JP2008105917A - Low temperature fired ceramic and multilayered circuit board using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low temperature fired ceramic satisfying both of high thermal expansion and chemical resistance and a multilayered circuit board using the same. <P>SOLUTION: The low temperature fired ceramic comprises quartz (Si), a monoclinic crystal (CM) of celsian and a hexagonal crystal (CH) of celsian as crystal phases, and when the X-ray intensity, by X-ray diffraction, of (101) plane of the quartz (Si) is expressed by A, the X-ray intensity of (112) plane of the monoclinic crystal (CM) of the celsian is expressed by B and the X-ray intensity of (101) plane of the hexagonal crystal (CH) of the celsian is expressed by C, the X-ray intensity ratio B/A is ≤0.2 and the intensity ratio of C/A is ≥0.6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a low-temperature fired porcelain suitably used as an insulating substrate of a multilayer circuit board capable of simultaneous firing with a low-resistance metal such as copper or silver as a wiring conductor, and a multilayer circuit board using the same.

  In recent years, with the advent of the advanced information era, information transmission has increased in speed and frequency, and mobile devices such as mobile phones and PDAs have rapidly developed as electronic devices that process high-frequency signals above GHz levels, such as optical communication and high-speed interfaces. is doing.

  A multilayer circuit board is used as a wiring board used in such electronic devices. Specifically, the multilayer circuit board includes an insulating base (porcelain) made of glass ceramics and a low-resistance wiring conductor made of copper or silver.

  Here, in a multilayer circuit board, in order to increase the connection reliability with an external circuit board (printed wiring board) having a high thermal expansion, it is required to increase the thermal expansion of the insulating base (porcelain). Furthermore, during the plating process in the manufacturing process, there is a problem that the insulating substrate (porcelain) is eroded by the plating solution, the plating solution remains in the eroded part, and black marks remain on the porcelain surface. The substrate (porcelain) is required to have chemical resistance so that erosion by the plating solution is suppressed.

  Conventionally, development of multilayer circuit boards that satisfy both high thermal expansion coefficient and chemical resistance at the same time has been underway, but trying to increase the thermal expansion coefficient decreases chemical resistance and attempts to improve chemical resistance. Then, the thermal expansion coefficient and chemical resistance are in a so-called trade-off relationship such that the thermal expansion coefficient decreases, and it is difficult to satisfy both the high thermal expansion coefficient and the chemical resistance at the same time.

For example, by firing a high thermal expansion porcelain composition comprising a glass containing BaO and an inorganic filler containing a metal oxide and cordierite, cordierite reacts with the BaO component of the glass to precipitate serdian, A high thermal expansion porcelain with improved chemical resistance has been proposed (see Patent Document 1). Patent Document 1 also shows that the fracture toughness is improved and the porcelain strength is increased by precipitating serdian as hexagonal serdian having an average aspect ratio of 3 or more.
JP 2003-40670 A

  However, in the high thermal expansion porcelain described in Patent Document 1, the filler ratio of cordierite is increased in order to precipitate hexagonal serdian, but this has a problem that the thermal expansion coefficient is lowered.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a low-temperature fired ceramic, a low-temperature fired ceramic composition, and a multilayer circuit board that satisfy both a high thermal expansion coefficient and chemical resistance.

  The present invention includes quartz, Serdian monoclinic crystal and Serdian hexagonal crystal as crystal phases, and the X-ray intensity of the (101) plane of the quartz by X-ray diffraction is A, and the Serbian monoclinic (112) When the X-ray intensity of the plane is B and the X-ray intensity of the (101) plane of the Celsian hexagonal crystal is C, the X-ray intensity ratio B / A is 0.2 or less, and the X-ray intensity ratio C / A Is a low-temperature fired porcelain characterized by having a value of 0.6 or more.

  Further, the present invention is a low-temperature fired porcelain characterized by containing cobalt.

  The present invention further includes an insulating substrate formed by laminating a plurality of insulating layers formed of the low-temperature fired porcelain, and a wiring conductor formed on or in the surface of the insulating substrate. It is.

  According to the present invention, by mixing cobalt oxide as a low-temperature fired porcelain composition, a monoclinic serdian can be phase-transformed into a hexagonal serdian to precipitate a large number of hexagonal serdians, which has a high thermal expansion coefficient. In addition, a low-temperature fired porcelain and a multilayer circuit board satisfying both chemical resistance and the chemical resistance can be obtained.

