JP3073593B2 - Circuit board with through hole - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board with through holes for mounting a plurality of electronic components, and more particularly to a circuit board with through holes having contact portions on both sides of a plate-like circuit board.

[0002]

2. Description of the Related Art A conventional circuit board is formed by forming a circuit pattern of a conductor on an insulating plate-like substrate.
In recent years, in order to increase the mounting density of electronic components to be mounted, circuit patterns are formed on both sides of a circuit board, and electronic components are often mounted on both sides. In such a double-sided circuit board, a through hole (also called a via hole or the like) is required to make contact with the circuit pattern on each side.

There are various methods for forming through holes in a plate-like circuit board. As a general method of forming a through hole, a circuit pattern of a conductor is formed on both sides of a circuit board, and the circuit pattern is covered with an insulating layer. A hole is made in the center of the pad by using the method described above. After making this hole, a through hole is formed by plating or the like.

At present, there is a demand for a higher mounting density of electronic components mounted on a circuit board, and a circuit (wiring) pattern has been miniaturized for the higher density. It is also necessary. However, in the case of such a through-hole, the hole diameter of the through-hole is determined by the diameter of the drill for drilling the through-hole. At present, a practical drill having a drill diameter of about 0.2 mm is the minimum.

[0005]

In a conventional double-sided circuit board, the hole diameter of the through-hole formed in the circuit board is determined by the diameter of the drill. Need to be smaller. However, at present, it is difficult to obtain a drill that forms through holes of 200 microns or less on a circuit board of several hundred microns or more. Therefore, it is necessary to form a large number of through holes with a fine pitch of 200 microns or less on a circuit board. Has become difficult. Therefore, in a circuit board in which through-holes are arranged in a two-dimensional array like a universal circuit board, it has been very difficult to reduce the distance between the through-holes to 200 microns or less.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a substrate with through-holes which can easily and easily form through-holes in a plate-like circuit board at a fine pitch in a matrix. With the goal.

Another object of the present invention is to form a matrix-shaped through hole on a circuit board by using a combination of line grooves formed on both sides of the circuit board, not by a drill, with a fine pitch of 200 μm or less and a fine hole width. Another object of the present invention is to provide a circuit board with a through hole that can be formed in a circuit board.

[0008]

According to a first aspect of the present invention, there is provided a circuit board with through holes formed on one surface of a plate-shaped circuit board to solve the above-mentioned problems. A plurality of first line grooves, extending in a direction different from the first line grooves on the other surface of the circuit board;
A second line groove formed deeper than a groove bottom of the first line groove; a conductive material filled in the first line groove and the second line groove; and a first line groove formed. First on the surface
A third line groove formed so as to be deeper than the line groove and parallel to the second line groove on the opposite surface;
A fourth line groove formed deeper than the second line groove on the surface on which the second line groove is formed and between the grooves of the first line groove on the opposite surface; A plurality of through holes formed at a portion where a first line groove and a second line groove intersect are electrically separated from each other.

The circuit board with through holes is manufactured by the following method.

[0010] A plurality of first line grooves are formed in parallel on one surface of the plate-like circuit board, and the formed first line grooves are filled with a conductive material and solidified. On the other surface, a plurality of second line grooves extending in a direction different from the first line groove and deeper than the groove bottom surface of the first line groove are formed in parallel. When the conductive material is filled and solidified, and the third and fourth line grooves are respectively formed on one and the other surfaces of the circuit board filled with the conductive material, the third line groove is formed by the first line groove. The fourth line groove is formed deeper than the second line groove and located between the grooves of the second line groove and filled with an insulating material as necessary, while the fourth line groove is deeper than the second line groove and formed in the second line groove. Formed so as to be located between the grooves of one line groove and insulated if necessary It is a method that was filled with a fee.

Further, in the circuit board with through holes, a first line groove and a second line groove are formed on one and the other surface of the plate-like circuit board, respectively. It can also be manufactured by coating a conductive film on the groove surface and filling the first and second line grooves coated with the conductive film with a conductive material.

[0012]

According to the present invention, a through hole in a plate-like circuit board is formed without using a drilling tool such as a drill.
Through holes (via holes) are formed in a matrix by combining line grooves formed on both sides of a circuit board.

When a groove is formed on a plate-shaped circuit board by a mechanical processing method, a hole-shaped groove is formed, whereas a line groove is formed. In general, a groove width can be reduced. Using such a method, it is possible to form a line groove having a groove width of about 5 microns.

