JP2001284741A - Rub preventing mark for thick film circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rub preventing mark without projecting and recessing parts on a surface. SOLUTION: A thick film resistor layer included in the rub preventing mark 10 is constituted only of a Cu-Ni system and an LaB6 resistor, and an SnO2 resistor is not included. Thus, foaming is generated in the forming process of the rub preventing mark 10 and the generation of the projecting and recessing parts is suppressed on the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-scratch mark provided on a thick-film circuit board.

[0002]

2. Description of the Related Art A thick-film circuit board is formed by applying a plurality of types of thick-film printing paste in a predetermined pattern to a ceramic substrate made of alumina or the like by using a thick-film screen printing method or the like and performing a baking process. It is manufactured by producing a thick film from the paste. Since such a thick-film circuit board is sometimes handled by being superimposed in a manufacturing process, packing and shipping, etc., it is necessary to prevent the circuit patterns from being damaged by rubbing of the boards at that time. . Therefore, the position that does not overlap with the circuit pattern,
For example, in a dummy portion such as a corner of a substrate, a projection called a scratch prevention mark having a height of about 70 to 80 (μm) higher than its maximum height by, for example, about 20 (μm) is provided. I have.

In general, the above-mentioned rubbing prevention mark is used for suppressing the increase in the number of steps caused by providing the rubbing prevention mark. When a film or the like is formed, a thick film printing paste is applied to the position where the anti-scratch mark is to be formed at the same time and baked, whereby a plurality of thick films are laminated. At this time, when there are many types of components of the circuit pattern, since the height dimension of the anti-scratch mark becomes too high when all the thick films are laminated, the same thick film resistor is used for a plurality of types. One layer is selected for each material system. By the way, if the anti-scratch mark is too high, there is a problem that the bulk when packing it in an overlapping manner becomes large and the screen is easily damaged in the printing process.

[0004]

However, when the above-described anti-scratch mark is applied to a copper conductor substrate made of, for example, inexpensive copper having excellent migration resistance and used as a conductor material of a circuit pattern, a thick film is formed. At the stage of forming the resistor, it has been found that there is a problem that irregularities due to foaming are formed on the surface of the anti-scratch mark. When such unevenness occurs, the screen may be damaged by the anti-scratch mark in a thick film screen printing process for forming a thick film insulating layer, a resin film, etc. after the formation of the thick film resistor. Is significantly reduced.

[0005] The present inventors have revealed that intensive studies on the above problems, Cu-Ni system is selected as the resistor material in the copper conductor substrate, LaB ₆ based, a combination of SnO ₂ thick film resistor I found that it was one of the reasons. In other words, although the reason is not clear, LaB ₆ and
In circuit patterns using both SnO ₂ -based thick-film resistors, it was found that foaming and concavity and convexity occurred only when both were selected as constituent layers of the anti-scratch mark. Moreover, it has been clarified that this problem occurs not only in the case of the copper conductor substrate but also in the case of using other conductor materials in a thick film circuit board provided with both of these two types of thick film resistors. The present invention has been made based on such knowledge, and an object of the present invention is to provide a rubbing prevention mark having no unevenness on its surface.

[0006]

In order to achieve the above object, the gist of the present invention is to provide a circuit pattern comprising a plurality of types of thick films formed by using a thick film screen printing method. At the position on the surface of the thick film circuit board that does not overlap with the circuit pattern, a plurality of thick films including the thick film resistor layer are laminated at the same time as the circuit pattern using the thick film screen printing method, with a height higher than the maximum height. The anti-scratch mark formed, (a) the thick film resistor layer, La
It is to include one of the layers comprising a layer and SnO ₂ thick film resistor consists of B ₆ based thick film resistors.

[0007]

In this manner, the thick film resistor layer included in the anti-scratch mark includes one of the LaB ₆ thick film resistor and the SnO ₂ thick film resistor and does not include the other. The occurrence of irregularities due to foaming on the surface due to the inclusion of them is suitably suppressed.

