JPS6269583A - Cover lay thin article - 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] U 1 No A
O) relates to a thin coverlay having excellent adhesiveness and good moisture resistance. More specifically,
(A) an ethylene copolymer having at least an ethylene unit and at least one unit selected from the group consisting of a carboxylic acid unit, a dicarboxylic acid unit, an anhydride unit thereof, and a halfester unit thereof; and (B) at least an ethylene unit and a hydroxyl unit. , an uncrosslinked mixture of ethylene copolymers containing at least one unit selected from the group consisting of amine units and glycidyl units, or a thin product made of a crosslinked product thereof, and lamination of any of the above ethylene copolymers. The present invention relates to a thin coverlay film made of a thin coverlay material that not only has excellent heat resistance, water resistance, and electrical insulation properties, but also has thermal adhesive properties, and a thin adhesive film-like material that has good heat resistance. The purpose is to provide:

Ryosuetachi and Semiconductor Industry has integrated circuits ranging from flight back to MSL,
With the development of LSI and ultra-LSI, circuit density has increased, reliability has improved, and prices have been reduced. In particular, as mounting becomes more dense and multi-layered, and devices become smaller, die-cut, lighter R, and high-quality, low-volume production progresses, electrical insulation of circuit parts, rust prevention, dirt, and damage will become more important. For protection purposes, circuit protection coverlay materials have come to play an important role. Generally, a film type in which an adhesive is applied to an insulating film and a liquid thermosetting or UV curing type adhesive resin paint are used as coverlay materials.

Currently, polyester films, polyimide films, polyamide films, etc. are used as coverlay films. Typically, a thermoset resin (e.g.
An adhesive made of epoxy resin is used.

The characteristics required for a coverlay film are as follows:
It has excellent adhesion to copper foil, electrical insulation, heat resistance against /\\dak, long shelf life, and workability.

The polyester film and polyimide film described above have extremely poor adhesion to circuits and the like, so it is necessary to use an adhesive. This not only increases the number of work steps, but also deteriorates the heat resistance of the adhesive, resulting in a decrease in heat resistance to solder and adhesion at relatively high temperatures.

Furthermore, when an epoxy-based heat-resistant adhesive is used, problems such as poor temperature resistance and internal circuit deterioration due to humidity occur. In addition, the process of applying adhesive to the film and the accompanying drying process are not only complicated, but also increase processing costs, and the adhesive strength may decrease due to uneven adhesive application. Blisters may occur during high-temperature processing, which may cause circuit wiring to break, making it impossible to achieve the purpose of power-laying.

The present invention solves these drawbacks (problems) because of the following points:
In other words, it not only has excellent heat resistance and temperature resistance, but also can be used without using conventional thermosetting adhesives.
The object of the present invention is to obtain a thin coverlay that can be bonded by heating and pressurizing at 0°C to 300°C.

. According to the present invention, these problems are solved by: "An ethylene copolymer consisting of one type of unit and having an ethylene unit content of 30 to 99.5% by weight" [hereinafter referred to as "ethylene copolymer (A)"]
and (B) "consisting of at least ethylene units and at least one kind of unit selected from the group consisting of hydroxyl units, amine units and glycidyl units, and the content of ethylene units is 30 to 98% by weight." 5
[hereinafter referred to as "ethylene copolymer (B)"] 98 to 1% by weight of the ethylene copolymer (A) and This problem can be solved by a thin coverlay made by laminating any of the ethylene copolymers (B). The present invention will be explained in detail below.

(A) Ethylene copolymer (A) The ethylene copolymer (A) used in the present invention contains at least ethylene units and a group consisting of carboxylic acid units, dicarboxylic acid units, anhydride units thereof, and halfester units thereof. It is an ethylene copolymer containing 30 to 98.5% by weight of the ethylene units.

This ethylene copolymer (A) contains at least the second component (
A) Copolymers that can be obtained by copolymerizing the following monomers, multi-component copolymers of these and other monomers, and acid anhydride groups in these copolymers. Examples include those obtained by hydrolysis and/or alcohol denaturation.

