JPH1174418A - Wiring substrate and mounting structure thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the mounting structure having excellent long-time stability in the arrangement of a wiring substrate such as a package to an external electric circuit substrate such as a printed substrate. SOLUTION: When a wiring substrate is constituted by arranging a metalized wiring layer 3 such as Cu on the surface or inside an insulating substrate 1, a lithium-silicate based amorphous phase of 15-60 volume % and a metal oxide crystal phase having the thermal-expansion coefficient of 6 ppm/ deg.C or more at 40-400 deg.C are included at a rate of 85-40 volume % in total. The including amount of the amorphous phase is controlled within the above described range. Thus, thermal expansion coefficent at 40-400 deg.C can be minutely controlled in the range of 8-18 ppm/ deg.C. At the same time, the Young's modulus of a sintered body is decreased, and the mounting of a printed substrate to an external electric circuit substrate having the excellent long-time stability is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a wiring board having a metallized wiring layer and a mounting structure thereof.

[0002]

2. Description of the Related Art Conventionally, a wiring board has a structure in which a metallized wiring layer is disposed on the surface or inside of an insulating substrate.
As a typical example of the wiring substrate, a semiconductor element housing package for housing a semiconductor element, particularly a semiconductor element such as an LSI, has a metallized wiring layer such as W or Mo on its surface and inside. An insulating substrate made of alumina ceramic or the like having connection terminals disposed on its bottom surface, and a cavity for accommodating a semiconductor element formed at the center of the upper surface of the insulating substrate are formed, and the cavity is hermetically sealed by a lid. .

Generally, as the degree of integration of a semiconductor device increases, the number of electrodes formed on the semiconductor device also increases. As a result, the number of terminals in a semiconductor housing package for housing the same increases. However, as the number of electrodes increases, there is a limit in increasing the size of the package itself, and further reduction in size is required, and it is necessary to increase the formation density of connection terminals in the package.

As a structure for increasing the terminal density in a conventional package, a pin grid array (P) in which metal pins such as Kovar are connected to the lower surface of the package is known.
GA) is the most common, but recently, a quad flat package (QFP) of a type in which gull-wing (L-shaped) metal pins are connected to metallized wiring layers led to four sides of the package, A leadless chip carrier (LCC) with electrode pads on the four sides without lead pins, a chip size package (CSP) with flip-chip mounting of a Si chip, and a number of spherical terminals made of solder are arranged on the lower surface of the insulating substrate. There is a ball grid array (BGA) and the like, and among these, BGA is said to be the most capable of high density.

In this ball grid array (BGA), a spherical pad made of a brazing material such as solder is soldered to a connection pad, and the spherical terminal is placed on and abutted on a wiring conductor of an external electric circuit board. Thereafter, the terminal is heated and melted at a temperature of about 250 to 400 ° C., and the spherical terminal is bonded to a wiring conductor to be mounted on an external electric circuit board. With such a mounting structure, each electrode of the semiconductor element housed in the semiconductor element housing package is electrically connected to an external electric circuit via the metallized wiring layer and the connection terminal.

[0006]

The ceramics such as alumina and mullite used as an insulating substrate in these packages have a high strength of 200 MPa or more, and have a high reliability as a multi-layered technology with metallized wiring layers. Although the thermal expansion coefficient is about 4-7 ppm / ° C., the glass-epoxy insulating layer, which is most frequently used as an external electric circuit board on which the package is mounted, has a high thermal expansion coefficient. The thermal expansion coefficient of the printed circuit board on which the wiring layer is formed is as very large as 11 to 18 ppm / ° C.

Therefore, when a semiconductor element is accommodated in a wiring board or a package for accommodating a semiconductor element and then mounted on a printed circuit board or the like, heat generated during operation of the semiconductor element is repeatedly applied to both the insulating substrate and the printed circuit board. Then, a large thermal stress is generated due to a difference in thermal expansion between the insulating substrate and the printed board. This thermal stress has no effect when the number of terminals in the package is 300 or less, but the thermal stress increases as the number of terminals exceeds 300 or as the size of the package increases.

[0008] Therefore, thermal stress acts on the outer peripheral portion of the connection pad on the lower surface of the insulating substrate and the bonding interface between the wiring conductor and the terminal of the external electric circuit board due to repetition of the operation and stop of the semiconductor element, and the connection pad is insulated. There has been a defect that the wiring board or package cannot be stably and electrically connected to the printed board for a long period of time because the wiring board or the package is peeled off from the substrate or the terminal is peeled from the wiring conductor.