[0008]

In another embodiment of the present invention, preferably, the plurality of thick films include a thick conductor layer, a thick resistor layer, and a thick insulator layer. With this configuration, the thick-film conductor layer and the thick-film insulator layer also form part of a plurality of thick films constituting the anti-scratch mark, so that only the thick-film resistor layer or the thick-film resistor layer is formed. As compared with the case where the anti-scratch mark is formed from only one of them, the height can be easily secured.

Preferably, the thick-film resistor layer is formed by stacking three or more thick-film resistors. In this case, since the number of stacked thick-film resistors is sufficiently large, a sufficient height for protecting the circuit pattern can be reliably obtained in combination with the thick-film conductor layer and the thick-film insulator layer. .

Preferably, the thick-film resistor layer includes:
At least a LaB ₆ -based thick film resistor is included. In this case, since two or three types of LaB ₆ -based thick film resistors are usually used for one circuit pattern, the SnO ₂ -based thick film resistor that often uses only one type is rubbed. The height can be easily secured as compared with the case where the prevention mark is selected as a constituent layer. More preferably, the above-mentioned thick film resistor layer contains a Cu-Ni based thick film resistor. Even when the LaB ₆ thick film resistor and the Cu—Ni thick film resistor are superimposed, foaming does not occur, so that the superposition of these makes it easier to secure the height.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a plan view showing an entire thick film circuit board 12 to which a rubbing prevention mark 10 according to one embodiment of the present invention is applied. In the drawing, a thick film circuit board 12 is formed by applying a thick film printing paste by using a thick film screen printing method in a circuit pattern region 16 provided on an inner peripheral portion of one surface of an alumina substrate 14, for example, and firing it. And a circuit pattern including a thick-film conductor, a thick-film resistor, a thick-film insulator, and the like. This circuit pattern is formed by repeating printing, drying, and firing in a predetermined pattern for each type of conductor, resistor, insulator, or the like in which one or more types are used. However, as will be described later, for some thick film resistor pastes, other thick film resistor pastes or the like are applied after drying and before firing, unless there is a problem in characteristics, and a plurality of types of thick film resistor pastes are applied. Are fired simultaneously (c
o-firing)

The rubbing prevention marks 10 are formed on the alumina substrate 14 on the surface on which the circuit pattern is formed, for example, at four corners outside the circuit pattern region 16, that is, at four positions not overlapping with the circuit pattern. It is provided in. The anti-scratch mark 10 is formed at the same time when a thick film printing paste for forming the circuit pattern is applied in a predetermined pattern using a thick film screen printing method in the process of forming the components of the circuit pattern described above. It is formed by applying a paste, and has a substantially circular plane shape with a diameter of, for example, about 2 (mm).

FIG. 2 is a view for explaining a cross-sectional structure of the anti-scratch mark 10 by enlarging a cross section taken along line II-II in FIG. The anti-friction mark 10 is, for example, an alumina substrate 14
A plurality of layers, for example, five thick films 20, 22, 2,
4, 26 and 28, one side of which
The height from 8 is about m = 70 to 80 (μm). The first layer 20 constituting the lowermost layer is made of the same material as the thick film conductor 30 such as a wiring of a circuit pattern or a pad, and has a thickness of about 5 to 20 (μm) similar thereto. With dimensions. The first layer 20 and the thick-film conductor 30 are, for example, thick-film copper generated by applying a thick-film copper paste on the substrate 14, drying and firing.

The second layer 22 located on the first layer 20
Is, for example, several tens to several hundreds (m
Ω / □), for example, the same material as the first resistor having a low resistivity of about 40 (mΩ / □), and a similar thickness of about 5 to 20 (μm). Have.
The second layer 22 and the first resistor layer are made of, for example, Cu-Ni.
The thick film resistor paste is placed on the substrate 14 (strictly speaking,
The second layer 22 is a Cu-Ni-based thick film resistor formed by applying the entirety of the second layer 22 on the first layer 20, drying and firing.

