JPH10209612A - Circuit board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent protecting material such as solder resist, etc., from flowing out to part to be exposed in a circuit board such as electrodes for joining circuit members, etc., by providing grooves for preventing the protecting material from flowing out into the regions of junctions, in the hems of the junctions. SOLUTION: Grooves 22 are formed by etching a conductive layer such as a copper foil, etc., attached to an insulating board, simultaneously by an etching process for forming lands 21 or distributing wires, etc., into a specified pattern. A solder resist 40 is used as a protective material for covering and protecting the insulating board, lands 21, wired parts, etc., and is intended to use for materials having fluidity capable of applying by screen printing. It does not matter if this protecting material is either a thermosetting or thermoplastic material. Consequently, it becomes possible to prevent the protecting material from flowing out onto the surfaces of the lands 21 by the grooves 22, even if the protecting material is fluidized by heating, etc., during a circuit board manufacturing process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a circuit board and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 6 shows a method of manufacturing a circuit board, such as a BGA (Ball Grid Array), in which lands for bonding external connection terminals such as solder balls or lead pins are provided on the outer surface of the circuit board. . In such a method of manufacturing a circuit board, first, a resist is applied to the surface of the copper foil 20a of the material substrate in which the copper foil 20a as the conductor layer is applied to one entire surface of the insulating substrate 10, and exposure and development are performed. A resist pattern is formed leaving the resist 32 only on the land and the wiring portion connected to the land (FIG. 6A).

Next, the copper foil 20a is etched using the resist 32 as a mask to form lands 21 and wiring in a predetermined pattern. FIG. 6B shows a state where the lands 21 are formed by etching the copper foil 20a. Next, the resist 32 is dissolved and removed, leaving only the lands 21 and required wiring on the insulating substrate 10. In the case of a circuit board using a resin substrate, finally, a solder resist 40 is applied as a protective film on the surface of the wiring pattern. Solder resist 40 is used for insulating substrate 10
And the wiring surface. The land 21 covers the peripheral side surface of the land 21 and exposes the surface of the land 21. FIG. 6 (d) shows the land 21 with the solder resist 40.
In a state covered with.

[0004]

When the solder resist 40 is applied by the above-mentioned method for manufacturing a circuit board, a printing method using a screen plate is usually used. In this method, a portion of the substrate on which the solder resist 40 is not applied is masked with a screen plate so that the solder resist 40 does not adhere. However, in the case of this method, when the solder resist 40 is applied, the solder resist 40 flows out from the periphery of the mask, and the solder resist 4 is applied to a portion to be exposed on the circuit board 12 such as the land 21.
In some cases, 0 may protrude, and a proper exposed area may not be secured. FIG. 6D shows a state in which the solder resist 40 has flowed from the periphery of the land 21 to the center.

On the circuit board 12, in addition to the lands 21,
It is necessary to prevent the electrodes for mounting the circuit components such as the chip capacitors from being covered with the solder resist 40. When the portion to be exposed on the circuit board 12 is covered with a protective material such as the solder resist 40, the external connection terminals cannot be securely joined, and the reliability of the circuit board is impaired. There is.

SUMMARY OF THE INVENTION The present invention has been made to solve these problems in manufacturing a circuit board, and an object of the present invention is to provide a land or circuit for connecting a protective material such as a solder resist to an external connection terminal. Provided is a circuit board which can be provided as a highly reliable circuit board and can be easily manufactured, and which can be provided as a highly reliable circuit board and a method for manufacturing the same, which prevents the semiconductor device from flowing or protruding into a portion to be exposed on a circuit board such as an electrode portion for joining components. It is in.

[0007]

The present invention has the following arrangement to achieve the above object. That is, in a circuit board in which the surface of the substrate is covered with a protective material by exposing a joint portion to which an external connection terminal or the like of a conductor pattern formed on the surface of the insulating substrate is joined, an edge of the joint portion is formed. And a groove for preventing the protection material from flowing into the region of the joint.