An embodiment of the present invention will be described.
FIG. 1 is a schematic view showing a crystal state of a low-temperature fired ceramic according to the present invention, where Q is quartz (SiO ₂ ), CH is hexagonal (Hexagonal) of Celsian (BaAl ₂ Si ₂ O ₈ ), and CM is Celsian ( BaAl ₂ Si ₂ O ₈ ) monoclinic crystal, E is enstatite (MgSiO ₃ ), and a is an amorphous part of glass.

  As shown in FIG. 1, the low-temperature fired ceramic of the present invention contains quartz, enstatite, serdian hexagonal crystal (hexagonal serdian) and serdian monoclinic crystal (monoclinic serdian) as crystal phases.

  Here, the ratio of the X-ray intensity B of the (112) plane of the monoclinic serdian to the X-ray intensity A of the (101) plane of the quartz crystal by XRD (X-ray diffraction), that is, the X-ray intensity ratio B / A is 0.2 or less. Further, the ratio of the X-ray intensity C of the (101) plane of hexagonal serdian to the X-ray intensity A of the (101) plane of the quartz crystal by XRD (X-ray diffraction), that is, the X-ray intensity ratio C / A is 0.6 or more.

  Since quartz is a high thermal expansion crystal phase, it is preferable that more quartz is precipitated from the viewpoint of the coefficient of thermal expansion, but by adding more quartz as a porcelain composition, the density of the porcelain after heat treatment is increased. May decrease. In addition, when there are many amorphous glass portions that are not crystallized in the low-temperature fired ceramic, the amorphous glass portions are easily eroded by the plating solution. Therefore, it is necessary to precipitate a large amount of high thermal expansion crystal phase as an alternative crystal phase of quartz.

  Here, hexagonal celsian and monoclinic celsian are listed as alternative crystal phases of quartz, but hexagonal celsian has higher thermal expansion than monoclinic celsian and is more resistant to acids and alkalis (excellent chemical resistance). Therefore, it is important to deposit more hexagonal serdians than monoclinic serdians, specifically to satisfy the X-ray intensity ratio.

In order to further increase the coefficient of thermal expansion and improve the chemical resistance, the X-ray intensity ratio B / A is preferably 0.1 or less, and the X-ray intensity ratio C / A is preferably 0.7 or more.

  In FIG. 2, as a plurality of peaks in each crystal, the quartz is represented by a circle, the hexagonal serdian is triangular, and the monoclinic serdian is represented by a square. In determining the X-ray intensity ratio, the X-ray intensity of the (101) plane is selected for quartz, the X-ray intensity of the (101) plane is selected for hexagonal serdian, and (112) for monoclinic serdian. The reason why the X-ray intensity of the surface is selected is that the maximum peak exists in this portion. In FIG. 2, the X-ray intensity A of the (101) plane of quartz is black circles, the X-ray intensity C of the (101) plane of hexagonal serdians is black triangles, and (112 ) Surface X-ray intensity B is represented by a black square. As a comparative example, FIG. 3 shows data of the low-temperature fired porcelain composition without addition of cobalt tetroxide by a dotted line, which indicates that hexagonal serdian precipitation is small.

  In the low-temperature fired ceramic according to the present invention, enstatite and the like are precipitated in addition to quartz, hexagonal serdian and monoclinic serdian. It is also confirmed by chemical analysis that cobalt is contained.

Then, in order to obtain a low-temperature fired porcelain described above, the SiO ₂ of 40 to 50 mol%, 5-10 mol% _Al 2 _{O 3,} and 24-30 mol% of MgO, 7 to 10 mol% of B It is important to fire a low-temperature fired ceramic composition in which silica and cobalt oxide are mixed as fillers in a glass powder containing ₂ O ₃ , 7 to 15 mol% BaO, and 1 to 3 mol% CaO. It is.

Here, as the glass component in the low-temperature fired porcelain composition, the respective content ratios (mol%) of SiO ₂ , Al ₂ O ₃ , MgO, B ₂ O ₃ , BaO, and CaO are in the above ranges. Depending on the reason.

Since SiO ₂ is a component that forms a network structure of glass, if the content of SiO ₂ is less than 40 mol%, each glass characteristic may be deteriorated. In particular, since the sinterability is significantly reduced and the porcelain surface is not densified, the chemical resistance may be reduced. On the other hand, when the content of SiO ₂ is more than 50 mol%, the amount of precipitated crystals after firing decreases, and accordingly, the amount of precipitated hexagonal serdian, which is a high thermal expansion crystal phase, also decreases. The coefficient of thermal expansion of the porcelain decreases.