The third layer 24 and the fourth layer 26 located on the second layer 22 are, for example, about several tens (Ω / □) to several (kΩ / □) of the resistors of the circuit pattern, respectively. For example, about 50 (Ω / □), about 1 (kΩ / □), or 5 (k
Ω / □) is made of the same material as the second or third resistor 32 having a medium resistivity of about Ω / □, and has a thickness dimension of, for example, about 5 to 20 (μm). . The third layer 24, the fourth layer 26, the second resistor, and the third resistor 32 are made of, for example, a LaB ₆ thick film resistor paste on the substrate 14.
Above (strictly speaking, the third layer 24 is the whole of the second layer 2
2, the fourth layer 26 is entirely on its third layer 24)
LaB ₆ produced by applying, drying and baking
It is a system thick film resistor. Usually, the above-mentioned LaB ₆ -based resistor paste is applied after drying the above-mentioned Cu-Ni-based resistor paste, and after drying, they are simultaneously fired. That is, the third layer 24 is applied thereon after the second layer 22 is dried, and the fourth layer 26 is applied thereon after the third layer 24 is dried. 26 are fired simultaneously. In the drawing, the first of the circuit patterns
This shows a range in which neither the resistor nor the second resistor exists, and only the third resistor 32 exists on the thick film conductor 30.

The fifth layer 28 located on the uppermost layer includes a protective glass 34 for protecting the thick film conductor 30 of the circuit pattern, the first resistor, the second resistor, the third resistor 32, and the like. 5-20
(μm). These fifth layers 28
The protective glass 34 is formed by applying a lead borosilicate thick film glass paste on the substrate 14 (strictly speaking, the entirety of the fifth layer 28 is disposed on the fourth layer 26), followed by drying and firing. This is a thick-film insulator layer generated as a result.

The anti-friction mark 1 constructed as described above
The surface of each of the constituent layers 20 to 28 of No. 0 is smooth, and no irregularities due to foaming or the like are formed thereon. Therefore, when the circuit pattern and the anti-scratch mark 10 are simultaneously formed using the thick film screen printing method as described above, the surface of the anti-scratch mark 10 in the forming process is always kept smooth. Therefore, even if the screen comes into contact with the anti-scratch mark 10, which gradually becomes higher than the circuit pattern in the process of forming the circuit pattern, damage to the screen due to the contact is unlikely to occur, thereby suppressing a reduction in the life of the screen.

That is, in this embodiment, the thick film resistor layer included in the anti-scratch mark 10 is made of Cu--Ni or La
Be those that are composed of only B ₆ based resistor, since it does not contain SnO ₂ based resistors, foaming occurs in the formation process of preventing mark 10 rubbing, and by extension that irregularities on the surface caused It is suppressed.

In FIG. 2, the thick film conductor 3
The part 36 of the circuit pattern in which the 0, the third resistor 32, and the protective glass 34 are laminated is the highest laminated part in the circuit pattern, and the height dimension from one surface 18 is c = 50. About 60 (μm). Therefore, in this embodiment, the anti-scratch mark 10 is formed about 20 (μm) higher than the maximum height of the circuit pattern.
That is, the anti-scratch mark 10 is formed by the thick film resistor layer (second
Layer 22 to the fourth layer 26) and a thick conductor layer (the first layer 2).
0) and the thick-film insulator layer (fifth layer 28), the thick-film resistor layer is composed of three layers.
Since the circuit pattern is formed sufficiently high with respect to the circuit pattern in the circuit pattern region 16, the circuit pattern is suitably protected from damage due to physical contact during handling or the like.

