JPH11135899A - Ceramic circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic circuit board in which bonding strength of surface layer wiring has enhanced reliability. SOLUTION: This ceramic circuit board 10 is produced by integrally sintering a surface layer wiring 2 on a substrate made of a glass-ceramic material which can be sintered at 800-1,000 deg.C. The glass-ceramic material contains 45-70 wt.% of low melting point crystallized glass powder and 55-30 wt.% of ceramic powder, wherein the glass powder contains substantially 15-25 wt.% of Al2 O3 , 40-43 wt.% of SiO2 , 3-5 wt.% of CaO, 10-15 wt.% of ZnO, 15-17 wt.% of MgO, and 4-7 wt.% of B2 O3 .

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 a surface wiring formed on a substrate made of a glass-ceramic material and on a laminated body in which a plurality of insulating layers made of a glass-ceramic material are laminated. It is.

[0002]

2. Description of the Related Art For example, a ceramic circuit board using a laminated body (substrate) in which a plurality of insulating layers made of a glass-ceramic material are laminated has a structure which can be fired at a lower temperature of 800 to 1000 ° C. than before. In addition, low resistance materials such as Ag, Cu, and Au (and at the same time, low melting points) can be used for interior conductors and surface wirings arranged between insulating layers, so that they have been widely used. The interior conductor formed inside the laminated main body is fired simultaneously with the laminated main body, but the surface wiring layer is fired simultaneously with the laminated main body, and when the surface of the sintered laminated main body is subjected to a baking treatment. There is.

Generally, as a glass-ceramic material that can be fired at 800 to 1000 ° C., a predetermined amount of a refractory filler (ceramic powder) such as alumina and a crystallized glass component are mixed, and the mixture is fired at 800 to 1000 ° C. In addition, the crystallized glass component is precipitated on the grain of the refractory filler, and good strength can be achieved.

The interior conductor is made of an Ag-based, Cu-based, or Au-based metal material. In order to improve the bonding strength with the glass-ceramic layer, Ag-based, Cu-based, or Au-based Cu is used.
To the conductive paste, 0 to 1.0 wt% of glass frit and 0 to 5.0 wt% of oxide were added. further,
The surface wiring was made of an Ag-based, Cu-based, or Au-based metal material.

[0005]

In the above-described ceramic circuit board, the surface wiring is made of a conductive paste to which a glass component and an oxide component are added in order to improve the bonding strength between the surface wiring and the surface of the laminated body in the same manner as the interior conductor. When the baking treatment is performed, a glass component or an oxide component tends to precipitate on the surface of the surface wiring. As a result, the solder wettability of the surface wiring is reduced, and it is difficult to solder electronic component elements and the like.

Even if the surface wiring is formed by the conductive paste to which the glass component is added as described above, even if the initial bonding strength is strong, the bonding strength is greatly reduced by a heat cycle test or the like. . This is because, compared to the interior conductor, the surface wiring is exposed to the outside and is subjected to severe environmental conditions.

In order to avoid this, it is conceivable to form the surface wiring with a conductive paste to which no glass component or the like is added. However, in such a case, the bonding strength between the laminated body and the surface wiring is greatly reduced. I will.

That is, even if the surface wiring is formed by the conductive paste to which the glass component is added as described above,
In many cases, the initial bonding strength is greatly reduced by the heat cycle test. This is because, compared to the interior conductor, the surface wiring is exposed to the outside and is subjected to severe environmental conditions.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a ceramic circuit board having a surface wiring integrally sintered with a substrate made of a glass-ceramic material. It is another object of the present invention to provide a ceramic circuit board having improved reliability of the bonding strength of the surface wiring, particularly, the reliability of the bonding strength after the temperature cycle test.

[0010]

SUMMARY OF THE INVENTION According to the present invention, an 800
In a ceramic circuit board obtained by integrally sintering surface wiring on a substrate made of a glass-ceramic material which can be fired at ~ 1000 ° C., the glass-ceramic material of the substrate is a low melting point crystallized glass powder of 45%. ~ 70% by weight,
The ceramic powder contains 55 to 30% by weight, and the glass powder contains 15 to 25% by weight of Al ₂ O ₃ and 4 to 4% of SiO ₂ .
0 to 43% by weight, 3 to 5% by weight of CaO, 10% of ZnO
15 wt%, the MgO 15 to 17% by weight, a ceramic circuit board, characterized by containing a B ₂ O ₃ 4 to 7 wt%.