Therefore, it is conceivable to match the coefficient of thermal expansion of the insulating substrate with the coefficient of thermal expansion of the printed circuit board. However, in the case of conventional alumina and mullite, since the coefficient of thermal expansion is largely different from the beginning, even if the composition or the like is changed. It is very difficult to match the coefficient of thermal expansion of the printed circuit board.

Therefore, the present inventors have proposed a lithium silicate-based crystallized glass having a thermal expansion coefficient of 6 at 40 to 400 ° C.
A molded body comprising an inorganic filler of not less than ppm / ° C. is fired to obtain a lithium silicate crystal phase and the thermal expansion coefficient of 6 p.
By using a sintered body having a thermal expansion coefficient of 8 to 18 ppm / ° C. made of a metal oxide crystal phase of pm / ° C. as a substrate material, a difference in thermal expansion coefficient with an external electric circuit board such as a printed board is reduced. It was proposed that the reliability of mounting the wiring board on the printed circuit board could be improved. Further, at this time, by lowering the Young's modulus of the substrate material,
The stress acting on the terminal portion is reduced.

In this proposal, a lithium-silicate crystallized glass is used to precipitate a lithium-silicate crystal phase having a high thermal expansion coefficient and a metal oxide crystal phase, thereby obtaining a glass ceramic sintered body having a high thermal expansion. Things. Therefore, the thermal expansion coefficient and Young's modulus of the glass ceramic sintered body are almost uniquely determined by the type of crystallized glass to be used and the metal oxide as a filler, and the amount thereof. On the other hand, even in an external electric circuit board such as a printed circuit board having a high coefficient of thermal expansion, the coefficient of thermal expansion also changes depending on the material of the insulating substrate in the printed circuit board. A glass for producing a glass-ceramic sintered body in order to control the coefficient of thermal expansion of the wiring board,
The fillers and their amounts needed to be changed.

In the lithium silicate crystallized glass, a lithium silicate crystal phase is formed at about 850 ° C.
When the temperature is raised to ℃ or more, this crystal phase dissolves and disappears, and has a crystallization mechanism in which a lithium silicate crystal phase is generated again in the cooling process after firing, but in such a complicated dissolution and precipitation process, The precipitation amount of the lithium silicate crystal phase is likely to fluctuate depending on the firing conditions. For example, when Al ₂ O ₃ is contained in the glass, a low thermal expansion crystal phase such as eucryptite may be precipitated. In some cases, precipitation of the low thermal expansion crystal phase hinders high thermal expansion.

Accordingly, the present invention provides a method for connecting a wiring board having a metallized wiring layer on the surface or inside of an insulating board having high thermal expansion characteristics to an external electric circuit such as a printed board firmly and stably for a long period of time. It is an object of the present invention to provide a wiring board having high reliability for maintaining a state, and capable of controlling the thermal expansion coefficient and the Young's modulus even with the same composition, and a mounting structure thereof.

[0014]

Means for Solving the Problems The present inventors have repeatedly studied the above problems, and as a result, using lithium silicate glass and an inorganic filler, in the process of molding and firing the same, lithium silicate glass is used. After raising the temperature of the system glass to the firing temperature, the cooling rate is controlled, and particularly by increasing the cooling rate, a lithium silicate-based amorphous phase is generated. Since the coefficient of thermal expansion increases due to the increase in the spacing between the atoms and the atoms, the Young's modulus of the sintered body decreases at the same time, and the precipitation of the low-thermal-expansion lithium aluminum silicate crystal phase is also suppressed. Even in the composition, by controlling the generation amount of the amorphous phase, it is possible to adjust the thermal expansion coefficient further higher in an arbitrary range and find that the Young's modulus can be further reduced, It has led to the present invention.

That is, the wiring substrate of the present invention comprises an insulating substrate and a metallized wiring layer, and the insulating substrate is made of a lithium silicate based amorphous material containing 5% by weight or more of Li in terms of oxide. 15-60 volume% of the phase, 40-400
It contains a metal oxide crystal phase having a thermal expansion coefficient of 6 ppm / ° C. or higher at 85 ° C. in a total ratio of 85 to 40% by volume, a Young's modulus of 100 GPa or lower, and a thermal expansion coefficient of 40 to 400 ° C. of 8 to 40%. It is characterized by comprising a sintered body of 18 ppm / ° C.

