JPH05275564A - Circuit board with through hole - Google Patents

Abstract

PURPOSE:To simply and easily manufacture a double sided circuit board having a double sided circuit patterns of a fine pitch by forming through holes in a matrix state by combination of line grooves formed on both side surfaces of a platelike circuit board. CONSTITUTION:The circuit board with through holes comprises a plurality of line grooves 12 formed on one side surface (surface A) of a platelike circuit board 11, and second line grooves 15 formed deeply in a direction different from those of the grooves 12 on the other side surface (surface B). The board also comprises third line grooves 18 formed in parallel with the grooves 15 deeper than the grooves 12 on the surface A and fourth line grooves 19 formed between the grooves 12 deeper than the grooves 15 on the surface B. Further, conductive materials are filled in the grooves 12, 15, a plurality of through holes are formed at intersections where both the grooves 12 and 15 cross, and electrically isolated. Thus, it can be simply and easily formed.

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 parts, and more particularly to a circuit board with through holes provided with contact portions on both sides of a plate-shaped circuit board.

[0002]

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

There are various methods for forming through holes in a plate-shaped circuit board. The general method of forming through holes is to form a circuit pattern of a conductor on both sides of the circuit board, cover the circuit pattern with an insulating layer, and then remove the insulating layer at the through hole forming part (pad part) by etching and drill. Make a hole in the center of the pad. After making this hole, a through hole is formed by plating or the like.

At present, there is a demand for higher packaging density of electronic components mounted on a circuit board, and due to this higher density, circuit (wiring) patterns are also becoming finer. It will also be 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 that opens the through hole, but currently the practical diameter is about 0.2 mm.

[0005]

In the conventional double-sided circuit board, the diameter of the through holes formed in the circuit board is determined by the diameter of the drill. Therefore, when forming a large number of through holes at a fine pitch, Need to be small. However, at present, it is difficult to obtain a drill for forming through holes of 200 microns or less on a circuit board having a thickness of several hundreds of microns or more. Therefore, it is necessary to form many through holes having 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 is very difficult to set the distance between the through holes to 200 μm or less.

The present invention has been made in consideration of the above-mentioned circumstances, and provides a substrate with through holes capable of easily and easily forming through holes on a plate-like circuit substrate in a matrix at a fine pitch. With the goal.

Another object of the present invention is to form a matrix of through-holes on a circuit board, not a drill, but a line groove formed on both surfaces of the circuit board to form fine holes with a fine pitch of 200 microns or less and a fine hole width. It is to provide a circuit board with a through hole that can be formed in.

[0008]

In order to solve the above-mentioned problems, the circuit board with through holes according to the present invention is formed on one surface of a plate-like circuit board as described in claim 1. A plurality of first line grooves, and 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 the 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 were formed. First on the surface
A third line groove formed so as to be located deeper than the line groove and parallel to the second line groove on the opposite surface thereof;
A fourth line groove formed on the surface on which the second line groove is formed so as to be located deeper than the second line groove and between the grooves of the first line groove on the opposite surface thereof; The plurality of through holes formed at the intersections of the first line groove and the second line groove are electrically separated from each other.

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

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 to be solidified. On the other surface, a plurality of second line grooves extending in a direction different from that of the first line groove and deeper than the groove bottom surface of the first line groove are formed in parallel, and the second line groove is formed. When the conductive material is filled and solidified, and the third and fourth line grooves are formed on one and the other surfaces of the circuit board filled with the conductive material, respectively, the third line groove is the first Of the second line groove is formed deeper than the second line groove and filled with an insulating material as needed, while the fourth line groove is deeper than the second line groove and Formed so that it is located between the groove of the 1 line groove and insulated as necessary It is a method that was filled with a fee.

Further, in the circuit board with through holes, after the first line groove and the second line groove are formed on one surface and the other surface of the plate-shaped circuit board, respectively, the first line groove and the second line groove are formed. It is also possible to coat the groove surface with a conductive film and fill the conductive film into the first and second line grooves coated with the conductive film.

[0012]

The present invention does not use a drilling tool such as a drill to form a through hole in a plate-shaped circuit board,
Through holes (via holes) are formed in a matrix by combining line grooves formed on both surfaces 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 can be formed. It is possible to form a line groove having a groove width of about 5 μm by using the above.

