JPS60194596A - Hybrid integrated circuit 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 [I] Objects of the Invention The present invention relates to a bent and/or drawn hybrid integrated circuit board. More specifically, (A) a plate of a metal selected from the group consisting of aluminum, copper, and iron or an alloy containing these metals as a main component, (B) (1) ethylene-acrylic acid copolymer and/or ethylene - A mixture consisting of a methacrylic acid copolymer and (2) a saponified product of an ethylene-vinyl acetate copolymer is extruded into a thin shape at a temperature of 250°C or less under conditions that do not cause fish eyes, and the resulting thin product is (C) A hybrid integrated circuit obtained by bending and/or drawing a laminate obtained by sequentially laminating conductive metal foils and (C) a crosslinked product obtained by heating and pressurizing at a temperature between 400°C and 400°C. The purpose is to provide a four-piece integrated circuit board (board) that is bent and drawn and has excellent heat resistance as well as excellent adhesion even at high temperatures. .

[II] Background of the Invention Conventionally, metal substrates have been used to improve the heat dissipation of integrated circuit (IC) substrates. In the case of a metal substrate, the surface is insulated to prevent IJ from conducting conductors formed thereon, or a laminate consisting of a metal substrate, adhesive, and copper foil is used. Recently, in fields where these integrated circuit boards are used, electronic equipment has become smaller and smaller.
With the trend toward thinner products, there is a trend toward greater consideration when it comes to mounting components on printed bases. In particular, recently, these metal plate-based substrates are subjected to bending or drawing processing to reduce the storage volume of the substrate, or to use one side of the metal plate as an exterior. In other words, designing a circuit on the inner surface of the exterior metal plate is being considered. In particular, if bending and curved surface processing can be applied to boards for audio equipment such as car radios and radio cassettes, switching power supplies, motor controls, and automotive applications such as ignition systems, the range of board mounting will expand. , a substrate can be used as the structure, and it is also possible to use it as an exterior material (51).

When an aluminum plate is used as a metal substrate, it has a structure in which a copper foil is further attached using an adhesive to an aluminum plate that has been subjected to an insulating treatment such as alumite treatment [7]. This alumite layer serves not only as an insulating layer but also as a resist during machining and chipping. , the substrate itself is required to be thin, but as the substrate becomes thinner, not only is it difficult to anodize it, but it is also impossible to manufacture large boards such as 1m x 1m.Therefore, when producing hybrid integrated circuits, On the other hand, in the case of a laminate consisting of a metal substrate, adhesive and copper foil, after circuit formation such as +tt rod processing or drawing processing,
When post-processing is performed, if the thickness of the adhesive is thin, the insulation between the copper foil and the substrate on the bent curved surface will deteriorate due to I)J breakage of the adhesive layer. On the other hand, if it is thick, the adhesion ability will be reduced after bending, resulting in blisters during processing, which may cause not only the conductor to peel off, but also a decrease in the withstand voltage (I). In order to improve these drawbacks, a board for integrated circuits has been proposed that has a structure in which one side of an aluminum plate is further layered with a polyimide film (copper film) coated with an adhesive on both sides. When applying hybrid integrated circuits, heat-resistant types that can be used in high-temperature processing are desirable, and heat-resistant film/adhesive combinations such as polyamide-imide/epoxy and polyamide/epoxy are used. and polyester/epoxy systems are used.

However, in these laminates, adhesive is applied to both sides of the insulating heat-resistant film, which makes the process extremely complicated, increases processing costs, and reduces adhesive strength due to uneven adhesive application. This is undesirable because it may cause a decrease in the coating temperature or cause blistering during high-temperature heating. Furthermore, since the insulating layer does not stretch during bending or drawing, peeling from the adhesive often occurs.