Further, according to the mounting structure of the wiring board of the present invention, on an external electric circuit board in which a wiring conductor is adhered and formed on an insulator containing at least an organic resin, the insulating board converts Li into oxide. 15 to 60% by volume of a lithium silicate-based amorphous phase containing 5% by weight or more, and a total of 85 to 40% by volume of a metal oxide crystal phase having a thermal expansion coefficient of 6 ppm / ° C. or more at 40 to 400 ° C. Contains 10% of Young's modulus
A wiring board made of a sintered body having a heat expansion coefficient of 0 to 18 ppm / ° C. at 40 to 400 ° C. at 0 GPa or less is mounted on the wiring conductor by brazing.

In the wiring board and its mounting structure, the metal oxide crystal phase in the insulating substrate is at least one selected from the group consisting of forsterite, quartz, cristobalite, enstatite, alumina and lithium silicate. It is desirable.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings showing an embodiment. FIG. 1 is a view showing one embodiment of a BGA type semiconductor element housing package and a mounting structure thereof according to the present invention. This package has a so-called metallized wiring layer provided on the surface or inside of an insulating substrate. The wiring board has a basic structure,
A indicates a semiconductor element storage package, and B indicates an external electric circuit board.

The package A for housing a semiconductor element is composed of an insulating substrate 1, a lid 2, a metallized wiring layer 3 and connection terminals 4. The insulating substrate 1 and the lid 2 are for hermetically housing the semiconductor element 5 therein. Is formed. Then, the semiconductor element 5 is bonded and fixed to the insulating substrate 1 via an adhesive such as glass or resin in the cavity 6.

A metallized wiring layer 3 is provided on the surface and inside of the insulating substrate 1 so that the semiconductor element 5 is electrically connected to connection terminals 4 formed on the lower surface of the insulating substrate 1. Has been established. According to the package of FIG. 1, the connection terminal 4 has a spherical terminal 4b made of a high melting point solder (tin-lead alloy) attached to the connection terminal 4a with a brazing material via a connection pad 4a.

On the other hand, the external electric circuit board B is composed of an insulator 7 and a wiring conductor 8, and the insulator 7 is made of a material containing at least an organic resin. Specifically, a glass-epoxy composite material It is made of an insulating material having a thermal expansion coefficient of 12 to 16 ppm / ° C. at 40 to 400 ° C., and a printed board or the like is generally used. In addition, the wiring conductor 8 formed on the surface of the substrate B usually has a thermal expansion coefficient matching with the insulator 7 and a good electric conductivity in terms of good electrical conductivity.
It is made of a metal conductor such as Cu, Au, Ag, Al, Ni, and Pb-Sn.

In order to mount the semiconductor element housing package A on the external electric circuit board B, the insulating board 1 of the package A
The spherical terminal 4b on the lower surface is connected to the wiring conductor 8 of the external electric circuit board B.
It is mounted on the external electric circuit board B by being heated by a brazing material such as low melting point solder at a temperature of about 250 to 400 ° C. to be joined to the wiring conductor 8. You. At this time, a brazing material is desirably formed on the surface of the wiring conductor 8 in order to facilitate connection with the spherical terminal 4b using the brazing material.

(Material of Insulating Substrate) According to the present invention, as the insulating substrate 1 in a wiring board such as a package for housing a semiconductor element mounted on the surface of the external electric circuit board B, a temperature of 40 to 400 ° C. It is important that the sintered body has a coefficient of thermal expansion in the range of 8 to 18 ppm / ° C., particularly 9 to 16 ppm / ° C., and more preferably 10 to 15 ppm / ° C. This is important to alleviate the generation of thermal stress due to the difference in thermal expansion between the external electric circuit board B and the external electric circuit board B, and to maintain a good electrical connection between the external electric circuit board B and the package A for a long time. Whose coefficient of thermal expansion is less than 8 ppm / ° C. or 18 ppm / ° C.
If the temperature is higher than ° C., the thermal stress caused by the difference in thermal expansion becomes large, and it is impossible to prevent the electrical connection between the external electric circuit board B and the package A from deteriorating. On the other hand, when it is higher than 18 ppm / ° C., when a semiconductor element is mounted on a wiring board, a difference in thermal expansion between the semiconductor element and the semiconductor element becomes large, and a special mounting method is required.

The insulating substrate 1 has a Young's modulus of 10
It is also important that it is 0 GPa or less, especially 90 GPa or less. In the package A mounted on the external electric circuit board B, a compressive stress toward the center of the wiring board and a bending stress perpendicular to the package A are generated due to a difference in thermal expansion.
However, this compressive stress is relieved by the package A being distorted, and the bending stress is relieved by the flexure of the package A. When the Young's modulus is greater than 100 GPa, the compressive stress acting on the package A It is not possible to prevent the bending stress from increasing and the electrical connection between the external electric circuit board B and the package A from deteriorating.