Therefore, when the through holes are formed in a matrix by a combination of the line grooves formed on both surfaces of the plate-like circuit board, the through holes can be formed at a fine pitch of, for example, about several tens of microns. Therefore, the arrangement pitch of the through holes arranged on the circuit board is 200 microns or less, for example, about several tens microns,
It is possible to manufacture a double-sided circuit board (also referred to as a via-hole board) in which the width of the through hole is about several microns to several tens of microns.

[0015]

An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an example of a double-sided circuit board 10 with through holes on which electronic components such as various electronic devices are mounted. The double-sided circuit board 10 has a thickness of several hundred microns to about 2 mm. It is composed of a plate-like circuit board 11 made of an insulating material such as ceramic. On one surface of the circuit board 11, a plurality of first line grooves (dicing grooves) 12 are formed in parallel with a required fine pitch using a dicing saw or the like. The first line groove 12 has a groove width of several microns to several tens of microns, for example, 50 microns, and is formed to a depth of, for example, about 分 の of the thickness of the circuit board 11. The groove width and depth of the first line groove 12 can be changed from about 5 microns to several hundred microns by selecting the width of the blade of the dicing saw.

The first substrate formed on one surface of the circuit board 11
Is filled with a conductive resin material 13 such as epo-tek417, which is used as a conductive adhesive, and is solidified. This conductive resin material 13
Is made of, for example, a thermosetting conductive resin material in which silver or the like is mixed in an epoxy resin.

The first surface of the circuit board 11 is also provided on the other surface.
A plurality of second line grooves 15 extending in a direction intersecting with the line grooves 12 of, for example, an orthogonal direction are formed in parallel at a required fine pitch, and the second line grooves 15 are also filled with a conductive resin material 16. , Solidified. The second line groove 15 is formed so as to be deeper than the groove bottom of the first line groove 12, and the first and second line grooves 12,
15 allows a large number of through holes to be formed in the circuit board 11 in a matrix.

The circuit board 11 in which the first and second line grooves 12 and 15 are filled with a conductive material is required to have third and fourth line grooves 18 and 19 on one and the other surface by a dicing saw or the like. The third and fourth line grooves 18 and 19 are filled with insulating materials 20 and 21, respectively, and solidified. The groove widths of the third and fourth line grooves 18 and 19 are appropriately selected similarly to the first and second line grooves 12 and 15.

A third substrate formed on one surface of the circuit board 11
The line groove 18 is formed slightly deeper than the first line groove 12, for example, at a depth of about 7/10 of the plate thickness. The third line groove 18 intersects with the first line groove 12 and is formed in parallel so as to be located between the second line grooves 15.

The fourth line groove 19 is connected to the third line groove 18.
Similarly to the above, the second line grooves 15 are formed in parallel with each other so as to intersect with each other and to be located between the first line grooves 12.

In this manner, through-hole lands (via hole lands) formed on the substrate surface of the circuit board 11
The area of A is adjusted. The substrate surface of the formed circuit board 11 is polished, and thereafter, a circuit pattern (not shown) is mounted on both sides of the circuit board 11 in accordance with the position of the through-hole and integrated to form the double-sided circuit board 10. Is done.

The double-sided circuit board 10 has a through-hole land A
When it is desired to reduce the size of the substrate or when the line conductive material is unnecessary, the insulating layer 23 (see FIG.
After (I), the circuit pattern may be formed.

Next, a method of manufacturing the double-sided circuit board 10 will be described with reference to FIG.
This will be described with reference to (A) to (I).

FIGS. 2A to 2I are process diagrams showing a method for manufacturing a double-sided circuit board. First, as shown in FIG. 2A, a plate made of a circuit board material such as ceramic is used. A circuit board 11 is prepared, and a first line groove (dicing groove) 12 having a groove width of, for example, about 50 μm is formed on one surface of the circuit board 11 by a dicing saw at a required pitch and a required pitch. For example, at a depth of about 3/5.

Subsequently, the first line groove 12 formed on the circuit board 11 is filled with a conductive material 13 as shown in FIG. The conductive resin as the filled conductive material 13 is sufficiently degassed by evacuation or the like, and then cured.

Next, the plate-like circuit board 11 is shown in FIG.
2 (C), the second line groove is formed on the other surface of the circuit board 11 in a direction different from the first line groove 12 as shown in FIG. Fifteen
In the first line groove 1 at the required pitch by the required number.
2 is formed at a position deeper than the groove bottom, for example, about ５ of the plate thickness. At this time, a large number of through holes (via holes) are formed in the circuit board 11 in a matrix by the first and second line grooves 12 and 15 formed in the circuit board 11.

