JP2001043730A - Conductor composition and wiring board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conductor composition which improves adhesive strength of a metallized wiring layer and an insulating substrate, suppresses camber of the substrate and superior in solder wetting property and a wiring board using the composition. SOLUTION: This composition is a conductor composition containing zinc silicate at a ratio of 0.1 to 10 pts.wt. for low resistance metallic powder 100 pts.wt. A wiring board 1 using the composition is provided with an insulating substrate 2, made of glass ceramics and a metallized wiring layer 3 adhered and formed on the surface and/or at the inside of the insulating substrate 2. The metallized wiring layer 3 is formed by adhering and baking the conductor composition on the insulating substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a conductor composition and a wiring board using the same.

[Prior art]

In recent years, wiring boards have been required to be compatible with high-frequency circuits, have high densities, and have high speeds. As a result, a low dielectric constant can be obtained as compared with conventional alumina-based ceramic materials, and the resistance of the wiring layers has been reduced. Possible low-temperature fired wiring boards are drawing attention.

As such a low-temperature fired wiring board, there is known an insulating board made of glass ceramic provided with a metallized wiring layer mainly composed of a low-resistance metal such as copper, gold and silver. This wiring board is printed at 800 to 1000 ° C. after printing a conductor paste containing the powder of the low-resistance metal on a sheet-shaped molded body made of a glass ceramic composition.
At the same time. In addition, the low-temperature fired wiring board has a low resistance of a wiring layer, a low dielectric constant and a low dielectric loss of an insulating substrate, and has a semiconductor element housing package for housing a semiconductor element, a wiring circuit board, a mobile phone, and a personal computer. Applications to various fields such as a handy phone system and a high-frequency multilayer wiring board used for various satellite communications are being promoted.

For example, when forming a metallized wiring layer containing copper powder as a main component on the surface and inside of an insulating substrate made of glass ceramic, a slurry prepared by adding a solvent to glass ceramic raw material powder and an organic binder is used. Formed into a sheet by doctor blade method or the like, punching a through hole in the obtained green sheet, filling the through hole with a conductive paste mainly composed of copper powder, and at the same time, mainly applying copper powder on the green sheet. A conductor paste as a component is printed by a screen printing method or the like to form a wiring pattern. Then, a plurality of green sheets having a via hole conductor in which a conductor is filled in a wiring pattern or a through-hole are laminated under pressure and fired at 800 to 1000 ° C. to obtain a wiring board having a metallized wiring layer.

However, since the conductor paste has a poor affinity for glass ceramics, the bonding strength between the formed wiring conductor and the glass ceramic porcelain is low, so that the bonding strength of a pin or a pad for ball attachment is high. In a required part, there has been a problem that when a thermal or mechanical stress is applied, the wiring conductor and the glass ceramic porcelain are easily separated. Therefore, in order to improve the adhesive strength, ZnO or the like is added to a conductor paste mainly containing copper oxide powder (Japanese Patent Laid-Open No. 1-317184), or a glass containing ZnO as a conductor paste mainly containing copper powder is used. It has been proposed to add a powder (JP-A-3-46706).

[0006]

However, in the method of adding ZnO or the like to a conductor paste mainly composed of copper oxide powder, the sinterability of copper is impaired, and the shrinkage behavior of the glass-ceramic substrate during firing is reduced. Since the displacement occurs, the wiring board is warped, and when sintering is significantly inhibited, the adhesive strength is deteriorated.

On the other hand, a method of adding a glass powder containing ZnO to a conductor paste containing copper powder as a main component is a suitable example to be applied to a high-purity AlN substrate, and this method is applied to a glass ceramic substrate. In this case, the sinterability of the copper powder is improved, but the interaction with the glass-ceramic substrate causes the separation of copper and the glass component, and the glass component contained in the conductive paste becomes the surface of the copper metallized layer. And hinder solder wettability.

An object of the present invention is to provide a conductor composition which improves the adhesive strength between a metallized wiring layer and an insulating substrate made of glass ceramics, suppresses warpage of the substrate, and is excellent in solder wettability. It is to provide a wiring board.

