JP2001284808A - Laminated circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated circuit board wherein bonding reliability is improved. SOLUTION: In this laminated circuit board, a plurality of insulating layers 1a-1e are laminated, a wiring pattern 2 is arranged in a laminated board 1 having a cavity 51, an electrode 2 for bonding wire connection is stuck on the periphery of an aperture of the cavity 51 of the laminated board 1, an IC chip 5 is accommodated in the cavity 51, and the IC chip 5 and the electrode 2 are connected by using a bonding wire W. An insulating film 6 is interposed between insulating layers 1a, 1b in regions of the electrode 2 and the inner wall surface of the cavity 51.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated circuit board in which an IC chip is housed in a cavity and a bonding wire is connected between the IC chip and a bonding wire connection electrode around the cavity. Things.

[0002]

2. Description of the Related Art In recent years, with the increase in frequency and miniaturization of components used in mobile phones and the like, laminated circuits in which a dielectric material is fired at a low temperature and Ag, Au, Cu, or an alloy thereof of an internal pattern are applied. Substrates have been proposed. That is, high performance and high density of the laminated circuit board are required.

For this reason, a resonance circuit has been formed in a laminated circuit board, and an IC chip and the like have been accommodated for its operation.

[0004] For example, in general, as shown in FIG. 4, a cavity portion 51 for accommodating an IC chip 5 is formed on a laminated substrate 1 composed of, for example, insulating layers 1a to 1e.

The insulating layers 1a to 1e of the laminated substrate 1
And a via-hole conductor 4 extending in the thickness direction of each of the insulating layers 1a to 1e.
Are formed. On the surface of the laminated substrate 1, a surface wiring pattern constituting the bonding wire connection electrode 2 and the like is formed.

[0006] Then, I
The C chip 5 is accommodated, and the input / output electrodes of the IC chip 5 and the bonding wire connection electrodes 2 are connected by bonding wires W.

The internal wiring pattern 3 has a capacitance component, an inductance component,
Further, it is used for a ground conductor film or the like.

A method for manufacturing the above-described laminated circuit board will be described.

First, green sheets to be the insulating layers 1a to 1e are prepared. For example, a green sheet, for example,
An inorganic filler of a dielectric ceramic powder, an oxide powder for low-temperature firing, a low-melting glass powder, and a slurry made of an organic binder such as an alkyl methacrylate are prepared, and tape-formed by a doctor blade method, etc. Cut to dimensions to create a green sheet.

Next, a through hole serving as the via hole conductor 4 is formed in a predetermined green sheet, and the through hole serving as the via hole conductor 4 and the cavity portion 51 (the insulating layer 1) is formed in the through hole.
a, 1b only).

Thereafter, a conductor serving as the via hole conductor 4 is formed in the through hole serving as the via hole conductor 4 by filling with a conductive paste, and a conductor film serving as a surface wiring pattern such as the bonding wire connection electrode 2 and the internal wiring pattern are formed. 3
Is formed by printing a conductive paste.

The conductive paste is made of an Ag-based material (eg, Ag alone or an Ag—Pd alloy), and if necessary, for example, a predetermined amount of a low-melting borosilicate glass, and an organic binder such as ethyl cellulose. 2.2.4-
It is adjusted by homogeneously mixing an organic solvent such as trimethyl-1.3-pentadiol monoisobutyrate.

A green sheet on which a conductor film serving as a surface wiring pattern such as a through hole serving as a cavity portion 51, an internal wiring pattern 3, a via hole conductor 4, and a bonding wire connection electrode 2 is formed is laminated on a laminated substrate. In accordance with the order of lamination, thermocompression bonding is performed to form an unfired laminated substrate.

Thereafter, the unfired laminated substrate is integrally fired at a relatively low temperature of 800 to 1000 ° C. in an air atmosphere or a neutral atmosphere.

After that, the fired laminated substrate 1 is burned with a thick-film resistive film on the surface wiring pattern or covered with an insulating protective film, if necessary. The IC chip 5 is housed and joined in the tee portion 51, and a connection is made between the input / output electrode of the IC chip 5 and the bonding wire connection electrode 2 around the opening of the cavity portion 51 by a bonding wire W.

The IC chip 5 is molded with resin if necessary, or the cavity is formed in a two-stage structure, and the IC chip 5 is hermetically sealed with a metal cover or the like.

In the above-described laminated circuit board, the bonding wire connecting electrode 2 formed around the opening of the cavity portion 51 is arranged as close as possible to the extent that the printing misalignment is allowed in order to achieve miniaturization. For example, when viewed in a plan view, the distance between the bonding wire connection electrode 2 and the inner wall surface of the cavity 51 is arranged close to, for example, about 200 μm.