Therefore, when the through holes are formed in a matrix by combining the line grooves formed on both surfaces of the plate-like circuit board, the through holes can be formed with a fine pitch of, for example, about several tens of microns. Therefore, when the arrangement pitch of the through holes arranged on the circuit board is 200 microns or less, for example, about several tens of 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 several microns to several tens of microns.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 parts such as various electronic devices are mounted. The double-sided circuit board 10 has a thickness of several hundreds of microns to 2 mm. The circuit board 11 is made of an insulating material such as ceramic. A plurality of first line grooves (dicing grooves) 12 are formed in parallel on one surface of the circuit board 11 with a dicing saw or the like at a required fine pitch. The first line groove 12 has a groove width of several microns to several tens of microns, for example, 50 microns, and is formed at a depth of, for example, about ⅓ 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 hundreds of microns by selecting the width of the blade of the dicing saw.

The first surface formed on one surface of the circuit board 11.
The line groove 12 is filled with a conductive resin material 13 such as epo-tek 417, 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 epoxy resin.

Also, on the other surface of the circuit board 11, the first
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 the conductive resin material 16. , Solidified. The second line groove 15 is formed to be deeper than the groove bottom of the first line groove 12, and the first and second line grooves 12,
A large number of through holes are formed in the circuit board 11 in the form of a matrix by 15.

In the circuit board 11 in which the first and second line grooves 12 and 15 are filled with a conductive material, the third and fourth line grooves 18 and 19 are formed on one and the other surfaces by a dicing saw or the like. Are formed in parallel at a fine pitch, and the third and fourth line grooves 18 and 19 are filled with insulating materials 20 and 21, respectively, and are 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.

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

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

Through hole lands (via hole lands) formed on the surface of the circuit board 11 in this manner
The area of A is adjusted. The substrate surface of the formed circuit board 11 is polished, and thereafter, circuit patterns (not shown) are placed on both sides of the circuit board 11 in accordance with the positions of the through holes to be integrated to form the double-sided circuit board 10. To be done.

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

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).

2A to 2I are process diagrams showing a method for manufacturing a double-sided circuit board. First, as shown in FIG. 2A, a plate formed of a circuit board material such as ceramics is used. 1. A circuit board 11 is prepared, and a first line groove (dicing groove) 12 having, for example, a groove width of about 50 μm is formed on one surface of the circuit board 11 by a dicing saw at a necessary pitch and a required thickness. Is formed to a depth of, for example, about 3/5.

Subsequently, the first line groove 12 formed in the circuit board 11 is filled with a conductive material 13 as shown in FIG. 2 (B). The filled conductive resin 13, which is the conductive material 13, is sufficiently degassed by evacuation or the like, and then cured.

Next, the plate-shaped circuit board 11 is shown in FIG.
2C, the second line groove is formed on the other surface of the circuit board 11 in a direction different from that of the first line groove 12, preferably in the orthogonal direction, as shown in FIG. 2D. 15
1st line groove 1 at the required pitch by the required number
It is formed at a position deeper than the groove bottom of 2, for example, about 3/5 of the plate thickness. At this time, a large number of through holes (via holes) are formed in a matrix on the circuit board 11 by the first and second line grooves 12 and 15 formed on the circuit board 11.

Then, the second line groove 1 of the circuit board 11 is formed.
As shown in FIG. 2 (E), the conductive material 16 is filled in, and degassed to cure.

Conductive materials 13, 1 are formed on both surfaces of the circuit board 11.
After being filled with 6 and cured, as shown in FIG. 2 (F), the fourth line grooves 19 are formed on the other surface (one surface) of the circuit board 11 with a dicing saw at a required pitch. The fourth line grooves 19 are formed in the required number so as to be positioned in a direction intersecting with the second line grooves 15 and preferably in a direction orthogonal thereto and in parallel between the grooves of the first line grooves 12. The fourth line groove 19 is deeper than the second line groove 15, and is carved, for example, in a thickness of about 10 minutes 7.

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

After that, the circuit board 11 is turned over and the circuit board 11 shown in FIG.
As shown in (H), the 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 the insulating material 20. Let it solidify.

In the steps shown in FIGS. 2F to 2H, the fourth line groove 19 is formed on 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 No. 8 is formed is shown, the opposite may be possible. That is, the third line groove 18 may be first formed, and the fourth line groove 19 may be formed after the insulating material 20 is filled and cured in the line groove 18.

Through hole lands (via hole lands) formed on the surface of the circuit board 11 by appropriately selecting the groove widths of the third and fourth line grooves 18 and 19 filled with the insulating materials 20 and 21. 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 the insulating materials 20 and 21 and hardened, the surface of the board is polished and the circuit patterns are placed on both surfaces of the board to be integrated. To do.