Representative examples of such monomers include acrylic acid, methacrylic acid, and ethacrylic acid, which have at most 25 carbon atoms.
unsaturated monocarboxylic acids as well as maleic anhydride, tetrahydrophthalic anhydride, maleopimaric anhydride, 4-methylcyclohexan-4-ene-1,2-carboxylic anhydride and bicyclo(2,2,1)-hebutyric anhydride. -5-en-
4-50 carbon atoms such as 2,3-dicarboxylic anhydride
unsaturated dicarboxylic acid anhydrides.

Other monomers include unsaturated carbon atoms having at most 30 carbon atoms (preferably 10 or less) such as methyl (meth)acrylate, ethyl (meth)acrylate, hydroxymethyl (meth)acrylate and diethyl fumarate. Examples include carboxylic acid esters and vinyl esters having at most 30 carbon atoms, such as vinyl acetate and vinyl propionate.

Among the ethylene copolymers (A) listed below, copolymers of ethylene and unsaturated dicarboxylic anhydrides or multicomponent copolymers of these and unsaturated dicarboxylic esters and/or vinyl esters are hydrated. The dicarboxylic anhydride units of these copolymers can be converted to dicarboxylic acid units or Hafester units by decomposition and/or modification with alcohol. In the present invention, an ethylene copolymer (A) obtained by replacing part or all of the unsaturated dicarboxylic anhydride units of the copolymer or multicomponent copolymer with dicarboxylic acid units or halfester units is also preferred. It can be used with

To carry out the hydrolysis, the ethylene copolymer (A
) in the presence of a catalyst (e.g. tertiary amine) in an organic solvent (e.g. toluene) that dissolves the copolymer.
It can be obtained by reacting with water at a temperature of ~100°C for 0.5 to 10 hours (preferably 2 to 6 hours, preferably 3 to 6 hours), followed by neutralization with an acid.

To carry out the alcohol modification, the ethylene copolymer (A) can be obtained by the solution method or crosslink method described below.

The solution method is similar to the case of hydrolysis, in which the reaction is carried out in an organic solvent in the presence or absence of the above-mentioned catalyst (the reaction is slow in its absence).
2 minutes to 5 hours at the reflux temperature of the alcohol used in
Preferably from 2 minutes to 2 hours, preferably from 15 minutes to 1 hour.
time).

On the other hand, in the kneading method, tertiary amine and Generally from 0.1 to dicarboxylic acid units in the copolymer.
3.0 times mole (preferably 1.0 to 2.0 times mole)
of saturated alcohol at a temperature above the melting point of the ethylene copolymer (A) but below the boiling point of the alcohol used, using a kneading machine such as the Banbury Mixer 1 extruder commonly used in the fields of rubber and synthetic resins. This is a method in which the reaction is carried out while kneading for several minutes to several tens of minutes (preferably 10 to 30 minutes).

The saturated alcohol used in the above modification with alcohol is a linear or branched saturated alcohol having 1 to 12 carbon atoms, and includes methyl alcohol, ethyl alcohol, and -butyl alcohol.

In the case of the above hydrolysis and in the case of modification with alcohol, the conversion rate to dicarboxylic acid and the halfesterization rate are both 0.5 to 100%, and 10.0 to 100%.
100% is desirable.

The ethylene units in this ethylene copolymer (A) are 30
-99.5% by weight, preferably 30-99.0% by weight, particularly preferably 35-98.0% by weight. Also,
The proportion of carboxylic acid units, their anhydride units and halfester units in the copolymer is 0.1 to 70% by weight in total, preferably 0.5 to 70% by weight, particularly 0.5% by weight. ~80% by weight is preferred.

If an ethylene polymer in which the proportion of carboxylic acid units, anhydride units and halfester units in this ethylene copolymer (A) is 0.1% by weight is used, the ethylene copolymer described below When heating and crosslinking the composite (B), not only the crosslinking is incomplete, but also the adhesion to the metal layer is poor. On the other hand, even if the content exceeds 70% by weight, the characteristics of the present invention are exhibited, but it is not necessary to exceed 70% by weight, which is not preferable from the viewpoint of production and economy.

In addition, when using a multicomponent copolymer containing the unsaturated carbon dioxide ester and/or vinyl ester, the total amount thereof is usually at most 70% by weight, and 6% by weight.
It is preferably 0% by weight or less. If an ethylene copolymer with a copolymerization ratio of unsaturated dicarbonate ester and/or vinyl ester exceeds 70% by weight is used, the softening point of the copolymer will be high and the fluidity will be low at temperatures below 150°C. This is not only undesirable because of the damage it causes, but it is also undesirable from an economic point of view.