In the present invention, 55 to 55 ceramic powders are used.
The reason for setting the content to 30% by weight is that if the content exceeds 55% by weight (the glass powder content is less than 45% by weight), the density of the fired body decreases, and the bending strength and moisture resistance of the substrate deteriorate. On the other hand, if the content is less than 30% by weight (glass powder exceeds 70% by weight), the bending strength of the substrate is deteriorated, or the shape is lost during firing, and the substrate is not formed.

The above-mentioned glass component SiO ₂ is a glass network former. For example, if the glass component is less than 40% by weight, the softening point becomes too low and the heat resistance is lowered. It is not preferable because the surface wiring tends to be deformed during the baking process (re-baking) on the surface of the baked substrate. On the other hand, if it exceeds 43 wt%,
The softening point of the glass increases, and it is not possible to form sufficient crystallized glass at the interface between the ceramic particles, and as a result,
It lowers the density of the substrate and further deteriorates the water resistance.

The glass component Al ₂ O ₃ is an essential component for improving the water resistance of the glass and for precipitating a predetermined crystal phase. If the content of Al ₂ O ₃ is less than 15% by weight, the precipitation of crystallized glass becomes insufficient, leading to deterioration in the bending strength of the substrate and the adhesive strength with the surface wiring. On the other hand, if it exceeds 25 wt%, the softening point of the glass increases, for example, 800 to 10%.
Even at a sintering temperature of 00 ° C., a crystalline phase is hardly precipitated.

In the glass component, CaO, ZnO, MgO
Is a component necessary to precipitate a predetermined crystal phase. The predetermined crystal phases are anorthite, willemite, garnite, etc., which are necessary for precipitating these crystal phases. If the above-mentioned range is exceeded, crystals are not sufficiently formed, and the bending strength of the substrate is deteriorated. I do.

B ₂ O ₃ is used as a flux component, but if it is less than 4%, the softening point of the glass becomes high, and the sintering temperature becomes high. On the other hand, if it exceeds 7.0% by weight, the remaining glass component which has not been crystallized increases, and the heat resistance and the bending strength deteriorate.

[0016]

In the present invention, a substrate material composed of a powder having a glass composition in the above range and a ceramic powder such as alumina ceramic is coated with an Ag-based material (Ag alone or an Ag alloy),
When a conductor film serving as a surface wiring made of u-based or Au-based is formed by printing and drying, and the substrate material and this conductor film are integrally baked, the glass component of the substrate material is softened, and the ceramic powder granules are formed. As a result, the glass becomes crystallized glass and is precipitated on the substrate, and penetrates between the metal particles of the surface wiring. As a result, the glass component goes around the interface of the metal particles that have undergone the sintering reaction in the vicinity of the substrate joining, and the metal particles and the glass component of the substrate material are firmly joined by the anchor effect. Thus, the surface wiring can be bonded stably even with respect to the stress generated during the temperature cycle.

At the same time, near the junction of the surface wiring, a strong junction is achieved by the glass component of the substrate material,
The glass component of the substrate material is unlikely to be deposited on the surface portion of the surface wiring, whereby an electronic component or the like can be stably and firmly solder-bonded on the surface wiring via solder.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a ceramic circuit board according to the present invention will be described with reference to the drawings. In the embodiments, a laminated substrate (laminated main body) in which a plurality of insulating layers are laminated will be described as a substrate. FIG. 1 shows a ceramic circuit board using the laminated board of the present invention.

In FIG. 1, reference numeral 10 denotes a ceramic circuit board. The ceramic circuit board 10 is composed of a laminated body 1 and a surface wiring 2 and, if necessary, soldered on the surface wiring 2 and the surface wiring 2. The joined electronic components 3 are mounted.

The laminated body 1 has, for example, four insulating layers 1a.
To 1d are stacked.

The interior conductors 11 are arranged between the layers, and the insulation layers 1a to 1d are used to connect the interior conductors 11 between the insulation layers and to connect the interior conductor 11 and the surface wiring 2. Are formed.

The insulating layers 1a to 1d are composed of a ceramic component as a refractory inorganic filler and a crystallized glass component. Specifically, a ceramic sheet, a low melting point glass powder containing various glass components that precipitate a predetermined crystal phase, a green sheet in which a binder, a solvent, etc. are homogeneously mixed, and an insulating layer formed by printing and drying are fired at a low temperature. Is achieved by Since the binder and the solvent are burned off during the drying or baking treatment, the insulating layers 1a to 1d are substantially composed of a ceramic component and a glass component. Examples of the ceramic component include alumina, cristobalite, stone random (α-alumina), and the like. The glass component is 800 to 100.
Cordierite even when calcined at a relatively low temperature of 0 ° C.
It is composed of a glass powder capable of precipitating at least one of crystal phases such as mullite, anorthite, serdian, spinel, carnite, willemylomite, petalite, ozumilite and substituted derivatives thereof.

