JP2000022315A - Circuit components mounting board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid short-circuits with the bleed, etc., of adhesives to improve the reliability by providing storing trenches for the adhesives between lands for adhering circuit components and protective film. SOLUTION: On a circuit board 1 a printed wiring 2 and protective film 8 covering the printed wiring 2 are provided, a pair of lands 6 are provided at openings 8A of the protective film 8, storing trenches 11 are provided between the lands 6 as recesses surrounded by cut parts 7 of the lands 6 and openings 8A of the protective film 8, and when each terminal 9A of the circuit component 9 is fixed to each land 6, using a conductive adhesive 10, bleeds 12 from the adhesive 10 are housed in the storing trenches 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit component mounting board in which a circuit composed of, for example, semiconductor components, chip resistors, capacitors, etc. is provided on a circuit board. The present invention relates to a circuit component mounting board configured to be adhered on a board.

[0002]

2. Description of the Related Art In general, a circuit component mounting board provided with elements is used, for example, in a control unit for controlling an engine of an automobile. In this type of conventional control unit, circuit components such as a chip resistor and a capacitor are mounted together with semiconductor components on a circuit board, and these circuit components and semiconductor components are provided on the circuit board. They are connected using printed wiring.

Here, a pair of lands are provided on the circuit board at positions where the respective circuit components are mounted and connected to printed wiring. A pair of lands arranged for each circuit component is formed as a pedestal portion wider than the printed wiring, for example, to connect minute circuit components between the lands, and has a space corresponding to the length dimension of the circuit component. Are opposed to each other.

Further, an insulating protective film for covering the printed wiring is provided on the circuit board. The protective film is provided with a plurality of openings for exposing the lands to the outside, and each of the openings has a shape corresponding to each land.

Further, the circuit component has a pair of terminals formed on both ends thereof connected to each land within the opening of the protective film. In this case, a conductive adhesive or the like formed by mixing a conductive material such as silver or copper with a solvent, a curing agent, or the like is applied onto each land, and the circuit component uses this adhesive. And is fixed on the land.

When the circuit component is fixed on each land, first, a conductive adhesive or the like is applied on each land, and then each terminal of the circuit component is placed on the land so as to sandwich the adhesive. I do. Subsequently, the adhesive is cured by, for example, heating or leaving the circuit board, so that each terminal of the circuit component is fixed on the land.

[0007]

By the way, in the above-mentioned prior art, a minute circuit component is connected to a land using a conductive adhesive, and is fixed. But,
Since this adhesive is a mixture of a conductive material, a solvent, a curing agent, and the like, the mixed state may be unstable depending on, for example, the temperature and time when the adhesive is solidified.

As a result, when the adhesive solidifies, a phenomenon (so-called bleed) may occur in which the conductive material, solvent, curing agent and the like in the adhesive applied on the land gradually flow out to the periphery of the land. is there. In addition, the liquid component in the adhesive may flow out from the land to the periphery due to a capillary phenomenon or the like, and may flow between the lands along the length direction of the circuit component.

For this reason, in the prior art, despite the fact that an adhesive is applied only between each terminal of the circuit component and the land,
This adhesive may flow out between the lands due to bleeding, capillary action, or the like, causing a short circuit between the terminals of the circuit component, resulting in a malfunction of the circuit component and a reduction in reliability.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to store an adhesive applied between a circuit component and a land and securely fix the circuit component on each land. It is another object of the present invention to provide a circuit component mounting board which can be connected, can maintain a good operation state of an electronic circuit, and can improve reliability.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a circuit board made of an insulating material, a printed wiring provided on the circuit board, and a circuit connected to the printed wiring. A pair of lands provided on the substrate and facing each other at an interval, and an insulating protective film provided on the circuit board as a thin film covering the printed wiring and having a plurality of openings for exposing each of the lands to the outside The present invention is applied to a circuit component mounting substrate comprising circuit components fixed on each of the lands at each opening position of the protective film using a conductive adhesive and connected between the lands. .

A feature of the structure adopted by the invention of claim 1 is that a storage groove is provided between each of the lands and the protective film and located between the pair of lands to store the adhesive flowing from the lands. Has been established.

[0013] With this configuration, when the conductive adhesive applied between the circuit component and each land is about to flow out from the land to the surroundings, the adhesive is stored between the lands. Can be flowed into and stored
The storage groove can prevent the adhesive from short-circuiting between the pair of lands.

Further, in the invention according to claim 2, the opening of the protective film is formed corresponding to the outer shape of the land, and a portion of the outer edge of the land located between the lands is provided with the protective film. A cut-out portion for forming the storage groove is provided in the opening.

[0015] With this arrangement, a cutout portion can be provided between the lands and at the outer edge of the land, and a storage groove can be formed in each of the cutout portions between the land and the protective film. .

Further, in the invention according to claim 3, the opening of the protective film is formed so that a portion located between the lands is larger than the outer shape of the land, and the opening is formed between the outer edge side of the land and the opening. The storage groove is provided at a position.