On the other hand, from the point of view of insulation, it is preferable that the total thickness of the adhesive and the filter be thicker;
The total thickness of adhesive and film needs to be as thin as possible and controlled. Furthermore, unless the layers are stacked uniformly so that the thickness unevenness is within a few microns, there will be unevenness in withstand voltage and insulation, especially in deformed substrates, leading to localized overcurrent and risk of circuit destruction. .

[111] Based on the structure of the invention, the inventors of wood have discovered that these drawbacks are not addressed, that bending and drawing are capable of rNf, and that these processes are performed. As a result of various searches to obtain a highly integrated circuit board that is free from peeling of conductive metal foils and metal plates and has excellent heat resistance, we found that (A) a circuit board selected from the group consisting of aluminum, copper, and iron; (B) (1) Ethylene-acrylic acid copolymer and/or ethylene-methacrylic acid copolymer (2) Ethylene-vinyl acetate copolymer It is a mixture consisting of saponified polymers, and the mixing ratio of ethylene-acrylic acid copolymer and/or ethylene-methacrylic acid copolymer in the mixture is 20 to 80% by weight. A crosslinked product obtained by extruding into a thin shape under conditions that do not cause fish eyes at a temperature below ℃ and heating and pressurizing the resulting thin-walled product at a temperature of 100°C to 400°C (C) 11.10f processing and /
The inventors have also discovered that a hybrid integrated circuit board formed by drawing processing is a board that can solve the problems (defects) as described in 111 (2) above, and have arrived at the present invention.

[IV] Effects of the invention Although the integrated circuit board obtained by the present invention is subjected to bending and/or drawing processing,
Demonstrates effects (characteristics) such as the following.

(1) Take advantage of the heat dissipation properties of the metal plate and significantly improve the reliability of the insulating film.

(2) Good workability, bending pressurization and drawing pressurization are possible, and the manufacturing process can be simplified.

(3) Despite not using a primer, it is extremely effective against cross-linked metal plates and metal foils, and has cross-linking ability even at high temperatures (approximately 360°C), so it can also be used at high temperatures. Excellent adhesion.

(4) A circuit can be formed by etching like a conventional printed wiring board, and then subjected to bending or drawing using a mold.

Since the hybrid integrated circuit board obtained by the present invention exhibits similar effects (features), hybrid y F' r
Not only can it be used for c'l, (plates, insulating heat transfer plates for semiconductors, switching circuit boards, chip carrier boards, thyristor boards, I/Lancy star array boards, etc.) It can be used for electronic devices that require thinner walls and lighter weight, such as by using the blank side as an exterior.

[V] Detailed Description of the Invention (A) Metal Plate The metal plate of the present invention can be bent and drawn, and also plays a role such as heat radiation, and has a thickness of 0.1- 3mm (preferably 0.1-2.5n+m)
The one with θr is preferable. Examples of metals include metals such as aluminum, copper, and iron, as well as alloys containing these metals as main components (for example, stainless steel). By applying metal plates such as iron plates and copper plates and making use of their magnetic effects, they are promising for use in motor magnetic circuits, communication circuit switches, electronic exchanges, and heat dissipation boards.

(B) Conductive metal foil The thickness of the conductive metal foil is 5 to 400 microns, preferably 5 to 100 microns, particularly 20 microns.
Examples of conductive metals preferably having a diameter of 50 microns include metals such as copper, nickel, and aluminum, alloys containing these metals as main components, and two or more of these metals and alloys. Examples include cladding (bonding). Generally, 1L copper foil or rolled copper foil having a thickness of 17 to 35 microns is used.

(C) Ethylene-acrylic acid copolymer and ethylene-
Methacrylic acid copolymer Furthermore, the ethylene-acrylic acid copolymer and/or ethylene-methacrylic acid copolymer used in the present invention is prepared by mixing ethylene and acrylic acid or ethylene and methacrylic acid at high pressure (generally 50 kg/crrf). 2,
(preferably less than 100 kg/cm') in the presence of a free radical generator (usually 41 peroxide). The physical properties of each of these are well known. The copolymerization ratio of acrylic acid or methacrylic acid in these copolymers is 1 to 50% by weight, respectively, and 5 to 50% by weight.
is desirable. If the copolymerization ratio of acrylic acid or methacrylic acid in these copolymers is less than 1% by weight, a uniformly thin product cannot be obtained. On the other hand, if it exceeds 50% by weight, the softening point will be too low, making handling and transportation inconvenient.

