JPS6225491A - Printed wiring board and making thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a printed wiring board and a method for manufacturing the same.

[Background technology]

Conventionally, methods for mounting components on printed wiring boards include, for example, IC
In the case of parts with lead wire terminals such as DIP type packages, the lead wire terminals were inserted into through holes in the printed wiring board and brazed with solder.

Recently, in response to the increase in the degree of integration of ICs, the external shape of ICs has become D.
There is a shift from TP type packages to flat packages. However, when mounting components such as flat packages and chip components such as resistors and capacitors on a printed wiring board that are connected to conductor circuits formed on the surface of the printed wiring board, conventional printed wiring boards cannot be used. However, this method lacks a positioning aid such as a through hole for lead wire terminal type parts, and has the drawbacks of being time-consuming and having poor positioning accuracy. Furthermore, at the time of implementation,
Stress during curing of ultraviolet curable resin.

The component may be moved by vibration, force applied during brazing, etc., causing the terminal position to shift and come into contact with the terminal of another component.

Furthermore, when mounting a lead '41A terminal type component, a through hole is required in the printed wiring board as described above, and connection and fixation cannot be achieved using only one side of the printed wiring board. In particular, when mounting IC flat packages and chip components together, a different mounting method must be used for each component, which increases the cost of mounting the components.

Therefore, a printed wiring board as shown in Figure 4 was developed.

As you can see in the figure, this printed wiring board is based on &51 surface is covered with adhesive layer 52. Further, a photoresist N54 having a thickness of approximately 10 to 15 μm is formed on the surface of the adhesive N52, except for the portion where the component terminal 53 is attached. The part where the component terminal 53 is attached has 1 attached 1 [!] by electroless plating. 155 is photoresist j!
It is formed to be thinner than i54. That is,
The part where the component terminal 53 is attached is a photoresist layer 54
It is more concave and stepped. In the figure, 56
is solder.

In this way, this printed wiring board is an attempt to solve various problems when mounting components, but it has the following problems. (2) Since the photoresist layer forms a step with the copper layer 1, it was possible to create a step of only about 10 μm. ■Because the edges of the photoresist layer were rounded, the stability of component terminals during mounting was poor. ■Since the photoresist layer is made of organic material, it is soft and could be scraped when positioning component terminals. For these reasons, it has not been possible to fully satisfy the objectives. Moreover, in the printed wiring board shown in FIG. 4, since no brazing material such as solder is attached to the photoresist layer, the bonding area of the brazing material is small, and the bonding reliability of the brazing material after component mounting is low.

[Purpose of the invention]

In view of the above circumstances, the present invention facilitates positioning of component terminals when mounting components, has good positioning accuracy, and
To provide a printed wiring board and a method for manufacturing the same, in which there is no fear of positional displacement, parts can be mounted at low cost, and the reliability of bonding of a brazing material after parts is mounted can be improved.

[Disclosure of the invention]

In order to achieve the above object, the present invention provides a printed wiring board in which a conductor circuit is formed on a substrate, and a component terminal is attached to a part of the conductor circuit, in which the component terminal is attached. The first aspect of the invention is a printed wiring board characterized in that a conductive circuit portion is recessed from the surrounding conductor circuit portion, and at least the inner surface of the recess is covered with a material having good brazing properties. In order to obtain a printed wiring board, a first conductive layer is formed on the board, and the first conductive layer other than the part that will become the conductor circuit is covered with a first resist layer, and the conductor to which the component terminal is attached is formed. The circuit portion is covered with a second resist layer, and a second conductor layer is formed on the remaining portion of the first conductor layer that is not covered by both resist layers, so that the conductor circuit portion to which the component terminal is attached is surrounded by a second resist layer. After making a recess from the conductor circuit portion, removing the second resist layer, and covering at least the inner surface of the recess with a third resist layer, the portion not covered with the third resist layer is solderable. The second method of manufacturing a printed wiring board is to cover the printed wiring board with a material of good quality, remove the second and third resist layers, etch the entire surface, and remove the first conductive layer other than the conductive circuit. The summary is as follows.