In order to arrange the internal wiring patterns 3 at a high density, an insulating layer constituting the inner wall of the cavity 51, in FIG. 4, between the insulating layers 1a and 1b, for example, 1a
The internal wiring pattern 3 is formed close to the cavity portion 51 between the layers 1b and 1b and between the layers 1b and 1c.

[0019]

However, the bonding wire connecting electrode 2 disposed around the opening of the cavity 51 as described above cannot stably obtain a flat surface as shown in FIG. There was a problem.

This is because, when the internal wiring pattern 3 is formed between the insulating layers 1a to 1c around the opening of the cavity 51 and the internal wiring pattern 3 is not formed, This is because a difference in lamination thickness occurs.

That is, at 200 μm from the periphery of the inner wall of the cavity portion 51, for example, the internal wiring pattern 3 is not arranged at all, so that the lamination thickness is reduced in this region.

When the green sheets are laminated, a pressing force is applied in the vertical direction, but the cavity 5
In the vicinity of the opening 1, the pressing force escapes to the cavity 51 side.

By these two actions, actually, as in the laminated circuit board shown in FIG. 3, an inclined surface S which falls toward the cavity 51 is formed around the opening of the cavity 51.

The flatness of the bonding wire connection electrode 21 is reduced by the influence of the inclined surface S, and when the bonding wire connection electrode 21 is bonded by a bonding wire, a bonding failure occurs. For example, the incidence was about 1%.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a laminated circuit board having high bonding reliability to bonding wire connection electrodes arranged around a cavity. Things.

[0026]

According to the present invention, a plurality of insulating layers are laminated, an internal wiring pattern is arranged in a laminated substrate having a cavity, and an inner wiring pattern is formed around the opening of the cavity of the laminated substrate. An electrode for bonding wire connection is attached, and an IC chip is accommodated in the cavity,
In a laminated circuit board formed by connecting the IC chip and the bonding wire connection electrode by bonding wires, the bonding wire connection electrode and the cavity portion inner wall surface are disposed between insulating layers located on the inner wall surface of the cavity portion. Characterized in that an insulating film is interposed in a region between the two.

Preferably, the insulating film is made of substantially the same insulating material as the insulating layer, and has a thickness substantially equal to or greater than the thickness of the internal wiring pattern.

As described above, on the side surface of the cavity, the insulating film is interposed between the insulating layers in the region between the bonding wire connection electrode and the inner wall surface of the cavity. That is, even if an internal wiring pattern is arranged close to the inner wall surface on the side surface portion of the cavity portion, the displacement difference of the thickness is suppressed by interposing the dummy insulating film for adjusting the lamination thickness. Can be.

With this, even if pressure bonding is performed during the laminating step, the influence of the presence or absence of the internal wiring pattern can be avoided, and as a result, the substrate surface around the opening of the cavity can be flattened. That is, the flatness of the bonding wire connection electrode arranged around the opening of the cavity is improved, and stable bonding by the bonding wire can be achieved.

Further, even if the insulating film protrudes into the inner wall of the cavity during the formation of the insulating film or the pressure bonding, the insulating film does not cause a short circuit or malfunction of the IC chip because it is an insulating material.

Further, by making the insulating film substantially the same material as the insulating layer, the sintering behavior of the insulating layer and the insulating film match. In addition, the bonding strength of the bonding between the two can be maintained, and peeling does not occur at all.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The laminated circuit board of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of the laminated circuit board of the present invention, and FIG. 2 is a cross-sectional view of main steps of the present invention.

In the figure, reference numeral 10 denotes a laminated circuit board;
The laminated circuit board 10 includes a laminated substrate 1 on which insulating layers 1 a to 1 e are laminated, a surface wiring pattern 2 formed on the surface of the laminated substrate 1, an internal wiring pattern 3 disposed inside the laminated substrate 1, And a via-hole conductor 4.

The insulating layers 1a to 1e constituting the laminated substrate 1
Is composed of a ceramic material and an oxide or a low-melting glass material that can be fired at a low temperature.

As one combination, ceramic materials such as BaO—TiO ₂ , CaO—TiO ₂ ,
MgO—TiO _{2 and the} like can be exemplified, and CuO, Li ₂ O, B ₂ O ₃ , MnO _{2 and the} like can be exemplified as oxides for low-temperature firing.