When it is desired to reduce the size of the through-hole land A formed on the circuit board 11 or when the line-shaped conductive material is unnecessary, as shown in FIG. 2I, insulation is provided on the unnecessary portion. A layer 23 may be provided and masked before the circuit pattern is formed. In this way, the double-sided circuit board 10 is manufactured.

According to this double-sided circuit board 10, a through hole is formed by combining line-shaped grooves from both surfaces of the circuit board 11 without using a drilling tool for forming the through hole. Therefore, a dicing machine or the like capable of forming a groove having a groove width of about 5 μm can be used. Therefore, it becomes possible to manufacture through holes in which the arrangement pitch of the through holes arranged in a matrix form is several tens of microns and the hole width is several microns to several tens of microns, and a double-sided circuit board having a fine pitch double-sided circuit pattern is provided. be able to.

FIGS. 3A to 3J show a double-sided circuit board 10A.
FIG. 8 is a process drawing showing another example of the manufacturing method of FIG.

Similar to the double-sided circuit board 10 shown in FIG. 2, the plate-shaped circuit board 11 made of a circuit board material such as ceramic is first shown in FIG.
As shown in (A), the number of first line grooves 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 to a depth of about ⅓ 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.

As shown in FIG. 3C, the conductive material 13 is filled in the first line groove 12 coated with the conductive film 25, well degassed, and then cured.

Next, the circuit board 11 is turned over (see FIG.
(See (D)), the 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 with the required number and plate thickness. For example 5
It is formed to a depth of about 3 minutes (see FIG. 3E). Then, the surface of the second line groove 15 is also coated with the conductive film 26 by using a method such as vapor deposition, sputtering, and plating as in the step 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 the conductive material 16, and the filled conductive material 1
After degassing 6 well, it is cured.

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 them, in the steps of FIGS. 3 (H) to 3 (I), Similar to the case shown in FIG. 2, the third or fourth line grooves 18 and 19 are formed on one surface or the other surface of the circuit board 11 to a necessary number, for example, a depth of about 7/10 of the plate thickness. Then, the insulating material 20, 21 is filled in the third or fourth line groove 18, 19 and cured.

When the third and fourth line grooves 18 and 19 are formed, their front-back relation does not matter.

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

Double-sided circuit board 1 shown in FIGS.
At 0A, after forming the first and second line grooves 12 and 15 for forming the through holes, each line groove 1
Before filling the conductive material 13, 16 into the 2, 15, the first
Alternatively, the conductive film 2 is formed on the surfaces of the second line grooves 12 and 15.
Since 5, 26 are formed, a good conductive state can be obtained even if bubbles or the like are mixed when the conductive materials 13, 16 are filled.

Double-sided circuit board 1 manufactured in this way
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, etc. (see Japanese Patent Application No. 3-293047).

Two-dimensional array ultrasonic probe 3 shown in FIG.
In No. 0, a piezoelectric vibrator (ultrasonic vibrator) 31 is placed on the double-sided circuit board 10 and covered with a matching layer 32. Electrode 3 of each element composed of piezoelectric vibrator 31
The leads 34 are taken out from the No. 3 via the through holes 17 of the double-sided circuit board 10. At this time, the piezoelectric vibrator 31
When the element pitch is less than 200 microns and the number of elements reaches several hundreds to several thousands, it is necessary to form the through holes 17 formed in the double-sided circuit board 10 in the same pattern.

Since the through holes 17 formed in the double-sided circuit board 10 are formed by combining the first line groove 12 and the second line groove 15, each pitch of the through holes 17 arranged in a matrix. Can be easily molded to less than 200 microns. Therefore, it is possible to provide a circuit board suitable for an ultrasonic probe having an element pitch of 200 microns or less.

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

[0051]

As described above, according to the present invention, since the through holes are formed in a matrix by the combination of the line grooves formed on both sides of the plate-like circuit board, the through holes are formed like a drill. It is not necessary to use a drilling tool, and the array pitch of the through holes formed in a matrix can be easily formed to a fine pitch of, for example, 200 microns 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 drawings]

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

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

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

FIG. 4 is a 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)

[Claims] 1. A plurality of first line grooves formed on one surface of a plate-shaped circuit board, and a first line groove extending in a direction different from that of the first line groove on the other surface of the circuit board. The second line groove formed deeper than the groove bottom of the line groove, the conductive material filled in the first line groove and the second line groove, and the second line groove formed on the 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 thereof; and a second line groove formed on the surface on which the second line groove is formed. A fourth line groove formed deeper and located between the grooves of the first line groove on the opposite surface thereof, the first line groove and the second line groove.
A circuit board with through holes, characterized in that a plurality of through holes formed at the intersections of the line grooves are electrically separated from each other.