JP2002359473A - Surface-mounted multilayer circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a surface-mounted multilayer circuit board that is improved in mountability by suppressing the occurrence of delamination between insulation layers. SOLUTION: Air entrainment is prevented at formation of a large-sized multilayered substrate 1, by laminating large-sized substrates upon another by forming a surface recessed section 12 in the peripheral edge section on the surface of the substrate 1. The surface recessed section 12 can also prevent infiltration of a sealing member 7 into the rear surface side of the substrate 1 at application of the member 7.

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, and more particularly to a surface mount type multilayer circuit board whose component mounting surface is covered with a sealing member.

[0002]

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

In order to simplify the manufacturing process, a large-sized multilayer substrate from which a plurality of such multilayer substrates can be extracted has been used. Specifically, it is manufactured as follows. First,
A conductor pattern to be a front wiring layer, a rear wiring layer, 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 on which the conductor patterns are formed are laminated, and the large-sized multilayer substrate is integrated by thermocompression bonding.
At this time, if necessary, a dividing groove is formed using a mold. Next, the large-sized thermocompression-bonded multilayer substrate is fired. Next, circuit components are joined and mounted on a large-sized multilayer substrate 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 board on which the circuit components are mounted is covered with a sealing member such as a resin, so that a large surface mount type A multilayer circuit board is obtained. Finally,
By performing the division processing using the above-described division grooves, a surface-mounted multilayer circuit board as a final product is obtained. In addition,
The large surface-mount type multilayer circuit board may be cut using a dicing saw or the like without performing the dividing groove and the dividing process (hereinafter, referred to as separation including the dividing / cutting).

Here, in the above manufacturing method, air is interposed between the green sheets when the green sheets are laminated, and the air does not sufficiently escape even when thermocompression-bonded, and this air is delaminated during firing. There was a problem that caused it.

Therefore, as shown in FIG. 7, conventionally, air entrapment preventing through holes 19a to 19e are previously formed in the same place of the green sheet to be the insulating layers 1a to 1e, and the through holes 19a to 19e are formed at the time of lamination. A method of preventing the above-described delamination has been performed by allowing air to escape from the through-hole 19 formed by overlapping the holes 19e.

[0006]

However, if the large multi-layer substrate 11 is provided with the through holes 19 for preventing air entrapment, as shown in FIG. The member 7 enters the through hole 19 and goes around the back side of the substrate 1. Then, there is a problem that the enclosing sealing member 7 adheres to the terminal electrode 5 on the rear surface side of the multilayer substrate, or irregularities are generated on the rear surface of the multilayer substrate 1, so that mounting on the motherboard becomes impossible. .

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a surface mount type multilayer circuit board capable of preventing delamination due to air entrained during lamination and thermocompression bonding of green sheets. To provide.

[0008]

According to the surface mounting type multilayer circuit board of the present invention, a surface wiring layer and a circuit component are arranged on a surface of a multilayer board on which a plurality of insulating layers are laminated. In a surface-mounted multilayer substrate formed by covering a circuit component with a sealing member and forming a terminal electrode on the back surface of the multilayer substrate, a surface depression is formed on the surface of the multilayer substrate, and the surface depression is formed in the surface depression. Was filled with the sealing member.

Preferably, a back surface dent portion is formed on the back surface facing the front surface dent portion with one of the insulating layers interposed therebetween.

[0010] More preferably, the surface depression is formed in a peripheral portion of the multilayer substrate.

Here, the surface depression is formed by a through hole formed in a predetermined number of insulating layers in the stacking direction from the surface of the multilayer substrate, and has a concave shape in which the bottom surface is closed by the predetermined insulating layer. Has become. Also, a concave portion formed on the mounting surface side of the multilayer substrate is also called a surface concave portion. Also,
A surface dent formed over the end face of the multilayer board, divided into two adjacent multilayer boards by a large multilayer circuit board,
The surface dent formed over the corner of the multilayer substrate is divided into four by a large multilayer circuit board and an adjacent multilayer substrate. These are all called surface depressions.

[0012]

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 formation position of a surface depression formed on the large-sized multilayer substrate of FIG.

In the figure, reference numeral 11 denotes a surface mount type 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-mounted multilayer circuit board; 8 denotes a snap line (division groove) for separating the surface-mounted multilayer circuit board 11 into each multilayer board 1; is there. Reference numeral 12 denotes a surface depression.

The multilayer substrate 1 has, for example, 50 to 50 layers per layer.
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
For example, A1_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 to penetrate 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.