Then, in the solid components of the insulating layers 1a to 1d,
The low melting point crystallized glass powder contains 45 to 70% by weight and the ceramic powder contains 55 to 30% by weight.

Further, the glass powder described above, the glass powder raw medium, A1 ₂ O ₃ 15 to 25 wt%, a SiO ₂ 40
~ 43wt%, CaO 3 ~ 5wt%, ZnO 10 ~
15 wt%, the MgO 15 to 17 wt%, B ₂ O ₃ to 4
-7% by weight.

The interior conductor 11 and the via-hole conductor 12 are
Mainly composed of low-resistance metal materials such as Ag (Ag alone or Ag alloy), Cu, and gold, as necessary to match the bonding strength with the substrate material and the sintering behavior during integral sintering And does not hinder the generation of the crystallized glass component of the substrate material. Specifically, for example, using a conductive paste obtained by homogeneously mixing an Ag powder, a low-melting glass component, and an organic vehicle, printing and coating are performed on a glass-ceramic green serving as a substrate material, and on a green sheet. Filled, coated and dried in the formed through holes,
It is baked integrally with the substrate material.

The surface wiring 2 is mainly made of a low-resistance metal material such as an Ag-based material (Ag alone or an Ag alloy), a Cu-based material, or a gold-based material. Specifically, for example, using a conductive paste in which Ag powder and an organic vehicle are homogeneously mixed, printing and coating are performed on a glass-ceramic green serving as a substrate material, and firing treatment is performed integrally with the substrate material.

The surface wiring 2 constitutes a wiring of a predetermined circuit on the substrate, and also functions as a mounting pad for mounting the electronic component 3, an output pad, and a terminal electrode connected to an external wiring substrate. .

The electronic component 3 can mainly be exemplified by a chip resistor, a chip-type multilayer capacitor, a piezoelectric oscillator, an IC chip, etc., and is soldered via cream solder or solder balls.

Next, an example of a method for manufacturing a ceramic circuit board of the present invention will be described.

First, as a glass-ceramic material, 50 wt% of alumina powder in a solid component, 50 wt% of a low melting point glass powder shown in Sample No. 3 in Table 1, an organic binder such as alkyl methacrylate, and a plasticizer such as DBP And an organic solvent such as toluene, for example, and mixed with a ball mill for 48 hours to prepare a slurry. The alumina powder and the glass powder have an average particle size of 1.0 to 1.0, respectively.
It is 5.0 μm, preferably 1.5 to 3.0 μm. The slurry is formed into a tape by a doctor blade method or the like, and cut into a predetermined size to form a green sheet. Note that the green sheet is a large green sheet partitioned into element regions that become a plurality of circuit boards, and the interior conductor 11, the via-hole conductor 12, and the surface wiring 2 of each element region are created in common.

Next, through holes are formed by punching at positions where the via hole conductors 12 are to be formed in the green sheets to be the insulating layers 1a to 1d.

Next, a conductor to be a via-hole conductor 12 is formed by filling and drying the above-described conductive paste containing an Ag-based material into the through-holes formed in the green sheets to be the respective insulating layers 1a to 1d. At the same time, a conductive film to be the surface wiring 2 is formed on the green sheet to be the insulating layer 1a by printing and applying the above-described conductive paste made of, for example, an Ag-based material. Further, a conductor film serving as the interior conductor 11 is formed on the green sheet serving as the insulating layers 1b to 1d by printing and drying the above-described conductive paste made of, for example, an Ag-based material.

The green sheets thus obtained are laminated and pressed in accordance with the order of the laminated body 1 to form a laminated substrate of large green sheets. In addition, if necessary, a division groove is formed to divide each element region after firing.

Next, the above-described laminated substrate of large green sheets is fired at about 800 to 1000 ° C. in an oxidizing atmosphere. The substrate material, the inner conductor 11, the via-hole conductor 12, the surface wiring 2
The organic vehicle contained in each conductor is burned off, and the glass component of the substrate material softens at around 700 ° C.
The glass component penetrates into the grains of the ceramic powder of the substrate material and the grains of the metal particles of the surface wiring 2, and at about 800 to 1000 ° C., the glass component is strongly crystallized in a predetermined crystal phase.

