JP2002359474A - Surface-mounted multilayer circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized surface-mounted multilayer circuit board that can prevent the delamination of insulating layers, is improved in mountability on a mother board, and can be surface-mounted to high density. SOLUTION: On the surface of this multilayer circuit board, prescribed surface wiring layers 4 and circuit components 6 are arranged. On the rear surface of this circuit board which serves as the mounted surface of the board, recessed sections 15 which pass through the substrate 1, except for one uppermost insulation layer, are formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type multilayer circuit board.

[0002]

2. Description of the Related Art A surface mounting type multilayer substrate is widely used as a mounting substrate on which various electronic components and semiconductor elements are mounted, and as a substrate on which various circuit functions are formed. For example, ceramics such as alumina have heat resistance, durability,
Since it is excellent in thermal conductivity and the like, it is suitable as a material for this multilayer substrate. In high-frequency circuits, a substrate made of a ceramic material having a predetermined dielectric constant has been used.

[0003] In order to simplify the manufacturing process, this surface-mounted multilayer circuit board is divided or cut using a large-sized multilayer board from which a plurality of surface-mounted multilayer circuit boards can be extracted.

In a specific manufacturing process, first, a conductor paste to be a surface wiring layer, a terminal electrode, an internal wiring layer, and a via hole conductor is screen-printed on a green sheet made of a low-temperature fired glass ceramic material or the like. Next, a plurality of green sheets are integrated by lamination and thermocompression bonding to form a large surface-mounted multilayer circuit board. At this time, if necessary, a mold is used to form a dividing groove. Next, the unfired large-sized surface-mounted multilayer circuit board is fired. Next, circuit components are joined and mounted on a large surface-mount type multilayer circuit board by soldering, flip-chip mounting, wire bonding, or the like. Next, if necessary, in order to protect the circuit components from the external environment, the entire surface of the component mounting surface of the multilayer board on which the circuit components are mounted is covered with a sealing member such as a resin, so that the large surface mounting is performed. A multi-layer circuit board is obtained. Finally, by performing the dividing process with the above-mentioned dividing groove,
A surface-mounted multilayer circuit board as a final product is obtained.
Note that a large multilayer substrate may be cut using a dicing saw or the like without performing the dividing groove and the dividing process (hereinafter, referred to as a dicing saw).
Separation, including division and cutting).

In the above-mentioned manufacturing method, there is a problem that if air is trapped between the green sheets during the lamination and compression of the green sheets, the air cannot escape and this air causes delamination during firing.

[0006] Therefore, as shown in FIG.
The through-hole 19 (1
9a to 19e) are formed in advance, and this through hole 1
The air between the green sheets escapes through 9a to 19e.

[0007]

However, as shown in FIG. 7, when the sealing member 7 is applied on the multilayer substrate 1,
The sealing member 7 penetrates into the through hole 19 and goes around the mounting surface side of the multilayer substrate 1. As a result, there has been a problem that the enclosing sealing member 7 adheres to the terminal electrode 5 on the mounting surface side of the multilayer substrate 1 or the mounting surface becomes uneven, and mounting on the motherboard becomes impossible.

Further, since the portion where the through hole 19 is formed becomes a dead space in the surface mount type multilayer circuit board 10, when mounting the surface wiring layer 4 and the circuit component 6, small and high-density mounting is required. It was a major obstacle.

When the dividing process is performed from the large-sized surface-mount type multilayer circuit board 10, if the sealing member 7 is subordinate to the through hole 19, there is a problem that the dividing process becomes difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and has as its object to prevent delamination between insulating layers, improve mountability on a motherboard, and reduce the size and surface height. An object of the present invention is to provide a surface mounting type multilayer circuit board capable of density mounting.