Subsequently, the second line groove 1 of the circuit board 11
As shown in FIG. 2 (E), the conductive material 16 is filled in the film 5, and then degassed and cured.

The conductive materials 13 and 1 are provided on both sides of the circuit board 11.
After filling and curing, as shown in FIG. 2F, fourth line grooves 19 are formed on the other surface (one surface) of the circuit board 11 at a required pitch using a dicing saw. The required number of the fourth line grooves 19 are formed in a direction intersecting with the second line grooves 15, preferably in a direction perpendicular to the second line grooves 15, and in parallel with each other between the first line grooves 12. The fourth line groove 19 is formed to be deeper than the second line groove 15, for example, to have a plate thickness of about 7/10.

Subsequently, as shown in FIG. 2 (G), the fourth line groove 19 of the circuit board 11 is filled with an insulating material 21 and cured.

Thereafter, the circuit board 11 is turned over, and FIG.
As shown in (H), a third line groove 18 is formed on one surface of the circuit board 11 in the same manner as the fourth line groove 19, and the third line groove 18 is filled with an insulating material 20. And solidify.

In the steps shown in FIGS. 2F to 2H, the fourth line groove 19 is formed in the other surface of the circuit board 11.
Is formed first, and then the third line groove 1 is formed on one surface.
Although the example in which 8 is formed is shown, the reverse may be applied. That is, the third line groove 18 may be formed first, and the line groove 18 may be filled with the insulating material 20 and cured, and then the fourth line groove 19 may be formed.

By properly selecting the widths of the third and fourth line grooves 18 and 19 for filling the insulating materials 20 and 21, through-hole lands (via hole lands) formed on the substrate surface of the circuit board 11. The area of A can be adjusted.

After the third and fourth line grooves 18 and 19 of the circuit board 11 are filled with insulating materials 20 and 21 and cured, the board surface is polished, and a circuit pattern is mounted on both sides of the board to be integrated. I do.

When it is desired to reduce the size of the through-hole land A formed on the circuit board 11 or when a line-shaped conductive material is unnecessary, as shown in FIG. The layer 23 may be provided and masked, and then a circuit pattern may be formed. Thus, the double-sided circuit board 10 is manufactured.

According to the double-sided circuit board 10, a through-hole is formed by a combination of linear grooves from both sides of the circuit board 11 without using a drilling tool such as a drill for forming the through-hole. Therefore, a dicing machine or the like capable of forming a groove with a groove width of about 5 μm can be used. Therefore, it is possible to manufacture through holes in which the arrangement pitch of through holes arranged in a matrix is several tens of microns and the hole width is several microns to tens of microns, thereby providing a double-sided circuit board having a fine-pitch double-sided circuit pattern. be able to.

FIGS. 3A to 3J show a double-sided circuit board 10A.
FIG. 7 is a process chart showing another embodiment of the manufacturing method of FIG.

In this embodiment, as in the case of the double-sided circuit board 10 shown in FIG. 2, a plate-like circuit board 11 made of a circuit board material such as ceramic is first used.
1A, a first line groove 12 having a groove width of, for example, about 50 microns is formed on one surface of the circuit board 11 by a dicing saw to a depth of about 分 の of the plate thickness. Form.

Subsequently, as shown in FIG. 3B, a conductive film (metal film) 25 is coated on the surface of the formed first line groove 12 by a method such as vapor deposition, sputtering, and plating.

The first line groove 12 coated with the conductive film 25 is filled with a conductive material 13 as shown in FIG. 3 (C), thoroughly degassed, and then cured.

Next, the circuit board 11 is inverted (FIG.
(Refer to (D)). After that, a second line groove 15 similar to the first line groove 12 is formed on the other surface of the circuit board 11 so as to intersect the first line groove 12 in a required number and thickness. For example 5
It is formed to a depth of about three minutes (see FIG. 3E). Then, the conductive film 26 is also coated on the surface of the second line groove 15 by using a method such as vapor deposition, sputtering, or plating similarly to the process of FIG. 3B (see FIG. 3F). .

After coating the conductive film 26, FIG.
As shown in (G), the second line groove 1 of the circuit board 11 is formed.
5 is filled with a conductive material 16, and the filled conductive material 1
After thoroughly defoaming 6, harden.

After filling the first and second line grooves 12 and 15 of the circuit board 11 with the conductive materials 13 and 16 and solidifying the same, the steps shown in FIGS. Similarly to the case shown in FIG. 2, third or fourth line grooves 18 and 19 are formed on one surface or the other surface of the circuit board 11 to a required number and a depth of, for example, about seven tenths of a plate thickness. Then, the third or fourth line grooves 18 and 19 are filled with insulating materials 20 and 21 and cured.

