JPH049667B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a highly reliable heat-resistant laminate made of polyimide resins used as materials for electronic parts and the like. [Prior Art] Polyimide resin is known as a material having excellent heat resistance and electrical properties. The laminate is used for a variety of purposes, including as a material for electronic components such as flexible printed circuit boards, and further development is expected in the future. Thus, while it is hoped that polyimide resins will advance in lamination technology, as is well known, polyimide resins have weaknesses such as poor processability and poor adhesion, and are unable to form strong bonds when used alone. Therefore, at present, lamination is carried out with the aid of epoxy adhesives, etc., which have poor heat resistance (see, for example, Japanese Patent Application Laid-Open No. 164387/1987). Therefore, in order to solve the essential problem of poor heat resistance of epoxy adhesives, we proposed a method using an adhesive layer made of aromatic polyamideimide and an adhesive agent (see JP-A-55-15826). has been done. Unfortunately, however, none of these methods has been able to satisfy the recent high heat resistance requirements. [Problem to be solved by the invention] In other words, the epoxy adhesives in practical use have an inherent problem of being inferior in heat resistance by about 150°C compared to polyimide resins, and this becomes the bottleneck for laminated products. There is a problem that the overall heat resistance becomes low. In addition, the adhesive made of the aromatic polyamideimide and an adhesion promoter proposed to improve this problem certainly exhibits considerably higher heat resistance than epoxy adhesives, but it The problem remained that adhesion was insufficient when subjected to both heat and humidity loads, and that reliability was lacking in harsh environments. [Means for Solving the Problems] As a result of extensive studies in order to solve the above problems, the present inventors found that by using an adhesive layer made of aromatic polyamideimide resin with a specific filler added,
The inventors have discovered that an excellent laminate can be obtained that has excellent solder heat resistance, does not change color even under high temperatures, and has high adhesion reliability under hot and humid conditions, and has thus arrived at the present invention. That is, the present invention provides a heat-resistant laminate in which at least one layer is a polyimide resin layer, wherein the adhesive layer is a composition comprising a polar organic solvent-soluble aromatic polyamide-imide resin and a highly thermally conductive filler. The present invention provides a flexible laminate. The present invention will be explained in detail below. At least one layer of the laminate of the present invention must be a polyimide resin layer. Polyimide resin is usually produced from pyromellitic acid dianhydride and 4,4'-diaminodiphenyl ether through an intermediate of polyamic acid, and is commercially available such as KAPTON (trade name manufactured by DuPont). products can be used. The other layers can be selected from metal, ceramic, plastic, and others depending on the purpose and use, but in the case of electronic component materials, especially flexible printed circuit boards, metal layers are often used. Of course, the adhesive layer of the present invention can firmly adhere to both the metal layer and the polyimide resin layer. As the metal layer, it can be applied to all metals such as copper foil and aluminum thin plate. Further, as the ceramic layer, all ceramics such as alumina, zirconia, silicon nitride, boron nitride, and silicon carbide can be used. Furthermore, other layers can also be used except for special ones. Next, the aromatic polyamide-imide resin used in the adhesive layer, which is the main part of the present invention, is an aromatic polyamide-imide resin soluble in a polar organic solvent, and has the general formula: Or, (However, X represents an oxygen atom, a sulfur atom, a sulfonyl group, a carbonyl group, or a methylene group, and n represents an integer of 2 or more) or a mixture thereof is used. The reduced viscosity of the aromatic polyamideimide resin used in the present invention is not particularly limited as long as it is 0.5 or more, but
Practical solution viscosity at the time of use is around 3.5. If the reduced viscosity is too low, the mechanical strength and flexibility will decrease, and if the reduced viscosity is too high, the solubility in polar organic solvents will decrease, making it impractical. These aromatic polyamide-imide resins can be produced by a known method, for example, by reacting an aromatic diamine with trimellitic anhydride chloride or reacting an aromatic diisocyanate with bisimidodicarboxylic acid. Among these reactions, a representative example will be described below. (X in the formula has the same meaning as above) or