When the content of Al ₂ O ₃ is less than 5 mol%, the chemical durability of the glass is lowered (the network structure is cut), and it is difficult to precipitate serdian as a crystal phase after firing. For this reason, high thermal expansion and chemical resistance may not be satisfied. When the content of Al ₂ O ₃ is more than 10 mol%, to lower the glass viscosity sinterability is deteriorated, the open porosity of the porcelain is reduced.

  When the content of MgO is less than 24 mol%, the amount of enstatite deposited decreases, and the thermal expansion coefficient of the low-temperature fired ceramic decreases. Moreover, when producing glass, after overheating and melting the glass, crystals precipitate (devitrification) in the process of cooling the melt, and the glass is likely to be phase-separated. On the other hand, when the content of MgO is more than 30 mol%, it is advantageous in that the crystallization start temperature is increased by loosening the viscosity gradient of glass, but cordierite which is a low thermal expansion crystal phase is precipitated. The coefficient of thermal expansion of the porcelain will decrease.

When the content of B ₂ O ₃ is less than 7 mol%, the viscosity of the glass increases and the transition point and yield point increase. If the glass transition point and yield point increase, low-temperature firing may become difficult. On the other hand, if the content of B ₂ O ₃ is more than 10 mol%, low temperature firing becomes possible due to the decrease in the viscosity of the glass, but the crystallization of the glass is inhibited and the amorphous in the porcelain increases, Accordingly, there is a possibility that the thermal expansion coefficient of the porcelain may decrease due to the fact that the crystal phase is inevitably small.

  When the content of BaO is less than 7 mol%, it is difficult to precipitate serdian as a crystal phase after firing, and a ceramic having high thermal expansion and good chemical resistance cannot be obtained. On the other hand, when the content of BaO is more than 15 mol%, the chemical durability of the glass is lowered (cutting the network structure), the chemical resistance of the porcelain is lowered and the dielectric constant is increased. There is concern about signal delay.

  When the content of CaO is less than 1 mol%, the glass viscosity is increased in a high temperature range and the wettability with the filler may be reduced. On the other hand, if the content of CaO is more than 3 mol%, the glass viscosity at high temperature can be reduced, the wettability with the filler can be improved, and the effect of densification of the porcelain can be expected. It may cause light precipitation, and the thermal expansion coefficient of the porcelain may be extremely reduced.

And it is important that the above-mentioned glass powder is mixed with SiO ₂ (silica) powder and cobalt oxide powder. The amount of these contained is 55 to 65% by volume of glass, and SiO ₂ (silica) as a filler is 45 to 35% by volume, and cobalt trioxide (Co ₃ O ₄ ) is 0.1 to 0.1% by external addition. The ratio is preferably 0.7% by volume. When the amount of the SiO ₂ (silica) powder is within this range, the density of the low-temperature fired ceramic after firing is appropriate, and preferable values can be obtained for the thermal expansion coefficient and the dielectric constant. In addition, when the amount of cobalt oxide, particularly tribasic cobalt oxide (Co ₃ O ₄ ) is within this range, the X-ray intensity ratio B / A is 0.2 or less, and the X-ray intensity ratio C / A is 0.00. A large amount of hexagonal serdian can be precipitated so as to be 6 or more, and the crystallization temperature does not become low. More preferably, with respect to 58 to 62% by volume of the glass, 42 to 38% by volume of SiO ₂ (silica) as a filler and 0.1 to 0.7% by volume of cobalt trioxide (Co ₃ O ₄ ) by external addition. % Should be used.

By mixing SiO ₂ (silica) powder as a filler, the fired low-temperature fired ceramic obtained by firing this low-temperature fired ceramic composition contains quartz, and the coefficient of thermal expansion can be increased. Here, the average particle diameter of SiO ₂ (silica) is preferably 1.0 to 6.0 μm, and more preferably 1.0 to 4.0 μm. Thereby, the low-temperature fired porcelain can be further densified, and the void diameter and void ratio can be reduced. Furthermore, the specific surface area of SiO ₂ (silica) is preferably 5 m ² / g or less, more preferably 3 m ² / g or less. Thereby, when the raw material powder is slurried, the shortage of organic content relative to the powder surface area can be alleviated, and the slurry viscosity can be lowered to improve the moldability.