The surface mounting type multilayer circuit board 11 of the present invention is characterized in that a surface depression 12 is formed on the surface of the multilayer substrate 1 and the above-described sealing is provided in the surface depression 12. The member 7 is filled. The specific position where the surface depression 12 is formed is, for example, as shown in the large-sized surface mount type multilayer circuit board 10 shown in FIG. I have. That is, in the surface mount type multilayer circuit board 11, it is formed at an end face and a corner. In a large-sized surface-mounted multilayer circuit board 10 from which a plurality of surface-mounted multilayer circuit boards 11 can be extracted, a surface depression 12 is formed so as to straddle a separation line. As a result, it is located at the periphery of the multilayer substrate 1.
The through holes 12a to 12d serving as the surface depressions 12 are only the insulating layers 1a to 1d, and the insulating layer 1e is
To 12d are closed to form a concave portion 12 having a concave shape. The through holes 12a to 12d of the insulating layers 1a to 1d are
They are formed at the same location so as to overlap with 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. The sealing member 7 has entered the inside of the surface depression 12. However, the sealing member that has entered the surface recess 12 is blocked by the insulating layer 1e and does not go around the mounting surface side of the multilayer substrate 1 at all.

As shown in FIG. 3, the surface depression 12 is formed at a portion corresponding to the intersection of the separation lines 8 in the large surface mount type multilayer circuit board 10.

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 insulating layer 1
A through hole for a via hole of, for example, 0.2 mmφ is formed at a plurality of predetermined positions using a punching machine, a punching machine, or the like in accordance with 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 12 at the same positions overlapping in the laminating direction.
a to 12d are formed. Then, no through hole serving as the surface depression 12 is formed in the green sheet serving as the insulating layer 1e located at the lowermost layer.

Then, such green sheets as the insulating layers 1a to 1e are laminated, and the large-sized multilayer substrate 10 is
For example, they are integrated by thermocompression bonding under the conditions of 80 to 150 ° C. and 500 to 2500 N / cm ² . Thereby, a large-sized 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 electric continuous belt furnace, for example, in air at 900 ° C.
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 large multi-layer substrate that has passed is subjected to a surface treatment. For example, a thick resistive film is baked on the surface wiring layer 4 or an insulating protective film is coated.

Next, the circuit component 6 is 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-mount type multilayer substrate 11 of the present invention, a part of the surface of the multilayer substrate 1 is formed as a whole by the through holes 12a to 12d of the insulating layers 1a to 1d in the above-described manufacturing method. It has a concave shape. That is, surface depression 1
2 are formed. In addition, the surface recess 12 is filled with the sealing member 7 applied to the multilayer substrate 1.

That is, in such a large-sized surface-mounted multilayer circuit board 10, when the insulating layers 1a to 1e are stacked, the adjacent insulating layers 1a and 1b, the insulating layers 1b and 1c, The air engulfed between the layers 1c and 1d and between the insulating layers 1d and 1e can easily escape to the front side of the multilayer substrate 1 through the surface depressions 12. For this reason, even if the baking treatment is performed, occurrence of delamination between the insulating layers 1a to 1e can be effectively prevented.

Further, since the surface depression 12 composed of these through holes 12a to 12d is closed by the lowermost insulating layer 1e, even if the sealing member 7 is applied to the surface of the multilayer substrate 1, In addition, it does not go around the back surface side, which is the mounting surface of the multilayer substrate 1 at all. For this reason, it is possible to solve the problem that the mounting surface of the multilayer board 1 becomes uneven as in the related art, and mounting on the motherboard becomes impossible.

The surface recess 12 is formed in the peripheral portion of the multilayer substrate 1 so that the surface mounting type multilayer circuit substrate 1 is formed.
1, the surface dead space is reduced, and the surface mounting type multilayer circuit board 11 suitable for small size and high density mounting is obtained. Specifically, as shown in FIG. 3, the surface recess 12 in the large-sized surface-mounted multilayer circuit board 10 has four corners of each multilayer substrate region to be the surface-mounted multilayer circuit board 10, that is, the separation line 8. Formed at the intersection of.

The shape of the surface depression 12 is not particularly limited to a circular shape. For example, in the case of a circular shape as shown in the figure, if the diameter is small, the surface depression 12 will be crushed in the lamination press-bonding process, and the above-mentioned air will be released. Can not. Therefore, after firing, it is desirable that the thickness be 0.3 mm or more, preferably 0.4 mm or more.

The upper limit of the diameter of the surface depression 12 is not particularly limited, but the size of the surface mount type multilayer circuit board 10 and the high density mounting of the surface are taken into consideration. Specifically, it is desirable that the thickness after firing is 4 mm or less. Further, when the opening shape is other than the circular shape, the opening shape becomes another shape having an opening corresponding to the opening area.