〔Example〕

Next, the present invention will be specifically explained using Examples and Comparative Examples, but the present invention is not limited thereto. The evaluation methods and conditions for the laminates in Examples and Comparative Examples are as follows. Solder heat resistance: test piece in a 300℃ solder bath
The presence or absence of blistering and peeling was observed when immersed for 30 seconds. Color change: Place the test piece in an oven at 300℃ for 30 minutes.
The color change was observed when heat treated for a minute. Adhesion: Measured by cross-cut tape method.
After cross-cutting the polyimide surface of the test piece according to the cross-cut test method of JIS K5400, PET tape was attached and then peeled off to measure the number of squares remaining among the 100 squares. In the adhesion test, the laminate was heat-treated at 350°C for 3 hours, and the laminate was left in a pressure cooker at 121°C and 2 atmospheres for 1 hour.The reliability under high temperature and heat and humidity was confirmed. Example 1 Organic polar solvent soluble aromatic polyamideimide resin (hereinafter abbreviated as PAI; reduced viscosity 1.6: specific gravity 1.5) synthesized from 4,4'-diaminodiphenyl ether (DADPE) and anhydrous trimellitic acid chloride (TMAC) 100 450 parts by weight of N-methylpyrrolidone was added to the parts by weight to dissolve the PAI. Next, fine boron nitride powder (BN) with an average particle size of 1.5 μm (Showa Denko BN: specific gravity 2.25)
A solution in which 35 parts by weight of NMP is dispersed in 60 parts by weight of NMP is mixed with the above PAI resin solution, and BN is mixed with a ball mill.
was uniformly dispersed to obtain a paste composition. Next, this composition was coated in a paste form with a thickness of 50 μm on surface-polished SUS304, and after pre-drying at 70°C for 2 minutes, Kapton film (manufactured by Toray DuPont, thickness 25 μm) was superimposed on this composition, and the top and bottom were coated. Sandwich the cushion material of Teflon and silicone rubber sheets and press 5kg/
cm ² Heat and press at 180°C for 30 minutes, then reduce to normal pressure to 250°C.
A laminate of Kapton and SUS was created by heat treatment at ℃ for 20 minutes. This laminate was evaluated using the method described above, and as a result, no blistering or peeling was observed in terms of solder heat resistance, and no change in color was observed. Furthermore, as a result of the adhesion test, the blank was 100/
Adhesion was good at 100/100 after high temperature treatment at 100°C and 350°C for 3 hours, and at 100/100 after pressurization. Comparative Example 1 Using Kapton for coverlay with adhesive (manufactured by Nikkan Co., Ltd., Nikaflex (film thickness 25 μm, adhesive thickness 35 μm)), on the same SUS304 as in Example 1,
A laminate of Kapton and SUS was produced by bonding them together using the method and conditions specified by Nitzkan. This laminate was evaluated using the same method and conditions as in Example 1. As a result, blistering was observed in terms of solder heat resistance.
The color turned blackish brown and the appearance was severely impaired. Note that the color change does not occur even if only the Kapton film is heat-treated at 300°C, but only when the above-mentioned adhesive-attached film is heat-treated, so this discoloration is thought to be due to the poor heat resistance of the adhesive. It will be done. Furthermore, in the adhesion test, the blank was 100/100, but after high-temperature treatment at 350°C for 3 hours, it was O/100, and after pressurization treatment, it was 36/100, showing that the laminated layer of Example 1 was resistant to heat and humidity. It turned out to be significantly inferior to the real thing. Example 2 A thin film with a thickness of about 10 μm was made using an applicator from the composition used in Example 1, and then heated at 130°C and 190°C.
Each sample was heat-treated at ℃ for 30 minutes. Next, a thin layer of N-methylpyrrolidone was sprayed onto one side of each of a Kapton film (manufactured by Toray DuPont, thickness 25 μm) and a thin alumina plate (manufactured by Noritake, thickness 635 μm), and the Kapton and alumina sheets were placed between the above films. and were superimposed. Next, press from above and below with cushioning material made of Teflon and silicone rubber sheets, and
Kg/cm ² After pressing at 180℃ for 30 minutes, release the pressure and 130
℃, 190℃, and 250℃ for 10 minutes each to produce a laminate of Kapton and ceramics. As a result of evaluating this laminate, no blistering or peeling was observed in the solder heat resistance, and no change in color was observed. Adhesion is 100/100 in both blank 350℃ high temperature treatment and pressure coating.
The laminate was found to be extremely reliable. Examples 3 to 7 Polyimide laminates as shown in Table 1 were prepared by the same method as in Example 1, and each laminate was evaluated. The results are shown in Table 1. Both laminates showed excellent effects.

〔Effect of the invention〕

As explained above, the present invention compensates for the drawbacks of conventional polyimide resins, has excellent soldering heat resistance, does not change color even under high temperatures, and greatly improves adhesive reliability under hot and humid conditions. The present invention provides a laminate that exhibits excellent effects. Therefore, by using the heat-resistant laminate of the present invention, it is expected that the reliability of electronic components against heat will be further improved. Furthermore, the adhesive composition of the present invention can be used in either liquid or film form, and has the effect of greatly contributing to the simplification and economicalization of the manufacturing process of laminates.

Claims (1)

[Claims] 1. A laminate in which at least one layer is a polyimide resin layer, characterized in that the adhesive layer is a composition comprising a polar organic solvent-soluble aromatic polyamide-imide resin and a highly thermally conductive filler. Heat-resistant laminate. 2 The polar organic solvent soluble aromatic polyamideimide resin has the general formula Or, (However, X represents an oxygen atom, a sulfur atom, a sulfonyl group, a carbonyl group, or a methylene group, and n represents an integer of 2 or more) or a mixture thereof. The heat-resistant laminate according to item 1. 3. The heat-resistant laminate according to claim 1, wherein the highly thermally conductive filler is boron nitride or alumina.