JPS6258601A - Printed resistance substrate - 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 [Field of Industrial Application] The present invention relates to printed resistive substrates. In particular, the present invention relates to a printed resistor substrate that can improve the heat resistance properties of printed resistors and prevent thermal deterioration, shrinkage, and warping of the base material.

[Summary of the invention]

The printed resistor substrate of the present invention has a resin layer formed by photo-curing a photocurable photosensitive composition between the base and the printed resistor, thereby causing changes in the base and resistance value. This prevents such problems and also makes mass production possible.

[Conventional technology]

Conventionally, in printed resistor substrates, a resin layer has been interposed as an undercoat between the base and the printed resistor. As this resin material, thermosetting epoxy or phenol ink is recommended due to its adhesion to other layers (printed resistor, copper foil that is its lead, i-jumper, overcoat, symbol, etc.). Mainly used. However, this conventional thermosetting ink has a 130 to 15
Because it passes through the heat curing process at 0°C, there are problems in that the base material undergoes significant thermal deterioration, shrinkage, and warpage. Another problem is that the heat curing time is long (10 to 30 minutes), making it unsuitable for mass production.

On the other hand, conventionally, solder dipping is often performed during the manufacturing process of printed resistor boards, which adds heat, but since the conventional resin materials mentioned above have a large thermal contraction, this shrinkage stress makes it difficult to adhere to the base or resistor. The force may be degraded and the resistance properties may be adversely affected. Further, the heat generated by the solder dip may cause a drift (variation in resistance value) of the resistor, and this problem is particularly noticeable in a structure in which a printed resistor is formed on the pattern side of the substrate. In order to prevent this drift, it is desirable that the undercoat resin material has little change due to thermal changes.

However, the conventional thermosetting ink has high shrinkage stress,
The resistance value drift is large.

There are two types of conventional printed resistor board structures: one in which the resistance is formed on a partial surface opposite to the wiring pattern surface, and the other in which the resistance is formed on the pattern surface. In the former structure, the heat of the solder is not directly applied to the printed resistor, and the fluctuation in resistance value due to heat does not become so large. For example, when a conventional thermosetting ink was used as an undercoat, the drift after soldering was within ±5% (5 seconds diff at 260°C).

(tested twice).

However, in the latter structure where resistance is formed on the pattern surface,
Drifting is a big problem. For example, the structure shown in Figure 3 (A) (
In structure A), a pattern 2 is formed of copper on a substrate 1, and a printed resistor 4 is formed on the pattern 2 side. An undercoat 5 is formed on the part where the printed resistor 4 is to be formed, the printed resistor 4 is formed on the undercoat 5 with carbon paste, and a silver electrode 6 is formed over the printed resistor 4 and the copper pattern 2. A top coat 7 is applied to cover the printed resistor 4, the silver electrode 6, and a part of the pattern 2.
When solder dipping is performed on this structure A, the heat of the solder is almost directly applied to the printed resistor 4, and therefore the drift of the resistance value due to heat is also very large.

The structure (Structure B) shown in FIG. 3CB) also has the printed resistor 4 formed on the pattern 2 side, and has a similar problem.

In this structure B, a pattern 2 is formed of copper on the substrate l and an undercoat 5 is applied as in structure A, but then a silver electrode 6 connected to the pattern 2 is formed, and two silver electrodes 6 are formed.
A printed resistor 4 is formed between the two. In this structure B, since the connecting portion between the silver electrode 6 and the printed resistor 4 can be made smaller as a whole, the influence of diffusion from the interface can be reduced. However, on the other hand, since the printed resistor 4 is long, it may shrink more when heat is applied, resulting in a larger drift.

As mentioned above, devices in which resistance is formed on the pattern surface have large resistance fluctuations due to solder dips, so they have not been put into practical use. There are various soldering techniques such as not only solder dip but also reflow one-way method, tunnel furnace method, etc., but in any case, this problem is unavoidable because heat is added, and in fact, reflow one-way method heats at a higher temperature. Therefore, this problem is large. Although this problem is small in the configuration in which the resistor is formed on the component surface, the space in which other components can be mounted becomes smaller, making it impossible to achieve higher board density. . Therefore, in order to further improve the density, size, and operation speed of the substrate, it is desired to put into practical use a structure in which a resistor is formed on the pattern surface. With such structures 1A and B, there is no need for through holes for the paste, there is no through hole, and it is possible to form a copper pattern under the resistor, allowing for higher density and lower costs. be.

There are various factors that can be considered to cause the drift of the resistor after heat treatment such as solder dips and other heat treatment.
dimensional change, ti6, undercoat 5, printed resistor 4
There are changes in the dimensions of itself, changes in the top coat (hander coating) 7, etc., but in the present invention, the undercoat 3
This problem can be solved by improving the material.

[Problem that the invention seeks to solve]

As mentioned above, conventional printed resistance boards require high temperatures for the undercoat material to heat cure, causing changes in the board, and the long heat curing time, making them unsuitable for mass production.Also, the resistance value is low due to large heat shrinkage stress. The problem is that it can bring about change.