Further, by mixing cobalt oxide, monoclinic serdian that precipitates as a crystalline phase after firing can be phase-transformed to hexagonal serdian. The reason why a large amount of hexagonal serdian is precipitated by this phase transition is considered to be that more heterogeneous nucleation is more likely to occur by adding cobalt oxide. By precipitating hexagonal serdian, it is possible to increase the thermal expansion of the porcelain and improve the chemical resistance. Here, as the cobalt oxide, cobalt trioxide (Co ₃ O ₄ ) is particularly preferable. Tricobalt tetraoxide (Co ₃ O ₄ ) is more suitable than, for example, TiO ₂ , ZrO ₂ or the like that functions as a nucleating agent because it is not significantly affected by redox or heat treatment.

  Thus, by adding cobalt oxide that functions as a so-called nucleating agent, the precipitation of monoclinic serdian is small, the precipitation of hexagonal serdian can be increased, and the high thermal expansion coefficient and chemical resistance are excellent. A low-temperature fired porcelain can be obtained.

Next, a method for manufacturing the low-temperature fired porcelain of the present invention will be described.
First, as a starting material, glass powder having the above composition, SiO ₂ (silica) powder and cobalt oxide powder are mixed at a predetermined ratio according to the firing temperature, the thermal expansion coefficient, and the amount of precipitated crystal phase. . That is, the a SiO ₂ 40 to 50 mol%, _Al 2 _{O 3} 5 to 10 mol%, the MgO 24-30 _mol%, the B 2 _{O 3} 7 to 10 mol%, 7-15 mol% of BaO, SiO ₂ (silica) powder and cobalt oxide powder are mixed with glass powder containing 1 to 3 mol% of CaO. Here, 55 to 65% by volume of glass powder, 45 to 35% by volume of SiO ₂ (silica) as a filler, and 0.1 to 0.7% by volume of cobalt trioxide (Co ₃ O ₄ ) by external addition. It is preferable to set the ratio. More preferably, the glass powder is 58 to 62% by volume, the filler SiO ₂ (silica) is 42 to 38% by volume, and cobalt trioxide (Co ₃ O ₄ ) is 0.1 to 0.7% by external addition. % Should be used.

After adding an appropriate organic binder to the mixture of glass powder, SiO ₂ (silica) powder, and cobalt oxide powder blended in this manner, the desired molding means such as a doctor blade, a rolling method, a die press, etc. After molding into a predetermined shape, firing is performed. In baking, the organic binder component mix | blended for shaping | molding is removed first. The removal of the organic binder is performed at about 500 to 750 ° C. for about 3 hours in an air atmosphere or a nitrogen atmosphere. At this time, the shrinkage start temperature of the molded body is desirably about 700 to 850 ° C., and if the shrinkage start temperature is lower than this, it becomes difficult to remove the organic binder. It is desirable to control the transition point and yield point. Then, it is obtained by baking for about 1 hour in a temperature range of 850 ° C. to 1050 ° C., and 900 to 950 ° C. is particularly preferable. If the firing temperature at this time is lower than 850 ° C., it is difficult to densify, and if it exceeds 1050 ° C., simultaneous firing with a metallized wiring layer such as copper or silver becomes difficult when a wiring board to be described later is formed. . The firing atmosphere in this case is appropriately selected depending on the metal type of the metallized wiring layer to be used. For example, when copper is used, a non-oxidizing atmosphere is preferable, and when silver is used, an oxidizing atmosphere is preferable.

  A multi-layer circuit having excellent long-term reliability due to a configuration including an insulating base composed of a plurality of insulating layers formed of a low-temperature fired porcelain manufactured in this way and a wiring conductor formed on or inside the insulating base. A substrate is obtained.

Hereinafter, the low-temperature fired porcelain of the present invention will be specifically described based on examples.
First, as a glass powder, a glass powder having a glass composition shown in Table 1, a SiO ₂ (silica) powder, a tribasic cobalt oxide (Co ₃ O ₄ ) powder, 60% by mass of a glass powder, and a SiO ₂ powder of 40%. Mass% and Co ₃ O ₄ powder were weighed and mixed so that the ratio was 0.5 mass%. Here, the average particle diameter of the glass powder was 2.0 μm, the average particle diameter of SiO ₂ (silica) was 1.5 μm, and the average particle diameter of Co ₃ O ₄ was 3.7 μm.

  Next, after pulverizing this mixture, an organic binder and an organic solvent were added and mixed well to prepare a slurry, and a green sheet having a thickness of 100 μm was prepared by a doctor blade method. After laminating the obtained green sheets, the binder was treated for 3 hours in a nitrogen atmosphere containing 725 ° C. water vapor, followed by firing at 900 ° C. for 1 hour. The temperature rising rate was 300 ° C./Hr.

  For the low-temperature fired porcelain thus obtained, this porcelain was first pulverized in a mortar, and the X-ray intensity (peak) of the precipitated crystal was determined by an X-ray diffractometer (XRD). As the measurement conditions, 2α was in the range of 10 ° to 60 °, and Kα1 was analyzed.

  As shown in FIG. 2, the X-ray intensity A of quartz in the present invention is the peak of (101) plane (2θ = 26.639), and the X-ray intensity B of monoclinic serdian is the peak of (112) plane (2θ = 25.644), the X-ray intensity C of hexagonal serdian is the peak of (101) plane (2θ = 2.487), and based on these X-ray intensities, the X-ray intensity ratio B / A and the X-ray intensity ratio C / A was determined.

The thermal expansion coefficient was obtained by taking a thermal expansion curve from room temperature to 400 ° C. using a thermomechanical analyzer. In order to check the chemical resistance, the porcelain after firing is infiltrated into the plating solution, and the weight reduction rate (subtracting the weight after plating from the weight before plating from the weight difference before and after plating) After obtaining the value divided by the previous weight, the degree of surface staining was observed with a red check flaw detection liquid. The results are shown in Table 1.

  According to the results shown in Table 1, Samples Nos. 3, 5, 8, 10, 12, 14, and 16 could not satisfy the thermal expansion coefficient and chemical resistance.

Specifically, Sample No. In No. 3, since the SiO ₂ in the glass is less than 40 mol% and the X-ray intensity ratio B / A exceeds 0.2, the chemical resistance is lowered. Sample No. In No. 5, since the SiO ₂ in the glass exceeds 50 mol% and the X-ray intensity ratio C / A is less than 0.6, the coefficient of thermal expansion is lowered. Sample No. In No. 8, since Al ₂ O ₃ in the glass is less than 5 mol% and the X-ray intensity ratio C / A is less than 0.6, the coefficient of thermal expansion is lowered. Sample No. No. 10, since the Al ₂ O ₃ in the glass exceeds 10 mol% and the X-ray intensity ratio B / A exceeds 0.2, the chemical resistance is lowered. Sample No. No. 12, since the MgO in the glass exceeds 30 mol% and the X-ray intensity ratio C / A is less than 0.6, the thermal expansion coefficient is lowered. Sample No. In No. 14, since the MgO in the glass is less than 24 mol% and the X-ray intensity ratio B / A exceeds 0.2, the coefficient of thermal expansion is lowered. Sample No. No. 16 has a B ₂ O ₃ content exceeding 10 mol% in the glass and an X-ray intensity ratio C / A of less than 0.6.

  Further, according to FIG. 3 shown as a comparative example, the hexagonal serdian is less precipitated unless cobalt tetraoxide is added to the low-temperature fired porcelain composition.

  In contrast, it can be seen that the present invention satisfies both the high thermal expansion coefficient and chemical resistance.

It is explanatory drawing which shows an example of the low-temperature baking ceramics of this invention. It is a graph which shows the measurement result by X-ray diffraction. It is a graph which shows the measurement result by the X-ray diffraction of the state which has not added tribasic cobalt oxide as a comparative example.

Explanation of symbols

Si: Quartz crystal phase CH: Hexagonal serdian CM: Monoclinic serdian E: Enstatite a: Amorphous part of glass

Claims (3)

Quartz, Serdian monoclinic and Serdian hexagonal as crystal phases,
According to X-ray diffraction, the X-ray intensity of the (101) plane of the quartz is A, the X-ray intensity of the (112) plane of the Serbian monoclinic crystal is B, and the X-ray intensity of the (101) plane of the Serbian hexagonal crystal Is a low-temperature fired porcelain, wherein the X-ray intensity ratio B / A is 0.2 or less and the X-ray intensity ratio C / A is 0.6 or more. The low-temperature-fired porcelain according to claim 1, comprising cobalt. An insulating base formed by laminating a plurality of insulating layers formed of the low-temperature fired ceramic according to claim 1 or 2, and a wiring conductor formed on or inside the insulating base, Multi-layer circuit board.

Images