JPS63241902A - Manufacture of printed resistance board - 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] [Industrial Application Field] The present invention relates to a method for manufacturing a printed resistor board, and in particular, a method for preventing changes in the resistance value and variations in the resistance value of a printed resistor during the manufacturing process of the printed resistor board. The present invention relates to a method of manufacturing a printed resistor substrate.

[Summary of the invention]

When manufacturing a printed resistor board with resistors formed by screen printing technology, the present invention incorporates a heat treatment process to ensure adhesion between the solder-resistant protective layer and each layer to the resistance value adjustment process of the printed resistor. By performing this step before adjusting the resistance value, it is intended to eliminate changes in resistance value and variations in resistance value during the manufacturing process after resistance value adjustment.

[Conventional technology]

Generally, a solder-resistant protective layer is formed on the printed resistor forming the printed resistor substrate in order to protect the printed resistor from heat during the solder dipping process.

In other words, the solder resistance All is formed of, for example, photo-curing ink or thermosetting ink, and prevents a 4rL change in resistance of the printed resistor due to heat generated during solder dipping performed during the manufacturing process of the printed resistor board. It is designed to prevent this.

Conventionally, in order to manufacture this type of printed resistance board, electrodes are formed on the substrate via an insulating layer, a resistor material such as carbon paste is printed on the electrode, and then the resistor t This trimming process is performed to adjust the resistance to a predetermined value. Finally, after printing and forming a solder-resistant protective layer to cover the resistor whose resistance value has been adjusted, heat treatment is performed to harden the protective layer and ensure adhesion between each layer, thereby creating a printed resistor board. I was creating it.

[Problem that the invention seeks to solve]

In this way, conventionally, after trimming to adjust the resistance value, a solder-resistant protective layer was formed and heat treatment was performed.

For example, if a thermosetting ink is used as the solder-resistant protective layer, the printed resistance board may be heated to a temperature of 100 to 150°C.
The protective layer is cured by heat treatment with C for about 10 to 30 minutes, and when using a photocurable ink, for example, after curing by irradiation with ultraviolet rays, the protective layer is heated with C for about 10 to 30 minutes to improve the adhesion between each layer.
Heat treatment is performed at 150°C for about 10 to 30 minutes.

Therefore, in this heat treatment process, a so-called thermal history occurs in the printed resistor, resulting in a problem that resistance value changes and resistance value variations occur. That is, the conventional manufacturing method has a major problem in that the resistance value, which has already been adjusted with high precision, changes due to the final heat treatment.

-i, if the tolerance of the resistance value of the finished product is within ±5% of the resistance value immediately after trimming, it is considered to be a practical problem, but with the above manufacturing method, this tolerance is about ±10%. This is a major cause of reduction in manufacturing yield and reliability of printed resistor substrates.

Therefore, the present invention has been proposed in view of the above-mentioned conventional situation, and is a printed resistor substrate that has extremely small resistance change and variation after adjusting the resistance value of the printed resistor, and has excellent manufacturing yield and reliability. The purpose is to provide a manufacturing method for.

[Means for solving problems]

In order to achieve the above object, the method for manufacturing a printed resistance board of the present invention includes forming a circuit pattern including electrodes on the board;
Next, a printed resistor is formed so as to be connected to the electrode, and then a first protective layer is formed to cover the printed resistor and subjected to heat treatment, and then the resistance value of the printed resistor is adjusted. This method is characterized in that a second protective layer is then formed.

[Effect]

In the present invention, after forming the printed resistor, the first protective layer is printed and heat-treated to ensure adhesion between each layer, and then the resistance value is adjusted. There is no change in the resistance value or variation in resistance value.

Furthermore, since a second protective layer is formed at the end to protect the printed resistor from the heat of the solder dipping process, the resistance value does not change during this soldering process.

〔Example〕

Hereinafter, a method for manufacturing a printed resistor board according to the present invention will be described in accordance with the process order with reference to the drawings.

In order to manufacture a printed resistance board according to the present invention, first, a first
As shown in the figure, a conductive film (2) is formed on a substrate (1), and a pattern resist is applied thereon to obtain a desired circuit pattern [in this example, the conductive film (2) is [shape that remains at equal intervals], after forming the coating film,
For example, 3 100W, 4m/Min mercury lamps
Cure the resist using a lamp. Next, FeC
The conductive film (2) is patterned into a predetermined shape by etching using an enochinda solution such as J2t or CuCff1□. Thereafter, the remaining resist film is peeled off using a NaOH aqueous solution to create a substrate (1) having a conductive film (2) with a desired pattern.

Here, examples of the substrate (1) include a paper-based phenolic resin laminate, a paper-based epoxy resin laminate, a glass cloth-based epoxy resin laminate, and a CEM material.

Examples include ceramic substrates.