An object of the present invention is to provide a printed resistance board that solves these problems.

[Means for solving problems]

In the present invention, a photocurable photosensitive composition containing as main components (a) epoxy-modified acrylate and (b) unsaturated polyester acrylate is photocured between the base of a printed resistor substrate and the printed resistor. The above object is achieved by having a structure in which the formed resin layer is interposed.

According to the present invention, (1) Since photocuring is used, the heat during curing does not become excessive, and the heat cycle is, for example, 80° C. for about 10 seconds, so that thermal deterioration, shrinkage, and warping of the substrate can be suppressed.

(2) Since the curing time is short, for example, about 10 seconds, mass production is possible.

■) Unlike conventional epoxy-based and phenolic-based inks that have high shrinkage stress (2000 to 5000 kg/d), this material has low shrinkage stress (for example, about 30 kg/-), so it has good thermal aging properties. Show the results.

(2) Good adhesion to each layer.

Examples of the epoxy-modified acrylate in the photocurable photosensitive composition of the present invention include epoxy-modified urethane acrylate represented by the following formula.

A. Epoxy] In this case, the molecular weight is preferably 3,000 to 5,000. Note that the above [urethane] is, for example, polyurethane obtained from a trifunctional monomer.

Further, as the unsaturated polyester acrylate in the photocurable composition of the present invention, the following compounds can be exemplified. That is, 2-hydroxyethyl acrylate, neopentyglycol diacrylate, 2-hydroxyethyl methacrylate, neobenziglycol dimethacrylate,
Ethylene glycol diacrylate, triethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, 1
．． These include 6-hexanediol diacrylate, trimethylolpropane triacrylate, 1,6-hexanediol diacrylate, and trimethylolpropane trimethacrylate. In addition, various unsaturated polyester acrylates can be appropriately employed. The molecular weight is preferably about 100 to 1000.

In a preferred embodiment, the photocurable composition of the present invention includes a base resin containing epoxy-modified acrylate as a main component, a diluent monomer containing unsaturated polyester acrylate as a main component, and a polymerization initiator. filler and
It consists of an antifoaming agent and a leveling agent. In this case, 20 to 60 parts of base resin, 40 to 80 parts of diluted top resin,
It is preferable to use 1 to 3 parts of a polymerization initiator, 10 to 20 parts of a feeler, 0.5 to 2 parts of an antifoaming agent, and 0.5 to 2 parts of a leveling agent.

As the polymerization initiator, anything that has the function of initiating polymerization to cure the photocurable composition of the present invention can be used, such as benzoin ether, isopropyl benzoin ether, benzoin ethyl ether, benzoin methyl ether, α- Examples include acryl oxime ether, benzyl ketal, hydroxycyclohexylphenyl ketone, acetophenone derivatives, benzyl, benzophenone, methyl-0-benzoin benzoate, and thioxanthone derivatives.

Examples of fillers include finely divided calcium carbonate, silica, silane coupling agent coating, talc, MgO, alumina, benzoguanamine resin spherical fine powder, and crosslinked polystyrene beads.

Examples of antifoaming agents include acrylic-based, silicone-based, and fluorine-based defoaming agents.

Examples of leveling agents include acrylic ones and liquid paraffin.

As the photocurable resin composition of the present invention, an ultraviolet curable composition can be preferably used.

For example, the composition containing the above-mentioned epoxy-modified urethane acrylate can be photocured using, for example, three metal halide lamps or a mercury lamp (300 W).

In addition, the constituent materials for other parts of the printed resistance board include:
Substrates include phenol, epoxy, glass epoxy, composites, etc. Silver electrodes include epoxy-based silver pastes such as XA-208 (Fujikura Kasei) and other thermosetting resin-based ones; carbon pastes include phenolic carbon. Paste e.g. TU-100-
5゜TU-IK-5, Tu-ioK-s (7 Sahi Kaken), other thermosetting resin pastes such as phenol and epoxy, etc. As the top coat, epoxy-modified urethane acrylate used as the undercoat is used. It is possible.

By using the above constituent materials and using a photocurable photosensitive composition as an undercoat between the substrate and the printed resistor, it is possible to obtain the advantageous printed resistor substrate as described above.

[Embodiments of the invention]

Examples of the present invention will be described below. It should be noted that, as a matter of course, the present invention is not limited to the Examples shown below.

Example 1 In this example, the present invention is applied to the printed resistor substrate of structure A described above. Further, in this example, a UV (ultraviolet light) curable epoxy-modified urethane acrylate ink was used as the photocurable composition that is the material of the layer interposed between the substrate and the printed resistor.

With reference to FIG. 1, this embodiment will be explained in the order of its manufacturing steps. First, as shown by reference numeral a in FIG. 1, a pattern 2 is formed on a base 1 of a substrate. Paper-phenol (XPC-PR) was used as the material for the substrate in this example. Note that the substrate 1 may be a single-sided or double-sided substrate, or a multilayer board, and can be implemented in various embodiments.

