JP2000022300A - Wiring board and electronic unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the stable electric connectivity between a wiring board and electronic components, and at the same time to secure the sufficient junction strength between the wiring board and the electronic components without increasing costs or the like. SOLUTION: In a wiring board 10, a recessed part 12r is formed on the surface of an electrode 12, where the recessed part 12r can capture a conductive particle 32 of an anisotropy conductive junction material. Also, in an electronic unit 1, a bare IC chip 20 is mounted onto the wiring board 10 where the recessed part 12r is provided on the surface of the electrode 12 via the anisotropy conductive junction material. Also, in an electronic unit 1', a bare IC chip 20' is mounted onto the wiring board 10' where a recessed part 12'r is provided on the surface of an electrode 12' via an anisotropy conductive junction material 30', and at the same time the wiring board 10' is jointed to the bare IC chip 20' by insulation resin 40' for sealing the anisotropy conductive junction material 30'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wiring board on which electronic components are mounted via an anisotropic conductive bonding material and an electronic component mounted on the wiring board via an anisotropic conductive bonding material. It relates to an electronic unit.

[0002]

2. Description of the Related Art A semiconductor device as an electronic component is mounted on a wiring board.
As one of the methods for mounting on a (printed wiring board), there is a flip chip mounting method (flip chip bonding method) using an anisotropic conductive bonding material.

As shown in FIG. 14, a bare IC chip A as a semiconductor device has electrodes Aa, Aa... Made of a conductive material on its mounting surface (bottom in the figure).
The bumps Ab, Ab... are formed from a metal material such as Au (gold) on the surfaces of a.

The wiring substrate B on which the bare IC chip A is mounted has wiring patterns Ba, Ba... Made of a conductive material on its mounting surface (upper surface in the figure).
Electrodes Bb, Bb,... are formed on the tip surfaces of a, Ba,.

Further, an anisotropic conductive bonding material C for bonding the bare IC chip B to the wiring board B is composed of a film-shaped insulating resin Ca and a large number of conductive particles Cb, Cb.
. Are mixed.

To mount the bare IC chip A on the wiring board B, first, the anisotropic conductive bonding material C is heated (80 ° C., about 2 seconds) and pressed on the wiring board B, The anisotropic conductive bonding material C is temporarily bonded to the mounting position of the bare IC chip A in B.

Next, the bare I is placed on the anisotropic conductive bonding material C.
The C chip A is placed, the bare IC chip AC is pressurized, and the anisotropic conductive bonding material D is heated (180 ° C., about 2 ° C.).
(0 second), and the bare IC chip A is permanently bonded to the wiring board B, whereby the electronic unit U as shown in FIG. 15 is manufactured.

Here, when the bare IC chip A is fully bonded to the wiring board B, each bump Ab on the bare IC chip A is used.
Are sandwiched between the conductive particles Cb, Cb,... Of the anisotropic conductive bonding material C between the IC chip A and the wiring board B. At the same time, when the insulating resin Ca of the anisotropic conductive bonding material C is thermally cured, the bare IC chip A is mechanically bonded to the wiring board B.

[0009]

In the configuration described above, the bottom surface of each bump Ab in the bare IC chip A and the upper surface of the electrodes Bb, Bb.
Since both have a flat shape without unevenness, bare IC
When the bare IC chip A is pressed against the wiring board B via the anisotropic conductive bonding material C in order to fully bond the chip A to the wiring board B, the insulating resin Ca in the anisotropic conductive bonding material C
Due to the fluidity of the bumps Ab on the bare IC chip A
.. Of the anisotropic conductive bonding material C flow out from between the bottom surface of the substrate and the upper surface of the electrode Bb of the wiring board B.

As a result, it becomes difficult to secure an appropriate amount of conductive particles Cb between the bump Ab on the bare IC chip A and the electrode Bb on the wiring board B.
As a result, there is a disadvantage that the electrical connectivity between the bump Ab and the electrode Bb is significantly reduced.

On the other hand, in order to secure a sufficient number of conductive particles Cb between the bump Ab and the electrode Bb, an anisotropic conductive bonding material C containing a large amount of conductive particles Cb is used.
Is used, the insulation between adjacent electrodes or bumps is reduced, the connection strength between the wiring board B and the bare IC chip A is reduced, and the cost due to the use of the expensive anisotropic conductive bonding material C is reduced. It leads to an increase.