(D) Saponified product of ethylene-vinyl acetate copolymer,
The saponified product of the ethylene-vinyl acetate copolymer used in the present invention is converted to f4+ by saponifying (hydrolyzing) the ethylene-vinyl acetate copolymer. Hydrolysis is generally carried out in methyl alcohol using a caustic sorter. In producing the saponified product of the present invention, it is usually preferable that the hydrolysis rate is 90% or more. The raw material ethylene-vinyl acetate copolymer is obtained by copolymerizing ethylene and vinyl acetate in the same manner as the ethylene-acrylic acid copolymer and ethylene-methacrylic acid copolymer described above. be. The copolymerization ratio of vinyl acetate in this ethylene-vinyl acetate copolymer is generally 1 to 60'ff% by weight, particularly preferably 5 to 60% by weight. If the joint ratio of vinyl acetate in the joint is less than 1% by weight, a uniformly thin-walled product cannot be obtained. On the other hand, if it exceeds 60% by weight, the softening point will decrease and handling at room temperature will become difficult.

These saponified products of ethylene-acrylic acid copolymer, diethylene-methacrylic acid copolymer, and ethylene-vinyl acetate copolymer are industrially produced and used in a wide range of fields, and their production methods are It is also well known.

(E) Mixing ratio The mixing ratio of ethylene-acrylic acid copolymer and/or ethylene-methacrylic acid copolymer in the mixture of the present invention is 20 to 80% by weight (i.e., ethylene-vinyl acetate copolymer The mixing ratio is preferably 80-20% by weight), 25-75% by weight, particularly 30-70%
@Amount% is preferred. If the proportion of ethylene-acrylic acid copolymer and/or ethylene-methacrylic acid copolymer in these mixtures is less than 20% by weight, the number of levoxy groups (-1:0OH) will increase. Since the number of hydroxyl groups (-OH) is smaller than that of 4, 1,S hydroxyl groups remain that do not contribute to the condensation reaction, resulting in poor heat resistance. On the other hand, if it exceeds 80% by weight, there will be too many carboxyl groups contributing to the condensation reaction, leaving unreacted groups and not improving heat resistance and temperature resistance, which is undesirable.
,).

(F)R synthesis method To produce the mixture of the present invention, the following two ethylene-acrylic acid copolymers and/or ethylene-methacrylic acid group polymers and ethylene-vinyl acetate copolymers are homogeneously saponified. This can be achieved by mixing.

As a mixing method, a mixer such as a Henschel mixer, which is commonly used in the field of olefin polymers, is used.1. ) may be used for tri-blend, /kun/-
It can be obtained by melt-kneading using a mixer such as a Lee mixer, a Nigu, a roll mill, and a single screw extruder. At this time, a homogeneous mixture can be produced by rough tri-blending and melt-kneading the resulting mixture. In addition,
5) When melt-kneading, the carboxylic acid group (-COD) of the ethylene-acrylic acid and/or ethyl-methacrylic copolymer used in this process and the saponified product of the ethylene-vinyl acetate copolymer have Hydroxyl group (-O
It is necessary that f() undergoes essentially no crosslinking reaction (condensation reaction) and no formation of eyelids (it may be slightly crosslinked). From this, the melting temperature is the temperature at which the saponified products of these ethylene-acrylic acid copolymers and/or ethylene-methacrylic acid copolymers and ethylene-vinyl acetate copolymers melt, but the crosslinking reaction does not occur. The temperature is such that there is no fish eye. The melting temperature varies depending on whether or not a crosslinking accelerator is added in the latter stage, as well as their type and amount, but in the case where a crosslinking accelerator is not added, it is usually 180°C or lower, especially 100 to 150°C.
0°C is preferable. If the temperature is less than 100°C, these resins will not be completely melted, which is not preferable. On the other hand, when adding (blending) a crosslinking accelerator, the -shell has a +40°
CC sea lions are included, and the test is carried out at 100°C or higher.