An embodiment of this will be explained in detail below based on the accompanying drawings.

As shown in FIGS. 1(al), (b), and (c), in this printed wiring board, one surface of the substrate 1 is covered with an adhesive N2. The surface of the adhesive layer 2 may also serve as an insulating layer.
For example, w4) circuit 3... is formed. Terminals 5 of components (for example, a flat package as shown in the figure) 4 are attached to a part of the conductor circuit 3 with brazing material (solder in this example) 6. It looks like this. The conductor circuit portions 7 to which the component terminals 5 are attached are recessed from the surrounding conductor circuit portions. The inner surface of this recess is made of a material 8 with good brazing properties (solder in this example) and has a thickness of 1 to 3 μm.
covered with a layer of m. Because the conductor circuit part where the component terminal is attached is recessed than the surrounding conductor circuit part,
Compared to conventional printed wiring boards with flat conductor circuits, it is easier to position component terminals when mounting components, and the positioning accuracy of component terminals is also better. It is now restricted by the conductor circuit part, and the position of the component terminal will not shift due to vibration, force applied during brazing, etc.

Furthermore, by recessing the conductor circuit portion to which the component terminal is mounted relative to the surrounding conductor circuit portions, problems ①, ②, and ③ of the conventional printed wiring board shown in FIG. 4 can also be solved. In other words, in response to problem (3), as will be described later, the level difference between the conductive circuit part to which the component terminal is attached and the surrounding conductive circuit part can be arbitrarily set, and the level difference can be increased. This can be resolved. Problem ■,
In contrast to (2), since the part corresponding to the photoresist layer is made of a conductor such as copper, the edge part 9 can be formed with a sharp point, and the risk of chipping when positioning the component terminal can be eliminated, so these problems can be solved. It can be resolved. In addition, the bonding area of the brazing material such as solder at the component terminal increases, and since the wall of the recess also serves as the bonding area of the brazing material, the bonding area of the brazing material on the conductor circuit side increases, and the bonding of the component terminal after component mounting increases. It can also improve reliability. Moreover, since the inner surface of the recess is covered with a material with good brazing properties, the wettability of the brazing material is improved when brazing the component terminals, and the bottom and sides of the recess can be reliably joined. This makes it possible to further improve the bonding reliability of component terminals.

Figure 2 (at) and (b) show chip parts 4 such as chip resistors.
An example of usage is shown below. In the figure, the numbers correspond to those in FIG. In this example, a brazing material is selected as a material with good brazing properties, and the thickness of the material layer with good brazing properties is 50 μm.
That's all. In this way, if a brazing material is selected as a material with good brazing properties, the thickness of the material layer with good brazing properties is 50 μm or more, and the amount is sufficient to attach component terminals, the temperature can be reduced during component mounting. Component terminals can be mounted simply by raising the temperature above the melting point of a material with good attachment properties. This eliminates the need for equipment such as brazing metal that was required when mounting components, and also eliminates bridging between component terminals, which was a problem during brazing.

In addition to the foot package and chip components mentioned in the examples, various components such as lead terminal type components, variable resistors, and switches can be mounted on this printed wiring board in the same manner as in the above example. Conventionally, when mounting a lead wire terminal type component, a through hole was required on the printed wiring board, but the printed wiring board according to the present invention eliminates the need for a through hole and can be mounted on only one side of the printed wiring board. Connections can be fixed. In particular, when mounting together with IC flat packages, chip components, etc., all can be mounted using the same method, so components can be mounted at low cost.

The printed wiring board as described above can be obtained in the following manner. This will be explained in detail below based on FIG. 3 (al to U).