Thereafter, a thick low-antibody film is baked at a predetermined position of the surface wiring 2 of the baked laminated main body 1, an insulating protective film is formed, or a cream solder is applied to form the predetermined electronic component element 3. It arrange | positions and joins by a reflow process. At the same time, if necessary, the ceramic circuit boards are separated along the dividing grooves.

In the present invention, the glass component of the glass powder of the substrate material contains 15 to 25% by weight of Al ₂ O ₃ and SiO ₂
The 40-43 wt%, CaO 3-5% by weight, ZnO of 10-15% by weight, the MgO 15 to 17 wt%, B ₂ O
₃ contains 4 to 7% by weight.
forming a conductor film as a surface wiring made of g-based (Ag alone or Ag alloy), Cu-based, and Au-based by printing and drying;
When the substrate material and the conductor are integrally baked, the glass component of the substrate material is softened, becomes crystallized glass at the grain boundaries of the ceramic powder, and is precipitated on the substrate.
Between metal particles. As a result, the glass component also wraps around the interface of the metal particles of the surface wiring 2 that has undergone a sintering reaction near the substrate bonding. Then, due to the anchor effect between the metal particles and the glass component of the substrate material, the laminated main body 1 and the surface wiring 2 are firmly joined. In addition, extremely stable bonding can be maintained even with respect to stress generated during a temperature cycle.

At the same time, although strong bonding is achieved by the glass component of the substrate material in the vicinity of the junction of the surface wiring 2, the glass component of the substrate material is unlikely to be deposited on the surface portion of the surface wiring 2. The electronic component element 3 and the like can be stably and firmly soldered on the surface wiring 2 via solder.

The inventor of the present invention used the glass powder as the glass component shown in Table 1 to measure the strength (flexural strength) of the laminated body (substrate), the bonding strength in the initial state with the surface wiring 2, and the temperature cycle test TCT. (The temperature was changed at −40 ° C. and 125 ° C. every 30 minutes for 100 cycles). The strength was determined by soldering a lead wire on a 2 mm square surface wiring pattern and pulling the lead wire vertically upward when the solder was peeled off from the surface wiring 2.
Alternatively, it is indicated by the load at the time of peeling from the substrate material and the surface wiring 2.

[0039]

[Table 1]

As a result, when SiO ₂ is less than 40 wt% (36.9 wt%) in the glass component as in Sample No. 1, the softening point of the glass component becomes too low, and the heat resistance is lowered. Warpage easily occurs on the surface of the substrate material, and the bonding strength between the substrate material (laminated main body 1) and the surface wiring 2 is extremely reduced. Therefore, the bonding strength (2 mm square) with the surface wiring 2 is 0.4 kg weight in the initial state. In addition, the ceramic powder of sample number 1
When it is on the order of wt%, the bending strength tends to further decrease, and high bending strength (for example, 25 kg weight / thickness 2 m)
m) or more was not obtained.

As shown in sample No. 2, CaO was 3w
At less than t% (2.7 wt%), it can be understood that anorthite which is a Ca-based crystal phase is not sufficiently formed.

[0042] In addition, includes the K ₂ O, the K ₂ O
Remains as the residual glass, and the dielectric loss is reduced in electrical characteristics. In particular, the bonding strength after the heat cycle test is 1.
It will be less than 5kg weight.

As shown in Sample No. 4, MgO was 15
If it is less than 1 wt% (14.0 wt%), forsterite, which is a Ma-based crystal phase, is not easily formed, and uncrystallized glass remains. For this reason, the amount of crystallized glass bonded to the surface wiring decreases, so that the bonding strength in the initial state was 2.2 kgf / 2 mm square, but the bonding strength was significantly reduced after the heat cycle test. I will.

As shown in Sample Nos. 5 and 6, Al ₂
O ₃ exceeds 25 wt%, 26.4 wt%, 27.7 wt%
When it is wt%, the softening point of the glass is high and the fluidity is poor. For example, even at a sintering temperature of 800 to 1000 ° C., a crystallized glass is hardly generated, and a glass component that cannot be crystallized becomes a normal glass. It tends to remain.