In view of the above situation, the present invention provides a state in which an electronic component is mounted on a wiring board via an anisotropic conductive bonding material without lowering insulation properties and connection strength and without inadvertently increasing costs. In the above, an object of the present invention is to provide a wiring board and an electronic unit capable of obtaining stable electrical connectivity between the wiring board and the electronic component.

The electronic unit U described above is connected to the wiring board B and the bare IC chip A via the anisotropic conductive bonding material C.
Therefore, it is difficult to secure an appropriate bonding strength.

On the other hand, in order to increase the bonding strength,
When an anisotropic conductive bonding material having a large film thickness or an anisotropic conductive bonding material having a large amount of insulating resin is used, the use of the expensive anisotropic conductive bonding material C causes an increase in cost.

An object of the present invention is to provide an electronic unit capable of securing a sufficient bonding strength between a wiring board and an electronic component without inadvertently increasing the cost in view of the above situation.

[0016]

According to a first aspect of the present invention, there is provided a wiring board having a concave portion formed on a surface of an electrode for capturing conductive particles of an anisotropic conductive bonding material.

According to a second aspect of the present invention, there is provided the electronic unit, wherein the anisotropic conductive bonding material is provided on a wiring substrate having a concave portion capable of capturing conductive particles of the anisotropic conductive bonding material on the surface of the electrode. Electronic components are mounted via.

According to a third aspect of the present invention, there is provided the electronic unit, wherein the anisotropic conductive bonding material is provided on a wiring substrate having a concave portion capable of capturing conductive particles of the anisotropic conductive bonding material on the surface of the electrode. The electronic component is mounted on the wiring board and the wiring board and the electronic component are joined by an insulating resin for sealing the anisotropic conductive bonding material.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing embodiments. FIG. 1 shows an electronic unit 1 according to the present invention manufactured by a flip chip mounting method.

As shown in FIGS. 1 and 2, the electronic unit 1 includes a wiring board 10 according to the present invention and a bare IC chip 20 as an electronic component. It is configured by mounting the bare IC chip 20 on the wiring board 10.

As shown in FIG. 3, the electronic unit 1 includes a step Sa of temporarily bonding the anisotropic conductive bonding material 30 to the wiring board 10 and a step Sb of forming a bump on the bare IC chip 20. And a step Sc of permanently bonding the bare IC chip 20 to the wiring board 10 via the conductive conductive bonding material 30.

As shown in FIG. 4, the wiring board 10 is made of a glass epoxy resin or the like, and a mounting surface (upper surface in the drawing) on which the bare IC chip 20 is mounted has a plurality of wiring patterns made of conductive material. An electrode 12 is formed on the front end surface of each wiring pattern 11 by gold plating. In addition, each wiring pattern 11
Except for the part of the electrode 12, it is covered with the solder resist 13.

As shown in FIGS. 5A and 5B, the surface of the electrode 12 in the wiring pattern 11 is formed with a plurality of concave portions 12r capable of capturing conductive particles of an anisotropic conductive bonding material described later. The recess 12r is a V-shaped groove extending in a direction substantially perpendicular to the extending direction of the wiring pattern 11, and has a depth of about 1 to 5 μm.

The recess 12r is formed by a plating method, that is, a method of forming the electrode 12 in the wiring pattern 11 in a plating step, or a shaving method, that is, a plating layer forming the electrode 12 in the wiring pattern 11. Is formed by using a method of shaving off with a tool.

As shown in FIGS. 6A and 6B, the electrode 1
The recess 12r may be formed by a V-groove extending in the direction in which the wiring pattern 11 extends in the surface of the second pattern 2. Also, as shown in FIGS. 7A and 7B, the concave portion 12r can be formed by a V-groove obliquely intersecting the surface of the electrode 12 with the extending direction of the wiring pattern 11.

On the other hand, bare IC chip 2 as an electronic component
0 is the mounting surface facing the wiring board 10 as shown in FIG.
Electrodes 21, 21... Made of a conductive material such as Al (aluminum) are formed on the bottom surface (in the figure).

The electrodes 21, 21,...
Are arranged corresponding to the electrodes 11A, 11A,... On the surfaces of the electrodes 21, 21,... Of the bare IC chip 20 before the mounting on the wiring board 10 (step Sb in FIG. 3).
Are formed from Au (gold) or Sn-Pb (tin-lead) alloy.

The anisotropic conductive bonding material 30 for mounting the bare IC chip 20 on the wiring board 10 is made of an insulating resin 31.
Are mixed with conductive particles 32 having a particle diameter of about 3 to 10 μm to form a film. The anisotropic conductive bonding material 30 has a shape that is slightly larger than the mounting surface of the bare IC chip 20 described above (in terms of area ratio of 1.0).
5 times).

Hereinafter, the electronic unit 1 having the above configuration will be described.
, That is, a process of mounting the bare IC chip 20 on the wiring board 10 will be described.

First, as shown in FIG. 8, the anisotropic conductive bonding material 30 is placed on the mounting surface of the wiring board 10, and then the anisotropic conductive bonding material 30 is heated by a heat tool (not shown). 80 ° C, about 5 seconds)
The temporary bonding of the anisotropic conductive bonding material 30 is carried out to 0 (step Sa in FIG. 3).

Next, as shown in FIG. 9, after the bare IC chip 20 is placed on the anisotropic conductive bonding material 30 temporarily bonded, the bare IC chip 20 is pressed using The isotropic conductive bonding material 30 is heated (1
At 80 ° C. for about 20 seconds), the bare IC chip 20 is fully bonded to the wiring board 10 (step Sc in FIG. 3).

Thus, the anisotropic conductive bonding material 3 in which the wiring substrate 10 and the bare IC chip 20 are melted and then hardened.
And the conductive particles 32 of the anisotropic conductive bonding material 30 between each electrode 11A of the wiring board 10 and each electrode 21 (bump 22) of the bare IC chip 20. Are electrically connected to each other.

Here, the bare IC is heated by the heat tool H.
In the step of pressing the chip 20, the anisotropic conductive bonding material 3
., The bare IC chip 2
As a result, the electrode 12 is caught by the concave portion 12r of each electrode 12 along with the drop of 0, so that an appropriate amount of space is formed between the electrode 12 on the wiring board 10 and the electrode 21 (bump 22) of the bare IC chip 20.
(Approximately 5 to 20 conductive particles 32 per 100 square μm) are secured.

In this manner, a sufficient number of conductive probes are interposed between the electrodes 12 on the wiring board 10 and the electrodes 21 (bumps 22) of the bare IC chip 20.
Stable electrical connectivity between the wiring substrate 10 and the bare IC chip 20 is obtained.

In the step of pressing the bare IC chip 20 with the heat tool H, the bare IC chip 20
As shown in FIG. 9, the bumps 22 formed on the electrodes 21 are deformed so as to bite into the recesses 12r of the electrodes 12 on the wiring board 10 and are brought into close contact with each other. 10 electrodes 12 and bare IC
The electrical connectivity with the bumps 22 of the chip 20 is greatly improved.

Further, as described above, the bare IC chip 20
Bumps 22 are recessed portions 1 of electrodes 12 in wiring board 10.
2r so that the wiring board 1 and the insulating resin 31 in the anisotropic conductive bonding material 30
0 and the bare IC chip 20 are greatly improved in mechanical connectivity.

The electronic unit 1 'shown in FIG. 10 includes a wiring board 10' and a bare IC chip 20 '. The bare IC chip 20' is mounted on the wiring board 10 'using an anisotropic conductive bonding material 30'. It is configured by mounting and sealing the anisotropic conductive bonding material 30 ′ with the insulating resin 40 ′.

Further, as shown in FIG. 11, the electronic unit 1 'includes an anisotropic conductive bonding material 30'
Sa, a step Sb of forming bumps on the bare IC chip 20 ', and a step Sc of permanently bonding the bare IC chip 20' to the wiring board 10 'via the anisotropic conductive bonding material 30'. It is manufactured through a step Sd of forming a dam on the wiring board 10 'and a step Se of supplying an insulating resin 40'.

Since the structure of the electronic unit 1 'other than the sealing with the insulating resin 40' is the same as that of the electronic unit 1 described above, the same operation as that of the electronic unit 1 is shown in FIGS. The elements to be formed are shown in FIGS.
The same reference numerals as those described above are denoted by '(dash), and detailed description is omitted.

In the manufacturing process of the electronic unit 1 ', the process of manufacturing the electronic unit 1 described above is the same as the process of completely bonding the bare IC chip 20' to the wiring board 10 '(process Sc in FIG. 11). Nothing changes.

In the case of manufacturing the above-described electronic unit 1 ', after a bare IC chip 20' is permanently bonded to the wiring board 10 ', a dam 14' is formed on the upper surface of the wiring board 10 'as shown in FIG. (Step Sd in FIG. 11). Here, as shown in FIG. 10, the dam 14 'is formed on the solder resist 13' of the wiring board 10 'so as to surround the bare IC chip 20'.

Next, for example, a paste-like insulating resin 40 'is supplied to the inside of the dam 14' (step Se in FIG. 11). At this time, the insulating resin 40 'is supplied so as to fill the area surrounded by the outer peripheral surface of the bare IC chip 20' and the inner peripheral surface of the dam 14 'and cover the surface of the anisotropic conductive bonding material 30'. Is done.

Thereafter, by curing the insulating resin 40 ', the anisotropic conductive bonding material 30' is sealed by the insulating resin 40 ', and the wiring board 10 and the bare I
The C chip 20 is joined to each other.

In the electronic unit 1 'having the above-described structure, the wiring board 1 is provided similarly to the electronic unit 1 described in detail above.
In the step of permanently bonding the bare IC chip 20 'to the conductive particles 32', 3 'of the anisotropic conductive bonding material 30'.
Are captured by the concave portion 12r 'of the electrode 12', so that the electrode 12 'of the wiring board 10' and the bare IC chip 2
0 ′ electrode 21 ′ (bump 22 ′).
The conductive particles 32 '(about 5 to 20 particles per square micrometer) are secured, and stable electrical connection between the wiring board 10' and the bare IC chip 20 'can be obtained.

The bare IC chip 2 is mounted on the wiring board 10 '.
In the step of fully bonding the first IC chip 0 ', the bumps 22' of the bare IC chip 20 'become
r 'so as to bite into the electrode r', the electrode 12 'of the wiring board 10' and the bump 2 of the bare IC chip 20 '.
The electrical connectivity with 2 'is greatly improved.

Further, as described above, the bare IC chip 2
Since the 0 'bumps 22' bite into the recesses 12r 'of the electrodes 12' of the wiring board 10 'and come into close contact therewith, the mechanical connectivity between the wiring board 10' and the bare IC chip 20 'is greatly improved.

Further, in the electronic unit 1 'having the above structure, the insulating resin 3' in the anisotropic conductive bonding material 30 'is used.
1 ', the wiring board 10' and the bare IC chip 20 '
The wiring board 10 'and the bare IC chip 20' are also mechanically joined by the insulating resin 40 'covering the anisotropic conductive joining material 30 in addition to the mechanical joining of Thus, it is possible to secure sufficient bonding strength between the wiring board 10 'and the bare IC chip 20'.

In each of the embodiments described above, a film-like anisotropic conductive bonding material (anisotropic conductive film) is used as an anisotropic conductive bonding material for flip-chip mounting a bare IC chip on a wiring board. ), But
Paste-like anisotropic conductive bonding material (anisotropic conductive paste)
It is also possible to employ.

In each of the above-described embodiments, a bare IC chip is exemplified as an electronic component mounted on a wiring board. Needless to say, the present invention can be effectively applied to a wiring board or an electronic unit on which various electronic components other than the chip are mounted.

[0050]

As described above in detail, the wiring board according to the first aspect of the present invention has a concave portion on the surface of the electrode which can capture the conductive particles of the anisotropic conductive bonding material. In the above configuration, when the electronic component is permanently bonded to the wiring board, since the conductive particles of the anisotropic conductive bonding material are trapped in the concave portions of the electrodes, the anisotropic conductive bonding material containing a large amount of conductive particles should be used. In addition, it is possible to secure a sufficient number of conductive particles between the electronic component and the wiring board, and according to the wiring board of the present invention, the insulation and the connection strength are reduced and the cost is increased carelessly. , Stable electrical connection between the wiring board and the electronic component can be obtained.

