JP2003008224A - Multilayer substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To fully reduce wiring resistance of an inner wiring conductor constituted by piercing conductors that are vertically overlapped on each other inside a multilayer substrate, and to prevent degradation of the strength of the multilayer substrate. SOLUTION: This multilayer substrate 11 is constituted so that a plurality of insulation layers 11a, 11b are laminated, and in each of the two vertically overlapped insulation layers 11a, 11b, a plurality of piercing conductors, composed of conductors 13 filled in piercing holes 12 formed in the insulating layers 11a, 11b, are arranged so that parts of an end face of each piercing conductor are successively overlapped on each other. The end face is almost a rectangular shape or an elliptical shape, and parts of the end face are overlapped mutually in the longitudinal direction. The area of the end face of the overlapping side is larger than that of the end face of the opposite side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-layer substrate including a ceramic multi-layer substrate on which semiconductor elements and the like are mounted.

[0002]

2. Description of the Related Art Conventionally, a multilayer consisting of a ceramic multilayer substrate
The board is a ceramic green sheet with wiring conductors and through conductors.
Apply the conductor paste that will become the body by printing, and
It is made by stacking green sheets and firing.
Be done. For example, alumina (Al ₂O₃) From ceramics
In the case of a multilayer board consisting of
As tungsten, tungsten (W), molybdenum (M
o), manganese (Mn) and other refractory metals as the main component
Use a conductive paste containing
It is applied by printing on the designated area of the board, and then ceramic green
A stack of multiple sheets, reducing atmosphere at about 1600 ℃
It is made by baking in.

Further, in the case of a multi-layer substrate made of glass ceramics, a conductor paste containing silver (Ag) or copper (Cu) as a main component is used as a conductor paste which becomes a wiring conductor or a through conductor, and is made of glass ceramic green. It is produced by printing and applying to a predetermined portion of the sheet, then laminating a plurality of the green sheets, and firing in a reducing atmosphere at about 800 to 1000 ° C.

In the case of such a multilayer substrate made of alumina ceramics, the electric resistivities of W and Mo, which are materials for the wiring conductor and the through conductor, are 5.5 μΩ, respectively.
・ Cm, 5.7μΩ ・ cm, Ag 1.6μΩ ・
cm, which is several times or more the size of Cu, which is 1.67 μΩ · cm. Therefore, the wiring is thinned to achieve high-density wiring, and the high-speed signal transmission IC,
For those equipped with semiconductor elements such as LSI, W,
Since the electric resistivity of Mo is large, the wiring conductor made of W and Mo is not suitable for high-density wiring and high-speed transmission.

Further, in the case of a multilayer substrate made of glass ceramics, a wiring conductor having a low resistance such as Ag and Cu can be formed, but the wiring resistance is insufficient in the field of computers and the like where high speed transmission is advanced.

In order to solve such a problem, as shown in FIG. 2, in a multilayer substrate 1 formed by laminating a plurality of insulating layers 1a, 1b, 1c, the insulating layers 1a, 1b, 1c which are vertically overlapped with each other are formed. Through holes 2, 3, 4 each having a part of opening overlapping each other
It has been proposed that the through hole 2, 3, 4 is provided with a wiring material to reduce the wiring resistance value (see Japanese Patent Laid-Open No. 10-4266).

[0007]

However, in the above-mentioned prior art, if the degree of overlap (overlap) of the through holes 2, 3, 4 is increased in order to reduce the wiring resistance value, the current passage area increases. Although the wiring resistance value becomes smaller, the distance between the through holes 2, 3, 4 in the same insulating layer 1a, 1b, 1c becomes smaller and the insulating layer 1a,
There is a problem that the strength of the multilayer substrates 1 and 1b and 1c is reduced. Therefore, the degree of overlap between the through holes 2, 3 and 4 cannot be increased unduly, and the reduction of the wiring resistance value is limited.

Therefore, the present invention has been completed in view of the above circumstances, and an object thereof is to sufficiently reduce the wiring resistance value of an internal wiring conductor formed by through conductors formed inside a multilayer substrate and vertically stacked. It is possible to prevent the deterioration of the strength of the multilayer substrate.

[0009]

In a multilayer substrate of the present invention, a plurality of insulating layers are laminated, and in each of the two insulating layers which are vertically stacked, a through hole formed in the insulating layer is filled with a conductor. A plurality of through conductors each having a plurality of through conductors, the end faces of which are sequentially opposed to each other so that a part thereof overlaps each other, wherein the end faces have a substantially rectangular shape or a substantially oval shape, and a part thereof in a longitudinal direction thereof. Overlap each other, and the area of the end surface on the overlapping side is larger than the area of the end surface on the opposite side.

