JPH08255969A - Printed-circuit board device - Google Patents

Abstract

PURPOSE: To obtain a printed-circuit board device whose structure is simple and in which two kinds of solder layers in different thicknesses can be formed simultaneously. CONSTITUTION: An auxiliary layer 16 composed of a conductive layer identical to a soldering land 14a is formed around the soldering land 14a on a printed- circuit board 12, and a solder-thickness adjusting layer 20 is formed to nearly surround the soldering land 14a. Since the solder-thickness adjusting layer 20 protruding from the land 14a is formed selectively around the land, a solder layer whose thickness is comparatively thick and a solder layer thinner than that can be formed simultaneously on the same printed-circuit board by the same printing screen treatment. Thereby, since cream solder can be printed by using printing screens whose thickness is identical and which are used usually, low-cost printing screens can be utilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board device, and in particular, by selectively forming a solder thickness adjusting layer, it is possible to simultaneously form a normal solder thickness layer and a thicker solder layer with a simple structure. The present invention relates to a printed circuit board device.

[0002]

2. Description of the Related Art In the current printed wiring technology, surface mounting has progressed, and quite large chip parts such as electrolytic capacitors, terminal boards and module parts are often surface mounted.

Along with this surface mounting, there is a strong demand for higher mounting density, and the pitch between wirings and the area (pattern width) of the land for soldering tend to be narrowed. The thickness of the printing cream solder formed on the land also tends to be thin. This is to prevent ridges in the printed solder layer that cause bridges (short circuits) between lands.

[0004]

By the way, when soldering a large chip component as described above, it is necessary to make the thickness of the solder layer used larger than that of the small chip component. Even on the substrate, there are lands where the solder layer needs to be printed thick and lands of normal thickness.

On the other hand, when the solder layer is formed by screen printing, the thickness of the solder layer (printing thickness) is determined in principle by the thickness of the printing screen (metal mask) used. In order to simultaneously form a thin solder layer and a thicker solder layer using the same printing screen, two kinds of thickness (thick portion (for example, 200 μm) and Thin part (1
50 μm)).

To do so, the printing screen used must have a half-etch mask configuration. The printing screen of the half etching mask structure is expensive,
When there are many places of the half etching mask, there is a problem that the handling thereof must be done carefully.

Therefore, the present invention solves such a conventional problem, and a printed circuit board device (printed circuit device) capable of screen printing having a thickness according to the purpose even if a printing screen having the same thickness is used. Device).

[0008]

In order to solve the above-mentioned problems, in the invention described in claim 1, the solder thickness is adjusted so as to substantially surround the soldering land formed on the printed circuit board. It is characterized in that a layer is formed.

[0009]

[Function] Since only the soldering land on which a large chip component is to be mounted, the solder thickness adjusting layer is formed around the soldering land so as to substantially surround the soldering land, the solder thickness is adjusted by the thickness of the solder thickness adjusting layer. The printed solder layer can be thicker than the soldering land without the adjustment layer.

The thickness of the printing screen used in this case is the printing screen itself used when mounting small chip components. Even if a printing screen having the same thickness is used by forming this solder thickness adjusting layer, a thick solder layer and a thinner solder layer can be simultaneously formed on the printed board.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an example of a printed circuit board device according to the present invention will be described in detail with reference to the drawings.

According to the present invention, when a small chip component and a relatively large chip component are mounted on the same printed circuit board,
In particular, the solder thickness adjusting layer is formed so as to substantially surround only the periphery of the soldering land for mounting a large chip component. A specific example thereof will be described with reference to FIG.

In FIG. 1, a patterned conductive layer 14 is formed at a predetermined position on the upper surface of the printed circuit board 12. The conductive layer 14 is composed of a soldering land 14a to which a chip component or the like is connected and a wiring portion 14b as shown in FIG. Around the soldering land 14a of the conductive layer 14, the land 14 is formed so as to substantially surround the land 14a.
The auxiliary layer 16 is formed at a predetermined distance from a.

The auxiliary layer 16 is a pattern layer for adjusting the thickness used for increasing the thickness of the solder layer printed on the surrounding soldering land 14a as compared with the usual case. Therefore, the auxiliary layer 16 is formed only around the land for mounting a particularly large chip component. Auxiliary layer 16
Are usually formed simultaneously with the conductive layer 14. Therefore, this auxiliary layer 16 is also a conductive layer. This means that the auxiliary layer 16 may use a part of the wiring pattern.