Next, as shown in Figure 2, conductor films (2
), (2), parts (2a), (2b), and the entirety of the conductor film (2) at the central position, an insulating layer (3) called an undercoat layer is formed by printing.

The above-mentioned undercoat i (3) is a so-called solder resist formed by ordinary printing technology, and the printed solder resist is heated at 130 to 150 mL for 10 to 30 minutes.
Cured by applying heat at °C.

Next, as shown in FIG.
x (4) , (4) is formed. As a result, these electrodes (4), (4) are connected to the conductive film (2) at both left and right end positions.
, (2) is now electrically connected.

As the snow shovel (4), a conductive paste is suitable, and in this example, Ag paste was used, and after being printed, it was heated and hardened at a temperature of 130 to 150'C for 10 to 30 minutes.

After that, as shown in FIG.
) A resistor (5) is formed so as to cover the undercoat (3) between ). For example, carbon paste is suitable for the resistor (5), and the method for forming this is to apply it by a printing technique such as screen printing, and then apply it to a
It can be formed by heating and curing at a temperature of 150 to 180°C for 0 minutes.

Note that the electrode forming step shown in FIG. 3 and the resistor forming step shown in FIG. 4 may be performed one after the other, and the electrodes may be formed after the resistor is formed.

Subsequently, as shown in FIG. 5, a layer was formed to cover the conductor layer (2), undercoat layer (3), electrode (4), and resistor (5) laminated on the substrate (1). 1 protective layer (6
) is applied and cured by heat treatment.

The purpose of this first protective layer (6) is particularly to ensure adhesion with each layer and to prevent damage to the resistor (5) during the resistance value adjustment process described later. The thickness l of this first protective film (6) is preferably set to about 5 to 20 μm. In other words, when the film thickness l is 5 μm or less, the 3I7! ! The above-mentioned effect due to (6) is diminished, which is not preferable. On the other hand, if the film thickness 2 is set to 20 μm or more,
If the above-mentioned resistance value adjustment is performed using a laser beam, for example, trimming requires a considerable amount of time and a large laser power, and during this trimming, heat is diffused into the resistor (5), causing resistance value fluctuations. Undesirable.

Here, the first protective layer (6) is preferably made of a material whose shrinkage residual stress due to thermal shrinkage is within the range of 200 to 900 kg/cffl. This shrinkage residual stress is 900 kg
/cff1 or more is not preferable because when solder dipping is performed, the stress applied to the printed 1 resistor (5) becomes large and the change in resistance value becomes significant.

As the first protective layer (6) that satisfies these requirements, it is preferable to use, for example, a base resin mainly composed of a cresol novolak type epoxy resin and an organic film mainly composed of an acrylate diluent monomer.

The cresol novolak type epoxy resin used as the base resin for the above-mentioned organic coating is used to improve the mechanical coating strength, and is expressed by the following formula.

(However, in the above formula, R represents hydrogen or a -valent hydrocarbon group, and n represents an integer.) The molecular weight of the cresol novolak type epoxy resin is 3000 to 10000.
It is preferable that the degree of

Further, the base resin of the organic coating may be one obtained by adding an epoxy-modified urethane acrylate to the cresol novolac type epoxy resin.

The above-mentioned epoxy-modified urethane acrylate is a photocurable resin and is used to reduce thermal shrinkage of the printed resistor after soldering and to reduce resistance value fluctuation, and is expressed by the following formula.

In this case, the molecular weight of the epoxy-modified urethane acrylate is preferably about 2,000 to 3,000.

The above-mentioned epoxy-modified urethane acrylate and Talesol novolac-type epoxy resin are basically preferably used in a blending ratio of epoxy-modified urethane acrylate:cresol novolac-type epoxy resin - 1:1. However, the coating film hardness required to improve the cheek appearance of the printed resistance board is required to be within the range of 4H to 91-1. Therefore, from the viewpoint of the coating film hardness conditions after curing of the above-mentioned epoxy-modified urethane acrylate and Talesol novolac-type epoxy resin, epoxy-modified urethane acrylate: Cresol novolak-type epoxy resin =
The ratio is preferably 7:3 or more. Therefore, considering only the strength of the coating film, only Talesol novolak type epoxy resin may be used as the heath resin as the organic coating material.

Furthermore, from the viewpoint of photocuring conditions and shrinkage stress of the organic coating material, the ratio of epoxy modified urethane acrylate:cresol novolak type epoxy resin is preferably in the range of 7:3 to 6:4.