Thus, a gap can be formed between the lands and the outer edge of the land in the opening of the protective film, and the gap can form a storage groove.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a circuit component mounting board according to an embodiment of the present invention will be described in detail with reference to FIGS.

Reference numeral 1 denotes a circuit board made of an insulating material provided in a control unit for controlling the engine. A plurality of printed wirings 2, 2,... Are provided on the circuit board 1 in a predetermined pattern. Each printed wiring 2 constitutes an electronic circuit together with electronic components 3, 4, 5 composed of, for example, integrated circuit elements, transistors and the like, and circuit components 9 described later.

Reference numerals 6 and 6 denote a pair of lands provided on the circuit board 1 connected to the respective printed wirings 2.
Is, for example, aluminum, as shown in FIGS.
It is made of a thin metal film of copper, palladium or the like, is disposed at a predetermined position on the circuit board 1 together with the printed wiring 2 by means of printing or the like, and is protected at the position of each opening 8A of the protective film 8 described later. It is exposed on the film 8. Each land 6 is formed in a substantially square shape of, for example, about 1 to 3 mm square, protrudes onto the circuit board 1 with a fixed height (film thickness), and conforms to the length of the circuit component 9. They are opposed to each other with an interval.

Numerals 7 and 7 denote cutouts provided on each land 6. Each cutout 7 is formed as a quadrangular recess at a portion of the outer edge of the land 6 located between the lands 6. A storage groove 11 is formed between the protective film 6 and the protective film 8.

Reference numeral 8 denotes a protective film that covers each printed wiring 2. The protective film 8 is made of an insulating material such as a resist, an oxide film, a nitride film, and a glass film, as shown in FIGS. By coating or coating on the circuit board, it is provided on the circuit board 1 with a film thickness substantially equal to that of the printed wiring 2. The protective film 8 is provided with openings 8A, 8A at the positions of the lands 6, and the portion of the protective film 8 located therebetween is a partition 8B that partitions between the openings 8A.

Further, the opening 8A is formed in a rectangular shape substantially corresponding to the outer shape of the land 6, and between the protective film 8 and the land 6, except for the position of the cutout portion 7, as shown in FIG. For example, a gap having a dimension S of about 1 to 10 μm is formed.

Reference numeral 9 denotes a circuit component comprising, for example, a chip resistor and a capacitor. The circuit component 9 is formed in a substantially square shape with a length of about 2 to 5 mm and a width of about 1 to 3 mm. Both ends in the vertical direction are a pair of terminals 9A, 9
A. In the circuit component 9, each terminal 9 </ b> A is fixed on each land 6 using conductive adhesives 10, 10, and is connected to each land 6 via these adhesives 10. The adhesive 10 is formed by mixing a conductive material such as silver or copper with a solvent, a curing agent, or the like.

Numerals 11, 11 are storage grooves for storing the adhesive 10 flowing out from the lands 6. Each of the storage grooves 11 is a substantially square surrounded by the cutout 7 of each land 6 and the opening 8 A of the protective film 8. It is provided on the circuit board 1 as a concave portion having a shape. Each storage groove 11 has a width dimension W of, for example, about 150 to 350 μm and a depth dimension corresponding to the thickness of the printed wiring 2 (protective film 8), and is arranged between the lands 6. .

When the circuit components 9 are fixed on the lands 6, as shown in FIG. 3, a part of the adhesive 10 applied on each of the lands 6 becomes, for example, a bleed 12 and flows out around the lands 6. Then, between the lands 6, the bleed 12 flows into the storage groove 11.

The circuit component mounting board according to the present embodiment has the above-described configuration. Next, a method for manufacturing the circuit component mounting board will be described with reference to FIGS.

First, in FIG. 5, each printed wiring 2, land 6 and the like having a predetermined pattern are provided on the circuit board 1 by using a means such as printing, for example. It is formed. Then, by applying or coating an insulating material such as a resin or a resist on the circuit board 1, a protective film 8 in which each opening 8 </ b> A is provided corresponding to the land 6 is provided on the circuit board 1. Thereby, each storage groove 11 is formed between the land 6 and the protective film 8.

Next, in FIG. 6, a liquid or paste-like adhesive 10 is applied on each land 6, and in FIG.
Each terminal 9A of the circuit component 9 is placed on each land 6 so as to sandwich the terminal 9A. In this state, the circuit component 9 is fixed and connected to each land 6 by heating or leaving the circuit board 1 to solidify the adhesive 10.

In this case, the adhesive 10 applied on each land 6 is first crushed and spread between the circuit component 9 and the land 6, and then a part thereof becomes a bleed 12 to surround the land 6. To the circuit components 9 due to capillary action
And may try to flow in the length direction.

However, since the storage grooves 11 are provided between the lands 6, as shown in FIG. 3, even if the bleeds 12 flow out between the lands 6, they flow into the storage grooves 11 and are stored therein. The bleed 12 does not connect (short-circuit) between the lands 6.