By the way, the above-mentioned rubbing prevention mark 10
Thick film resistor layer is included in a part of its height direction,
As the thick-film resistor layer is made of LaB ₆ based resistivity of Cu-Ni-based resistors and two layers of one layer as described above, in the circuit pattern area 16, for example three approximately LaB ₆ based resistivity In addition to these, about two types of SnO ₂ -based resistors and the like are also provided. That is, in the present embodiment, the rubbing is performed only during the formation of three types of thick film resistors of Cu-Ni-based and LaB ₆ -based selected from about six or more types of these thick-film resistors in total. The thick film printing paste is applied to the position where the prevention mark 10 is formed, and the thick film printing paste is applied only to the circuit pattern region 16 when another thick film resistor is formed. This is to suppress the occurrence of irregularities on the surface of the rubbing prevention mark 10. Hereinafter, the results of an experiment on the occurrence of the unevenness will be described.

Table 1 below shows the thick film printing paste used in the experiment for each layer to be laminated. For the first layer, a Cu-based conductor paste constituting the conductor layer 30 and the first layer 20 is used. The second to fourth layers are Cu-Ni based resistors,
Three types are selected and used from a total of six types of LaB ₆ type resistor and SnO ₂ type resistor paste. The Cu—Ni-based thick film resistor paste A is for forming the first resistor and the second layer 22, and is composed of LaB ₆ -based thick film resistor pastes B to B.
D is for configuring any one of the second resistor, the third resistor 32 and another resistor in the circuit pattern, and any two of them are used for the anti-scratch mark 10. ing. Table 2 below shows combinations for each sample. In the fifth layer, the protective glass 34 is used.
And a lead borosilicate-based insulating paste for forming the fifth layer 28 is used. Such pastes were sequentially applied in the same pattern using a thick film screen printing method, dried, fired and laminated to evaluate the appearance and the film thickness. However, Cu-Ni
The system resistor and the LaB ₆ system resistor were simply applied and dried, and then the following pastes were applied in layers and fired at once. The firing was performed in a nitrogen atmosphere. The maximum temperature was 900 (° C) for all conductors and resistors, and 650 for insulators.
(° C.). In addition, SnO ₂ -based thick film resistor pastes E and F
Used two types having different resistivity from each other. Table 1
In the above, "resistivity" is a sheet resistance value of a resistor film generated from each resistor paste, and "dry film thickness" is a target film thickness value after drying (set value). The target value of the total film thickness of one to five layers was 70 to 90 (μm).

[0023] [Table 1] material resistivity dry film thickness ([mu] m) 1-layer Atsumakudo paste 22 Cu-Ni paste A 40 (mΩ / □) 25 LaB 6 based paste B 50 (Ω / □) 22 2~ LaB ₆ paste C 1 (kΩ / □) 22 4th layer LaB ₆ paste D 5 (kΩ / □) 22 SnO ₂ paste E 100 (kΩ / □) 25 SnO ₂ paste F 300 (kΩ / □) 25 Fifth layer Glass paste 20

[Table 2] No. Resistor combination Appearance Film thickness (μm) 1 A, B, C good 68-78 2 A, B, D good 73-78 3 A, C, D good 72-804 B , C, D good 68-745 A, C, E foam ─── 6 A, D, E foam ─── 7 C, D, E foam ─── 8 A, C, F foam ─── 9 A , D, F foam ─── 10 C, D, F foam ───

The evaluation results are as shown in the “Appearance” and “Film thickness” columns of Table 2. The appearance was examined by using a stereoscopic microscope for the presence or absence of foaming or peeling, and those showing no abnormality were rated "good". The film thickness is measured by a surface roughness meter (for example,
The maximum value of the concavities and convexities on the substrate 14 detected by using Surfcom manufactured by Tokyo Seimitsu Co., Ltd. was defined as the film thickness. However, the appearance is 4
After the firing of the layer, that is, before and after the formation of the fifth insulating layer, the film thickness was evaluated after the formation of the fifth layer. As is clear from the results shown in Table 2, the resistor pastes A to D
In any combination of (Cu-Ni system and LaB ₆ based) foaming was not observed at all, it was possible to obtain a suitable thickness. The effect was also confirmed by changing the stacking order of the resistor layers (the second to fourth layers), but no change was observed.