With the above structure, the present invention can sufficiently reduce the wiring resistance value of the internal wiring conductor formed by the through conductors which are formed inside the multilayer wiring substrate and which are vertically stacked. Further, since the area of the end surface on the overlapping side of the through conductor is larger than that on the opposite side, the area of the current passage is increased, the wiring resistance value is reduced, and the inductance is also reduced. Further, since the shape formed by the upper and lower penetrating conductors becomes substantially wavy and forms a smooth and shortened current path, it is suitable for transmitting, for example, a high frequency signal with low loss. Furthermore, since the area of the end surface on the side where the through conductors overlap is larger than the area of the end surface on the opposite side, the volume of the insulating layer between the through conductors increases and the reduction in strength of the insulating layer and the multilayer substrate is suppressed.

In the present invention, preferably, the area of the side where the end faces overlap is 10 to 6 in terms of area ratio than the opposite side.
It is characterized by being 0% larger.

According to the present invention, since the shape formed by the upper and lower penetrating conductors is substantially corrugated and the current path is smooth and shortened, the present invention can transmit, for example, a high frequency signal with low loss. In addition, the volume of the insulating layer between the penetrating conductors is increased, and the reduction in strength of the insulating layer and the multilayer substrate is suppressed.

In the present invention, preferably, the length of the overlapping portion of the end faces in the longitudinal direction is not less than ⅕ and less than ⅓ of the length of the end faces in the longitudinal direction. To do.

According to the present invention, due to the above-mentioned constitution, the passage area of the current becomes large and the wiring resistance value becomes small, and
The volume of the insulating layer between the penetrating conductors is secured, and the reduction in strength of the insulating layer and the multilayer substrate is suppressed.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION The multilayer substrate of the present invention will be described below. A cross-sectional view of the multilayer substrate of the present invention is shown in FIG. In the figure, reference numeral 11 denotes a plurality of through-hole conductors formed by laminating a plurality of insulating layers, and filling the through-holes formed in the insulating layers with conductors in each of the two vertically overlapping insulating layers. It is a multi-layer substrate which is provided so as to be sequentially opposed to each other so that portions thereof overlap each other. 11a, 11
Reference numeral b is an insulating layer, 12 is a through hole, and 13 is a conductor filled in the through hole 12.

The insulating layers 11a and 11b of the present invention are made of alumina (Al ₂ O ₃ ) ceramics, aluminum nitride (Al
N) ceramics, mullite (3Al ₂ O ₃ · 2Si
It is made of a ceramic material such as O ₂ ) ceramics, silicon carbide (SiC) ceramics, glass ceramics, and silicon nitride (Si ₃ N ₄ ) ceramics.

When the insulating layers 11a and 11b are made of alumina ceramics, they are manufactured as follows. First, for example, a suitable binder, a solvent, etc. are added to and mixed with a raw material powder such as Al ₂ O ₃ , silicon oxide (SiO ₂ ), magnesium oxide (MgO), and calcium oxide (CaO) to form a slurry. This slurry is made into a ceramic green sheet by adopting a doctor blade method or a calendar roll method, and then punching processing or the like for forming the through holes 12 is performed on the ceramic green sheet, and a conductor paste to be the conductor 13 is screen-printed. Then, the through hole 12 is filled by a press fitting method. It is produced by laminating a plurality of ceramic green sheets and firing them at a temperature of about 1600 ° C.

The conductor paste of the conductor 13 filled in the through holes 12 is obtained by adding and mixing an organic solvent and a solvent to powders of W, Mo, Mn, Cu, Ag and the like. When the insulating layers 11a and 11b are made of ceramics, the conductor paste may contain a predetermined amount (about 1 to 50% by weight) of the ceramic component. In that case, the insulating layers 11a and 11b may be contained.
The bondability between b and the conductor 13 is improved.