According to the present invention, the insulating substrate having such a high coefficient of thermal expansion is formed by changing the lithium silicate-based amorphous phase to 15
-60% by volume and a metal oxide crystal phase having a thermal expansion coefficient of 6 ppm / ° C or more at 40-400 ° C for a total of 85-4
0% by volume, the coefficient of thermal expansion at 40 to 400 ° C. is 8 to 18 ppm / ° C., and the Young's modulus is 100
It is composed of a sintered body having a GPa or less.

The reason that the ratio of the lithium silicate-based amorphous phase to the metal oxide crystal phase is limited to the above range is that the amount of the lithium silicate-based amorphous phase is controlled within the range of 15 to 60% by volume. Thus, the coefficient of thermal expansion of the sintered body can be shifted to a higher one, and can be controlled to an arbitrary coefficient of thermal expansion. Therefore,
When the ratio of the lithium silicate-based amorphous phase is less than 15% by volume, in other words, when the ratio of the other metal oxide crystal phase is more than 85% by volume, the Young's modulus is not significantly reduced,
Also, Li-A having low thermal expansion such as spodumene during the sintering process.
This is because a large amount of l-Si-based crystals and the like are precipitated, and the original high thermal expansion using lithium silicate glass is hindered.

On the contrary, when the ratio of the lithium silicate-based amorphous phase is 6
If the ratio is more than 0% by volume, in other words, if the ratio of the other metal oxide crystal phase is less than 40% by volume, the characteristics of the sintered body are largely controlled by the characteristics of the amorphous phase, so that various metal oxides are produced. There is a problem that it is difficult to control properties such as thermal expansion characteristics, strength, and electrical characteristics of the sintered body due to the presence of the product crystal phase. In addition, there is also a problem that the sintering start temperature becomes low, so that it becomes impossible to sinter simultaneously with a wiring conductor such as copper.

In the present invention, the lithium silicate-based amorphous phase means that Li is 5% by weight or more in terms of oxide, especially Li
5 to 30 wt% of ₂ O and SiO ₂ comprise a proportion of 60 to 85 wt%, especially the total amount is in the amorphous phase the total amount of SiO ₂ and Li ₂ O, to be 65 to 95 wt% desirable. In the amorphous phase, the above-mentioned Li ₂ O or SiO ₂
Besides, Al ₂ O ₃ , CaO, MgO, TiO ₂ , P
_It may contain ₂ O ₅ , ZnO, alkali metal oxide, F and the like. This lithium silicate-based amorphous phase has a thermal expansion coefficient of 10 to 15 pp at 40 to 400 ° C. itself.
m / ° C. is desirable.

On the other hand, when controlling the thermal expansion coefficient of the entire sintered body to 8 to 18 ppm / ° C., the thermal expansion coefficient of the metal oxide crystal phase itself is 6 ppm / ° C.
More specifically, it is necessary to be 8 ppm / ° C. or more.

As such a metal oxide having a coefficient of thermal expansion of 6 ppm / ° C. or more, cristobalite (Si
O ₂ ), quartz (SiO ₂ ), tridymite (SiO
₂ ), forsterite (2MgO.SiO ₂ ), spinel (MgO.Al ₂ O ₃ ), wollastonite (Ca
O.SiO ₂ ), Monticellanite (CaO.MgO)
.SiO ₂ ), nepheline (Na ₂ O.Al ₂ O ₃ .S)
iO ₂ ), lithium silicate (Li ₂ O · Si
O ₂ ), diopside (CaO.MgO.2Si)
O ₂ ), melvinite (3CaO.MgO.2Si)
O ₂ ), Akermite (2CaO.MgO.2Si)
O ₂ ), magnesia (MgO), alumina (Al
₂ O ₃ ), nepheline (Na ₂ O.Al ₂ O ₃ .2Si)
O ₂ ), jade (Na ₂ O.Al ₂ O ₃ .4Si)
O ₂ ), Carnegieite (Na ₂ O.Al ₂ O ₃ .2S)
iO ₂ ), enstatite (MgO.SiO ₂ ), magnesium borate (2MgO.B ₂ O ₃ ), celsian (BaO.Al ₂ O ₃ .2SiO ₂ ), B ₂ O ₃ .2M
gO.2SiO ₂ , garnite (ZnO.Al
₂ O ₃ ) and petalite (LiAlSi ₄ O ₁₀ ).

