of glass ceramics as an insulating substrate.
FIG. 1 is a schematic sectional view of a ceramic wiring board of the present invention.

Referring to FIG. 1, a ceramic wiring board 1 according to the present invention includes an insulating substrate 2, a wiring circuit layer 3, a resistor layer 4, and a via-hole conductor 5. The insulating substrate 2 is composed of a laminate formed by laminating a plurality of glass ceramic insulating layers 2a to 2d, and a wiring circuit made of a low-resistance metal is provided between the insulating layers 2a to 2d and on the front and back surfaces of the insulating substrate 2. A layer 3 and a resistor layer 4 made of a metal plate or a metal foil of a high resistance metal of 20 μΩcm or more are formed. Further, the wiring circuit layer 3 and the resistor layer 4 are connected by a via-hole conductor 5 filled with a low-resistance metal powder to form a circuit network.

It is preferable that the conductor material filled in the via hole is filled with a conductor mainly composed of the same component as that of the above-described wiring circuit layer 3, but is not necessarily limited to the above-mentioned component. .

Further, the wiring circuit layer 3 on the surface of the wiring board 1
Are used as pads for mounting various electronic components 6 such as IC chips, as conductive films for shielding, and as terminal electrodes for connection to external circuits. The various electronic components 6 are soldered to the wiring circuit layer 3. And a conductive adhesive 7 or the like. Although not shown,
If necessary, a wiring protection film made of glass, epoxy resin, or the like may be formed.

According to the present invention, it is important that the resistor layer 4 is formed of a metal plate or a metal foil made of a high-resistance metal having a specific resistance of 20 μΩcm or more. Since the metal plate or metal foil itself has much smaller shrinkage than the conventional thick film resistor compared to the shrinkage accompanying baking of the resistor powder, etc., it has excellent dimensional accuracy. By doing so, the resistance value does not change and it can be formed with high precision, so that a step such as trimming is not required.

It is desirable for the resistor constituting the resistor layer 4 to have a melting point higher than the firing temperature of the ceramic insulating substrate for simultaneous firing.
i, Cr, Mn, Fe, Ag, Pt, Pd, Sn, A
1, Si, Rh, Ir, Ru, Re and Au, or a mixture or alloy thereof are used.

On the other hand, the wiring circuit layer 3 is made of Cu, Ag, A
One, or a mixture or alloy of two or more selected from l, Au, Ni, Pt, Pd, W, Mo, and Mn, may be a metal having a melting point higher than the firing temperature of the ceramic insulating substrate. Desirable for simultaneous firing, especially for ceramic insulating substrates, firing temperature is 800 to 1000
When made of low-temperature fired ceramics such as glass ceramics at ℃, Cu, Ag, Al, Au, N
It is possible to use low resistance metals such as i, Pt and Pd or mixtures or alloys thereof.

The wiring circuit layer 3 is generally made of a sintered body made of the above-mentioned metal powder. In particular, a part or all of the wiring circuit layer 3 may be made of the above-mentioned metal plate or metal foil like the above-mentioned resistor layer. desirable.

The material of the insulating substrate 2 includes a wiring circuit layer 3
The material is not particularly limited as long as it is a ceramic material that can be fired at a temperature equal to or lower than the melting point of the metal forming the resistor layer 4, and well-known ceramic substrate materials such as alumina, mullite, Si ₃ N ₄ , AlN, and glass ceramics are used. However, in particular, a low-temperature fired ceramic material having a firing temperature of 800 to 1000 ° C., specifically, a glass ceramic obtained by firing a glass powder or a mixture of a glass powder and a filler powder can be selected by selecting a material of a resistor layer. And the low-resistance metal can be used as the wiring circuit layer 3.

Examples of the glass used for producing glass ceramics include silica glass, soda lime glass, lead glass, lead alkali silicate glass, borosilicate glass, aluminoborosilicate glass, zinc borosilicate glass, aluminosilicate glass, and phosphate glass. And the like, in particular,
Borosilicate glass is preferred. Examples of the ceramic filler include SiO ₂ , Al ₂ O ₃ and ZrO.
_{2, TiO 2, ZnO, MgAl} 2 O 4, ZnAl 2 O
₄ , MgSiO ₃ , MgSiO ₄ , Zn ₂ SiO ₄ , Z
n ₂ TiO ₄ , SrTiO ₃ , CaTiO ₃ , MgTi
O ₃ , BaTiO ₃ , CaMgSi ₂ O ₆ , SrAl ₂
Si ₂ O ₈ , BaAl ₂ Si ₂ O ₈ , CaAl ₂ Si ₂
O ₈ , Mg ₂ Al ₄ Si ₅ O ₁₈ , Zn ₂ Al ₄ Si ₅ O
₁₈ , AlN, SiC, mullite, zeolite, etc., which can be selected according to the application, and are not necessarily limited to the glass and ceramic fillers exemplified above.