As another combination, cristobalite, quartz, corundum (α-alumina) and the like can be exemplified as the ceramic material (inorganic filler material), and cordierite, mullite, anorthite, Celsian, Glass components capable of precipitating at least one of the crystal phases such as spinel, garnite, willemite, dolomite, petalite, osmilite and substituted dielectrics thereof can be exemplified.

The insulating layers 1a to 1e are 50 to 3 per layer.
It has a thickness of about 00 μm, and the via-hole conductor 4 is formed in the thickness direction.

Further, an internal wiring pattern 3 forming a predetermined circuit network is formed between the insulating layers 1a to 1e. The internal wiring pattern 3 is used as a pattern for forming an inductance component and a capacitance component in addition to forming a predetermined circuit network.

On the surface of the laminated substrate 1, an IC chip 5
Is formed therein.
Note that the bottom surface of the cavity portion 51 is constituted by the upper surface of the insulating layer 1c, and the internal wiring pattern 3 formed between the insulating layers 1b and 1c extends to the bottom surface of the cavity portion 51. .

A surface wiring pattern is formed on the surface of the laminate 1. Here, the surface wiring pattern is
In addition to being used as wiring for forming a predetermined circuit network on the surface of the laminated substrate 1, it is used as a bonding wire connection electrode 2 and as a terminal electrode connected to an external circuit.

The surface wiring pattern including the bonding wire connection electrode 2, the internal wiring pattern 3, and the via hole conductor 4 are made of Ag (Ag alone, Ag-Pd, Ag-P).
Ag alloy such as t), Cu-based (Cu simple substance, Cu alloy)
Of the conductive material.

The bonding wire connection electrode 2
Are formed close to the periphery of the opening of the cavity 51. For example, in order to reduce the size of the laminated substrate 1 and prevent the bonding wires from falling down, they are formed at a distance of, for example, about 200 μm.

This 200 μm is a value that allows a printing position shift when a conductive film serving as the bonding wire connection electrode 2 is formed by printing a conductive paste. It is desirable to arrange.

The cavity 5 of the laminated substrate 1
In the insulating layers 1a and 1b constituting the inner wall portion of the semiconductor device 1, internal wiring patterns 3 are formed on the upper and lower surfaces of the insulating layers 1a and 1b. In particular, among these internal wiring patterns, the internal wiring pattern close to the inner wall of the cavity portion 51 is denoted by “30”.

In the laminated circuit board 10 according to the present invention, for example, between the insulating layers where the internal wiring patterns 30 are formed,
Between a and 1b, an insulating film 6 is formed in a region between the tip of the internal wiring pattern 30 and the inner wall surface of the cavity portion 5.

The insulating film 6 is formed by selective printing using a paste of the above-mentioned slurry for forming an insulating layer. The insulating film 6 is the same as or slightly thicker than the thickness of the conductor film that will become the internal wiring pattern 30 when the insulating paste is applied.

In the cavity 51 formed on the surface of the laminated substrate 1, the IC chip 5 is bonded to the internal wiring pattern 3 exposed on the bottom of the cavity 51 by die attach or the like.

The IC chip 5 housed in the cavity portion 51 is for achieving a desired operation in a predetermined circuit of the laminated circuit board 10, and includes an input / output electrode on the upper surface side of the IC chip 5 and a cabinet. The bonding wire connection electrode 2 around the opening of the tee portion 51 is bonded by an Au wire or the like.

Although not shown in the figure, the laminated substrate 1
On the surface of the substrate, a thick-film resistor film and an insulating protective film are formed as required, in addition to the surface wiring pattern, and various electrode components such as a chip capacitor and a chip resistor are mounted.

According to the present invention, as described above, the internal wiring pattern 30 located on the upper and lower surfaces of the insulating layers 1a and 1b constituting the inner wall of the cavity 51, and the region up to the inner wall of the cavity 51, that is, In a region where no internal wiring pattern is present, an insulating film 6 having substantially the same or higher thickness as the internal wiring pattern 30 is interposed.

Incidentally, in the sectional view of FIG.
1 is formed in the region up to the inner wall surface.

For this reason, since the internal wiring pattern 30 does not exist in the related art, the drop which has occurred around the opening of the cavity 51 can be effectively prevented, and the flatness around the opening of the cavity 51 can be reduced. improves.

As a result, the surface flatness of the bonding wire connection electrode 2 formed around the opening of the cavity 51 can be maintained very stably. That is, even if a wire such as Au is bonded to the bonding wire connection electrode 2, a reliable connection can be achieved.

The insulating film 6 may be formed between the internal wiring pattern 30 and the inner wall surface of the cavity 51 at least in the pattern width of the internal wiring pattern 30. A ring-shaped insulating film may be formed so as to surround.