When the third and fourth line grooves 18 and 19 are formed, the order of the third and fourth line grooves 18 and 19 does not matter.

The third and fourth circuit boards 11
After the line grooves 18 and 19 are filled with insulating materials 20 and 21 and cured, both surfaces of the circuit board 11 are polished, and the conductive films 25 and 26 coated on the substrate surface are removed. Thereafter, the circuit board 1 is adjusted to the position of the through hole.
A circuit pattern (not shown) is placed on both sides of the substrate 1 and integrated, and a double-sided circuit board 10A is manufactured.

The double-sided circuit board 1 shown in FIGS.
At 0A, after forming first and second line grooves 12 and 15 for forming through holes, each line groove 1 is formed.
Before filling the conductive materials 13 and 16 into the conductive materials 2 and 15,
Alternatively, the conductive film 2 is formed on the surfaces of the second line grooves 12 and 15.
Since the conductive materials 13 and 16 are formed, a good conductive state can be obtained even if bubbles or the like are mixed in when the conductive materials 13 and 16 are filled.

The double-sided circuit board 1 manufactured as described above
0A is used for the two-dimensional array ultrasonic probe 30 shown in FIG. The ultrasonic probe 30 is used for transmitting and receiving ultrasonic waves in an ultrasonic diagnostic apparatus, an ultrasonic flaw detector, and the like (see Japanese Patent Application No. 3-293047).

The two-dimensional array ultrasonic probe 3 shown in FIG.
Numeral 0 indicates that a piezoelectric vibrator (ultrasonic vibrator) 31 is mounted on the double-sided circuit board 10 and is covered with a matching layer 32. Electrode 3 of each element constituted by piezoelectric vibrator 31
3, the leads 34 are taken out through the through holes 17 of the double-sided circuit board 10. At this time, the piezoelectric vibrator 31
When the element pitch is 200 microns or less and the number of elements reaches hundreds to thousands, the through holes 17 formed in the double-sided circuit board 10 also need to be formed in a similar pattern.

Since the through holes 17 formed on the double-sided circuit board 10 are formed by combining the first line grooves 12 and the second line grooves 15, the pitches of the through holes 17 arranged in a matrix are Can easily be formed to 200 microns or less. Therefore, a circuit board suitable for an ultrasonic probe having an element pitch of 200 microns or less can be provided.

In FIG. 4, reference numeral 35 denotes a resin between elements, and reference numeral 36 denotes a lead extraction pattern.

[0051]

As described above, according to the present invention, through holes are formed in a matrix by combining line grooves formed on both surfaces of a plate-like circuit board. The use of a drilling tool becomes unnecessary, and the arrangement pitch of the through holes formed in a matrix can be easily formed to a fine pitch of, for example, 200 μm or less. Therefore, a double-sided circuit board having a fine-pitch double-sided circuit pattern can be easily and easily manufactured and provided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a circuit board with through holes according to the present invention.

FIGS. 2A to 2I are process diagrams showing an example of a method for manufacturing a circuit board with through holes according to the present invention.

FIGS. 3A to 3J are process diagrams showing another example of a method for manufacturing a circuit board with through holes according to the present invention.

FIG. 4 is a cross-sectional view showing a two-dimensional array ultrasonic probe to which the circuit board with through holes according to the present invention is applied.

[Explanation of symbols]

 10, 10A Circuit board with through hole 11 Circuit board 12 First line groove 13, 16 Conductive material 15 Second line groove 17 Through hole 18 Third line groove 19 Fourth line groove 20, 21 Insulating material 23 Insulating layer 25, 26 Conductive film

Claims (1)

(57) [Claims] A first line groove formed on one surface of the plate-shaped circuit board and a first line groove formed on the other surface of the circuit board in a direction different from the first line groove; A second line groove formed deeper than a groove bottom of the line groove, a conductive material filled in the first line groove and the second line groove, and a second line groove formed on a surface on which the first line groove is formed. A third line groove formed so as to be located deeper than the first line groove and parallel to the second line groove on the opposite surface, and a second line groove formed on the surface on which the second line groove is formed. A fourth line groove formed so as to be deeper and located between the grooves of the first line groove on the opposite surface, wherein the first line groove and the second line groove are provided.
A plurality of through holes formed at portions where the line grooves intersect each other are electrically separated from each other.