As shown in Figure 3(b), adhesive N is applied to one side of the substrate 1.
A copper layer with 1 (first conductor layer 3a) is formed in advance through 2. As shown in FIG. 3(a), the copper layer 3a with 1 is formed by electroless plating on the substrate 1 whose one side surface is covered with the adhesive layer 2 to have a thickness of 1 to 3 μm. Figure 3 (
As shown in C), in the first step, a portion of the copper layer 3a other than the portion that will become the conductor circuit is covered with a solvent-soluble resist layer (first resist layer) 10. As shown in Figure 3(d), the second
In the process, the conductor circuit portion to which the component terminals are attached is covered with an alkali-soluble resist layer (second resist layer) 11.

As shown in FIG. 3(e), in the third step, electroplating is performed on the thin fader layer that is not covered by both resist layers 10 and 11 to form a thick copper layer with a thickness of 30 to 40 μm. layer 3b
form. As a result, the conductor circuit portion to which the component terminal is mounted is recessed from the surrounding conductor circuit portions. As shown in FIG. 3 if), in the fourth step, the alkali-soluble resist layer 11 is removed using a sodium hydroxide solution. At this time, the solvent-soluble resist layer 10 remains without being removed because it is not alkali-soluble. Figure 3 (gl
As shown in , in the fifth step, the inner surface of the recess and its vicinity are covered with a solvent-soluble resist layer (third resist layer) 12. As shown in FIG. 3(h), in the sixth step, electroplating is performed to cover the areas not covered with the solvent-soluble resist layer 12 with a material (in this example, solder) 9 with good brazing properties. cover with As shown in FIG. 3 (11), in the seventh step, the solvent-soluble resist layer 10.12 is removed with a solvent. As shown in FIG. 3 (j), in the eighth step, the entire surface is etched. Remove the copper layer other than the conductor circuit.

By doing the above, it is easy to obtain a printed wiring board in which the conductor circuit portion to which the component terminal is attached is recessed from the surrounding conductor circuit portion, and at least the inner surface of this recess is covered with a material with good brazing properties. be able to. The level difference between the conductor circuit portion to which the component terminal is mounted and the conductor circuit portion surrounding it can be arbitrarily set by changing the thickness of the second conductor layer. The first resist layer and the second resist layer are made of different materials. In this way, even if the second resist layer is removed, the first resist layer can remain. It is preferable to use the same material for the first resist layer and the third resist layer.

This is because, as we will see in the seventh step, it becomes possible to remove them at the same time using the same removal solution, thereby reducing the number of manufacturing steps.

The printed wiring board and the manufacturing method thereof according to the present invention are not limited to the above embodiments. Materials with good brazing properties include:
If the brazing filler metal is 5n-Pb solder, use the same 5n-Pb solder and tin as the brazing filler metal.

There are gold, silver, etc. Brazing filler metals include hard solder with a melting point of 450°C or higher, and soft solder with a melting point of 450°C or lower (so-called solder).
Examples of hard solder include limited solder and nickel solder, and examples of soft solder include 5n-Pb solder,
Examples include Sn-based solder, In-based solder, and AI solder. To form a material with good brazing properties on the inner surface of the recess,
There are methods such as wet and dry plating, methods of applying in paste form, etc., and there are no particular limitations. Examples of materials for conductive circuits include metals such as copper and nickel, conductive paints,
Examples include carbon, and there are no particular limitations on this as long as it is a conductor. The first four-layer may be formed not only by electroless plating but also by a PVD method such as ion blasting or sputtering. The second conductor layer is not limited to electroplating, but may also be formed by wet plating methods such as electroless plating, or dry plating methods such as ion blasting or sputtering. A method using electroplating is preferred because it is inexpensive. The first resist layer and the second resist layer may be formed in the opposite order or at the same time. The first and second conductor layers may be made of different materials. For example, nickel is used for the first conductor layer and copper is used for the second conductor layer.

The substrate may be made of a base material such as glass or paper impregnated with epoxy resin or phenol resin, or made of ceramic, and is not particularly limited. In addition, the conductor circuit may be recessed in the part where the component terminal is not attached. Conductor circuits may be formed on both sides of the substrate.