On the other hand, the resistor paste E or F
In the combination including, that is, the combination including both the LaB ₆ system and the SnO ₂ system, regardless of the presence or absence of the Cu-Ni system,
Foaming occurred during the firing of the fourth layer (that is, the SnO ₂ -based resistor), and the anti-scratch mark 38 having an uneven surface was formed as shown in FIG. Such uneven shape,
The screen is damaged in the thick film screen printing for forming the fifth insulator layer. Therefore, in the anti-scratch mark 10, in order to avoid damage to the screen, the resistor layer constituting the mark is made of Cu-Ni based material.
It consisted of only LaB ₆ resistors. The formation of the fifth layer and the evaluation of the film thickness were omitted for the combination in which the foaming occurred.

While the embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be embodied in still another embodiment.

For example, in the embodiment, the case where the present invention is applied to a copper conductor substrate provided with a circuit pattern using a copper-based material as a conductor on an alumina substrate 14 has been described. The same applies to other ceramic substrates such as mullite and glass substrates, etc., and the conductor material is not limited to copper-based materials, and similarly when various conductors such as gold, silver, platinum, and palladium are used. Applied.

Further, in the embodiment, the case where the anti-scratch mark 10 includes only the Cu—Ni-based and LaB ₆ -based resistors as the thick-film resistor layer has been described.
This can be enjoyed if both the LaB _6- based resistor and the SnO ₂ -based resistor are not used together. That is, for example, when it contains no Cu-Ni-based resistor, i.e. a combination of a case and, or Cu-Ni based and SnO ₂ based resistors constituting only just LaB ₆ based resistor or SnO ₂ based resistors The same applies to such cases as the above.

Further, in the embodiment, the anti-scratch mark 10 includes the first layer 20 made of a thick-film conductor, the second layer 22, the third layer 24, the fourth layer 26 made of a thick-film resistor, and the thick-film insulation. The case where the fifth layer 28 composed of the body is composed of five layers has been described, but the number of constituent layers is appropriately changed according to the individual film thickness and the required height dimension. For example, when a sufficient thickness dimension can be ensured only by the resistor layer, the first layer 20 and the fifth layer 28 may not necessarily be provided. In addition, the number of resistor layers is appropriately changed, and the number of resistor layers may be one or two, or four or more.

In the embodiment, the case where the anti-scratch marks 10 are provided at the four corners of the alumina substrate 14 has been described. Circuit pattern area 1
The present invention is also applicable to the case where it is provided at another position such as inside 6.

Although not specifically exemplified, the present invention
Various changes can be made without departing from the gist of the invention.

[Brief description of the drawings]

FIG. 1 is a plan view showing a thick-film circuit board to which a rubbing prevention mark of the present invention is applied.

FIG. 2 is a view showing a cross section taken along line II-II of FIG.

FIG. 3 is a diagram illustrating a state in which a conventional anti-scratch mark is formed.

[Explanation of symbols]

10: anti-scratch mark {22: second layer, 24: third layer, 26: fourth layer} (thick film resistor layer)

Claims (2)

[Claims] A thick-film resistor is provided on a surface of a thick-film circuit board provided with a plurality of types of thick-film circuit patterns formed by using a thick-film screen printing method so as not to overlap the circuit pattern. a prevention marks rubbed formed by high laminated than its maximum height at the same time as the circuit pattern using a thick film thick film screen printing multiple layers including layers, the thick-film resistor layer, LaB ₆ A rubbing prevention mark for a thick film circuit board, comprising one of a layer made of a thick film resistor and a layer made of a SnO ₂ thick film resistor. 2. The multi-layer thick film comprises a thick-film conductor layer, a thick-film resistor layer, and a thick-film insulator layer, and the thick-film resistor layer is formed by laminating three or more thick-film resistors. The mark for preventing abrasion of a thick film circuit board according to claim 1, wherein the mark is formed.