The end face of the through conductor formed by filling the through hole 12 with the conductor 13 has a substantially rectangular shape or a substantially oval shape, and parts of the end face overlap each other in the longitudinal direction, and the area of the end face on the overlapping side. Is larger than the other side. This is shown in FIGS. 1 (a) to 1 (c). FIG. 1B shows a through hole 12a.
FIG. 6 is a plan view of an end surface of a side surface of a through conductor formed by filling a conductor 13 with the conductor 13 and having an approximately rectangular shape. In this case, the through hole 12a has a quadrangular pyramid shape with a substantially rectangular bottom surface. In this case, the opening of the through hole 12a may be square. FIG. 1C is a plan view of an end surface on the overlapping side when the end surfaces of the through conductor formed by filling the through hole 12b with the conductor 13 are substantially oval (including an ellipse). In this case through hole 1
2b has an elliptical truncated cone shape whose bottom surface is substantially oval.

The quadrangular truncated pyramid-shaped and long truncated cone-shaped through holes 12a and 12b are overlapped with the through holes 12 when the above-mentioned ceramic green sheet is punched to form the through holes 12. Punch from the small opening side opposite to the large opening side.
Then, in order to form the through holes 12 having the shape of a quadrangular pyramid and the shape of an elliptic cone, a gap between the punch of the upper die and the hole for forming the through hole 12 of the lower die on which the ceramic green sheet is placed (punch) is formed. It can be formed by a method of adjusting 2 to 10% of the diameter).

Then, the larger end face of the through conductor is made to partially overlap each other in the longitudinal direction, and the insulating layer 11 is formed.
The multilayer substrate 11 is manufactured by superposing and joining a and 11b. When the insulating layers 11a and 11b are ceramic green sheets, about 1600 ° C after stacking
Sintering is performed by firing at.

In the present invention, it is preferable that the area on the side where the end faces of the through conductors overlap is larger by 10 to 60% than the area on the opposite side. If it is less than 10%, the current passage area tends to be small, and as a result, the wiring resistance value becomes large, and the current path is hard to form a smooth curve, and the current flow becomes poor, so that the inductance increases. In addition, the shape formed by the upper and lower penetrating conductors 12 is a square zigzag shape, and the current path C is not smooth and shortened as shown in FIG. 1A, and for example, a high frequency signal is transmitted with low loss. It is not suitable for. Further, the through holes 12 are formed in the same insulating layers 11a and 11b.
The volume of the insulating layers 11a and 11b between them becomes small, and the strengths of the insulating layers 11a and 11b and the multilayer substrate 11 are likely to decrease. If it exceeds 60%, the inclination angle of the inner surface of the through hole 12 becomes large, and it becomes difficult to process and form the through hole 12 with a punching die.

Further, as shown in FIG. 1 (a), the length (W in the longitudinal direction of the overlapping portion of the end faces of the through conductor).
1-W2) is preferably 2/5 or more and less than 3/4 of the length W1 of the end face in the longitudinal direction. If it is less than ⅕, the passage area of the current tends to be small and the wiring resistance value tends to be large. Above 3/4, the same insulating layer 11
With a and 11b, the volume of the insulating layers 11a and 11b between the through holes 12 becomes small, and the strength of the insulating layers 11a and 11b and the multilayer substrate 11 is likely to decrease.

Specifically, the length W1 in the longitudinal direction of the large end surface of the through conductor is about 0.1 to 5 mm, and the length W2 in the longitudinal direction of the small end surface of the through conductor is 0.05 to 4.5 m.
It is about m.

The multi-layer substrate according to the present invention includes individual insulating layers 11
It is also possible to bond them after manufacturing a and 11b. In that case, the arithmetic mean roughness of the end surface of the large through conductor is preferably 3 μm or less, and when it exceeds 3 μm, the gap between the upper and lower through conductors becomes large and the electric resistance at the connecting surface becomes large. In order to smooth the large end surface of the through conductor, the large end surface of the through conductor may be polished. Alternatively, the entire surfaces of the insulating layers 11a and 11b including the end faces can be polished.

Further, the insulating layers 11a and 11b formed with the through conductors of the present invention have two layers as one set,
The multilayer substrate 11 has a structure including two insulating layers 11a and 11b, a structure in which two insulating layers 11a and 11b are inserted in three or more layers, and two insulating layers 11a and 11b each have a plurality of layers. Any of the configurations that exist in pairs may be used.

The shape of the through-hole 12 formed in the insulating layer 11a is such that the area of the opening on the side where the through-hole 12 overlaps is larger than that on the opposite side. Specifically, various shapes as shown in FIG. Can have any shape. FIG. 3A shows a shape in which the area of the surface parallel to the opening surface of the through hole 12 is the same from the side where the opening is small to the middle and gradually increases from the middle. FIG. 3B shows a shape in which the side surface of the through hole 12 is a convex curved surface to the outside, and FIG. 3C shows a shape in which the side surface of the through hole 12 is a concave curved surface.