In order to improve properties and adjust viscosity, the above-mentioned organic coating material is made by adding a diluent monomer and, if necessary, a base resin containing the above-mentioned Talesol novolak type epoxy resin as a main component, in combination with epoxy-modified urethane acrylate. Then, a polymerization initiator, filler, and antifoaming agent are added. In this case, 20 to 100% of cresol novolac type epoxy resin is used.
Part by weight, 0 to 10 epoxy-modified urethane acrylate
0 parts by weight, 40 to 80 parts by weight of the diluent monomer, 1 to 3 parts by weight of the polymerization initiator, 10 to 20 parts by weight of the filler, and 0.5 to 2 parts by weight of the antifoaming agent.

Examples of the diluent monomers include 2-hydroxyalkyl acrylate, 2-hydroxyalkyl methacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, 1.6-hexanediol diacrylate, 1.6-hexanediol diacrylate, neopentylene rangelicol diacrylate,
Neopentylene gelicol dimethacrylate Triethylene glycol diacrylate, triethylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate and other unsaturated polyester acrylates, unsaturated polyester methacrylates (molecular weight 100-1000)
).

The above-mentioned polymerization initiator is added to initiate polymerization to cure the organic film, and examples thereof include benzoin ether, isobrobylhenzoin ether, benzoin ethyl ether, benzoin methyl ether, and α-acryloxime ether.

Penzil Ketal. Hydroxycyclohexyl phenyl ketone, acetone derivative, hensyl, benzophenone,
Methyl-〇-benzoin benzoate, thioisanthone 8R4 body, etc. are mentioned.

Examples of the filler include finely divided calcium carbonate, Nlica, talc coated with a silane coupling agent, talc, MgO, alumina, snow powder, spherical fine powder of Henzoguanamine resin, and crosslinked polystyrene beads.

Examples of the antifoaming agent include acrylic, silicone,
Examples include halogen-based antifoaming agents.

The solder-resistant protective material having the above-mentioned composition is used as a photocurable resin, and the photocuring method is curing with ultraviolet rays. In that case, for example, 2 to 3 80 to 100 W metal halide lamps or mercury lamps, 6 m
/Min or more, and the temperature is 70 to 0°C.

Or the first protection above! As (6), a thermosetting resin such as an epoxy resin may be used. However, even in this case, the shrinkage residual stress after thermosetting is 200 to 900 kg.
/cr? Using a material within the range of l, the film thickness is between 5 and 20
Let it be μm. For example, the shrinkage residual stress of an epoxy thermosetting resin is as large as 2,000 to 5,000 kg/c+l, and cannot be used as is, but it can be used by diluting it.

As described above, the printed resistor (5) is coated with the first protective layer (G
), in order to adjust the abrasive resistance of this resistor (5), as shown in Fig. 6, a conductor film located in the center (
2) Part of the printed resistor (5) formed on the pattern (
5a) and adjust it to a predetermined resistance value.

As means for adjusting the resistance value, there are a so-called laser trimming method using a laser beam and a method using mechanical means such as sandblasting, but laser trimming is preferable from the viewpoint of processing reliability and damage to peripheral members.

In this way, in the present invention, the printed resistor (5) is coated with the first protective N (6), and after being subjected to heat treatment to ensure adhesion between the protective layer (6) and each layer, the resistor is coated with the first protective layer (6). Since the value is adjusted, the change in resistance value during this heat treatment process is eliminated. At the same time, since the adhesion of the protective layer (6) is ensured, mechanical strength is also ensured.

Finally, the above printed resistor (5
), as shown in FIG. 7, a screen printing method was used to form a second protective layer (7) with a predetermined thickness so as to cover the first protective IJ (6). formed with
Thereafter, the protective layer (7) is cured to complete the printed resistance board.

Here, the second protective layer (7) is mainly composed of Hose resin, which is mainly based on the Talesol novolac type epoxy resin used in the first protective layer (1), and an acrylate-based diluent. A photocurable resin such as a resin is used. Moreover, it is more preferable to form the second protective layer (7) in two to three stages, rather than applying and curing it all at once.

In this way, in the present invention, since a photocurable resin is used for the second protective layer (7), it can be cured simply by irradiating the protective layer (7) with light. Therefore, the printed resistor (5) on the obtained printed resistor substrate is controlled to have a resistance value substantially equal to the resistance value after the resistance value adjustment. That is, in the printed resistance board to which the present invention is applied, the change in resistance value can be controlled within a predetermined resistance value tolerance range (±5%), so the reliability and manufacturing yield of the printed resistance board are significantly improved.

Further, the shrinkage stress of the second protective layer (7) is
The protective layer (6) of the resistor (5) acts as a cushion.
), so there is no concern that the resistance value of the resistor (5) will change significantly due to the shrinkage stress of this second protective layer (7).

Furthermore, the printed resistor (5) is covered with the first protective layer (6), and the protective layer (6) is heat-treated to ensure adhesion with each layer. The mechanical strength of the printed resistor board obtained is comparable to that of the conventional one.

The present inventors investigated changes and variations in the resistance value of printed resistor boards created through the above-described steps.