In producing this compound 41--, stabilizers against oxygen, light (ultraviolet rays), and heat, and metal deterioration prevention agents, which are commonly used in the field of olefin polymers, are used. Additives such as lz agents, flame retardants, electrical property improvers, antistatic agents, lubricants, processability improvers, and tack improvers are added without impairing the properties (physical properties) of the thin-walled products of the present invention. It may be added within a range. Further, an epoxy compound, P-1-luenesulfonic acid and A9. -- (By adding a crosslinking accelerator such as propoxide, the ethylene-acrylic acid copolymer and/or ethylene-
Crosslinking between the methacrylic buty copolymer and the saponified ethylene-vinyl acetate copolymer can be further completed. The amount added is usually at most 0.1 parts (preferably 0.01 to o, o5I?+g parts) per 100 parts by weight of these resins. Furthermore, it is also possible to improve the insulation properties by adding ceramics having insulation properties such as alumina and silicon nitride. Furthermore, inorganic powder,
The functionality of the present invention can be further improved by filling it with glass fibers, glass pieces, etc.

(G) Production of thin-walled products When the thin-walled products of the present invention are used in the form of a film or sheet, they are produced by a T-tie film or an inflation method, which is commonly used in the field of thermoplastic resins. A thin product can be produced by extruding it into a film or sheet using an extruder that is widely used. At this time, the extrusion temperature is 250°C or less. However, when extruded above 250°C, the ethylene-acrylic acid copolymer and/or
Alternatively, part of the saponified product of the ethylene-methacrylic acid copolymer and the ethylene-vinyl acetate copolymer is crosslinked and small gel-like particles 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 products, they are rapidly cooled in a water-cooling roll or water tank to prevent adhesion between the thin-walled products or between the thin-walled products and a take-up roll, etc., to improve transparency. You can get a thin product. The thickness of the thin-walled material thus obtained is generally 5 to 4 microns.
00 microns.

(H) Heating and Pressure Treatment The thin-walled product obtained as in I- has almost no crosslinking, and thus exhibits the same behavior as a normal thin-walled product. In order to impart adhesion and heat resistance to the conductive metal foil and metal plate to the thin-walled product, the mold is opened by heating and pressurizing the thin-walled product at a temperature in the range of 100 to 400°C. When the heating temperature is in the range of 100 to 160°C, 20 to 30 minutes, 160 to 2
By heating and pressurizing for 10 to 20 minutes at 40°C and 0.1 to 10 minutes at 240 to 400"C, a crosslinking reaction (condensation reaction) occurs within the resin, improving adhesiveness and I heat resistance. performance is significantly improved.

The thin material obtained by unexploded 11J1 is + o o'
In order to exhibit thermocompression bondability (adhesiveness) at a temperature of c or more, the effect of the present invention is expanded by bonding the metal plate and the conductive metal foil at the same time as the crosslinking treatment. That is, ethylene-acrylic acid copolymer and/or ethylene-
A mixture of a methacrylic acid copolymer and a saponified ethylene-vinyl acetate copolymer exhibits thermoplasticity at a temperature of 250°C or lower, but crosslinking can be achieved by heating the mixture to a temperature of 160°C or higher and applying pressure with a fist. reacts and exhibits adhesive properties at the same time.

(J) Production of laminate The laminate of the present invention can be produced by the following two methods, which can be broadly classified.