[0011]

According to the surface mounting type multilayer circuit board of the present invention, a surface wiring layer and circuit components are arranged on a surface of a multilayer board on which a plurality of insulating layers are laminated.
The surface wiring layer and the circuit component are covered with a sealing member, and a surface mounting type multilayer substrate in which terminal electrodes are formed on the back surface of the multilayer substrate, wherein a recess is formed on the back surface of the multilayer substrate. The recess is formed by a through hole provided in each insulating layer except for the uppermost insulating layer.

[0012] Preferably, the depression is formed at a peripheral edge of the multilayer substrate.

[0013] Here, the concave portion refers to a shape that is concave in the laminating direction from the mounting surface of the substrate. At the end surface portion of the multilayer substrate, the shape of the concave portion is divided into two parts.
Alternatively, in the corner portion, the shape of the depression is divided into four. The shape of the opening of the depression may be circular, roughly circular, or polygonal.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a surface mount type multilayer circuit board according to the present invention. In the drawings, the same parts as those in the related art are denoted by the same reference numerals. In addition, each code is not distinguished before and after firing in the manufacturing process.

FIG. 1 is a sectional view of a surface mount type multilayer circuit board according to the present invention. FIG. 2 is a partial cross-sectional view of a large multilayer substrate from which the multilayer substrate of FIG. 1 is extracted. FIG. 3 is a plan view showing a depression formed on the mounting surface of the large-sized multilayer substrate of FIG.

In the drawing, reference numeral 11 denotes a surface-mounted multilayer circuit board, 1 denotes a multilayer board, 1a to 1e denote insulating layers, 2 denotes an internal wiring layer formed inside the multilayer board 1, and 3 denotes an internal wiring layer. The formed via-hole conductor, 4 is a surface wiring layer formed on the surface of the multilayer substrate 1, 5 is a terminal electrode formed on the mounting surface side of the multilayer substrate 1, and 6 is a circuit configuration mounted on the surface wiring layer 4. The component 7 is a sealing member that covers the circuit component.

Reference numeral 10 denotes a large-sized surface-mount type multilayer circuit board; 8 denotes a separation line such as a snap line (division groove) for separating the surface-mount type multilayer circuit board 11 into each multilayer substrate 1; is there. Reference numeral 15 denotes a depression.

The multilayer substrate 1 has, for example, 50 to
Insulating layers 1a to 1e having a thickness of about 300 μm are laminated
It is configured. The insulating layers 1a to 1e are made of ceramic.
Materials, glass-ceramic materials that can be fired at low temperatures, etc.
Consists of For example, in glass-ceramic materials, ceramic
As a material for the lock, for example, Al_TwoO_Three, BaO-TiO _Two
System, CaO-TiO_TwoSystem, MgO-TiO_TwoSystem
Examples of oxides that can be fired at low temperatures include, for example, Bi.
VO_Four, CuO, Li_TwoO, B_TwoO_ThreeAnd so on.

A via-hole conductor 3 is formed penetrating in the thickness direction of each of the insulating layers 1a to 1e. Also, the insulating layer 1a
In addition to the predetermined wiring network, an internal wiring layer 2 including a capacitor electrode forming a capacitor, a conductor forming an inductance component, a conductor forming a strip line, and the like is formed between the layers 1 to 1e. On the surface of the insulating layer 1a, a surface wiring layer 4 including an electrode pad for mounting the circuit component 6 is formed. Further, on the back surface of the insulating layer 1e (the mounting surface of the surface mount type multilayer circuit board), a terminal electrode 5 for connecting the multilayer substrate 1 to a motherboard and a back surface conductor layer serving as a ground potential are formed.

The surface wiring layer 4, via-hole conductor 3, internal wiring layer 2, and terminal electrode 5 are connected to each other to form a predetermined circuit network. Also, these conductors
Ag-based (Ag alone or Ag-Pd, Ag-Pt, etc.
g alloy) or a conductive film (conductor) mainly composed of Cu (Cu simple substance or Cu alloy).

The circuit component 6 is exemplified by various electronic components such as a multilayer ceramic capacitor, a chip resistor, a SAW element, a chip-shaped inductance element, and a semiconductor element. The surface wiring layer 4 is formed by soldering, flip-chip mounting, wire bonding, or the like. Implemented above.