The auxiliary layer 1 on the upper surface of the printed circuit board 12.
A resist layer (solder resist layer) 18 is formed so as to cover the upper surface of 6 as well. The solder resist layer 18 is used as a protective film for preventing the solder from flowing to a portion other than a necessary portion as described later. Therefore soldering land 1
Although the solder resist layer 18 is formed in a state where the upper surface of 4a is removed, the solder resist layer 18 is formed so that a part of the outer peripheral edge of the land is hidden as shown in FIG.

A solder thickness adjusting layer 20 is formed around the soldering land 14a so as to surround it. In this case, the solder thickness adjusting layer 20 is formed so as to be located at least on the upper surface of the auxiliary layer 16 and to cover a part of the outer peripheral edge of the soldering land 14a. By forming the adjustment layer 20, the soldering lands 14a corresponding to the thickness of the adjustment layer 20 are formed.
Will protrude from the upper surface of.

As a result, the printing screen 22 shown in FIG.
When the cream solder is applied using, the land having the solder thickness adjusting layer 20 is printed thicker than the solder layers of the other lands by the thickness of the adjusting layer 20 even if the printing screen 22 having a uniform thickness is used. To be done. In other words, only by selectively forming the solder thickness adjusting layer 20, the cream solder layer 24 having two types of thickness is simultaneously formed by one printing process. The layer difference t of the solder layer 24 is determined by the thickness of the solder thickness adjusting layer 20, which is exemplified by several tens of μm.

Since the solder thickness adjusting layer 20 is selectively formed as described above, the solder thickness adjusting layer 20 is not formed around the land 14a on which a relatively small chip component is mounted. .

As shown in FIG. 2, the solder thickness adjusting layer 20 and the auxiliary layer 16 are formed so as to surround the soldering lands 14a so as to correspond to the planar shape, especially the outer peripheral edge shape. FIG. 2 shows an example thereof, and FIG. 3A shown as an example of a modification thereof shows that both the auxiliary layer 16 and the solder thickness adjusting layer 20 are formed in a “D” shape so as to surround a part of the land 14a. This is the case. FIG. 3B shows the auxiliary layer 1 in the shape of “U”.
6 and the solder thickness adjusting layer 20 are formed. These are examples of the shape surrounding the land 14a.

Subsequently, the printed circuit board device 10 shown in FIG.
An example of the manufacturing process will be described with reference to FIG.

The upper surface of the printed circuit board 12 has a thickness of 18 to
The copper foil conductive layer 14 is formed to have a thickness of about 35 μm,
This is patterned into the land 14a, the wiring portion 14b, and the auxiliary layer 16 (FIG. 4A). The auxiliary layer 16 is selectively formed as described above.

Subsequently, the solder resist layer 1 for insulation is formed on the entire surface of the printed board 12 so as to include the outer peripheral edge of the land 14a.
8 is deposited and formed with a thickness of several tens of μm (FIG. 9B). Thereafter, for example, using a printing screen (not shown), the solder thickness adjusting layer 20 is selectively formed so as to include the auxiliary layer 18 and extend to the outer peripheral edge portion of the land 14a (FIG. 8C). The solder thickness adjusting layer 20 can use, for example, an insulating ink, the thickness is determined by the thickness of the printing screen to be used, and the total thickness further projects from the printed circuit board 12 by the thickness of the auxiliary layer 20. The adjustment layer 20 can be formed at the same time as the screen printing layer for displaying the component numbers and the like formed on the printed board 12.

After the adjustment layer 20 is formed, the cream solder layer 24 is printed by using the printing screen 22 (D in the same figure). Since there is a region where the adjustment layer 20 is printed and a region where the adjustment layer 20 is not printed (E in the same figure) on the printed circuit board 12, the land 14a where the adjustment layer 20 is present.
The thickness (D in the figure) of the solder layer 24 printed and formed on the land is the same as that shown in FIG.
Is printed thicker than the solder layer 24 by at least the thickness t of the adjustment layer 20. That is, the same print screen 22
Even if cream solder is printed at the same time by using, two kinds of solder layers, that is, a thick solder layer and a thinner solder layer are simultaneously formed. After printing the solder layer 24, FIG.
The target chip component 26 has a pair of lands 14a,
They are connected by being placed between 14a and heated.

When the cream solder is printed, the relative position of the printing screen 22 to the printed circuit board 12 is slightly deviated, and for example, when the cream solder is positioned in the state of FIG. The solder layer 24 is printed in any shape. However, even if the cream solder is printed in such a misaligned state, the upper surface of the solder layer 24 carries a substantially flat surface.
This is because the adjustment layer 20 is formed around the land 14a so as to straddle the land 14a.
When the positional deviation is within the width of, that is, even when the positional deviation of the printing screen 22 occurs, the upper surface of the solder layer 24 is flat as long as the printing screen 22 extends over the adjustment layer 20. As a result, the deterioration of the joint with the chip component due to the displacement of the printing screen does not occur. That is, the reliability is improved.