The first method involves interposing a thin piece of the woody non-crosslinked mixture produced as described above between the metal plate and the conductive metal foil, and heating and pressurizing the mixture to the above temperature range. do it. At this time, if air or the like is involved between the thin material of the mixture with the metal plate or the thin material of the mixture and the conductive metal foil, it is necessary to perform thermocompression bonding using a hot press, a hot roll, or the like. Although it is possible to obtain a product with sufficient adhesive properties even if the heating temperature is 300°C or lower, in patents that feature heat resistance, the heating temperature is as high as possible (usually 200 to 3000°C).
It is preferable to press-bond the material. A laminate with good heat resistance and adhesion can be obtained by heat-pressing at a temperature 10° C. to 20° C. higher than the required one heat resistance temperature.

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

That is, the thin-walled lJ mixture obtained as described above was uniformly placed between a metal plate and a conductive metal foil, and
Temporary bonding is performed at 250°C, and then at 250°C.
This is a method of finishing by heating and pressurizing at the following temperatures. This method shows a 1M method in which multilayer molding is possible by temporarily adhering each layer one by one, and finally, after laminating all the layers, heat and pressure treatment is performed.

Generally, it is best to bend and draw the copper foil after etching the circuit to create a circuit, but even if processing is performed before etching, the copper foil may peel off during the subsequent etching process. Bye.

As a bending process, generally performed V +Il+
There are bending, U-bending, end bending, oblique bending, tension bending, etc.
The board placed on Tie-F is processed using a punch.

At this time, it is necessary to use a soft material, especially since the substrate surface may be scratched by sliding with the punch. The pressing force depends on, for example, the thickness of the aluminum plate. As for the bending radius (7)l],
It is best to use JIS H-4000-1976°' bending test inner radius of aluminum and aluminum alloy plates.The drawing process includes cylindrical drawing, square cylinder drawing, and double drawing, but pressed by a punch,
-7 The launch part is compressed in the cylindrical direction and tensile in the radial direction.The part where the launch part touches the local part of the tie is subjected to bending and unbending forces, so when deep drawing, the circuit pattern is taken into consideration and the force is applied to the wiring part. The 9th point is to perform processing or circuit design in a direction that does not cause problems. Can perform general aluminum bending and drawing processing.

Hereinafter, a laminate of the present invention and a hybrid integrated circuit board obtained by subjecting the laminate to bending and drawing will be described with reference to the drawings. Figure 1 shows 31 typical examples of laminates.
It is an i-minute enlarged sectional view. FIG. 2 is a partially enlarged sectional view of a typical example of a hybrid integrated circuit board obtained by bending. In addition, Fig. 3 is an enlarged cross-sectional view of a typical example of a hybrid integrated circuit board obtained by applying a drawing process. In Figs. 3 is a metal plate. Also, 2 is a thin material crosslinked with a mixture.

[VI Example and Comparative Example The present invention will be explained in more detail with reference to Examples below. In addition, in the Examples and Comparative Examples, the heat resistance test was conducted using lead/tin-90/10 (Tofn
It was evaluated by floating it in a solder bath with a ratio of 10 seconds, 20 seconds, and 180 seconds. In addition, the evaluation is shown in Table 1 in the form of a dotted line.