According to a second aspect of the present invention, in the electronic unit according to the present invention, the anisotropic conductive bonding material is provided on a wiring board having a concave portion capable of capturing conductive particles of the anisotropic conductive bonding material on the surface of the electrode. Electronic components are mounted via. In the above configuration, when the electronic component is permanently bonded to the wiring board, since the conductive particles of the anisotropic conductive bonding material are trapped in the concave portions of the electrodes, the anisotropic conductive bonding material containing a large amount of conductive particles should be used. Therefore, it is possible to secure a sufficient number of conductive particles between the electronic component and the wiring board, and thus, according to the electronic unit according to the present invention, the insulation and the connection strength are reduced and the cost is increased unintentionally. , Stable electrical connection between the wiring board and the electronic component can be obtained.

According to a third aspect of the present invention, there is provided the electronic unit, wherein the anisotropic conductive bonding material is provided on a wiring board having a concave portion capable of capturing conductive particles of the anisotropic conductive bonding material on the surface of the electrode. The electronic component is mounted on the wiring board and the wiring board and the electronic component are joined by an insulating resin for sealing the anisotropic conductive bonding material. In the above configuration, the wiring board and the electronic component are joined by the anisotropic conductive bonding material, and the wiring board and the electronic component are joined by the insulating resin that seals the anisotropic conductive bonding material. Without using a thick anisotropic conductive bonding material having a large thickness or an anisotropic conductive bonding material having a large amount of insulating resin, the wiring board and the electronic component can be firmly bonded to each other. According to the unit, it is possible to secure sufficient bonding strength between the wiring board and the electronic component without inadvertently increasing the cost.

[Brief description of the drawings]

FIG. 1 is a conceptual cross-sectional side view showing an electronic unit according to the present invention.

FIG. 2 is a conceptual diagram showing components of an electronic unit according to the present invention.

FIG. 3 is a conceptual cross-sectional side view showing a wiring board according to the present invention.

FIGS. 4A and 4B are a main part plan view and a main part sectional view showing electrodes of a wiring board according to the present invention.

FIGS. 5A and 5B are a main part plan view and a main part sectional view showing another embodiment of an electrode of a wiring board according to the present invention.

FIGS. 6A and 6B are a plan view and a cross-sectional view of a main part showing another embodiment of an electrode of a wiring board according to the present invention.

FIG. 7 is a flowchart showing a manufacturing process of the electronic unit according to the present invention.

FIG. 8 is a conceptual diagram showing a manufacturing process of an electronic unit according to the present invention.

FIG. 9 is a conceptual diagram showing a manufacturing process of an electronic unit according to the present invention.

FIGS. 10A and 10B are conceptual cross-sectional side views and a main part plan view showing another embodiment of the electronic unit according to the present invention.

11 is a flowchart showing a manufacturing process of the electronic unit shown in FIG.

FIG. 12 is a conceptual diagram showing a manufacturing process of the electronic unit shown in FIG.

FIG. 13 is a conceptual diagram showing a manufacturing process of the electronic unit shown in FIG.

FIG. 14 is a flowchart showing a conventional electronic unit manufacturing process.

FIG. 15 is a conceptual diagram showing components of a conventional electronic unit.

[Explanation of symbols]

 1, 1 ': electronic unit, 10, 10': wiring board, 11, 11 ': wiring pattern 12, 12': electrode, 12r, 12r ': concave portion, 20, 20': bare IC chip (electronic component), 30, 30 ': anisotropic conductive bonding material; 31, 31': insulating resin; 32, 32 ': conductive particles; 40': insulating resin.

Claims (3)

[Claims] 1. A wiring board on which an electronic component is mounted via an anisotropic conductive bonding material, wherein a recess capable of capturing conductive particles in the anisotropic conductive bonding material is provided on a surface of an electrode. A wiring board characterized by the above-mentioned. 2. An electronic component mounted on a wiring board having a concave portion capable of capturing conductive particles of an anisotropic conductive bonding material provided on a surface of an electrode, via an anisotropic conductive bonding material. Electronic unit featuring. 3. An electronic component is mounted on a wiring board having a concave portion capable of capturing conductive particles of an anisotropic conductive bonding material on a surface of an electrode, via the anisotropic conductive bonding material, and an electronic component is mounted. An electronic unit, wherein the wiring board and the electronic component are joined by an insulating resin sealing an isotropic conductive joining material.