For example, in sample No. 5, crystallized glass sufficient for the bonding strength with the surface wiring 2 could not be obtained, and the bonding strength was separated by 1.0 kg weight, and was stable after the heat cycle test. Even bonding cannot be achieved. In sample No. 6, the amount of glass was large, the amount of ceramic powder was relatively small, and the amount of SiO ₂ was too large.
The fluidity is further deteriorated, so that the grain boundaries of the ceramic powder cannot be sufficiently wetted, and a glass component that is not crystallized is deposited on the surface of the surface wiring 2.

Further, as shown in Sample No. 7, when Al ₂ O ₃ is suppressed and replaced with SiO ₂ (51.7 wt%), a good result that the bonding strength in the initial state is 2.2 kg weight is obtained. Although obtained, the heat cycle test results in a reduction in bonding strength to less than half. This is because CaO, which constitutes an anorthite-based crystal phase, becomes excessive, and as a result, remains as a normal glass component, so that the bonding strength after a heat cycle is reduced.

The present inventor changed the amount of the alumina powder added to the glass component shown in Sample No. 3 to 25 to 60% by weight, but the alumina powder exceeded 55% by weight (the glass powder was 45% by weight). %), It was confirmed that the density of the fired body was reduced and the bending strength of the substrate was less than 30 kgf / 2 mm. Further, it was confirmed that when the amount was less than 30 wt% (the amount of glass powder exceeded 70 wt%), the transverse rupture strength of the substrate was reduced to 25 kgf / 2 mm.

As described above, from various experiments, it is important to determine the transverse rupture strength of a substrate by blending a glass component capable of stably depositing a predetermined crystal phase. The mixing ratio is very important.
At the same time, in order to strengthen the bonding of the surface wiring 2 and increase the reliability after the heat cycle test, the glass component should be blended so that the fluidity of the glass component is good and a predetermined crystal phase is stably precipitated. It is important to have a ratio.

As described above, in the glass component of the glass powder of the present invention, SiO ₂ is used in the range of 40 to 43 wt%, Al ₂ O ₃ is used in the range of 15.0 to 25.0 wt%, and the predetermined crystal phase is used. To precipitate CaO, ZnO, M
gO, B ₂ O ₃ respectively 3.0~5.0wt%, 10.0
-15.0 wt%, 15.0-17.0 wt%, 4.0
By setting the content to ~ 7.0 wt%, a predetermined crystal phase (cordierite, foresterite, enstatite, garnite, anorthite, willemite, celsian, etc.) is precipitated, and a substrate having a transverse rupture strength of 25 kgf or more can be achieved. 1.5k, even in the initial state and after thermal cycling
The surface wiring 2 which is firmly bonded to the substrate with a weight of g or more and has good solder wettability can be obtained.

In the above-described embodiment, a laminated circuit board in which a plurality of insulating layers are laminated is used as the substrate. However, the surface wiring and the substrate material may be simultaneously baked using a substrate on a single plate. Similar results are obtained. Further, in addition to the Ag-based (Ag simple substance, Ag alloy), the surface layer wiring is Cu-based (Cu simple substance, C alloy).
The glass component of the substrate material stably penetrates between the metal powder grains at the joint portion of the surface wiring with the substrate even if it is an Au-based (Au alloy) or Au-based (Au simple substance, Au alloy), 1.5k initial joint strength and strength after thermal sile test
g weight or more can be achieved.

[0051]

According to the present invention, a strong substrate made of a glass-ceramic material is achieved, and even when in an initial state and after a heat cycle, the substrate is firmly bonded to the substrate and solder wettability is also improved. A good surface wiring can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a ceramic circuit board according to the present invention.

[Explanation of symbols]

 10 Ceramic circuit board 1 Base (one laminated body) la to 1d Ceramic layer 2 Surface wiring 3 Interior conductor 4 ..Via hole conductors 5 ..... Electronic components

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H05K 3/46 C04B 35/16 Z

Claims (1)

[Claims] 1. A ceramic circuit board obtained by integrally sintering surface wiring on a substrate made of a glass-ceramic material that can be fired at 800 to 1000 ° C., wherein the glass-ceramic material of the substrate has a low melting point. 45-70% by weight of crystallized glass powder and 55-70% of ceramic powder
Comprising 30 wt%, and the glass Konahitsuji is A1 ₂ O ₃ 15 to 25 wt%, a SiO ₂ 40 to 43
Wt%, CaO 3-5% by weight, ZnO of 10-15% by weight, the MgO 15 to 17 wt%, the ceramic circuit board, characterized by containing a B ₂ O ₃ 4 to 7 wt%.