In the embodiment shown in FIG. 1, since the adjusting layer 20 is projected from the upper surface of the land 14a, the land 14
This is an example in which the auxiliary layer 16 electrically isolated from the land 14a is formed around a. The specific means for realizing the present invention is not limited to the specific example of FIG. Another example will be described with reference to FIGS. 7 and 8.

In the embodiment shown in FIG. 7, the land 14a itself is patterned so as to be larger than the original area. The width at the time of patterning is made wider (larger) by “a” than usual. This wide area, that is, the expanded land area (outer peripheral area) 30 a is used as the auxiliary layer 20.

In this case, as shown in the figure, the solder resist layer 18 is formed so as to extend to the extended land region 30a, and the adjustment layer 20 formed on the upper surface thereof.
Is also formed to include this extended land region 30a. Then, at least the adjustment layer 20 formed on the upper surface of the extended land region 30a protrudes from the other portion by the thickness of the land 14a.
4 can be printed thick.

Of course, the auxiliary layer 16 and the extended land area 30
The adjustment layer 20 can be formed without providing a. In this case, for example, the solder resist layer 18 is formed so as to cover the outer peripheral edge of the land 14a as shown in FIG.
The adjustment layer 20 is formed so as to include the outer peripheral edge of the land. Then, at least the thickness of the adjustment layer 20 is projected, so that the solder layer can be printed thicker than other portions. In this case, it can be easily understood that if the thickness of the printing screen for forming the adjusting layer 20 is increased, the adjusting layer 20 having the thickness as shown in FIG. 1, FIG. 6 or FIG. 7 can be formed.

[0029]

As described above, according to the present invention, since the solder thickness adjusting layer which protrudes from the land is selectively formed around the land, the same printing screen treatment is performed on the same printed circuit board relatively. A thick solder layer and a thinner solder layer can be simultaneously formed.

According to this, since the cream solder can be printed using the normally used printing screen having the same thickness, a low-cost printing screen can be used and the cost for manufacturing the substrate device can be reduced. Since the printing screen for solder printing has the same thickness, it is easy to handle. Also in the manufacturing process of the printed circuit board device, the solder thickness adjustment layer can be simultaneously formed by silk screen printing for displaying the part number, which is printed even on a normal printed circuit board. Have.

Therefore, the present invention is extremely suitable when applied to a printed circuit board device in which large and small chip parts are mixedly mounted.

[Brief description of drawings]

FIG. 1 is a sectional view of essential parts showing an example of a printed circuit board device according to the present invention.

FIG. 2 is a plan view of a part thereof.

FIG. 3 is a plan view showing another example of the solder thickness adjusting layer.

FIG. 4 is a manufacturing process diagram (1/2) showing an example of the printed circuit board device according to the present invention.

FIG. 5 is a manufacturing process diagram (2/2) showing an example of the printed circuit board device according to the present invention.

FIG. 6 is a cross-sectional view of essential parts showing another example of the printed circuit board device according to the present invention.

FIG. 7 is a cross-sectional view of a main part showing another example of the printed circuit board device according to the present invention.

FIG. 8 is a cross-sectional view of essential parts showing another example of the printed circuit board device according to the present invention.

[Explanation of symbols]

 10 Printed Circuit Board Device 12 Printed Circuit Board 14 Conductive Layer 14a Land 14b Wiring Section 16 Auxiliary Layer 18 Solder Resist Layer 20 Solder Thickness Adjustment Layer 22 Printing Screen 24 Solder Layer

Claims (5)

[Claims] 1. A printed circuit board device, wherein a solder thickness adjusting layer is formed around a soldering land formed on a printed circuit board so as to substantially surround the soldering land. 2. An auxiliary layer made of the same conductive layer as the soldering land is formed around the soldering land,
The printed circuit board device according to claim 1, wherein the solder thickness adjusting layer is formed on an upper surface of the auxiliary layer. 3. The soldering land is expanded, a resist layer is formed on a peripheral portion of the expanded land, and the solder thickness adjusting layer is formed so as to include the resist layer. The printed circuit board device described. 4. The printed circuit board device according to claim 1, wherein the solder thickness adjusting layer is formed by a screen printing method. 5. A cream solder is formed on the soldering land by a screen printing method, and a solder layer thick by the thickness of the solder thickness adjusting layer and a thin solder layer are simultaneously formed. The printed circuit board device according to claim 1.