The surface of the circuit component 6 is covered with a sealing member 7 so as to cover the entire surface of the multilayer substrate 1 in order to protect it from the external environment. Examples of the sealing member 7 include a thermosetting resin such as an epoxy resin, a phenol resin, and a silicon resin, and an ultraviolet curing resin. In this way, the circuit component 6 and the sealing member 7 are formed on the multilayer board 1 to form the surface-mounted multilayer circuit board 11.

A feature of the surface mount type multilayer circuit board 11 of the present invention is that a recess 15 is formed on the mounting surface of the multilayer board 1.

The specific position where the concave portion 15 is formed is as follows.
For example, as shown by a large-sized surface-mount type multilayer circuit board 10 shown in FIG. 1, it is formed so as to straddle a boundary portion between adjacent multilayer boards 1. That is, the surface mount type multilayer circuit board 11
Is formed at the end face and at the corners. In the large-sized surface-mounted multilayer circuit board 10 from which a plurality of surface-mounted multilayer circuit boards 11 can be extracted, a recess 15 is formed so as to straddle a separation line. As a result, it is located at the peripheral portion on the mounting surface side of the multilayer substrate 1. The through holes 15b to 15e serving as the depressions 15 are only the insulating layers 1b to 1e, and the insulating layer 1a closes the through holes 15b to 15e.
A concave portion 15 having a concave shape is formed. This insulating layer 1b ~
The through-holes 15b to 15e of 1e are formed at the same location so as to overlap each other during lamination.

A surface wiring layer 4 is mounted on the surface of the surface mount type multilayer circuit board 11, and a circuit component 6 is mounted on the surface wiring layer 4. The surface wiring layer 4 and the circuit component 6 are mounted on the surface wiring layer 4. The sealing member 7 is coated on the entire surface of the multilayer substrate 1 so as to cover it.

As shown in FIG. 3, the recess 15 is formed on the mounting surface side of the large-sized surface-mount type multilayer circuit board 10.
It is formed at a portion corresponding to the intersection of the separation lines 8.

Next, a method of manufacturing the surface mount type multilayer circuit board 11 according to the present invention will be described.

First, the insulating layers 1a to 1e are made of, for example, CaO
_{-Al 2 O 3 -SiO 2 -B 2} O 3 based glass powder and alumina powder and glass were mixed for - a ceramic material.
The green sheets to be the insulating layers 1a to 1e are formed by forming a slurry of such a glass-ceramic material into a tape having a thickness of 0.2 mm by a doctor blade method, and further cutting into a predetermined size to form a sheet. As a result, a green sheet is obtained.

Such a green sheet is formed on each of the insulating layers 1
Via holes for punching, for example, 0.2 mmφ are formed at a plurality of predetermined positions using a punching machine, a punching machine, or the like according to the via hole conductors 3a to 1e. Also,
Ag, Ag-Pd, A
A conductor paste such as u, Cu or the like is filled, and at the same time, a conductor serving as the internal wiring layer 2, a surface wiring layer 4, and a conductor film serving as the terminal electrode 5 are formed by screen printing.

At this time, the green sheets serving as the insulating layers 1a to 1d are provided with the through holes 15 at the same positions overlapping in the laminating direction.
b to 15e are formed. Then, no through hole serving as the recess 15 is formed in the green sheet serving as the insulating layer 1a located at the uppermost layer.

Then, green sheets to be used as the insulating layers 1a to 1e are laminated, for example, at 80 to 150.degree.
It is integrated by thermocompression bonding under the condition of 00 to 2500 N / cm ² . As a result, a large multilayer substrate in an unfired state is obtained.

Next, if necessary, as shown in FIG.
Separation grooves are formed as separation lines 8 on both the front and back surfaces of the unfired large multilayer substrate.