[0008] Further, the groove is formed in a shape of continuously making a round following the peripheral shape of the joining portion. Thus, the inner region of the joint can be reliably secured as an exposed surface. Further, a bypass path is provided between the groove and an outer peripheral edge of the joint portion for discharging the protection material flowing into the groove to the outside. Thereby, when the protection material flows into the groove excessively, the protection material is discharged to the outside from the bypass path, so that the protection material does not adhere to the surface of the joint.

[0009] The present invention is characterized in that the groove is formed by etching. By forming grooves by etching, a circuit board can be easily manufactured. Further, by using a solder resist as the protective material, a highly reliable circuit board can be easily and reliably obtained.

[0010] Further, as a method of manufacturing a circuit board, a step of applying a resist to a surface of a conductor layer formed on an insulating substrate, a step of exposing and developing the resist to join external connection terminals and the like. Forming a mask pattern for forming a conductor pattern having a pattern on the insulating substrate, and forming an exposed portion of the conductor layer for forming a groove along an edge of the joint portion; Etching the conductor layer using the resist formed in the step as a mask to form the conductor pattern and forming the groove in the surface of the joint; removing the resist; and And exposing a protective material such as a solder resist on the insulating substrate. Further, the resist corresponding to the groove is patterned into a narrow slit shape to form the exposed portion, and the etching speed for forming the groove portion is set to be lower than the etching speed for forming the conductor pattern. And

[0011]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing one embodiment of a circuit board 12 according to the present invention. The figure shows the surface of the circuit board 12 on which the lands 21 are formed as joints for joining the external connection terminals. A large number of lands 21 are formed in a predetermined arrangement. Each land 21 forms a part of a conductor pattern formed on the surface of the insulating substrate 10 and is electrically connected to a semiconductor chip mounted on the circuit board 12. Have been. The surface of the circuit board 12 on which the lands 21 are formed is covered with a solder resist 40 as a protective material except for the lands 21. Reference numeral 14 denotes a storage recess for mounting a semiconductor chip.

FIG. 2 is an enlarged sectional view showing a land 21 on the circuit board 12. As shown in FIG. 10 is an insulating substrate,
A solder resist 40 covers and protects the insulating substrate 10 and wiring portions. The solder resist 40 is provided so as to cover the peripheral side surface of the land 21 similarly to the conventional circuit board. A feature of the circuit board 12 of the present embodiment is that a groove 22 is formed on the surface of the land 21 along the edge of the land 21 as shown in FIG. Groove 22
Acts as a dam for preventing the solder resist 40 from flowing out when the solder resist 40 is applied, and prevents the solder resist 40 from flowing out into the area of the land 21. Thus, a required bonding area can be secured on the surface of the land 21.

The circuit board shown in FIG. 1 has a land 21 provided with a groove 22. By providing the groove 22 as described above, the solder resist 40 is prevented from flowing to the surface of the land 21. In addition, a required bonding area required for bonding external connection terminals such as solder balls or lead pins is ensured.

The groove 22 can be formed simultaneously in an etching step of etching a conductor layer 20 such as a copper foil 20a formed on the insulating substrate 10 to form a land 21 or a wiring in a predetermined pattern. There is also an advantage that a separate step for forming is not required and the manufacturing efficiency of the circuit board is not reduced.

Incidentally, the solder resist 40 is formed on the insulating substrate 1.
The protective material according to the present invention is a fluid material that can be applied by a screen printing method. This protective material may be either a thermosetting material or a thermoplastic material. Even if the protective material is fluidized by heating or the like during the manufacturing process of the circuit board, the groove 22 prevents outflow on the surface of the land 21. can do.

Of course, as described above, the method of forming the groove 22 to prevent the protective material such as the solder resist 40 from flowing out is not limited to the portion where the land 21 is formed. The same can be applied to a portion that is not to be covered. For example, a groove 22 is formed at the edge of the electrode portion for joining the circuit components, so that when the protective material is applied, no extra protective material is applied to the surface of the electrode portion. The area can be secured.

The material and shape of the circuit board 12 shown in FIGS. 1 and 2 are not particularly limited. The circuit board 12 may be a sheet-like material such as FPC (Flexible Printed Circuit), TAB, or PCB (Printed Circuit). Circuit boards), plate-like ones such as ceramic substrates are the targets. As the conductor layer 20 forming the lands 21 and the like, a metal foil formed by plating or the like, for example, a copper foil can be suitably used.