FIG. 4 is a sectional view of another embodiment of the present invention. In this embodiment, the surface depression 12 is formed at a position away from the peripheral edge of the multilayer substrate 1 and at a position closer to the center of the substrate.

FIG. 5 is a plan view showing the formation position of the surface depression 12 of the present invention. In FIG. 5A, the surface depression 1
2 are formed at four corners of each substrate forming region to be the surface-mounted multilayer circuit board 10, that is, at the intersections of the separation lines 8.

In FIG. 5B, the surface depression 12 is formed on the side of each substrate forming region to be the surface mount type multilayer circuit board 10, that is, on the separation line 8. In FIG. 5C,
The surface depression 12 is formed at a position apart from the separation line 8 in each substrate forming region to be the surface-mounted multilayer circuit substrate 10. Here, the cross-sectional views of FIGS. 5A and 5B are like the surface-mounted multilayer circuit board shown in FIG. 1, and the cross-sectional view of FIG. 5C is the surface-mounted multilayer circuit board shown in FIG. It looks like a circuit board.

FIG. 6 is a partially enlarged view showing another embodiment of the surface mount type multilayer circuit board of the present invention. In this embodiment, the surface depression 12 is formed from the front side of the multilayer substrate 1, and the insulating layer closing the surface depression 12 is the insulation layer 1c located at the center in the stacking direction. Further, a surface depression 15 is also formed on the mounting surface side of the multilayer substrate 1. That is, the surface depression 12 and the surface depression 15
Are arranged with one layer of the insulating layer 1c interposed therebetween. In this case, air entrained between the layers between the insulating layers 1a and 1b and between the insulating layers 1b and 1c escapes from the surface depression 12 and becomes insulative.
The air entrained between the layers d, 1d and 1e can escape from the surface depression 15. In this case, it is not necessary to form the surface depression 12 on the front side of the multilayer substrate 1 and the surface depression 15 on the mounting side of the multilayer substrate 1 at the same location. That is, when the number of laminated insulating layers of the multilayer substrate 1 is N, the surface depression 12 is constituted by at least the insulating layer on the front side or through holes of (N−1) layers from the front side.

In such a structure, the amount of the sealing member 7 filled in the surface depression 12 in the large-sized surface-mount type multilayer circuit board 10 is reduced, so that the division and cutting can be easily performed.

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.

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

Further, a conductor film is attached to the inner wall surfaces of these surface depressions 12 and 15 so that, for example, the internal wiring layer 2 of the multilayer substrate 1 and the surface wiring layer 4 and the terminal electrodes 5 are electrically connected to each other. The connection may be made automatically.

[0049]

According to the surface mounting type multilayer circuit board of the present invention, a surface depression is formed on the surface side of the multilayer substrate, and the sealing member is filled in the surface depression. That is, in the manufacturing process, even if the shape of the large-sized surface-mount type multilayer circuit board is large, the surface dents that allow the air entrained between the layers of the green sheet to escape are dotted,
Delamination between the insulating layers can be effectively suppressed, and the internal wiring layer in the multilayer substrate can be formed stably.

Also, since the sealing member applied to the surface does not wrap around the surface mount type multilayer circuit board, the mountability on the motherboard is dramatically improved. Further, by forming the surface depressions on the periphery of the surface-mounted multilayer circuit board, the mounting efficiency of the surface wiring layer and circuit components on the surface of the surface-mounted multilayer circuit board is improved, and the surface-mounted multilayer circuit is improved. Small and high-density mounting of the substrate can be realized.

[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 partial 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 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.

FIGS. 5A to 5C are plan views showing formation positions of surface depressions of the present invention.

FIG. 6 is a partial sectional view showing a surface depression according to another embodiment 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 11 Surface mount type multilayer circuit board 12 Surface recessed part 10 Large surface mount type multilayer circuit board 1 Multilayer substrate 1a-1e Insulation layer 2 Internal wiring layer 4 Surface wiring layer 5 Terminal electrode 6 Circuit component 7 Sealing member 8 Separation line 12 Surface depression 12a-12d Through hole

Claims (3)

[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 a surface-mounted multilayer circuit board having terminal electrodes formed on the back surface of the multilayer board, while forming a surface depression on the surface of the multilayer board,
A surface-mounted multilayer circuit board, wherein the surface recess is filled with the sealing member. 2. The surface-mounted multilayer circuit according to claim 1, wherein a back surface depression is formed on the back surface facing the surface depression portion with one of the insulating layers interposed therebetween. substrate. 3. The multi-layer substrate according to claim 1, wherein the surface depression is formed at a peripheral edge of the multilayer substrate.
The surface-mounted multilayer circuit board as described.