Next, a large-sized multilayer substrate in an unfired state is placed in an air-type continuous belt furnace, for example, in air at 900.degree.
It is baked at 20 ° C. for 20 minutes. When the conductive paste is Ni or Cu, the paste is reduced or fired in a neutral atmosphere.

Next, an electrical test is performed to check the energization state, and the surface treatment is performed on the large multi-layer substrate that has passed. For example, a thick resistive film is baked on the surface wiring layer 4 or an insulating protective film is coated.

Next, the circuit components 6 are joined and mounted on the large-sized multilayer board by soldering, flip-chip mounting, wire bonding, or the like.

Next, the entire surface of the large multilayer substrate is covered with a sealing member 7 such as a resin. Note that as a sealing method, a method of sealing by a casting method using a liquid sealing material, or a method of sealing by a transfer molding method using a solid sealing material at normal temperature can be used. As a result, a large surface-mounted multilayer circuit board 10 is obtained.

The large surface mounted multilayer circuit board 10 thus obtained is divided along the separation line 8 to form the surface mounted multilayer circuit board 11 shown in FIG. Note that, other than the division processing, the large-sized surface-mounted multilayer circuit board 10 may be separated into the surface-mounted multilayer circuit board 11 by, for example, cutting processing.

According to the surface-mounted multilayer circuit board 11 of the present invention manufactured as described above, the mounting surface, which is the back surface of the multilayer board 1, has one layer on the front side of the insulating layer,
The recessed portion 15 for closing a is formed. That is,
The depression 15 is formed by through holes 15b to 15e formed in the insulating layers 1b to 1e. Thereby, in the above-described manufacturing method, between the green sheet serving as the insulating layer 1a and the green sheet serving as the insulating layer 1b, similarly between the insulating layer 1b and the insulating layer 1c, and between the insulating layer 1c and the insulating layer 1d.
During the thermocompression bonding, the air trapped between the insulating layer 1d and the insulating layer 1e escapes from the mounting surface side of the multilayer substrate 1 through the recessed portion 15 formed by the through holes 15b to 15e. Delamination occurring between the layers 1a to 1e can be effectively prevented.

Since the insulating layer 1a does not have the recessed portion 15 and does not have a through hole as in the prior art, the sealing member 7 on the front surface side of the multilayer substrate 1 is mounted on the mounting surface side. Never reach. For this reason, there is no problem that it adheres to the electrode pad on the mounting surface side of the multilayer substrate 1 or the mounting surface becomes uneven, and as a result, mounting on the motherboard becomes impossible.

The insulating layer 1a has the recess 15
Is not formed, and the entire surface of the insulating layer 1a becomes the surface of the surface mount type multilayer circuit board 11, so that there are no restrictions on the formation of the surface wiring layer 4, and
High-density mounting of the circuit component 6 is also possible. That is, a surface-mounted multilayer circuit board 1 that is small and can be mounted at high density.
It becomes 1.

Further, since the recess 15 is formed at the peripheral edge of the multilayer substrate 1, the dead space in the internal wiring layer 2 of the multilayer substrate 1 is reduced. The sealing member 7 is provided in the recess 15 of the large-sized surface-mount type multilayer circuit board 10.
Is not filled, there is an effect that division becomes easy.

When the recess 15 has a circular opening, for example, if the diameter is small, it will be crushed during lamination and compression.
It is desirable that the thickness after firing is 0.3 mm or more, preferably 0.4 mm or more. The upper limit of the diameter of the recess 15 is not particularly limited, but is preferably 4 mm or less after firing for high-density mounting of the internal wiring layer 2 of the large multilayer substrate 10.

FIG. 4 is a sectional view of a multilayer substrate according to another embodiment of the present invention. Thus, if necessary, the depression 15
May be formed at a position inside the substrate away from the peripheral portion of the multilayer substrate 1.