(B) Ethylene copolymer (B) In addition, the ethylene copolymer (B) used in the present invention (
B) contains at least ethylene units and hydroxyl units,
"At least one unit selected from the group consisting of amino units and glycidyl units" [hereinafter referred to as "second component (B)]", and the ethylene units thereof are 30 to 99.5
It is an ethylene copolymer containing % of the mold part.

This ethylene copolymer (B) is a copolymer that can be obtained by copolymerizing at least ethylne with the following monomers to constitute the second component (B), and a multicomponent system of these and other monomers. Examples include saponified products obtained by saponifying copolymers and copolymers of ethylene and vinyl esters (especially vinyl acetate).

Examples of this monomer include glycidyl alkyl (meth)acrylate and hydroxyalkyl (meth)acrylate represented by the following general formula (the number of carbon atoms in the alkyl group is usually 1).
~25 carbon atoms), α-alkenyl alcohols having 3 to 25 carbon atoms, α-amines having 2 to 25 carbon atoms, and primary or secondary aminoalkyl (meth)acrylates (the number of carbon atoms in the alkyl group is usually 1 ~25 items).

CH2=CR.

C=0 0- R2-CH-CH2 (here, R1 is H or a methyl group, R2 has 1 to 1 carbon atoms)
Representative examples of this monomer (12 linear or branched alkyl groups) include butenetricarboxylic acid monoglycidyl ester, glycidyl methacrylate, glycidyl acrylate-1, glycidyl ethacrylate I,
Itaconic acid glycidyl ester, hydroxymethyl (meth)acrylate, hydroxymethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, hydroxyhexyl (meth)acrylate, allyl alcohol, allyl ( allyl ) amines and aminoethyl (meth)acrylates.

Other examples include the unsaturated carboxylic acid esters and vinyl esters mentioned above.

The ethylene unit in this ethylene copolymer (B) is 30
-98.5% by weight, preferably 30-99.0% by weight, particularly preferably 35-99.0% by weight. Further, the proportion of hydroxyl units, amino units and glycidyl units in the copolymer is 0.1 to 70% by weight for the same reason as in the case of the ethylene copolymer (A), and is 0.5 to 0.5% by weight. 70% by weight is preferred, especially 0.5-60%
% by weight is preferred. Furthermore, when using a multicomponent copolymer containing the unsaturated carboxylic acid ester and/or vinyl ester, the total amount thereof is generally at most 70% by weight for the same reason as in the case of the ethylene copolymer (A). %, particularly preferably 60% by weight or less.

Melt index (JIS K-721) of the ethylene copolymer (A) and ethylene copolymer (B)
0, measured under condition 4, hereinafter rM, 1. J) is generally 0.001 to 1000 g/10 minutes, preferably 0.05 to 500 g/10 minutes,
Particularly suitable is 0.1 to 500 g/10 minutes. M,
1. When these ethylene-based copolymers have a weight of less than 0.01 g/10 min, it is not only difficult to mix the copolymers uniformly, but also the moldability is poor. .

Among these ethylene copolymers, when produced by copolymerization method, the amount is usually 500 to 2500 kg/c.
ethylene and the second component (A) or the second component (B) or these and other components in the presence of a fast chain transfer agent (e.g. an organic peroxide) at a temperature of 120 to 260 °C under high pressure of m' It can be obtained by copolymerizing the components,
Their manufacturing methods are well known. Furthermore, the method of manufacturing the ethylene copolymer (A) by hydrolysis and/or modification with alcohol and the method of manufacturing the ethylene copolymer (B) by saponification are also well-known methods. be.

(C) Production of mixture (]) Mixing ratio In producing the mixture of the present invention, ethylene copolymer (A) and ethylene copolymer (B
) Ethylene copolymer (A) in the total amount (total)
The mixing ratio of the ethylene copolymer (B) is 1 to 99% by weight [that is, the mixing ratio of the ethylene copolymer (B) is 98 to 1% by weight], and the mixing ratio is 5 to 8% by weight.
5% by weight is desirable, and 10 to 80% by weight is particularly preferred. Ethylene copolymer (A) in the total amount of ethylene copolymer (A) and ethylene copolymer (B)
Even if the mixing ratio is less than 1% by weight or more than 99% by weight, crosslinking will be insufficient when the mixture is crosslinked by the method described below.

(2) Mixing method This mixture can be produced by uniformly mixing the ethylene copolymer (A) and the ethylene copolymer (B). As a mixing method, tri-blending may be performed using a mixer such as a Henschel mixer, which is commonly used in the field of olefin polymers;
Examples include a method of melt-kneading using a mixer such as an extruder and a roll mill. At this time, a more uniform mixture can be obtained by triblending in advance and melt-kneading the resulting mixture. When melt-kneading, it is necessary that the ethylene copolymer (A) and the ethylene copolymer (B) do not substantially undergo a crosslinking reaction (if crosslinked, the resulting mixture is molded as described below). (This is undesirable because it not only deteriorates moldability, but also reduces the shape of the intended molded product and the heat resistance when crosslinking the molded product.) Therefore, the temperature for melt-kneading depends on the type and viscosity of the ethylene polymer used, but is preferably room temperature (20'O) to 150°C, and preferably 140°C or lower.

As a guideline for ``substantially no crosslinking,'' ``residual aroma with a diameter of 0.1 micron or more after extraction treatment in boiling toluene for 3 hours'' (hereinafter referred to as ``extraction residual aroma'') is generally 15% by weight. It is preferably at most 10% by weight, most preferably at most 5% by weight.

In producing this mixture, stabilizers against oxygen, light (ultraviolet rays) and heat, metal deterioration inhibitors, flame retardants, electrical property improvers, which are commonly used in the field of olefinic polymers, and Additives such as adhesives, lubricants, processability improvers, and tackiness improvers may be added to the extent that the properties (physical properties) of the thin-walled article of the present invention are not impaired. Furthermore, by adding a crosslinking promoter such as an epoxy compound, p-toluenesulfonic acid, and A1-impropoxide, the ethylene copolymer (A) and the ethylene copolymer (B) are crosslinked as described above. can be further completed. The amount added is usually at most 0.1 parts by weight (preferably 0 parts by weight) per 100 parts by weight of these resins.
．． 01 to 0.05 parts by weight). Furthermore, alumina,
It is also possible to improve the insulation by adding an insulating ceramic such as silicon nitride.

Furthermore, the function of the present invention can be further enhanced by filling with inorganic powder, glass fiber, glass beads, etc.

(D) Production of thin-walled products When the thin-walled products of the present invention are used in the form of a film or sheet, T-Guy films commonly used in the field of thermoplastic resins and films by the inflation method can be produced. A thin product can be obtained by extruding it into a film or sheet using an extruder that is widely used in the industry. At this time, the extrusion temperature is 250°C or lower. However, when extruded at a temperature exceeding 250°C, the ethylene copolymer (A) and the ethylene copolymer (
A part of B) is cross-linked and small lumps of gel-like material are generated, making it impossible to obtain a uniform extruded product. For these reasons, the extrusion temperature is in the same temperature range as in the case of melt-kneading described above, regardless of whether a crosslinking accelerator is added (blended) or not.

In any of the above cases, after manufacturing the thin-walled articles, the thin-walled articles with good transparency are made by rapidly cooling them in a water-cooling roll or a water tank to prevent adhesion between the thin-walled articles or between the thin-walled articles and the take-up roll. You can get things. The thickness of the thin-walled products thus obtained is generally between 5 microns and 400 microns.
It is micron.

(E) Heat/pressure treatment The thin-walled product obtained in the above manner exhibits the same behavior as a normal thin-walled product because crosslinking has hardly progressed. In order to impart heat resistance to the thin-walled material, it is necessary to heat and pressurize it in the range of 100 to 400°C. 10 when the heating temperature is in the range of 100 to 160℃
~20 minutes, 1~10 minutes in the range of 180~240℃,
In the range of 240 to 400°C, by heating and pressurizing for 5 minutes or less, a crosslinking reaction (condensation reaction) occurs within the resin, and the heat resistance is significantly improved.

The crosslinked thin-walled mixture of the mixture obtained as described above desirably has an extraction residue of 70% or more, particularly preferably 75% or more.

In the present invention, it is important to heat the thin-walled product thus obtained in a temperature range of 100 to 400°C in order to impart heat resistance, and a crosslinking reaction occurs within the mixture in this temperature range. , heat resistance is significantly improved.

(F) Production of laminate The above ethylene copolymer (A) and ethylene copolymer (B) are applied to the surface of the crosslinked thin material obtained as described above.
) can be laminated as shown in FIGS. 1-1 and 1-2 to obtain a thin coverlay having heat-joint pressure adhesive properties. 1-1
Figures 1 and 1-2 are partially enlarged cross-sectional views of typical laminates of the present invention. In these figures, 1 is a crosslinked thin material, and 2 is a thin material of ethylene copolymer (A) or ethylene copolymer (B). Crosslinked thin material 1
The ethylene copolymer (A) or ethylene copolymer (B) to be laminated on the surface of the ethylene copolymer (A) or ethylene copolymer (B) can be produced by lamination molding, extrusion (T-die) molding, or roll lamination, which are commonly used in the field of thermoplastic resins. Lamination can be carried out by a lamination method such as a lamination method or a press lamination method. That is, either the molten ethylene copolymer (A) or the ethylene copolymer (B) may be laminated on the surface of the crosslinked thin material.

The thinner the ethylene copolymer (A) or the ethylene copolymer (B) of this laminate is, the better the heat resistance and temperature resistance of the laminate will be. Generally 1-10
0 microns, preferably 2 to 50 microns,
Particularly suitable is 3 to 30 microns.

Although the effect of the present invention is exhibited even when the thickness is less than 1 micron,
Using a general molding machine is not often used because stable production is difficult. On the other hand, when it exceeds 100 microns, the adhesiveness improves because more reactive groups of the ethylene copolymer (A) or ethylene copolymer (B) remain unreacted during heating and pressure. This is not preferred because a thin coverlay having portions with poor heat resistance is obtained.

That is, an ethylene copolymer (A
) or ethylene copolymer (B) (2 in FIGS. 1-1 and 1-2) are stacked on top of each other so as to serve as adhesive surfaces, and heated and pressurized to obtain a coverlay laminate. At this time, the bonding temperature is usually 40 to 300°C, and 80 to 300°C.
250°C is preferred, and 100-200°C is particularly optimal.

The pressure may generally be from 1 to 100 kg/cm', and at temperatures of 100°C or higher, it is sufficient to apply pressure to the extent that air bubbles are not trapped in the adhesive surface. In other words, when the laminated ethylene copolymer (A) or ethylene copolymer (B) is heated, the reactive groups cause a reaction on the crosslinked thin object at the same time as the surface to be adhered, improving both adhesiveness and heat resistance. It is assumed that this will improve.

A typical example of a method carried out using the product of the present invention when used as a coverlay for a circuit-formed product will be described in detail with reference to FIG.

FIG. 2 is before lamination, and FIG. 3 is after lamination. In FIGS. 2 and 3, 4 is an ordinary printed circuit board, 3 is a circuit formed material such as copper (1 and 2 are the first
1 and 1-2).

As a manufacturing method, the thin-walled object may be placed on the surface of an object that requires surface protection (for example, a circuit formed object, 3 and 4 in Fig. 2), and then heated and pressurized to the above-mentioned temperature range. . If air is to be trapped between the protective surface and the thin material, it is necessary to use a heat press, heat roll, etc. to bond the material under heat. Although a product with sufficient adhesion can be obtained even if the heating temperature is 300°C or less, if heat resistance is required, it is preferable to press-bond at the highest possible temperature (usually 100 to 200°C). By applying heat and pressure, it is possible to obtain a laid circuit with good heat resistance and adhesion.

Even in the case of surfaces that require protection (e.g., circuit boards), the thin-walled products of the present invention are free from any ethylene-based copolymer (Figures 1-1 and 1-2) before being heated and pressed.
Since the part 2 in the figure shows thermoplasticity, it can sufficiently follow uneven parts, and even if the protective surface has a complicated shape, it is natural that the protective surface can be uniformly covered. In addition, a device (for example, a press mold) that can uniformly heat and press the surface even if it has an irregular cross section or curved surface.
By devising the following, it is possible to adhere to any surface.

Another method is to apply a method commonly used in manufacturing multilayer laminates.

That is, the thin-walled products obtained as described above were evenly distributed between each laminate, temporarily bonded at room temperature, and then
This is a finishing method that involves heating and pressurizing at temperatures above °C.

This method proposes a method in which multilayer molding is possible by temporarily adhering each layer one by one, and finally, after laminating all the layers, heating and ashing are performed.

The thin coverlay for circuit protection obtained by the present invention can be used as a thin coverlay (film or sheet) for protecting the surface of all types of equipment and circuit moldings since it exhibits the above-mentioned effects.

- Hereinafter, the present invention will be explained in more detail with reference to Examples.

In addition, in the Examples and Comparative Examples, the heat resistance test was performed using the obtained film as UL 79B (printed wiring board).
7. The film was thermocompressed for 10 minutes at the thermocompression temperature shown in Table 1 on a glass epoxy printed circuit board having the test pattern shown in Figure 1. Coverlaid printed circuit board held at 300°C Lead/Tin = 90/
10 (weight ratio) for 180 seconds in a solder bath for evaluation.

The mixture of ethylene copolymer (A) and ethylene copolymer (B) used in Examples and Comparative Examples is shown below.

Ethylene copolymer (A) and ethylene copolymer (B)
As a mixture with ethylene-acrylic acid copolymer (density 0.!35
4g/cm', acrylic acid copolymerization ratio 20% by weight
, hereinafter referred to as rEAA
97.5%, M, 1. 75g/10min, density 0. l
151 g/cm" (hereinafter referred to as "saponified material") [mixing ratio 50:50 (weight ratio)
, hereinafter referred to as "Mixture (I)", M, 1.
A mixture of an ethylene-methacrylic acid copolymer (density: 0.!350 g/cm", methacrylic acid copolymerization ratio: 25% by weight) and the saponification degree described above [mixing ratio: 50:50 (by weight) ratio), hereinafter referred to as "Mixture (II) J", M, 1. is 2+2g/1
Ethylene-ethyl acrylate-maleic anhydride ternary copolymer (ethyl acrylate copolymerization ratio
30.7% by weight, maleic anhydride copolymerization ratio 1.7% by weight, hereinafter referred to as rEAMJ), and L is 123 g.
/ 10 minutes with a terpolymer of ethylene-methyl methacrylate-hydroxy methacrylate (copolymerization ratio of methyl methacrylate-1: 20.7% by weight, copolymerization ratio of hydroxymethacrylate 11.7% by weight). Mixture [mixing ratio 50:50 (weight ratio), hereinafter referred to as "
mixture (■)] and M, 1. is l05g
terpolymer of ethylene-methyl methacrylate-maleic anhydride (copolymerization ratio of methyl methacrylate: 20.5% by weight, copolymerization ratio of maleic anhydride: 3.1% by weight) and ethylene-methylmethacrylate. −
A mixture with a terpolymer of glycidyl methacrylate-1 (copolymerization ratio of methyl methacrylate: 18.6% by weight, copolymerization ratio of glycidylmethacrylate-1: 12.7% by weight, hereinafter referred to as rGMAJ) [ Mixing ratio 30:
70 (weight ratio), hereinafter referred to as "1 compound (■)")
It was used. These 7-components were produced by tri-blending the respective copolymers or terpolymers for 5 minutes using a Henschel mixer.

Mixture (I) to IV) obtained as described above
In addition, FAA and the saponified material were each extruded to a thickness of 100 microns using an extruder equipped with a T-die (diameter 4Qn+m, die @ 30am, rotation speed 85 revolutions/min) under the conditions that the cylinder temperature is shown in Table 1. A film was formed. The extraction residue of the obtained film was measured. Table 1 Examples 1 to 7, Comparative Examples 1 to 4 Each film thus obtained was laminate with the thickness shown in Table 2. T when the temperature is 200°C
Lamination was performed using an extruder (diameter: 40 mm) equipped with a die to produce thin coverlays (laminated films) of the present invention and comparative examples.

In order to evaluate the heat resistance and adhesion of the obtained thin products, each of the obtained laminated films was heated at 250 °C for 10 minutes using a heat press machine at 20 kg/cm' (gauge pressure). A cover lay was performed on the test pattern, and a heat resistance test was conducted using a solder bath. In all of the samples obtained in Examples 1 to 7, no peeling, cracking, splitting, or other deformation was observed between the layers with the base insulating material or between the copper circuits. In addition, in the case of Comparative Example 4, part of the coverlay was found to be melted in the 300° C. solder heat resistance test, and the coverlay was separated from the copper circuit.

Furthermore, in all of the samples obtained in Comparative Examples No. 3 to 3, melting was observed in the coverlay at 300'C, and the original shape was not retained.

In addition, in the column ``1 Solder heat resistance °'' of Table 2, ``
"○" means that no deformation is observed, and "x" means that it is melted and does not retain its original shape.

(Left below) From the results of the above Examples and Comparative Examples, it is clear that the crosslinked thin material of the mixture of ethylene copolymer (A) and ethylene copolymer (B) used in the thin coverlay material of the present invention. Thin products made by laminating any of these ethylene copolymers are generally used because they not only have excellent adhesive properties but also have good heat resistance after adhesion (especially soldering heat resistance). It is easy to manufacture and therefore inexpensive compared to coverlay films using thermosetting adhesives, such as the coverlay films used in the past, and it is clear that the disadvantages of the conventional methods can be solved.

The thin coverlay for circuit protection obtained by the present invention exhibits the following effects (characteristics) including its manufacturing process.

(1) Since no thermosetting resin adhesive such as epoxy resin is used, not only the adhesion process is omitted, but also the complicated drying process associated with that process is eliminated.

(2) Excellent electrical properties (for example, insulation, withstand voltage, and dielectric loss tangent performance).

(3) It has good heat resistance, and can not only be used at temperatures above 250°C, but also by pressurizing it at temperatures above 40°C, without using the above-mentioned adhesive. It can be well adhered to metal foils or plates such as foils.

(4) Excellent flexibility.

(5) In particular, the thin film of the present invention is characterized by a relatively high temperature (200'C! or more) compared to conventionally used polyimide films and polyester films.
-2) Due to the crosslinking treatment, the laminate not only has excellent dimensional stability, but also has good adhesion even at high temperatures, has good adhesion, and has extremely few residual voids.

(6) Furthermore, even in the additive method, which has been used recently compared to the subtractive method, it is effective as a coverlay for all kinds of circuit moldings because it has better adhesion to, for example, electroless plated circuit patterns.

(7) Furthermore, the thin coverlay used in the present invention has good adhesion even in the screen printing method, which has recently been used to produce high-density circuit patterns, and the method of forming circuit patterns using conductive paint. The quality of the circuit pattern is good and the quality of the circuit pattern is stable, and the process is simple and easy.

(8) Moreover, by taking advantage of the adhesive properties described above, it can be used as a protective coating for obtaining environmental properties such as moisture-proofing, gas-proofing, and dust-proofing for all electronic devices other than coverlays for circuit protection.

As described above, the resin layer of the present invention not only has the electrical properties such as insulation resistance and dielectric constant required for thin coverlays for circuit protection, but also has dimensional stability, heat resistance, chemical resistance, moisture resistance, etc. Not only is the protective coverlay for a flexible substrate excellent in bending durability, but the protective coverlay for a flexible substrate exhibits flexibility that has not been previously achieved. In addition, with respect to adhesion to metal thin foil, it does not require an adhesive and has the characteristics of showing good adhesion even at relatively high temperatures simply by thermocompression bonding.

[Brief explanation of drawings]

1-1 and 1-2 are partially enlarged sectional views of the thin coverlay of the present invention, respectively. FIG. 2 is a partially enlarged sectional view of the thin coverlay layered on a printed circuit board. Moreover, FIG. 3 is a partially enlarged sectional view after lamination on a printed circuit board. ■...Crosslinked thin material 2...Ethylene copolymer (A) layer or ethylene copolymer (B) layer 3...Circuit portion 4... ··Printed board

Claims (1)

[Scope of Claims] (A) Consists of at least ethylene and at least one type of unit selected from the group consisting of carboxylic acid units, dicarboxylic acid units, anhydride units thereof, and half ester units, and the content of ethylene units is 30 -99.5% by weight of an ethylene copolymer; and (B) at least ethylene units and at least one unit selected from the group consisting of hydroxyl units, amino units and glycidyl units, and An ethylene copolymer having an ethylene unit content of 30 to 99.5% by weight; and a thin material that is a crosslinked mixture of 99 to 1% by weight of an ethylene copolymer and laminated with any of the above ethylene copolymers. Thin coverlay.