Thus, in the present embodiment, the circuit board 1
A cutout 7 is provided in each land 6 above, and a storage groove 11 surrounded by the cutout 7 and the opening 8A of the protective film 8 is arranged between the lands. 6
When fixed on the lands 6, even when the adhesive 10 applied on each land 6 becomes a bleed 12 or the like and flows out around the land 6, the bleed 12 is transferred into the storage groove 11 between the lands 6. It can be made to flow in and reliably stored in the storage groove 11.

As a result, the bleed 12 between the lands 6 can be solidified while being stored in the storage groove 11, and this bleed 12 reliably prevents short-circuiting between the terminals 9A of the circuit component 9. be able to.

As a result, the circuit component 9 can be stably fixed and connected between the lands 6, and a good operation state of the electronic circuit constituted by the electronic components 3, 4, 5 and the circuit component 9 can be maintained. Thus, the reliability as a circuit component mounting board can be improved.

Further, by providing the cutout 7 in the land 6, the storage groove 11 surrounded by the cutout 7 and the opening 8A of the protective film 8 can be reliably formed, and when the protective film 8 is formed, Even when the opening 8A is displaced to some extent with respect to the land 6, the opening area of the storage groove 11 can be stably held.

In the above embodiment, the storage groove 11 is formed between the cutout 7 provided in each land 6 and the opening 8A of the protective film 8, but the present invention is not limited to this.
It may be configured as in a modification shown in FIG.

That is, the opening 22 A of the protective film 22 formed corresponding to each land 21 is formed between the lands 21.
May be formed so as to be larger than the outer shape of the land 21, whereby the storage groove 23 is formed by a gap formed between the outer edge side of the land 21 and the opening 22 </ b> A of the protective film 22.

Thus, the shape of the land 21 can be simplified, and the storage groove 23 can be easily formed.

Further, in the above embodiment, the case where the circuit component mounting board is applied to the control unit for controlling the engine has been described as an example, but the present invention is not limited to this.
The present invention can be applied to any circuit component mounting board.

[0040]

As described above in detail, according to the first aspect of the present invention, since the storage grooves are provided between the lands and between the lands and the protective film, the circuit components are disposed on the lands. When fixing to the lands, even if the conductive adhesive applied on each land becomes bleed or the like and flows around the lands, it is possible to reliably store the bleed or the like in the storage groove between the lands. It is possible to reliably prevent the bleed from short-circuiting the circuit components between the lands. As a result, the circuit components can be stably fixed and connected between the lands, a good operation state of the electronic circuit can be maintained, and the reliability can be improved.

According to the second aspect of the present invention, a cutout portion for forming a storage groove in the opening of the protective film is provided at a portion of the outer edge of the land located between the lands. The storage groove surrounded by the cutout and the opening of the protective film can be reliably formed.

Further, according to the third aspect of the present invention, the opening of the protective film is formed to be larger than the outer shape of the land at a portion located between the lands, and is located in the opening and between the land and the outer edge side of the land. Since the configuration is such that the storage groove is formed, the shape of the land can be simplified, and the storage groove can be easily formed.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing a control unit using a circuit component mounting board according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of a circuit component and the like, showing an a portion in FIG. 1 in an enlarged manner.

FIG. 3 is a longitudinal sectional view of a land and the like as viewed from a direction indicated by arrows III-III in FIG. 2;

FIG. 4 is a cross-sectional view of a land and the like as viewed from a direction indicated by arrows IV-IV in FIG. 3;

FIG. 5 is a longitudinal sectional view showing a state in which a printed wiring, a protective film and the like are formed on a substrate.

FIG. 6 is a longitudinal sectional view showing a state where a conductive adhesive is applied on each land.

FIG. 7 is a longitudinal sectional view showing a state in which circuit components are bonded on each land.

FIG. 8 is an enlarged view of a main part as viewed from the same position as in FIG. 2, showing a modification of the circuit component mounting board according to the embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Circuit board 2 Printed wiring 6,21 Land 7 Cut-out part 8,22 Protective film 8A, 22A Opening 9 Circuit component 10 Adhesive 11,23 Storage groove

Claims (3)

[Claims] 1. A circuit board made of an insulating material, a printed wiring provided on the circuit board, and a pair of lands connected to the printed wiring and provided on the circuit board and opposed to each other with an interval, An insulating protective film provided on the circuit board as a thin film covering the printed wiring and having a plurality of openings for exposing the lands to the outside, and a conductive film formed on the lands at each opening position of the protective film. A circuit component mounting board comprising a circuit component fixed with an adhesive and connected between the lands, between the pair of lands and the protective film, between the lands. A circuit component mounting board, wherein a storage groove for storing an adhesive flowing from above a land is provided. 2. The opening of the protective film is formed corresponding to the outer shape of the land, and a portion of the outer edge of the land located between the lands is formed in the opening of the protective film. The circuit component mounting board according to claim 1, further comprising a cut-out portion that forms 3. An opening of the protective film is formed so that a portion located between the lands is larger than an outer shape of the land.
2. The circuit component mounting board according to claim 1, wherein the storage groove is provided in the opening between the land and an outer edge of the land.