The pattern 2 is made of copper (copper foil) or other material capable of forming a pattern, and the pattern can be formed by etching.

After the above pattern formation, an undercoat 3 is printed on the substrate 1 as shown by the reference numerals. This undercoat 3 is interposed between the base 1 and the printed resistor 4. In this example, a photocurable composition having the following composition was used as the material.

Base: 40 parts of epoxy-modified urethane acrylate (especially epoxy) Diluent monomer: 60 parts of triethylene glycol diacrylate Polymerization initiator: 2 parts of benzoin ether Filler: 15 parts of talc, coating with silane coupling agent Other: 1 part of antifoaming agent, 1 part of leveling agent 120 W/ca! of this composition using ultraviolet light. , 3 lamps, 3 m/M, 80°C, 10 seconds. A mercury or halide lamp was used as the ultraviolet light source. Here, the film thickness was set to 10 to 20 μm. This undercoat 3 is applied to the pattern 2 to be isolated.

Next, as shown by symbol C, carbon paste is printed on this undercoat 3 to form a printed resistor 4. In this example, the material is phenolic carbon paste TU-1.
Using -5 (Asahi Kaken, IQkΩ/mouth) for 0, 180
Cure for 1 hour. The film thickness was 10 to 20μ.

Next, a silver electrode 6 was printed as indicated by the symbol d. In this example, XA-208 (Fujikura Kasei) was used as the material, and the
After curing for 0 minutes, a silver electrode 6 was obtained. The film thickness was 10 to 20μ.

Next, as indicated by symbol e, a top coat 7 was printed.

In this example, the photocurable composition used for the undercoat 3 was used for the top coat 7. Curing was also carried out under similar conditions.

Characteristic evaluation of the printed resistor obtained in this example was as shown in the table below. As a comparative example, the table shows data for an example that has the same structure but uses a conventional epoxy resin for undercoat 3 (other parts of the comparative example are the same as the above example). In the table, the solder heat resistance drift is determined by performing a solder dip test at 260 t for 5 seconds twice, and the resistance value fluctuation is expressed in %. The drift after thermal aging was measured by testing at 85° C. for 1000 hours and measuring resistance value fluctuations. Thermal changes in the substrate were visually observed for color changes and other changes. The shrinkage of the substrate was measured in three dimensions, and the shrinkage rate was determined by measuring X and y in FIG. The warpage of the substrate was determined from X in FIG. Note that the sample has a size of 250 x 250 mm.

The adhesion force with each layer is the adhesion force of the undercoat to the substrate 1, which is the base, and the printed resistor 4.

As is clear from the table, the examples of the present invention are superior to, or at least as excellent as, the conventional examples in every respect. In particular, it is superior to conventional examples in that drift after thermal aging and various changes in the substrate are smaller. Note that the adhesion strength with each layer is about 50/100 with other UV curable inks other than those of the present invention.

Example 2 Next, Example 2 of the present invention will be described with reference to FIG. In this example, the present invention is applied to the printed resistor substrate of Structure B described above.

First, a pattern 2 is formed on a basic material as shown in a' in Fig. 2. Next, undercoat 3 is printed on this as shown in b'. This undercoat 3 was formed using the same UV-curable epoxy-modified urethane acrylate as used in Example-1. Next, in this example, the necessary silver electrode 6 is printed and formed here (c' in the figure). Next, 2 in the figure
Carbon paste is printed on the undercoat 3 over two silver electrodes 6 to form a printed resistor 4. next,
Top coat 7 was formed. The conditions for formation are the same as in Example-1.

In addition, the conditions of each process, the material of cloth book 1, pattern 2
, the materials of the undercoat 3, the printed resistor 4, the silver electrode 6, etc. are the same as those described in Example-1.

In this example, the same effects as in Example-1 were obtained.

〔Effect of the invention〕

As mentioned above, the printed resistance substrate of the present invention has a short curing time.
(e.g. 10 seconds), which makes it easy to mass-produce, is basically hard to cause warping or other changes during curing, has sufficient adhesion with each layer, and has low shrinkage (e.g. 1000 kg).
/- or less), and therefore resistance changes can be suppressed.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing the manufacturing process of one embodiment of the present invention, and FIG. 2 is a process diagram showing the manufacturing process of another embodiment. FIGS. 3(A) and 3(B) show a conventional example. FIG. 4 and FIG. 5 are schematic diagrams for explaining the evaluation method, respectively. 1...-Base, 2...-Pattern, 3-
----Undercoat, 4---Printed resistor. Patent Applicant Sony Corporation Patent Attorney Takazuki Takami Ubuchi-1 (A) Figure 3 W) Chi Assault Figure 4 1 Waho Shibu 4 Chumei 2 Figure 5

Claims (1)

[Claims] A photocurable photosensitive composition containing as main components (a) epoxy-modified acrylate and (b) unsaturated polyester acrylate is placed between the base of the printed resistor substrate and the printed resistor. A printed resistance board characterized by having a structure in which a resin layer formed by curing is interposed.