[0018]

Next, an embodiment of a method of manufacturing a circuit board will be described with reference to FIG. 3A to 3D are cross-sectional views illustrating the manufacturing method of the present invention in the order of steps. FIG. 4 shows a method of forming a land 21 for joining external connection terminals. FIG.
(a) is a method of applying a resist 32 on the surface of the copper foil 20a, exposing and developing the resist 32 on the surface of the copper foil 20a, and applying the resist 32 on the surface of the copper foil 20a. This shows a state after patterning.

In the case where the resist 32 is exposed and developed in a predetermined pattern, patterning is performed not only on the lands 21 but also on electric wiring portions and electrode portions for joining circuit components. As shown in FIG. 3 (a), the portion where the land 21 is to be formed is formed by removing the resist 32 at the portion where the groove 22 is formed along the edge of the land 21 to form a narrow gap portion 34. I do. This gap 3
Reference numeral 4 denotes a portion formed according to the width and shape of the groove 22. The land 21 is formed in a ring shape in a planar shape. The gap 34 is provided so that the surface of the copper foil 20a is exposed.

The method of patterning the resist 32 into a predetermined shape is by exposing the resist 32 to a predetermined pattern and dissolving and removing the resist 32 by development. When the negative type resist 32 is used, the copper foil 20
It is sufficient to expose only the portion where the resist 32 is left on a, and dissolve and remove the portion other than the exposed portion by developing. When the positive type resist 32 is used, only the portion to be dissolved and removed on the copper foil 20a is exposed and developed to dissolve and remove the exposed portion.

After the resist 32 is formed in a predetermined pattern as shown in FIG. 3A, the copper foil 20a is etched using the resist 32 as a mask pattern. Fig. 3 (b) shows the copper foil 2
0a is etched. Since the gap portion 34 provided in the resist 32 is formed in a narrow slit shape, when the copper foil 20a is etched using the resist 32 as a mask, it becomes difficult for the etchant to flow in the gap portion 34 and the land 21 is formed. The etching speed of the gap portion 34 becomes slower than the etching speed for patterning. As a result, even when the copper foil 20a on the outer portion of the land 21 is removed by etching, the etching does not proceed to the thickness of the copper foil 20a in the gap portion 34, and the recess 22 is formed as the groove 22. The groove 22 can be formed to a required depth by appropriately setting the width, depth, and etching time of the gap portion 34.

FIG. 3B shows the outline of the land 21 formed.
The groove 22 is formed on the upper surface of the land 21. Next, the resist 32 is dissolved and removed, and the land 21 having the groove 22 formed on the edge is obtained (FIG. 3C). FIG. 4 shows an example of forming a wiring pattern including a land 21 and a wiring portion 23 formed on a substrate. The land 21 has a circular outer shape, and the groove 22 is formed in a ring shape following the outer shape of the land 21. The wiring part 23 is a wiring electrically connected to the land 21. In this embodiment, the wiring part 23 is formed so as to be electrically connected to a through hole 50 provided in the substrate at the end of the wiring part 23.

After the conductor patterns such as the lands 21 and the wiring portions 23 are formed, the edges of the lands 21 and the wiring portions 23 are formed.
A solder resist 40 is applied as a protective material on the entire surface of the substrate to expose the lands. FIG. 3D shows a state where the solder resist 40 is applied. As described above, the solder resist 40 is applied so as not to adhere to the surface of the land 21 by a printing method.
By providing the groove 22 at the edge of the groove 22, the solder resist 40 is prevented from flowing at the groove 22 portion, and the solder resist 40 can be applied to the surface of the land 21 without adhering.

In the above embodiment, the groove 22 is formed to have a shape surrounding the land 22 in one round of the groove 22, but the shape of the groove 22 is not limited to such a ring. FIG. 5 shows another example of forming the groove 22 formed in the land 21. This embodiment is characterized in that a bypass path 25 is provided between the groove 22 and the outer edge of the land 21. The bypass passage 25 has a function of discharging the protective material such as the solder resist 40 flowing into the groove 22 to the outside. When the protective material is locally thickly applied, the protective material is discharged to remove the land 21. Ensure that no protective material flows inside. Thereby, it is possible to preferably prevent the insulating material from flowing into the land 21 beyond the groove 22.