[0009]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have used a conductor composition obtained by adding a predetermined amount of zinc silicate to a low-resistance metal powder such as a copper powder. When the metallized wiring layer is formed by the method, the adhesive strength to the insulating substrate made of glass ceramic is improved, the solder wettability is good, and the warpage of the substrate due to the difference in firing shrinkage between the insulating substrate and the conductive paste is reduced. They have found a new fact that they can be suppressed, and have completed the present invention.

That is, the conductor composition of the present invention comprises zinc silicate in an amount of 0.1 part by weight per 100 parts by weight of the low-resistance metal powder.
-10 parts by weight. In the present invention, the low-resistance metal powder has an average particle size of 0.5 to 1
It is preferably a 0 μm spherical powder. As a result, the sintering behavior such as shrinkage of the metallized wiring layer can be more closely approximated to the sintering behavior of the glass-ceramic substrate, so that the warpage of the substrate can be suppressed, and since the particle size is suitable for screen printing, printing is performed. The accuracy is improved.

The low-resistance metal powder is copper powder, and the whole or a part thereof is contained in the form of copper oxide which is reduced to simple copper by firing in a reducing atmosphere, and the amount of the copper oxide is reduced. By adjusting, the shrinkage rate of the metallized wiring layer due to the volume shrinkage during the reduction of copper oxide can be matched with the shrinkage rate of the insulating substrate. The wiring board of the present invention,
An insulating substrate made of glass ceramics, and a metallized wiring layer adhered and formed on the surface and / or inside of the insulating substrate, wherein the metallized wiring layer is formed by applying the conductor composition described above to the insulating substrate and firing the same. Characterized in that:

In the present invention, the insulating substrate may have a size of 0-4.
The coefficient of thermal expansion up to 00 ° C is preferably from 8 to 18 ppm / ° C. Thereby, the heat applied to the solder connection portion when the insulating substrate is surface-mounted on a printed wiring board having a thermal expansion coefficient of 13 to 30 ppm / ° C. containing an organic resin in the insulating substrate via a connection terminal such as a solder ball. Relieves the stress, resulting in improved mounting reliability.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a conductor composition of the present invention and a wiring board using the same will be described with reference to the drawings. FIG. 1 shows a structure of a wiring board according to an embodiment of the present invention, which is a multilayer wiring board including a plurality of glass ceramic insulating layers.

As shown in FIG. 1, a wiring board 1 includes an insulating substrate 2 and a metallized wiring layer 3. Insulating substrate 2
Is composed of a laminated body in which a plurality of glass ceramic insulating layers 2a... 2d are laminated, and a thickness mainly composed of a low-resistance metal powder such as copper powder is 5 to 30 μm on each interlayer and on the surface of the insulating substrate 2. The metallized wiring layer 3 is formed to a degree. Further, in the insulating substrate 2, each insulating layer 2a,.
A via hole conductor 4 having a diameter of about 50 to 200 μm penetrating 2d in the thickness direction is formed.

The insulating substrate 2 is made of glass ceramics made of glass containing at least SiO ₂ or a composite material of glass containing SiO ₂ and a filler.
Specifically, the glass component of the glass ceramic material is
Crystallization composed of a plurality of metal oxides, after sintering, amorphous or by sintering to precipitate cordierite, mullite, anorthite, serdian, spinel, garnite, willemite, dolomite, lithium silicate and substituted derivatives thereof Composed of glass.

As the glass component, for example, SiO 2_TwoOther than
To Li_TwoO, K_TwoO, Na_TwoOxidation of alkali metals such as O
Substances, alkaline earth metal oxides such as CaO and MgO, A
l_TwoO _Three, P_TwoO_Five, ZnO, B_TwoO_ThreeAnd PbO
Borosilicate glass containing one or more selected from the group consisting of:
, Alkali silicate glass, BaO-based glass, sodium
And soda glass. The filler component and
For example, quartz, cristobalite, quartz,
Random (α-alumina), diopside, mullite,
1 selected from cordierite and forsterite
Species or two or more can be used.

The ratio of the glass component to the filler component is 30 to 70% by weight for the glass component and 70 to 3% for the filler component.
Suitably, it is 0% by weight. The insulating substrate 2 according to the present invention has a coefficient of thermal expansion from 0 to 400 ° C. of 8 to 18.
It is preferably ppm / ° C. If the coefficient of thermal expansion of the insulating substrate 2 is lower than 8 ppm / ° C., there is a problem that a thermal stress is applied to a solder joint between the insulating substrate 2 and the printed wiring board, thereby lowering the mounting reliability. In addition, there is a problem that thermal stress is applied to a solder joint between the insulating substrate 2 and the silicon chip, and mounting reliability is reduced.

The metallized wiring layer 3 contains a low resistance metal powder as a main component. According to the present invention, the metallized wiring layer 3
It is formed by laminating and firing a conductive composition containing 0.1 to 10 parts by weight of zinc silicate with respect to 100 parts by weight of the low-resistance metal powder.

Examples of the low-resistance metal powder include powders of copper, silver, gold, and the like. Particularly, use of copper powder increases the density of a wiring board, reduces the cost of manufacturing a low-resistance conductor, and further improves reliability. It is also preferable from the viewpoint of the above. The low-resistance metal powder has an average particle size of 0.5 to 10 μm, preferably 2 to 7 μm,
More preferably, it is preferably a spherical powder of 3 to 5 μm, and when the average particle size is less than 0.5 μm, there is a problem that the copper powder causes oversintering and the adhesive strength is reduced,
Conversely, when the thickness exceeds 10 μm, there is a problem that fine wiring cannot be processed. As the zinc silicate, Zn
O and it may be a crystalline complex oxide comprising a reaction product of SiO _2, for example, ZnO · 2SiO ₂ (ZnSi ₂ O
₅ ) 2ZnO.SiO ₂ (Zn ₂ SiO ₄ ), 3Zn
O.SiO ₂ (Zn ₃ SiO ₅ ) and the like.

Since such a zinc silicate generally has a lower melting point than ZnO, the sintering of the wiring layer 3 proceeds at a lower temperature than that containing ZnO, so that there is an advantage that sinterability is improved. . For example, the melting point of ZnSi ₂ O ₅ is about 1512 ° C., and the melting point of ZnO is about 1972 ° C.
, The conductor composition of the present invention is approximately 900
The sintering proceeds at around 1000C, whereas the sintering of the conventional conductor composition containing ZnO proceeds at around 1000C. Therefore, when co-firing with the insulating substrate, Zn
Compared to the conductor composition to which O is added, the timing of sintering with the substrate is easily adjusted, the adhesive strength with the substrate is improved, and the warpage of the substrate can be effectively suppressed.

The zinc silicate is a low-resistance metal powder 1
When the content of zinc silicate is less than 0.1 part by weight, the metallized wiring layer 3 and the glass ceramics are required. Of the metallized wiring layer 3 and the insulating substrate 2 is weakened. On the other hand, when the content of zinc silicate is 1
When the amount exceeds 0 parts by weight, the sinterability of the low-resistance metal powder is deteriorated, and the solder wettability, the adhesive strength, the substrate warpage and the like are adversely affected. More preferably, zinc silicate is contained in a proportion of 1 to 5 parts by weight.

The zinc silicate used preferably has an average particle size of about 0.1 to 3 μm. The via hole conductor 4 is preferably a conductor having the same components as those of the metallized wiring layer 3.

The metallized wiring layer 3 on the surface of the multilayer wiring board
Are used as pads for mounting various electronic components 5 such as IC chips, as conductive films for shielding, and as terminal electrodes for connection to external circuits. Various electronic components 5 are joined to the wiring layer 3 via a joining agent 6 such as solder or a conductive adhesive. Although not shown, a thick-film resistor film such as molybdenum silicide, a wiring protection film, or the like may be formed on the surface.

Next, a method for manufacturing the wiring board of the present invention will be described. First, a glass ceramic composition as described above, or a glass component and a filler component are mixed to prepare a glass ceramic composition, an organic binder is added to the mixture, and then a doctor blade method, a rolling method, a pressing method, or the like. The sheet is formed into a green sheet by an appropriate forming means to obtain a green sheet.

Next, a conductor paste is printed on the surface of the green sheet in a wiring pattern by screen printing or the like. As the low-resistance metal powder which is a main component of the conductor paste, the above-described metal simple substance (for example, copper), an oxide of the metal (for example, copper oxide), or a mixture thereof is used. The metal oxide is substantially reduced to a simple metal powder by firing in a reducing atmosphere.

The conductive paste is homogeneously mixed with the above-mentioned inorganic components such as the low-resistance metal powder and a predetermined amount of zinc silicate, an organic binder such as an acrylic resin, and an organic solvent such as α-terpineol, dibutyl phthalate and butyl carbitol. It is prepared by mixing. The organic binder is preferably mixed at a ratio of 1 to 10 parts by weight with respect to 100 parts by weight of the inorganic component, and the organic solvent is preferably mixed at a ratio of 5 to 30 parts by weight with respect to 100 parts by weight of the inorganic component.

On the other hand, to form the via-hole conductor 4,
A through hole having a diameter of about 50 to 200 μm is formed in the green sheet by laser, micro drill, punching or the like, and the inside of the through hole is filled with the same conductive paste as the wiring layer 3. After that, the wiring layer 3 and the via hole conductor 4
The green sheets on which are formed are laminated and pressed to form a laminate. Next, the laminate is subjected to a heat treatment in a nitrogen atmosphere at 400 to 800 ° C. to decompose and remove organic components contained in the green sheet and the conductor paste.
Simultaneous firing in a nitrogen atmosphere (reducing atmosphere) at 1000 ° C. makes it possible to manufacture a multilayer wiring board including the metallized wiring layer 3 and the via-hole conductor 4.

The wiring board of the present invention is not limited to the above-described multilayer wiring board. A wiring pattern is printed on a single-layer glass ceramic green sheet with the same conductive paste as described above, and the wiring pattern is simultaneously printed. A fired wiring board is also included. Even if the substrate has a multilayer structure, only the internal metallized wiring layer 4 is baked simultaneously with the laminated body,
The wiring layer 4 on the surface may be formed by baking on the surface of the fired laminate.

[0029]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples, but the conductor composition of the present invention and a wiring board using the same are not limited to the following examples.

EXAMPLE As a material for a green sheet for an insulating substrate, 7% by weight was used.
4% SiO_Two-14% Li_TwoO-4% Al_TwoO_Three-2%
K_TwoO-2% ZnO-2% Na_TwoO (Yield point 480 ° C)
40% by volume of glass having a composition of
SiO as minute _Two30% by volume, Forsterite 30
What mixed volume% was used. This has a molecular weight of 300,000
Add acrylic binder and plasticizer, dispersant and solvent
And mix the resulting slurry using the doctor blade method.
Into a green sheet having an average thickness of 200 μm. one
On the other hand, zinc powder was added as an additive to copper powder having an average particle size of 4 μm.
Like (average particle size 1μm) or ZnO or Zn
O and glass powder were added at the ratios shown in Table 1,
Acrylic as an organic binder to 100 parts by weight of the component
Resin, 2 parts by weight of α-terpineol 1 as an organic solvent
5 parts by weight were added and kneaded to prepare a conductor paste.

Using the conductive paste and green sheet thus obtained, the following three types of samples were prepared. (1) Sample for Evaluating Adhesive Strength A pattern having a size of 2 cm × 2 cm and a thickness of 20 μm after firing was screen-printed on a green sheet, and the same five green sheets were laminated under the green sheet under pressure. (2) Sample for evaluating substrate warpage A pattern having a size of 10 mm × 10 mm and a thickness of 20 μm after firing was screen-printed on a green sheet, and one green sheet was laminated under the green sheet under pressure. (3) Sample for evaluating solder wettability A circular pattern having a diameter of 0.1 mm after firing was screen-printed on a green sheet, and the same five green sheets were laminated under the green sheet under pressure.

The unfired laminate on which the wiring pattern has been formed is held at 700 ° C. for 3 hours in a nitrogen atmosphere in order to decompose and remove organic components such as an organic binder. And heated for 1 hour and fired to obtain a wiring board. The thermal expansion coefficient at 0 to 400 ° C. of the insulating substrate obtained by firing the green sheet is 1
1.5 ppm / ° C.

The characteristics of each wiring board obtained by using the samples (1) to (3) were evaluated by the following methods. (1) Evaluation Method of Adhesive Strength A 1 μm-thick Ni plating was applied to a 2 mm square copper wiring layer present on the surface of the obtained wiring board, and a 0.1 μm-thick gold plating was applied to the surface. Next, a tin-plated copper wire having a diameter of 0.8 mm was soldered on the gold-plated layer in parallel with the substrate, and then the tin-plated copper wire was bent in a direction perpendicular to the substrate, so that the tin-plated copper wire became 10 mm / min. The film was pulled in the vertical direction at a pulling speed, and the maximum load when the interface between the copper wiring layer and the insulating substrate was broken was evaluated as the adhesive strength of the copper wiring layer. At this time, those having an adhesive strength exceeding 2 kg / 2 mm square were regarded as good products. (2) Evaluation method of substrate warpage A surface roughness of a copper wiring layer having a side of 10 mm on a surface of a wiring substrate and measuring 10 mm square was measured by a contact-type surface roughness meter along a diagonal direction (length 14.2 mm). Measured, 50μm / 14.2m
m or less were regarded as good products. (3) Solder wettability evaluation method A flux was applied to a copper wiring layer having a circular pattern existing on the surface of a wiring board, and was placed in a eutectic solder maintained at 235 ° C. at an angle of 45 ° with respect to the vertical direction. What was immersed for 5 seconds was observed with a stereoscopic microscope, and the one in which the entire pattern of the copper wiring layer was wet with solder was regarded as a good product. Table 1 shows the test results.

[0034]

[Table 1]

As is clear from the table, Sample No. 1 containing less than 0.1 part by weight of zinc silicate as an additive. In Examples 1 and 2, the adhesive strength was inferior and the warpage of the substrate was large. On the other hand, the sample No. having a zinc silicate content of more than 10 parts by weight. In No. 9, the adhesive strength was poor, the warpage of the substrate was large, and the solder wettability was also poor. Further, the sample No. In Nos. 13 to 16, although the adhesive strength is excellent, the warpage of the substrate and / or
Or the solder wettability was poor. On the other hand, the sample No. according to the present invention in which the content of zinc silicate is in the range of 0.1 to 10 parts by weight. In Nos. 3 to 8, 10 to 12, and 17 to 20, the adhesive strength was high, the warpage of the substrate was suppressed, and the solder wettability was also good.

[0036]

According to the present invention, by incorporating a predetermined amount of zinc silicate into a low-resistance metal, the affinity with an insulating substrate made of glass ceramics is particularly improved. There is an effect that a wiring board having good solder wettability and suppressing warpage of the board can be obtained.

[0037]

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a wiring board according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wiring board 2 Insulating board 3 Metallized wiring layer 4 Via-hole conductor 5 Electronic component

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kenichi Nagae 1-4-4 Yamashita-cho, Kokubu-shi, Kagoshima Inside the Kyocera Research Institute (72) Inventor Masaya Kokubu 1-4-4 Yamashita-cho, Kokubu-shi, Kagoshima F-term in Kyocera Research Institute (reference) 4E351 AA07 BB31 CC12 CC22 CC35 DD04 DD05 DD06 DD08 DD33 DD52 EE02 EE03 EE10 EE11 EE27 GG07 GG15 GG16 5G301 AA08 AA26 AA27 AB20 AD10 DA06 DA22 DA23 DD01

Claims (5)

[Claims] 1. A conductor composition comprising 0.1 to 10 parts by weight of zinc silicate based on 100 parts by weight of a low-resistance metal powder. 2. The low-resistance metal powder has an average particle size of 0.5-1.
The conductor composition according to claim 1, which is a spherical powder having a diameter of 0 µm. 3. The low-resistance metal powder is a copper powder, all or a part of which is contained in the form of copper oxide which is reduced to simple copper by firing in a reducing atmosphere. Conductor composition. 4. An insulating substrate made of glass ceramic,
4. A metallized wiring layer formed on the surface and / or inside of the insulating substrate, wherein the metallized wiring layer is formed by applying the conductor composition according to claim 1 to the insulating substrate and firing the metal. A wiring substrate, characterized in that: 5. The wiring board according to claim 4, wherein the thermal expansion coefficient of the insulating substrate from 0 to 400 ° C. is 8 to 18 ppm / ° C.