Next, as a method of manufacturing the ceramic wiring board of the present invention, a case of manufacturing a multilayer wiring board is shown in FIG. 2 as an example.

(1) First, a predetermined amount of the above-mentioned glass powder or the above-mentioned glass powder and the above-mentioned lamic filler are weighed and mixed to prepare a glass-ceramic composition, and an organic binder or the like is added to the mixture. The green sheet 10 is formed by forming the sheet into a sheet shape by a blade method, a rolling method, a pressing method, or the like.

(2) Next, a through hole is formed in the green sheet 10 by laser, micro drill, punching or the like, and the inside thereof is filled with a conductive paste to form a via hole conductor 11. The conductive paste contains an organic binder and an organic solvent together with the metal powder for forming a wiring circuit layer as described above, and may be prepared by adding and mixing an inorganic component such as glass in some cases.

(3) Next, a wiring circuit layer 12 is formed on the surface of the green sheet 10. In forming the wiring circuit layer 12, a conductive paste was printed by screen printing, gravure printing, or the like, or a wiring circuit layer made of metal foil was previously formed on the surface of the transfer film, and the wiring circuit layer was formed. After the transfer film is pressed against the surface of the green sheet, the transfer film is peeled off, whereby the wiring circuit layer can be transferred and formed on the surface of the green sheet.

The conductor paste is made of Cu, Ag, A
1, at least one selected from Au, Ni, Pt, and Pd
It is prepared by mixing at least one kind of metal powder as a main component and the same component as the via-hole conductor described above. Further, after printing, it is desirable to bury the wiring circuit layer 12 by applying pressure so as not to form unevenness on the surface in order to form a resistor layer with high dimensional accuracy thereon.

(4) Next, a resistor layer is formed on the surface of the green sheet 10. In forming the resistor layer,
First, through steps (4a) to (4d) in FIG. 2, a resistor layer having a resistance value adjusted on the surface of the transfer film is prepared.

That is, (4a) First, a specific resistance of 2 is applied to the surface of the transfer film 13 such as a polymer film via an adhesive.
A metal plate or a metal foil 14 having a thickness of 0 μΩcm or more is prepared. (4b) Next, a resist layer 15 having a circuit pattern is provided on the surface of the metal plate or the metal foil 14. (4c) Then, the resist layer 1 is formed by an etching method.
The metal in the region where 5 is not formed is removed. (4d) The resist layer 1 is removed by removing the resist layer 15.
6 is formed.

According to this method, the thickness of the metal plate or the metal foil can be controlled uniformly, and the etching method enables fine processing without cutting or sagging of the wiring.
The dimensional accuracy of the resistor in the lateral direction can be improved, and as a result, the resistor layer 16 serving as the resistor can be formed with high accuracy.

(5) Subsequently, the transfer film 13 provided with the resistor layer 16 as described above is aligned and laminated on the surface of the green sheet 10 of (3).
A pressure of about 0 kg / cm ² is applied to the resistive layer 16
Is pressed against the surface of the green sheet. By peeling off only the transfer film 13 while leaving the resistor layer 16 on the green sheet 10, the resistor layer 16 can be transferred to the surface of the green sheet 10, whereby the resistor layer 16 and the A single-layer wiring sheet 17 having the wiring circuit layer 12 can be formed.

The wiring circuit layer 12 and the resistor layer 16
The order of formation is not important in the formation of
Contrary to the method described above, after forming the resistor layer 16 first,
The wiring circuit layer 12 may be formed. In addition, the wiring circuit layer 1
As described above, when the metal foil 2 is formed by transferring a metal foil of a high-purity low-resistance metal to the surface of the green sheet 10 using the same method as the method of forming the resistor layer 16 as described above. I don't care. In this case, fine wiring, which is difficult to form by the conventional printing method, can be formed with high yield, and furthermore, the wiring resistance can be reduced, which is effective for further miniaturization, higher density, and higher functionality. .

(6) Thereafter, the wiring sheets 18 to 20 prepared in the same manner as in (1) to (5) are laminated and pressed together with the wiring sheet 17 to form a laminate.

(7) Next, this laminate is placed in the range of 400 to 850.
° C to decompose and remove the organic components in the green sheet and the via-hole conductor paste.
2 and at the same time lower than the melting point of the metal component forming the resistor layer 16. As the firing conditions, for example, when the wiring circuit layer 12 is formed of a conductive paste or copper foil containing Cu as a main component, the firing is performed in a nitrogen atmosphere at 800 to 1000 ° C.