○: No change in original shape ×: Peeling between layers with base insulating material and between copper circuits, Hihi,
Examples 1 to 3 in which deformations such as cracking and splitting were observed, Comparative Examples 1.2 Melt flow index (according to JIS K-6760, temperature was 190"c and load was 2.16kg)
Measured under the following conditions: rM, 1. J) is 3oog/
Ethylene-acrylic acid copolymer (density 0.
954g/crn', acrylic acid copolymerization ratio 20% by weight
) A saponified product obtained by saponifying an ethylene-vinyl acetate copolymer having 100 parts by weight and a vinyl acetate copolymerization ratio of 28% (saponification degree 87.5%)
, M, 1. -75g/10 minutes, density 0.95]g
/cm') 100 parts by weight were triblended for 5 minutes using a Henschel mixer. The obtained mixture [hereinafter referred to as "Compound (A)"] was extruded using a T-die (diameter: 40 mm, die width: 30 cm).
, rotation speed 85 revolutions/min), cylinder temperature C, = +20
A film (thickness: 100 microns) was formed using the following conditions: 'O, C: 2 = +40'C) and wound onto a water-cooled roll at 20'C (Examples 1 and 2). Also, instead of the ethylene-acrylic acid copolymer used in producing the mixture (A), M and l were 200 g/
Ethylene-methacrylic copolymer (density 0
．． A mixture [hereinafter referred to as "mixture (B)" 1] was prepared in the same manner as mixture (A) except that methacrylic acid (co-terminated ratio: 950 g/crn', co-terminated ratio: 25%) was used.

A film was produced from the resulting mixture in the same manner as described above (Example 3).

Furthermore, the ethylene-acrylic copolymer used in Example 1 (hereinafter referred to as REAAJ, Comparative Example 1) and the saponified product of ethylene-vinyl acetate copolymer (hereinafter referred to as "
It is called saponified matter. In Comparative Example 2), a film was produced in the same manner as in nQ.

Each film thus obtained had a thickness of 35 mm on the opposite side.
A micron electrolytic copper foil was layered with an aluminum plate with a thickness shown in Table 1 on the bottom surface, and cross-linked at 20 kg/cm' (gauge pressure) using a heat press at 320°C for 10 minutes. We manufactured copper-clad boards for manufacturing integrated circuit boards. The obtained plate (UL plate, 79
B (Printed wiring board) 7. Etching (ammonium persulfate etching) was performed on the test pattern shown in Figure 1.

tlled board test, bending test with V-shaped tie (groove width 70 mm, angle 90 degrees, sample width 50 mm) and rectangular tube drawing test (no flanch) (drawing depth 2 mm, corner radius: 5 mm). The results of the hang heat resistance test are shown in the tfJI table.

Table 1 Note that as a result of the bending and drawing tests of the raw substrates for printing obtained in Examples 1 to 3, there was no 113 breakage of the copper circuit, and V-shaped surface bevelling and drawing processing were also possible.

He was so talented that I couldn't even see him in the corner. On the contrary,
The one obtained in Comparative Example 1 had a V-shaped face, peeling 1 occurred at some corners, and the copper foil and aluminum were separated by a value I when narrowed down. Further, in the case of Comparative Example 2, peeling occurred at a part of the corner due to V-shaped chamfering, and the wiring was cut during the drawing process.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged sectional view of a typical example of a laminate. 21.DELTA. is a partially enlarged sectional view of a representative example of a hybrid integrated circuit board obtained by bending. Further, FIG. 3 is a partially enlarged sectional view of a typical example of a hybrid integrated circuit board obtained by drawing. 1... Conductive metal foil, 2... Thin material crosslinked with mixture 3...
Metal plate patent applicant Showa Denko Co., Ltd. Representative Patent attorney Sei Kikuchi - Figure 1 Figure 2

Claims (1)

[Scope of Claims] (A) a plate of a metal selected from the group consisting of aluminum, copper, and iron or an alloy containing these metals as a main component; (B) (1) an ethylene-acrylic acid copolymer and/or
or a mixture consisting of an ethylene-methacrylic acid copolymer and (2) a saponified product of an ethylene-vinyl acetate copolymer, in which the ethylene-acrylic acid copolymer and/or the ethylene-methacrylic acid copolymer occupy The mixing ratio is 20 to 80% by weight, and this mixture is extruded into a thin shape at a temperature of 250°C or less under conditions that do not cause fish eyes, and the resulting thin product is 10 (1
A cross-linked product obtained by heating and pressurizing at a temperature of ℃ to 400℃, and (C) a hybrid stack made by bending and/or drawing a laminate made of sequentially laminated conductive metal foils. circuit board.