Thus, according to the present invention, the current passage area between the through conductors is increased, the wiring resistance value is reduced, and the inductance is also reduced. Further, since the shape formed by the upper and lower penetrating conductors becomes substantially wavy and forms a smooth and shortened current path, it is suitable for transmitting, for example, a high frequency signal with low loss. Further, since the area of the end surface on the overlapping side of the through conductor is larger than that on the opposite side, the volume of the insulating layer between the through conductors in the same insulating layer is increased, and the strength of the insulating layer and the multilayer substrate is maintained.

The present invention is not limited to the above embodiment, and various modifications may be made without departing from the gist of the present invention.

[0030]

According to the present invention, a plurality of insulating layers are laminated, and a plurality of through-hole conductors formed by filling the through-holes formed in the insulating layers with conductors are formed in each of the two vertically overlapping insulating layers. In a multi-layer substrate in which end faces are sequentially opposed to each other so that portions thereof overlap each other, the end faces have a substantially rectangular shape or a substantially oval shape, and portions thereof overlap each other in the longitudinal direction and overlap each other. Since the area of the end face on the side is larger than the end face on the opposite side, it is possible to sufficiently reduce the wiring resistance value of the internal wiring conductor formed by the penetrating conductors formed inside the multilayer wiring board and stacked vertically. .

Further, since the area of the end surface on the side where the through conductors overlap is larger than that on the opposite side, the area of the passage of current increases, the wiring resistance value decreases, and the inductance also decreases. Further, since the shape formed by the upper and lower penetrating conductors becomes substantially wavy and forms a smooth and shortened current path, it is suitable for transmitting, for example, a high frequency signal with low loss. Further, since the area of the end surface on the overlapping side of the through conductor is larger than that on the opposite side, the volume of the insulating layer between the through conductors in the same insulating layer is increased, and the strength of the insulating layer and the multilayer substrate is maintained.

In the present invention, the area of the side where the end faces are overlapped is preferably 10 to 60% larger than that of the opposite side, so that the shape formed by the upper and lower penetrating conductors becomes substantially wavy and smooth. Since the current path is shortened, it is suitable for transmitting high-frequency signals, etc. with low loss, and the volume of the insulating layer between the through conductors is large in the same insulating layer, so that the insulating layer and the multilayer substrate The function and effect of maintaining the strength is further improved.

Further, according to the present invention, preferably, the length in the longitudinal direction of the overlapping portion of the end faces is not less than ⅕ and less than ¾ of the length of the end faces in the longitudinal direction, so that the passage area of the electric current is reduced. Becomes large, the wiring resistance value becomes small, and the volume of the insulating layer between the through conductors is secured in the same insulating layer, so that the reduction in strength of the insulating layer and the multilayer substrate is suppressed.

[Brief description of drawings]

FIG. 1A is a cross-sectional view showing an example of an embodiment of a multilayer substrate of the present invention, FIG. 1B is a plan view of an end surface on the overlapping side when the end surfaces of a through conductor are substantially rectangular, FIG. 3C is a plan view of the end surface of the through conductor in the case where the end surfaces of the through conductors are substantially oval and are overlapped with each other.

FIG. 2 is a cross-sectional view of an example of a conventional multilayer substrate.

FIG. 3 shows another example of the embodiment of the multilayer substrate of the present invention, and (a) to (c) are cross-sectional views showing various shapes of through holes.

[Explanation of symbols]

11: Multilayer substrate 11a, 11b: insulating layer 12: Through hole 13: Conductor

Claims (3)

[Claims] 1. A plurality of insulating layers are laminated, and a plurality of through conductors are formed by filling conductors in through holes formed in the insulating layer in each of the two vertically overlapping insulating layers. In a multi-layer substrate formed by sequentially facing each other so that portions thereof overlap each other, the end faces have a substantially rectangular shape or a substantially elliptical shape, and portions that overlap each other in a longitudinal direction thereof and overlap each other. The multilayer substrate, wherein the area of the end face is larger than that of the opposite end face. 2. The multilayer substrate according to claim 1, wherein the area of the side where the end faces overlap is larger than the area of the opposite side by 10 to 60% in area ratio. 3. The length of the overlapping portion of the end faces in the longitudinal direction is not less than two fifths and less than three quarters of the length of the end faces in the longitudinal direction. Item 2. The multilayer substrate according to item 2.