It is desirable that the insulating film 6 and the tip of the internal wiring pattern 30 on the cavity side contact each other. Even if the insulating film 6 overlaps the tip of the internal wiring pattern 30, the amount of overlap is 50 μm.
Within. If it overlaps with 50 μm or more, the lamination thickness of that part increases, and conversely, the flatness is deteriorated at the center part (the center part of the bonding) of the bonding wire connection electrode 2, and the bonding property is reduced. Will decrease.

Next, a method of manufacturing the above-described laminated circuit board 10 will be described.

First, a green sheet to be the dielectric layers 1a to 1e is prepared. For example, for the green sheet, for example, a slurry is prepared by mixing the above-mentioned ceramic powder (inorganic filler) and an oxide powder (glass powder) for low-temperature firing with an organic binder and a solvent. Then, the slurry is formed into a tape of about 100 μm by a doctor blade method and cut into a predetermined size to form a green sheet.

The slurry is further processed as a paste to form an insulating paste for forming the insulating film 6.

Next, a through hole serving as a via-hole conductor 4 is formed in a predetermined green sheet, and at the same time, the insulating layers 1a and 1b are formed.
A predetermined green sheet is formed with a through hole serving as the cavity 51.

Next, a through-hole serving as the via-hole conductor 4 is
A conductor serving as the via-hole conductor 4 is formed by filling a conductive paste, and a conductive film serving as a surface wiring pattern including the bonding wire connection electrode 2 and an internal wiring pattern 3 (30) are formed on each green sheet. A conductive film is formed by printing a conductive paste.

The above-mentioned conductive paste is made of, for example, a predetermined amount of Ag-based (Ag alone, alloy such as Ag-Pd, Ag-Pt, composite) metal powder, borosilicate-based low-melting glass, and ethyl cellulose. And an organic solvent such as 2.2.4-trimethyl-1.3-pentadiol monoisobutyrate.

Next, in FIG. 1, in the green seek serving as the insulating layer 1b, a region between the through-hole serving as the cavity portion 51 and the conductive film serving as the internal wiring pattern 30 substantially corresponds to the conductive film. Then, a coating film which becomes the insulating film 6 with the same thickness or more is formed. This coating film is formed by printing the above-mentioned insulating paste.

As described above, the bonding wire connection electrode 2
A green sheet on which a conductive film serving as a surface wiring pattern, a conductive film serving as an internal wiring pattern 3, and a conductor serving as a via-hole conductor 4 are formed by thermocompression bonding in accordance with the lamination order of the laminated substrate 1. An unfired laminated substrate 1 is formed.

Here, FIG. 2 shows a green sheet 10a to be the insulating layer 1a and a green sheet 10b to be the insulating layer 1b.
Shows the relationship. In FIG. 2, reference numerals 51a and 51b denote through-holes forming the cavity portion 51, reference numeral 20 denotes a conductor film serving as the bonding wire connection electrode 2,
Reference numeral 30a denotes a conductor film serving as the internal wiring pattern 30;
Numeral 0 is a coating film to be the insulating film 6.

FIG. 2A shows the green sheet 10.
a and 10b before lamination, FIG. 2 (b)
It is sectional drawing of the state which laminated | stacked and integrated the green sheets 10a and 10b.

That is, the green sheets 10a, 10b
In the stacking of the green sheets including the above, even if a pressing force in the vertical direction of the stacked body is applied, the surface of the green sheet 10a serving as the insulating layer 1a is very flat due to the presence of the coating film 60 around the through holes 51b. Will be transformed.

Further, the thickness of the coating film 60 is set to
By slightly increasing the thickness, a pressing force can be stably applied to the periphery of the cavity 30a in the vertical direction.

Next, the unfired laminated substrate 1 is integrally fired at a relatively low temperature of 800 to 1000 ° C. The binder removal process in this firing is performed in a temperature range of about 600 ° C. or less, and becomes a green sheet serving as the insulating layers 1 a to 1 e, a conductive film serving as a surface wiring pattern such as the bonding wire connection electrode 2, and an internal wiring pattern 3. Conductive film, conductor serving as via-hole conductor 4, coating film 60 serving as insulating film 6
This is the process of burning off the organic binder contained in the organic solvent.

The firing process is performed, for example, at a peak temperature of 800 to 1
It is an air atmosphere or a neutral atmosphere at 000 ° C., for example, 950 ° C. for 30 minutes. Thus, the insulating layers 1 a to 1 e are integrated to form the laminated substrate 1, and the bonding wire connection electrode 2, the internal wiring pattern 3, the via hole conductor 4, the insulating film 6, and the like are formed on the laminated substrate 1. Become.