〔Effect of the invention〕

As described above, in the printed wiring board according to the present invention, the conductor circuit portion to which the component terminals are attached is recessed from the surrounding conductor circuit portions, making it difficult to position the component terminals when mounting components. It is easy, has good positional accuracy, and
There is no risk of misalignment, and components can be mounted at low cost. Furthermore, since the inner surface of the recess is covered with a material that has good brazing properties, it is possible to improve the bonding reliability of the brazing material after component mounting. These things make it easier to automate the mounting of parts.

According to the method for manufacturing a printed wiring board according to the present invention, the printed wiring board as described above can be easily manufactured. In addition, it is possible to arbitrarily set the level difference between the conductor circuit part to which the component terminal is attached and the surrounding conductor circuit part, making it possible to increase the level difference, which is highly effective in facilitating positioning. Can you get printed wiring board?

[Brief explanation of the drawing]

FIG. 1+al is a plan view showing a part of an embodiment of a printed wiring board according to the present invention, and FIGS. 1(b) and (C) are sectional views taken along line A-A' and line B-B', respectively. Cross section, 2nd
Figures (al and fbl are a plan view and a cross-sectional view, respectively, showing an example of the use of the printed wiring board according to the present invention, and Fig. 3 (a)
-01 are explanatory diagrams showing one embodiment of the method for manufacturing a printed wiring board according to the present invention, and FIG. 4 is a cross-sectional view of a part of a conventional example of a printed wiring board. 1... Board 2... Adhesive layer 3... Conductor circuit
3a...54 layers with 1 (first conductor layer) 3b...
Thick 1IOIN (second conductor layer) 5... Component terminal 7... Conductor circuit portion to which the component terminal is attached 8...
・Solder (material with good brazing properties) 10... Solvent soluble resist layer (first resist layer) 11...
Alkali-soluble resist layer (second resist layer) 1
2...Solvent-soluble resist layer (third resist layer) Agent: Takehiko Matsumoto, patent attorney Figure 1 Figure 2 Figure 4 Figure 3 Hand 3 Funaho Seisho (Retrieved September 2, 1985) 1985 Patent Application No. 164426 2, Title of the invention 1. Hyakuhanasaka and its manufacturing method 3. Relationship with the case of the person making the amendment Patent applicant Location 1048 Oaza Kadoma, Kadoma City, Osaka Name (583) Matsushita Representative of Denko Co., Ltd. (Jl1m Teiyaku Sadao Ugai 4, Agent form 5, Specification subject to amendment 6, Contents of amendment (1) The entire text of the scope of claims column of the specification will be corrected as shown in the attached sheet) (2) In the third line of page 7 of the specification, the phrase “formed” has been replaced with “
"By forming," he corrects. (3) On page 7, line 8 of the specification, the word “second” has been replaced with “first”.
” he corrected. (4) Between the 10th true line 13 of the specification and the 14th line of the same page,
Insert the following text. When a component with multiple terminals, such as the flat package mentioned in the above example, is mounted, the center component terminal (there are two on the left and right in the figure) shown in Figure 1 (al) is surrounded by four corners. The conductor circuit portion to which the component terminal is attached may be recessed so that it is the same as the circumference of the component terminal, and a wall made of conductor circuit may be provided between all adjacent component terminals. In Figure 1 (al), there may be no conductor walls as described above between the component terminals at the four corners and the component terminals adjacent thereto, and conductor walls may be provided only on the outside of the component terminals at the four corners. Depending on the shape and density of the component terminals to be installed, the conductor circuit portion to which the component terminals are attached may be recessed so that each component terminal can be accommodated separately in its corresponding recess, or it may be recessed so that each component terminal can be accommodated separately in its corresponding recess. (5) In the 10th page, line 18 of the specification, the phrase ``in the parts'' should be corrected to ``the parts.'' (6) In the 9th line of page 11 of the specification, the phrase “one side” is corrected to “the entire surface.” (7) In the 10th line of page 11 of the specification, “(first conductor layer 3a
)” should be corrected to read “(first conductor layer) 3a.” (8) On page 11, line 12 of the specification, the phrase "one side surface" is corrected to read "the entire surface." (9) On page 14, line 6 of the specification, the word "and" is corrected to "and." 0ω The following words are inserted between "preferable" and "first" on page 14, line 19 of the specification. - The thickness of the first conductor layer is preferably 0.5 to l 07t m, more preferably 1 to 3 μm. (11) On page 16, line 8 of the specification, the phrase "obtained" is corrected to "obtained". 2. Scope of Claims (1) In a printed wiring board in which a conductor circuit is formed on a substrate and a component terminal is attached to a part of this conductor circuit, the conductor to which the component terminal is attached. A printed wiring board characterized in that a circuit portion is recessed from the surrounding conductor circuit portion, and at least the inner surface of the recess is covered with a material having good brazing properties. (2) The printed wiring board according to claim 1, wherein the material having good brazing properties is provided in an amount sufficient to attach component terminals. (3) The printed wiring board according to claim 1 or 2, wherein the conductive circuit is formed on the surface of an adhesive layer covering the surface of the substrate. (4) When obtaining a printed wiring board in which the conductor circuit portion to which the component terminal is attached is recessed from the surrounding conductor circuit portion, and at least the inner surface of this recess is covered with a material with good brazing properties, it is necessary to A first conductor layer is formed in advance, and the parts of the first conductor layer other than the part that will become the conductor circuit are covered with a first resist layer, and the four-body circuit part to which component terminals are attached is covered with a second resist layer. , forming a second conductor layer on the remainder of the first conductor layer not covered by both resist layers;
jLζ('ζ) A conductor circuit portion to which a component terminal is attached is recessed from the surrounding conductor circuit portion, the second resist layer is removed, and at least the inner surface of the recess is covered with a third resist layer. After that, the parts not covered with the third resist layer are covered with a material with good brazing properties, and the beams and the third resist layer are removed and the entire surface is etched to remove the first conductor other than the conductor circuit. A method for producing a printed wiring board, characterized in that the first resist layer and the second resist layer 1 are made of different materials. (6) The method for manufacturing a printed wiring board according to claim 4 or 5, wherein the first resist layer and the third resist layer are made of the same material.