Among them, at least one selected from the group consisting of forsterite, quartz, cristobalite, enstatite, alumina and lithium silicate
It is desirable to be made of a seed from the viewpoint of high thermal expansion.

Next, a method of producing a sintered body for forming the above-mentioned insulating substrate will be described. First, a lithium silicate glass powder is used as a starting material, and its thermal expansion coefficient at 40 to 400 ° C. is 6 ppm / ° C. or more. Is prepared. Lithium silicate glass is a component that forms a lithium silicate amorphous phase in a sintered body, and contains 5 to 30% by weight of Li ₂ O and 6 to 6% of SiO ₂ .
0 to 85% by weight, especially SiO 2
The total amount of ₂ and Li ₂ O is desirably 65 to 95% by weight in the glass. In the glass, the above Li
_{In addition to 2} O and SiO ₂ , Al ₂ O ₃ , MgO, CaO,
TiO ₂ , P ₂ O ₅ , ZnO, alkali metal oxide, F
Etc. may be included.

It should be noted that Li in the lithium silicate glass powder
_The reason why the amount of ₂ O is limited to 5 to 30% by weight is that when the Li ₂ O content is less than 5% by weight, the lithium silicate-based amorphous phase having high thermal expansion decreases, and when the content exceeds 30% by weight. The dielectric loss tangent becomes large, making it unsuitable as an insulating substrate.

The deformation point of the lithium silicate glass is preferably 400 to 800 ° C., more preferably 400 to 650 ° C. This is because when molding a mixture of glass and a metal oxide filler, a molding binder such as an organic resin is added, but this binder is efficiently removed and firing with a metallization that is fired simultaneously with the insulating substrate is performed. This is for matching the conditions.

That is, if the yield point is lower than 400 ° C., the sintering of the crystalline glass starts at a low temperature. This is because the binder is difficult to decompose and volatilize since the densification of the molded body starts at a low temperature, and the binder component remains to affect the properties. On the other hand, if the yield point is higher than 800 ° C., sintering becomes difficult unless the amount of crystalline glass is increased, so that a large amount of expensive crystalline glass is required, which increases the cost of the sintered body.

On the other hand, the metal oxide filler having a coefficient of thermal expansion of 6 ppm / ° C. or more, which is blended with the lithium silicate glass, is as described above. In particular, forsterite, quartz, cristobalite, enstatite, alumina and It is desirable from the point of high thermal expansion that it comprises at least one selected from the group of lithium silicic acid.

The lithium silicate glass and the metal oxide filler are desirably blended in such a ratio that the lithium silicate glass is 20 to 80% by volume and the metal oxide filler is 80 to 20% by volume. The reason for setting the mixing ratio of these components to the above ratio is that the amount of glass is 20% by volume.
If the amount is less than the above, it is difficult to fire at a low temperature, and it is difficult to simultaneously fire with metallization of copper or the like. If the amount exceeds 80% by volume, the firing temperature becomes too low and it becomes difficult to fire simultaneously with metallization of copper or the like. . Further, it is desirable that the amount of the metal oxide filler to be blended is appropriately adjusted according to the yield point of the lithium silicate glass. That is, when the yield point of the glass is as low as 400 ° C. to 650 ° C., the sinterability at low temperatures is increased, so that the content of the metal oxide filler is 50%.
Many can be blended in the range of ６０60% by volume. On the other hand, when the yield point of glass is as high as 650 ° C. to 800 ° C.,
It is desirable that the content of the filler be as small as 20 to 50% by volume because the sinterability is reduced.

The above-mentioned lithium silicate glass used in the present invention has a shrinkage initiation temperature of 700 ° C. or less when no metal oxide filler is added and melts at 850 ° C. or more, and is co-fired with a metallized wiring layer of copper or the like. Can not do it. However, by mixing the filler at a ratio of 20 to 80% by volume, it is possible to form a liquid phase for liquid phase sintering at the firing temperature. Also, since the shrinkage start temperature of the entire molded body can be increased,
By adjusting the content of the filler, it is possible to match the co-firing condition with the metallized wiring layer such as copper used. In order to reduce raw material costs, it is preferable to reduce the content of expensive crystalline glass.

For example, if the metallized wiring layer is made of Ag, Cu,
When one of Au is mainly constituted, the firing of these metallizations occurs at 600 to 1000 ° C., so that simultaneous firing requires a yield point of the crystalline glass of 40 ° C.
0 ° C to 650 ° C, and the content of the filler is 50 to 80.
It is preferably volume%. Further, by reducing the amount of the expensive crystalline glass, the cost of the sintered body can be reduced.

The mixture of the lithium silicate glass and the metal oxide filler is formed into a sheet by adding a suitable organic resin binder and then forming the sheet by a desired forming means, for example, a doctor blade, a rolling method, a mold press or the like. After forming into an arbitrary shape, it is fired.

In firing, first, the binder component blended for molding is removed.

The removal of the binder is performed in an air atmosphere at about 700 ° C. When Cu is used as the wiring conductor, the removal is performed in a nitrogen atmosphere containing water vapor at 100 to 850 ° C. At this time, the shrinkage start temperature of the molded body is 70
It is preferable that the temperature is about 0 to 850 ° C., and if the shrinkage onset temperature is lower than this, it is difficult to remove the binder. Therefore, the properties of the crystalline glass in the molded body, particularly the sagging point, should be controlled as described above. Is required.

The calcination is performed in an oxidizing atmosphere at 850 ° C. to 1000 ° C., whereby the relative density is increased to 90% or more. If the firing temperature at this time is lower than 850 ° C., densification cannot be achieved, and if it exceeds 1000 ° C., the metallized layer is melted by simultaneous firing with the metallized wiring layer. However, when Cu is used as the wiring conductor, 87
This is performed in a non-oxidizing atmosphere such as nitrogen at 0 to 950 ° C.

According to the present invention, by controlling the cooling rate after the sintering in the range of 400 ° C./hr to 1000 ° C./hr, a part or all of the compounded lithium silicate glass is made of lithium silicate glass. Simultaneously with the formation of the amorphous phase in the sintered body, the coefficient of thermal expansion of the sintered body can be shifted to a higher value than the case of perfect crystallization according to the amount of the amorphous phase. At the same time, the Young's modulus of the obtained sintered body can be reduced. Thereby, while having the same composition, the thermal expansion coefficient can be controlled to an arbitrary coefficient of thermal expansion with a predetermined width, and the Young's modulus can be adjusted.

Therefore, in the sintered body thus produced, the lithium silicate glass remains as a lithium silicate amorphous phase, and the metal oxide filler is sintered as a metal oxide crystal phase. Although generated in the body, in some cases, another crystal phase may be generated by a reaction between the metal oxide filler and a part of the lithium silicate glass.

The above sintered body was used as an insulating substrate,
In order to manufacture a wiring board or a package provided with a metallized wiring layer made of at least one of g, Cu, Ni, Pd, and Au, the above-described crystallized glass and filler for forming an insulating substrate are used. A suitable organic binder, a plasticizer, and a solvent are added to and mixed with the raw material powder made of to produce a slurry, and the slurry is used to form a green sheet (raw sheet) by employing a doctor blade method or a calendar roll method. Then, as a metallized wiring layer and connection pads, a metal paste obtained by adding and mixing an organic binder, a plasticizer, and a solvent to a suitable metal powder is printed and applied in a predetermined pattern on the green sheet by a known screen printing method. In some cases, the green sheet is appropriately punched to form a through hole, and the hole is filled with a metallizing paste.
By stacking a plurality of these green sheets and simultaneously firing the green sheets and metallization, a package having a multilayer structure can be obtained.

The thermal expansion coefficient of the insulating substrate is set to 8 to 18 p.
As the temperature increases to pm / ° C., the difference in thermal expansion from the semiconductor element having Si as a substrate increases. Therefore, it is necessary to appropriately select an adhesive for the semiconductor element to the insulating substrate so that the semiconductor element does not peel off due to a difference in thermal expansion. Desirably, it is desirable to bond with a flexible material capable of buffering the difference in thermal expansion. For example, an epoxy-based or polyimide-based organic adhesive or a metal such as Ag may be blended in some cases. Are preferably used.

[0048]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to more specific examples. A. As lithium silicate glass 75% SiO ₂ -14% Li ₂ O-4% by weight
B. Al ₂ O ₃ -3% P ₂ O ₅ -3% K ₂ O-1% Na ₂ O (bending point 480 ° C., BET specific surface area 1.5 m ² / g) 78% SiO ₂ -10% Li ₂ O-4% by weight
Al ₂ O ₃ -2% P ₂ O ₅ -4% K ₂ O-1% B ₂ O ₃
-1% Na ₂ O (yield point 650 ° C., BET specific surface area of 1.5m ² / g) C. 65% SiO ₂ -21% Al ₂ O ₃ -4 by weight
_{% Li 2 O-4% Na} 2 O-6% ZnO ( yield point 600 ° C., BET specific surface area of 1.5 m ² / g) with respect to the three glass powder, forsterite (2MgO · SiO _2, the thermal expansion A metal oxide filler having a coefficient (α = 10 ppm / ° C.) of quartz (SiO ₂ , a coefficient of thermal expansion of 15 ppm / ° C.) is added and mixed at a ratio shown in Tables 1 and 2,
Using this mixed composition, a green sheet having a thickness of 500 μm was prepared by a doctor blade method using toluene and isopropyl alcohol as a solvent, an acrylic resin as a binder, and DBP (dibutyl phthalate) as a plasticizer.

A metallized wiring layer was coated on the surface of the green sheet with a Cu metallized paste by screen printing. Further, a through hole was formed at a predetermined portion of the green sheet, and the inside of the through hole was filled with Cu metallized paste. Then, six green sheets to which the metallizing paste was applied were laminated and pressure-bonded while positioning the through holes. This laminate is
After debinding in N ₂ + H ₂ O at ~ 850 ° C, Table 1,
The metallized wiring layer and the insulating substrate were simultaneously fired in a nitrogen atmosphere at a firing temperature of 2 for 1 hour to produce a wiring substrate for a package. At this time, with respect to the Cu metallized layer formed by simultaneous firing, evaluation was made on the melting and sintering failure of the metallized layer.

The 5 × 4 × 40 mm and 3 × 3 × 15 mm elementary substrates fired at the same time were passed through a reflow furnace in a nitrogen atmosphere and heat-treated at 900 ° C. for 10 minutes.
The sample was cooled down to the temperature shown in Table 1 at a cooling rate shown in Table 1 and then cooled in a furnace.

The obtained 5 × 4 × 40 mm substrate was subjected to X-ray diffraction measurement to identify the crystal phase in the sintered body and to measure the Young's modulus. Further, the thermal expansion coefficient at 40 to 400 ° C. was determined using a 3 × 3 × 15 mm square bar. The results are shown in Tables 1 and 2.

The amount of the amorphous phase in the sintered body was determined by crushing the sintered body, quantitatively analyzing the generated crystal phase by the Rietveld method, and determining the remaining crystal phase as the amorphous phase.

Next, a concave portion was formed on the lower surface of the wiring substrate at a position connected to the through hole, and a connection pad made of Cu metallization was manufactured. Then, connection terminals made of solder (60 to 10% tin-40 to 90% lead) were attached to the connection pads as shown in FIG. The connection terminal is 1 cm ²
It was formed on the entire lower surface of the wiring board at a density of 30 terminals per contact. On the other hand, 40-200 made of a glass-epoxy substrate
A printed circuit board having a wiring conductor made of copper foil formed on the surface of an insulator having a thermal expansion coefficient of 15 ppm / ° C. at 15 ° C. is prepared, and the above-mentioned package wiring board is replaced with the wiring conductor on the printed board and the package insulating board. the connection terminals are aligned to be connected, which in an atmosphere of N ₂ 26
Heat treatment was performed at 0 ° C. for 3 minutes to mount the package wiring board on the surface of the printed board. By this heat treatment, it was confirmed that the solder connection terminals of the package wiring board were melted and electrically connected to the wiring conductors of the printed circuit board.

(Thermal Cycle Test During Mounting) The packaged wiring board mounted on the printed circuit board surface as described above was tested in a constant temperature bath controlled at -40 ° C. and 125 ° C. in the atmosphere of air. The sample was held for 15 minutes / 15 minutes as one cycle and repeated up to 1000 cycles.

The electrical resistance between the wiring conductor of the printed circuit board and the wiring substrate for the package was measured for each cycle, and the number of cycles until the electrical resistance changed was shown in Table 1.

[0056]

[Table 1]

[0057]

[Table 2]

As is evident from Table 1, in the glass ceramic composition having the same composition, the cooling rate was 100 to 10%.
As a result of changing the temperature in the range of 00 ° C./hr,
° C / hr, the coefficient of thermal expansion is up to +3.7 ppm / compared to the case where no lithium silicate-based amorphous phase is contained at all.
° C and the Young's modulus of the sintered body by 1
It was possible to reduce the pressure from 10 GPa to 100 GPa or less. However, when the amount of the amorphous phase was less than 15% by volume, the change in thermal expansion was less than +1.0 ppm / ° C. Further, the ratio of the lithium silicate-based amorphous phase is 1
At less than 0% by volume, slightly low thermal expansion spodumene was detected as a crystalline phase. Further, when the amount of lithium in the amorphous phase was determined by subtracting the amount of Li contained in the crystalline phase from the total amount, the composition was similar to the glass powder composition.

Also, in the different composition systems shown in Table 2, the cooling rate could be increased to a maximum of +3.6 ppm / ° C. by controlling the cooling rate at 100 to 1000 ° C./hr.

However, in Samples Nos. 8 and 9 in which the glass content was less than 20% by volume, a dense sintered body could not be obtained, and the amorphous phase was not increased even when the cooling rate was increased to 1000 ° C./hr. Is not more than 10% by volume, and the effect of improving the coefficient of thermal expansion and the Young's modulus is small.

Incidentally, in the samples shown in Tables 1 and 2,
A sintered body having a coefficient of thermal expansion of 8 to 18 ppm / ° C. was subjected to a thermal cycle test on a copper metallized wiring board using the sintered body. No change in electric resistance was observed between the wiring board and the wiring board, and an extremely stable and favorable electric connection state could be maintained.

Sample Nos. 26 to 29 using glass C having a Li ₂ O content of less than 5% by weight as the compounded glass.
By increasing the amount of the amorphous phase, the thermal expansion is improved and the Young's modulus is reduced, but the coefficient of thermal expansion of the sintered body is lower than 8 ppm / ° C. As a result, a stable connection is obtained in the thermal cycle test. Was not obtained.

[0063]

As described in detail above, when the wiring board of the present invention is mounted on an external electric circuit board such as a printed circuit board having a large thermal expansion coefficient, the stress caused by the difference between the two thermal expansion coefficients is large. Generation can be suppressed, and the package and the external electric circuit board can be accurately and firmly electrically connected for a long period of time. In addition, by suppressing the generation of the lithium silicate crystal phase as an insulating substrate, a wiring substrate including an insulating substrate having high thermal expansion and low Young's modulus characteristics can be manufactured.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a mounting structure of a BGA type semiconductor element housing package which is an example of a wiring board of the present invention.

[Explanation of symbols]

 Reference Signs List A Package for storing semiconductor element B External electric circuit board 1 Insulating substrate 2 Lid 3 Metallized wiring layer 4 Connection terminal 4a Connection pad 4b spherical terminal 5 Semiconductor element 6 Cavity 7 Insulator 8 Wiring conductor

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masaya Kokubu 1-4-4 Yamashita-cho, Kokubu-shi, Kagoshima Inside the Kyocera Research Institute (72) Inventor Yoji Kokubo 1-4-4 Yamashita-cho, Kokubu-shi, Kagoshima Kyocera Research Institute

Claims (4)

[Claims] 1. A wiring board comprising an insulating substrate and a metallized wiring layer, wherein the insulating substrate contains 15 to 60 volumes of a lithium silicate-based amorphous phase containing 5% by weight or more of Li as oxide. % And a metal oxide crystal phase having a coefficient of thermal expansion of 6 ppm / ° C. or more at 40 to 400 ° C. in a total of 85%.
４０40% by volume, Young's modulus is 100 GPa
A wiring substrate comprising: a sintered body having a thermal expansion coefficient of 40 to 400 ° C. and a thermal expansion coefficient of 8 to 18 ppm / ° C. 2. The wiring substrate according to claim 1, wherein said metal oxide crystal phase is at least one selected from the group consisting of forsterite, quartz, cristobalite, enstatite, alumina and lithium silicate. . 3. An external electric circuit board on which a wiring conductor is adhered and formed on an insulator containing at least an organic resin, the insulating board is made of a lithium silicate-based material containing 5% by weight or more of Li as oxide. 15-60 volume% of the amorphous phase, 40-4
Containing a metal oxide crystal phase having a thermal expansion coefficient of 6 ppm / ° C. or more at 00 ° C. in a ratio of 85 to 40% by volume in total;
Young's modulus is 100 GPa or less, and 40 to 400
A mounting structure for a wiring board, wherein a wiring board made of a sintered body having a thermal expansion coefficient at 8 ° C. of 8 to 18 ppm / ° C. is mounted on the wiring conductor by brazing. 4. The wiring board according to claim 3, wherein said metal oxide crystal phase is at least one selected from the group consisting of forsterite, quartz, cristobalite, enstatite, alumina, and lithium silicate. Mounting structure.