In this firing, the resistor layer 16 made of a metal plate or a metal foil does not exhibit a shrinkage behavior like a green sheet.
No. 7, 50 to 500 k from the uniaxial direction with respect to the green sheet laminate described above.
By applying a pressure of about g / cm ² or the like,
It is desirable that the green sheet be fired by a firing method that suppresses shrinkage in the XY directions and does not substantially shrink.

As described above, by firing in a method that does not substantially shrink in the XY directions, unlike the conventional thick film method, there is almost no deterioration in the precision of the resistance value due to the variation in shrinkage in firing. The resistor layer 16 formed with very high precision can be fired while maintaining its dimensional precision.

As described above, the ceramic wiring board of the present invention can be manufactured through the steps (1) to (7). However, when a wiring board having two front and back wiring circuit layers is manufactured. Is manufactured by performing the baking as shown in (7) after the steps (1), (2), (3), (4), and (5). In the case of manufacturing a multilayered wiring board,
After the steps (1) to (4), the wiring circuit layer 12 and the resistor layer 16 are formed on both surfaces of the green sheet 10 through the step (5).
Is formed and then fired as shown in (7).

According to the manufacturing method described above, in the step (4), the resistor layer 16 can be formed with much higher dimensional accuracy than the conventional printing method, and furthermore, substantially in the XY directions. By performing the firing without shrinking, the dimensional variation due to the firing can be suppressed. Therefore, unlike the conventional thick film method, a wiring board with high-precision resistors built into the surface layer and the inner layer is formed without simultaneous trimming and other processes by minimizing the cost increase by simultaneous firing. Thus, a wiring board that can cope with further miniaturization and higher density can be formed.

[0039]

EXAMPLE First, 70% by weight of borosilicate glass and 30% by weight of SiO ₂ were weighed, and prepared by adding an acrylic resin as a binder, DBP (dibutyl phthalate) as a plasticizer, and toluene and isopropyl alcohol as a solvent. Using the slurry thus obtained, a green sheet having a thickness of 300 μm was produced by a doctor blade method.

Next, an acrylic resin as an organic binder and DBP as a solvent were added to a Cu powder having an average particle size of 5 μm as a metal component and kneaded to prepare a copper paste for a wiring circuit layer and a copper paste for a via-hole conductor.

Then, via holes were formed at predetermined locations of the green sheet by punching, and the via hole conductor paste was filled in the via holes. Further, a wiring circuit layer was printed and formed on a predetermined portion of the green sheet by the screen printing method using the copper paste for a wiring circuit layer.

On the other hand, polyethylene terephthalate (PE)
An adhesive was applied to the transfer sheet surface of T), and a rolled metal foil of a Cu—Ni alloy having a specific resistance of 50 μΩcm and a thickness of 20 μm was bonded. Then, a photosensitive resist was applied to the surface of the metal foil, exposed through a glass mask to form a pattern, and then the non-pattern portions were removed by etching to form resistor patterns having different resistance values.

Then, the transfer sheet on which the resistor pattern was formed was laminated on the green sheet on which the via-hole conductor and the wiring circuit layer had been formed while positioning the via-hole, and thermocompression-bonded at 60 ° C. and 200 kgf / cm ² . . By peeling off the transfer sheet, the resistor layer was transferred to the surface of the green sheet to form a unit wiring sheet having a wiring circuit layer connected to via-hole conductors and a wiring layer formed by the resistor layer.

Further, the above-mentioned one unit of wiring sheet is made up of five layers,
Furthermore wiring sheet comprising the resistor layer is arranged one layer to come to the surface layer thereon, 60 ℃, 200kg / cm ²
Five sheets were laminated at a pressure of.

Finally, in order to decompose and remove organic components such as an organic binder, the green sheet laminate was kept at 750 ° C. for 1 hour in a nitrogen atmosphere, and then the laminate was placed at 200 kg / cm ² in the same atmosphere. 900 ° C with axial pressing
For 1 hour to produce a multilayer wiring board.

200 pieces of the above wiring boards were manufactured, and the variation in the resistance value of the inner layer resistance and the surface layer resistance was evaluated. In addition,
A variation of 2.5% or less was judged to be acceptable. Table 1 shows the results.

As a comparative example, a surface layer resistor was manufactured by a conventional thick film method, and the variation in resistance value before and after trimming was evaluated. At the same time, an inner layer resistor was prepared by a printing method and evaluated in the same manner.

[0048]

[Table 1]

As is apparent from Table 1, according to the present invention,
By forming the inner layer resistance and the surface layer resistance by simultaneous firing with a resistor layer made of a metal plate or a metal foil of a high resistance metal of 20 μΩcm or more, the variation in resistance value is reduced by 2.5 without going through a process such as trimming. % Or less, and a wiring board with a built-in high-precision resistor can be easily obtained.

On the other hand, in the conventional thick film method, the variation of the surface resistance cannot be reduced to 2.5% or less without trimming, and the same applies to the sample in which the inner layer resistance is formed by the printing method. there were.

[0051]

As described in detail above, according to the present invention,
In a wiring board comprising a ceramic insulating substrate and a wiring circuit layer formed on the surface and inside of the insulating substrate, a wiring circuit layer mainly composed of a metal, and a value of a specific resistance mainly composed of a metal and having a specific resistance. Is formed by a metal plate or a metal foil having a thickness of 20 μΩcm or more, without increasing the number of steps such as trimming, forming a high-precision resistance in the surface layer and the inner layer by simultaneous firing, further downsizing, It is possible to provide a wiring board having a resistor layer capable of increasing the density.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a multilayer wiring board which is one embodiment of a ceramic wiring board of the present invention.

FIG. 2 is a manufacturing process diagram for explaining a method for manufacturing the multilayer wiring board of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multilayer wiring board 2 Insulating board 2a-d Insulating layer 3, 12 Wiring circuit layer 4, 16 Resistor layer 5 Via hole conductor 6 Electronic component 7 Brazing material or adhesive 10 Green sheet 11 Via hole conductor 13 Transfer film 14 Metal foil 15 Resist 17-20 wiring sheet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (Reference) H05K 3/46 H05K 3/46 TSNF term (Reference) 4E351 AA07 AA09 AA13 AA14 BB01 BB05 BB22 BB26 BB30 BB49 CC12 CC17 CC19 CC22 DD04 DD05 DD12 DD17 DD18 DD19 DD20 DD21 DD31 DD42 DD52 DD54 EE10 EE11 GG09 GG20 5E346 AA12 AA14 AA15 AA24 AA43 BB01 BB20 CC17 CC18 CC25 CC31 DD09 EE24 EE27 EE29 FF18 H33H09H33GG03

Claims (10)

[Claims] 1. A ceramic wiring board in which a wiring circuit layer is formed on the surface and / or inside of a ceramic insulating substrate, wherein a metal plate of a high resistance metal of 20 μΩcm or more is provided on the surface and / or inside of the insulating substrate. A ceramic wiring board, wherein a resistor layer made of a metal foil is formed by firing simultaneously with the insulating substrate. 2. The method according to claim 1, wherein said resistor layer is made of Cu, Ni, Cr, M
n, Fe, Ag, Pt, Pd, Sn, Al, Si, R
2. The ceramic wiring board according to claim 1, comprising at least one metal selected from the group consisting of h, Ir, Ru, Re and Au. 3. The ceramic wiring board according to claim 1, wherein said resistor layer is formed inside said ceramic insulating substrate. 4. The ceramic wiring according to claim 1, wherein said ceramic insulating substrate is formed by firing glass powder or a mixture of glass powder and ceramic filler powder. substrate. 5. A step of producing a green sheet made of a ceramic insulating material; a step of forming a wiring circuit layer on the surface of the green sheet; and a step of forming a wiring circuit layer on the surface of the green sheet. Forming a resistor layer made of a metal plate or a metal foil of a high-resistance metal,
(D) pressing the transfer film on which the resistor layer is formed on the surface of the green sheet and then peeling off the transfer film to transfer and form the resistor layer on the surface of the green sheet; e) firing the green sheet on which the wiring circuit layer and the resistor layer are formed at a temperature lower than the melting point of the metal forming the wiring circuit layer and the resistor layer. Of manufacturing a ceramic wiring board. 6. In (e), before firing, (a)
6. The method for manufacturing a ceramic wiring board according to claim 5, further comprising the step of: (b) laminating another green sheet produced through (a) to (c). 7. The method for manufacturing a ceramic wiring board according to claim 5, wherein in the step (a), a via hole is formed in the green sheet, and a conductive paste is filled in the via hole. . 8. The resistor layer is made of Cu, Ni, Cr, M
n, Fe, Ag, Pt, Pd, Sn, Al, Si, R
8. The method for manufacturing a ceramic wiring board according to claim 5, comprising at least one metal selected from h, Ir, Ru, Re, and Au. 9. The ceramic wiring board according to claim 5, wherein said ceramic green sheet mainly comprises glass powder or a mixture of glass powder and ceramic filler powder. Production method. 10. The method according to claim 10, wherein the sintering is performed by using X-
6. The method for manufacturing a ceramic wiring board according to claim 5, wherein the method is performed while suppressing shrinkage in the Y direction.