Claims (6)

[Claims] (1) In a printed wiring board in which a conductor circuit is formed on the board and a component terminal is attached to a part of this conductor circuit, the conductor circuit portion to which the component terminal is attached is attached to the surrounding area. A printed wiring board characterized by being recessed from a conductor circuit portion and at least the inner surface of this recess is covered with a material having good brazing properties. (2) The printed wiring board according to claim 1, wherein the material having good brazing properties is provided in an amount sufficient to attach component terminals. (3) The printed wiring board according to claim 1 or 2, wherein the conductive circuit is formed on the surface of an adhesive layer covering the surface of the substrate. (4) When obtaining a printed wiring board in which the conductor circuit portion to which the component terminal is attached is recessed from the surrounding conductor circuit portion, and at least the inner surface of this recess is covered with a material with good brazing properties, it is necessary to A first conductor layer is formed, a portion of the first conductor layer other than a portion that becomes a conductor circuit is covered with a first resist layer, and a portion of the conductor circuit to which a component terminal is attached is covered with a second resist layer; A second conductor layer is formed on the remaining portion of the first conductor layer that is not covered by both resist layers, and the conductor circuit portion to which the component terminal is attached is recessed from the surrounding conductor circuit portion. After removing the resist layer and covering at least the inner surface of the recess with a third resist layer, the portion not covered with the third resist layer is covered with a material having good brazing properties, and the second and third resist layers are
A method for manufacturing a printed wiring board, which comprises removing the resist layer, etching the entire surface, and removing the first conductor layer other than the conductor circuit. (5) The method for manufacturing a printed wiring board according to claim 4, wherein the first resist layer and the second resist layer are made of different materials. (6) The method for producing a printed wiring board according to claim 4 or 5, wherein the first resist layer and the third resist layer are made of the same material.