FIG. 5 is a plan view showing the formation position of the depression 15 of the present invention. In FIG. 5A, the depressions 15 are formed at the four corners of each multilayer substrate formation region, that is, at the intersections of the separation lines 8. In FIG. 5B, the depressions 15 are formed on the boundaries between the multilayer substrate formation regions, that is, on the separation lines 8. In FIG. 5C, the depression 15 is formed at a position away from the separation line 8. Here, FIG.
The sectional views of FIGS. 5A and 5B are as shown in FIG.
FIG. 4 is a sectional view of FIG.

As shown in FIG. 6, a thermal via hole 13 for releasing heat is formed in the insulating layer 1a immediately above the depression 15, and an IC is formed in the region of the insulating layer 1a on the depression 15.
The chip 16 is mounted. In this way, the heat generated by the IC chip 16 is released to the recessed portion 15 on the mounting surface side through the thermal via hole 13, so that the thermal effect of the multilayer substrate 1 over a wide area can be reduced. Thereby, while the formation part of the recessed part 15 can be utilized effectively,
Since the length of the thermal via hole 13 can be reduced, the heat dissipation is also improved.

In the above-described embodiment, the surface mount type multi-layer circuit board has been described as an example of a multi-layer board made of a glass-ceramic material. However, a multi-layer board made of an organic material such as a glass epoxy material or a modified polyimide material may be used. .

Further, a conductive film may be formed on the inner wall surfaces of these recesses 15 so as to be electrically connected to, for example, the internal wiring layer 2 and the terminal electrodes 5 of the multilayer substrate 1.

It should be noted that the present invention is not limited to the above embodiment, and various changes and improvements may be made without departing from the scope of the present invention.

[0049]

According to the surface mounting type multilayer circuit board of the present invention, the mounting surface of the multilayer board is formed with a recess formed by a through hole excluding one insulating layer on the surface side of the insulating layer. I have. That is, the recess allows the air trapped between the insulating layers to escape from the region of the multilayer substrate to the outside of the mounting surface during the manufacturing process, and as a result, the surface mounting type multilayer circuit with less delamination between the insulating layers. It becomes a substrate.

Further, since the uppermost insulating layer is not provided with a through-hole forming the depression, there is no dead space on the surface of the multilayer substrate, and the device can be reduced in size and mounted with high density.

[Brief description of the drawings]

FIG. 1 is a sectional view of a surface mount type multilayer circuit board according to the present invention.

FIG. 2 is a cross-sectional view of a large-sized surface-mounted multilayer circuit board from which the surface-mounted multilayer circuit board of FIG. 1 is extracted.

FIG. 3 is a plan view of the mounting surface side of the large-sized surface-mount type multilayer circuit board of FIG. 2;

FIG. 4 is a sectional view of another embodiment of the surface mount type multilayer circuit board of the present invention.

FIG. 5 is a plan view showing a formation position of a concave portion in the large-sized surface mounting type multilayer circuit board of the present invention.

FIG. 6 is a cross-sectional view of a recessed portion according to another embodiment of the surface mount type multilayer circuit board of the present invention.

FIG. 7 is a cross-sectional view of a conventional large-sized surface-mount type multilayer circuit board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Multilayer board 15 Depression 10 Large surface mount type multilayer circuit board 11 Surface mount type multilayer circuit board 1a-1e Insulating layer 2 Internal wiring layer 3 Via hole conductor 4 Surface wiring layer 5 Terminal electrode 6 Circuit component 7 Sealing member 8 minutes Wires 15b to 15e Through-holes forming recesses

Claims (2)

[Claims] 1. A surface wiring layer and a circuit component are arranged on a surface of a multilayer substrate on which a plurality of insulating layers are stacked, and the surface wiring layer and the circuit component are covered with a sealing member. In the surface-mount type multilayer substrate in which terminal electrodes are formed on the rear surface of the multilayer substrate, a depression is formed on the rear surface of the multilayer substrate, and the depression is provided on each of the insulating layers except the uppermost insulating layer. A surface mount type multilayer circuit board characterized by being formed with a through hole. 2. The surface-mounted multilayer circuit board according to claim 1, wherein the recess is formed at a peripheral edge of the multilayer board.