Thereafter, if necessary, a thick-film resistance film is baked on the laminated substrate 1 so as to be connected to the surface wiring pattern, or an insulating protective film is coated.

Finally, the cavity 51 of the laminated substrate 1
Inside, the IC chip 5 is die-attached, and the bonding between the input / output electrode of the IC chip 5 and the bonding wire connection electrode 2 is performed with a bonding wire such as Au. Thus, the laminated circuit board 10 shown in FIG. 1 can be achieved.

Here, as described above, since the insulating film 6 is formed on the upper and lower surfaces of the insulating layers 1a and 1b formed on the side wall of the cavity 51 around the opening of the cavity 51, As described above, the periphery of the opening of the cavity portion 51 does not drop to the cavity portion 51 side to form the inclined surface S. Therefore, the bonding wire connection electrode 2 around the opening of the cavity 51 is formed in a very flattened portion.

As a result, stable bonding can be achieved even when the IC chip 5 and the bonding wire connecting electrode 2 are bonded with the wire W such as Au. In the experiments of the present inventor, it was confirmed that there was no bonding defect that had occurred at a rate of 1% in the past.

Even if the insulating film 6 interposed between the insulating layer 1a and the insulating layer 1b protrudes from the inner wall surface of the cavity 51, the insulating film 6 may be short-circuited with the IC chip 5 because it is an insulating material. And stable operation of the IC chip 5 can be maintained.

Further, since the insulating film 6 is substantially composed of the same insulating material as the substrate material (green sheet),
There is no difference in the sintering behavior between the insulating layers 1a and 1b and the insulating film 6 during the firing process, and no separation occurs at the joint surface between them.

In the above embodiment, the cavity 5
1 is formed of two insulating layers 1a and 1b,
The bottom surface of the cavity 51 is formed of the insulating layer 1c. Since the internal wiring pattern 30 is formed near the cavity 51 between the insulating layers 1a and 1b, the insulating film 6 is disposed between the insulating layers 1a and 1b. This insulating film 6 may be formed around the opening of the cavity 51 between the insulating layers 1b and 1c.

Even if the inner wall of the cavity 51 is a single insulating layer 1a (the insulating layer 1b forms the bottom surface of the cavity 51), an insulating film is provided between the insulating layers 1a and 1b. 6 may be interposed.

As the structure of the cavity portion, a large cavity portion including the cavity portion 51 may be formed, and the cavity portion 51 shown in FIG. 1 may be used as a bonding wire connecting step in the large cavity portion. Absent.

[0079]

According to the present invention, the smoothness of the surface of the laminated substrate is improved in the region around the cavity opening, and at the same time,
The surface smoothness of the bonding wire connection electrode close to the periphery of the cavity is improved. Thereby, even if the bonding wire connection electrode is brought close to the opening of the cavity, the surface smoothness can be maintained. The flatness of the bonding wire connection electrode disposed around the opening of the cavity is improved, and stable bonding by the bonding wire can be achieved. Short circuit of IC chip,
There is no malfunction or the like, and the deterioration of the bonding strength with the insulating layer does not occur.

[Brief description of the drawings]

FIG. 1 is a sectional view of a laminated circuit board according to the present invention.

2A and 2B are cross-sectional views illustrating a relationship between two insulating layers according to the present invention, wherein FIG. 2A illustrates a relationship before lamination, and FIG. 2B illustrates a relationship after lamination.

FIG. 3 is a cross-sectional view of a conventional laminated circuit board.

FIG. 4 is a cross-sectional view of a typical laminated circuit board.

[Explanation of symbols]

 10 laminated circuit board 1 laminated board 1a-1e insulating layer 2 bonding wire connecting electrode 3 internal wiring pattern 4 Via-hole conductor 6 ... Insulating film

Claims (2)

[Claims] An internal wiring pattern is arranged in a laminated substrate having a cavity portion, and a bonding wire connection electrode is attached around an opening of the cavity portion of the laminated substrate. In a laminated circuit board comprising an IC chip housed in the cavity and connecting the IC chip and the bonding wire connection electrode by a bonding wire, an insulating layer located on an inner wall surface of the cavity is provided. An insulating film interposed in a region between the bonding wire connection electrode and an inner wall surface of the cavity. 2. The laminated circuit board according to claim 1, wherein said insulating film is made of substantially the same insulating material as the insulating layer, and has a thickness equal to or greater than the thickness of the internal wiring pattern. .