That is, the first protective film (6) and the second protective film (7)
A mixture of the compositions shown below was used.

Epoxy-modified urethane acrylate 60 parts by weight Cresol novolac type epoxy resin 50 parts by weight Diluted hexamer: Triethylene glycol noacrylate
22ffiBt part Polymerization initiator: benzoin ether 2.3 parts by weight Filmer: ゛ Silane cuffing agent coating 1 piece 13ffiB
Part t Antifoaming agent 1 layer Part Then, the first protective layer (6) is printed and cured, and the resistance value variation after adjusting the resistance value of the printed resistor and the completed second protection layer (7 ) was investigated for the variation in resistance value after forming. The results are shown in Figure 8 (A) and Figure 8 (
Shown in B). Note that the number of measurements was 7000 for each.

As is clear from FIG. 8(A) and FIG. 8(B), it has been confirmed that by applying the present invention, the variation in the resistance value of the obtained printed resistor substrate can be controlled within ±2%. Ta. For comparison, we also investigated the change in resistance value of printed resistor boards made using the conventional manufacturing method, and found that the resistance value after heat treatment after adjustment of the resistance value varied by about 0 to -6%. ±10% for finished products
There was a degree of variation.

Therefore, it has been found that by applying the present invention, changes and variations in resistance values can be significantly improved, and a printed resistor substrate with excellent manufacturing yield and reliability can be provided.

〔Effect of the invention〕

As is clear from the above explanation, after forming the printed resistor of the present invention, the first protective layer is printed and heat treated to ensure adhesion between each layer, and then the resistance value is adjusted. Therefore, during this heat treatment process, the resistance value may change,
Alternatively, variations in resistance values do not occur. Therefore, a printed resistance substrate with excellent manufacturing yield and reliability can be obtained.

Furthermore, since a second protective layer is formed in the final step to protect the printed resistor from the heat of the solder dip process, the resistance value will not change due to the solder dip.

[Brief explanation of drawings]

1 to 7 show an example of a method for manufacturing a printed resistor board according to the present invention according to the process order.
Figure 2 is a cross-sectional view showing the pattern etching process, Figure 2 is a cross-sectional view showing the undercoat layer forming process, Figure 3 is a cross-sectional view showing the electrode printing process, and Figure 4 is a cross-sectional view showing the printed resistor printing process. 5 is a cross-sectional view showing the first protective layer forming step, FIG. 6 is a plan view showing the resistance value adjusting step, and FIG. 7 is a cross-sectional view showing the second protective layer forming step. FIG. 8(A) and FIG. 8(B) are characteristic diagrams showing the measurement results of resistance value variations in the printed resistor substrate produced according to the present invention, and FIG. 8(A) is a characteristic diagram after the resistance value adjustment. FIG. 8(B) shows the measurement results of the completed printed resistor board. 1...Substrate 2...Conductor film 3...Undercoat i 4...Electrode 5...Printed resistor 6...First Protective layer 7... Second protection 3i coral Figure 1 Figure 3 Figure 5 Figure 2 Figure 4 Figure 6 Figure 7 Figure 8 Figure 9 Procedural amendment (method) % formula ■, Indication of the following 1986 Patent side No. 75098 2, Name of the invention M-soaking method for printed resistor substrates 3, Relationship with the case of the person making the amendment Patent applicant address 6-7 Kitashinyo, Tokyo Parts Co., Ltd. No. 35 name (2
18) Sony Co., Ltd. Company Representative: Norio Oga 4, Agent Address: 2-6-4-Toranomon, Minato-ku, Tokyo 105, No. 1
1 Mori Building 11th floor Aim (508) 826G &+5 Showa 6
June 3, 1982 (Shipping date: June 30, 1986) 6. Subject of amendment 7. Contents of amendment (1) Specification, page 18, line 4 to line 5 [No. 8
It is shown in Figure (A) and Figure 8 (B). (2) In the same book, page 18, lines 7 to 8, the statement ``shown in Figures 8 and 9. The statement "As is clear from Figure CB)" has been amended to "As is clear from FIGS. 8 and 9." (3) In the same book, page 20, lines 4 to 8, “
No. 85 (A)...Respectively. '' has been amended as follows. "Figures 8 and 9 are characteristic diagrams showing the measurement results of resistance value variations in the printed resistor substrate produced according to the present invention, and Figure 8 shows the measurement results after adjusting the resistance value, and Figure 9 11 shows the results of the completed printed resistor board, respectively.

Claims (1)

[Claims] A circuit pattern including electrodes is formed on a substrate, a printed resistor is formed so as to be connected to the electrode, and a first protective layer is then formed to cover the printed resistor. A method for manufacturing a printed resistor substrate, which comprises: performing heat treatment, adjusting the resistance value of the printed resistor, and then forming a second protective layer.