Also, instead of forming the groove 22 in a round shape, the groove 22 is not formed at the connecting portion between the land 21 and the wiring portion 23 connected thereto, and the groove 22 is formed as a closed loop while the flat portion 26 remains. It is also effective not to form them.
This is because when the groove 22 is shaped to go around the land 21,
This is because if the groove 22 is formed deeply, the electrical connection between the land 21 and the wiring portion 23 may become uncertain. In this case, if a flat portion 26 that interrupts the groove 22 is provided, there is an advantage that electrical connection can be reliably performed. FIG.
Although an example in which one flat portion 26 is provided is shown, the flat portion 26 may be provided at a plurality of locations so that the groove 22 is divided at a plurality of locations. However, if the interval between the flat portions 26 is increased, the possibility that the protective material flows out into the lands 21 is increased. Therefore, the flat portions 26 are preferably formed as narrow as possible. In the above embodiment, the case where the insulating substrate 10 has a single layer has been described, but the present invention can be similarly applied to the case of a multilayer circuit substrate.

[0026]

According to the circuit board of the present invention, as described above, when a protective material such as a solder resist is applied to the surface of the board, the surface of the joint such as a land for joining the external connection terminals and the like is formed. Since the protective material does not adhere and the bonding area of the bonding portion can be reliably ensured, it is possible to provide a highly reliable circuit board. Further, according to the method of manufacturing a circuit board according to the present invention, a remarkable effect is obtained such that a highly reliable circuit board can be easily obtained without excessively attaching a protective material.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a land formation surface of a circuit board according to the present invention.

FIG. 2 is an enlarged sectional view showing a land portion of the circuit board according to the present invention.

FIG. 3 is a cross-sectional view illustrating a method for manufacturing a circuit board according to the present invention.

FIG. 4 is a plan view showing a land formation example of a circuit board according to the present invention.

FIG. 5 is a plan view showing another example of forming a land on the circuit board according to the present invention.

FIG. 6 is a cross-sectional view showing a conventional method for manufacturing a circuit board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Insulating board 12 Circuit board 20 Conductive layer 20a Copper foil 21 Land 22 Groove 23 Wiring part 25 Bypass path 26 Flat part 32 Resist 34 Gap part 40 Solder resist 50 Through hole

Claims (7)

[Claims] 1. A circuit board in which a bonding portion to which an external connection terminal of a conductor pattern formed on a surface of an insulating substrate is bonded and the surface of the substrate is covered with a protective material is provided. A circuit board, wherein a groove is provided in an edge portion to prevent the protection material from flowing into a region of the joint. 2. The circuit board according to claim 1, wherein the groove is formed in a shape that follows the peripheral shape of the joining portion and makes a continuous circuit. 3. Between the groove and the outer peripheral edge of the joint,
The circuit board according to claim 1, wherein a bypass path is provided for discharging the protection material flowing into the groove to the outside. 4. The circuit board according to claim 1, wherein said groove is formed by etching. 5. The circuit board according to claim 1, wherein the protective material is a solder resist. 6. A step of applying a resist on a surface of a conductor layer formed on an insulating substrate, exposing and developing the resist to insulate a conductor pattern having a joint portion to which an external connection terminal or the like is joined. A patterning step of forming a mask pattern for forming on the substrate, and forming an exposed portion of the conductor layer for forming a groove along an edge of the bonding portion; and a resist formed by the patterning step. Etching the conductor layer as a mask to form the conductor pattern and forming the groove in the surface of the joint; removing the resist; exposing the joint and soldering the resist, etc. Applying the protective material to the insulating substrate. 7. The resist corresponding to the groove is patterned into a narrow slit shape to form the exposed portion, and an etching speed for forming the groove portion is set to be lower than an etching speed for forming the conductor pattern. 7. The method for manufacturing a circuit board according to claim 6, wherein: