DE2063506A1 - Laminates containing polyimides - Google Patents

Description

Badische Anilin- & Soda-Fabrik AG

Our reference: OZ27 248 E / ef 6700 Ludwigshafen, December 22nd, 1970

Laminates containing polyimides

The invention relates to laminates composed of layers of an inorganic material and a high-temperature-resistant polyimide high bond strength.

Laminates using high-temperature-resistant, fully aromatic polyimides have only limited entry into technology found, since these polyimides can only be processed at high temperatures and high specific pressures, those for production of foils and plates oppose technical difficulties. Such polyimides are also poor with to bring other common, laminate-building materials into a sufficiently strong bond.

An exception is the polytetrafluoroethylene perfluoropropylene, which contains strongly polar groups and is used, among other things, for the production of printed circuits. For example, the copper conductor levels are inserted between a polyimide film based on pyromellitic dianhydride and 4,4'-diaminodiphenyl ether and a polytetrafluoroethylene perfluoropropylene film. The polytetrafluoroethylene perfluoropropylene film is then laminated onto the polyimide film using temperature and pressure. A disadvantage of such printed circuits, however, is that polytetrafluoroethylene perfluoropropylene only has a long-term service temperature of about 180 to 200 ^° C., so that the high thermal resistance of the polyimide material of up to 260 ^° C. in the presence of air cannot be used. The adhesion between the polyimide carrier material and the conductor material is also only slight. So that there is sufficient contact area between the polyimide carrier and the polytetrafluoroethylene perfluoropropylene layer, the printed circuit must be made of considerable area.

With regard to the printed and flexible circuits required in technology, the task was therefore to create a

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To find a composite that ensures the long-term temperature resistance of the high temperature resistant polyimide base material and has good bond strength with a small areal expansion.

It has now been found that laminates made of layers of an inorganic Material and / or a highly temperature-resistant polyimide then have high temperature resistance and high bond or adhesive strength if they have a connecting or adhesive Contain layer, which consists of a polyimide, which is built up from aromatic Tetracarbonsäuredianhydridsulfonen the general formula

and diaminoarylsulfones of the general formula

II H ₂ N [■ Ar-S -] _n

where η is each 1, 2 or 3 and where this is polyimide optionally 1 to 50 percent by weight of other polyimides may contain condensed.

The polyimides of this composite or adhesive layer have good adhesion to inorganic materials, as they are for such laminates are used, especially on metals, glass and ceramics. In addition, these polyimides also have Long-term thermal stress a high heat resistance. she are because of their good thermal insulation and sound-absorbing properties as insulating materials between metal foils and plates as well as ideally suited for joining metal and ceramics. After all, they are fully aromatic compared to others Polyimides have improved oxidation resistance.

The polyimide composite layer according to the invention is composed of Polycondensates from an aromatic tetracarboxylic dianhy-

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aridsulfone and a diaminoaryl sulfide. Suitable tetracarboxylic dianhydride sulfones and diaminoaryl sulfides of the general formulas I and II are above all those compounds in which the aromatic groups (Ar) are, in particular, benzene, ihiophene, naphthalene, pyridine or pyrrole radicals. Among the letracarboxylic acid dianhydride sulfones, tetrabenzenecarboxylic acid dianhydride sulfone and tetrathiophenecarboxylic acid dianhydride sulfone are particularly suitable. The anhydride moieties to AEEN aromatic groups of the formula I can more further Arylsulfonbrückenglieder also be interconnected by one or.

As Diaminoarylsulfide of formula II are more preferably 4.4 and 3.3 ^t -Diaminodiphenylsulfid ^I -Diaminodiphenylsulfid The arylamino groups can also be interconnected by one or more further Arylsulfidbrückenglieder.

In addition to these polyimides that form the composite or adhesive layer these polyimides can also contain further dicarboxylic acid dianhydrides and diamines at 1 to 50, preferably 20 to 30 percent by weight, based on the polyimides of the composite layer, condensed included, which by the general formulas III or IV can be described:

y / N

III ° \ C / ¹¹ - ^X - ^Ar \ C <°

IV H ₂ EF - Ar - Y - Ar -g

CH- i J In these formulas, X stands for - CO, -0-, -S- and - C -,

> Ar - X - Ar <for

Y for - O -, -CH ₀ -, -C-, -SO ₀ - and -CO- and

c. t 4

^0H 3.

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- Ar - Y - Ar - fur - (/ \ - and

Particularly suitable "compounds of the formula II are pyromellitic dianhydride , 3,3 '^^' benzophenone tetracarboxylic acid anhydride, Bisphenol tetracarboxylic acid anhydride and 2,3,6,7 ~ naphthalenetetracarboxylic acid dihydride.

Particularly suitable compounds of the formula IV are 4,4-Diaminodiph.enylath.er, 4,4'-diaminobenzophenone, 4,4'-diaminodiphenyl sulfone, m-phenylenediamine, 2,7-diamino naphthalene, and 4,4'-diaminodiphenylmethane.

The tetracarboxylic dianhydride sulfones and diaminoaryl sulfides are condensed by customary processes. For example, it can be prepared by dissolving the starting components in polar solvents such as N-Methylpyrrölidon at temperatures below 6O ⁰ C the corresponding polyamic acid in the solution obtained, which together with the removal of the solvent by distillation and further heating under condensing the desired polymeric imide products. The degree of polymerisation of these products should expediently be above 50.

A polyimide film is obtained, the thickness of which is adjusted as required can be. For use in the manufacture of electrical printed circuits, an oil thickness of 10 to 50 μm preferred. ■

In addition to the polyimide, the film can also contain fillers and reinforcing materials in fibrous, granular or powdery form in a type and amount customary for this field of technology.

The Polyimidverbundfolie obtained is placed between the layers to be bonded of the inorganic and the high temperature-resistant polyimide material and at a temperature between 300 and 45O ⁰ C, preferably 310 to 35O ⁰ C under

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Pressure from 1 "to 100 kg / cm, preferably 10 Ms 50 kg / cm pressed. The pressing time "is 10 seconds to several hours, preferably 20 seconds to 1 hour. As pressing tools can especially heatable plate presses are used. Metal plates heated in a muffle furnace can also be used after placing them in between the layers to be connected are pressed hydraulically.

The layers to be connected to one another consist on the one hand of an inorganic and a high temperature resistant Polyimide material on the other hand. As an inorganic material is Above all, metal, ceramic and glass should be mentioned, but graphite, mica, asbestos and similar materials can also be used.

The inorganic material can be used in the form of plates, but also in the form of fabrics. For making printed Circuits, copper is preferably used as the metal.

The high temperature resistant polyimide layer consists of polyimides preferably based on pyromellitic dianhydride and aromatic diamines such as compounds of the general Formula IV, the 4,4'-diaminodiphenyl ether being used as the diamine very particularly expediently.

This polyimide layer can also contain conventional fillers and Reinforcing materials, such as glass fibers, carbon fibers and Contains graphite in the usual type and quantity.

To increase the adhesive strength of the composite layer on the high-temperature-resistant polyimide layer, the latter can be etched be subjected to the surface. The conventional, imide bonds hydrolyzing, Reagents, especially solutions of alkaline substances in water such as alkali hydroxides, as well as hydrazine and amines.

The composites according to the invention achieve continuous use temperatures of 250 to 300 ⁰ C. Short term is an increase in temperature to 450 to 500 ⁰ C without any significant affect

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Impairment of the mechanical properties possible. The most important areas of application are the manufacture of printed circuits and, due to the still thermoplastic character of the connecting polyimide layer, the manufacture of high-temperature-resistant laminates using the hot-melt adhesive process at temperatures above about 30O ⁰ C for heat and sound insulation purposes.

example 1

A 50 μm thick polyimide film made from pyromellitic dianhydride and 4,4'-diaminodiphenyl ether is treated for 25 minutes with an aqueous sodium hydroxide solution containing 30% by weight at room temperature, then rinsed with distilled water and dried. Between these thus pretreated film and a previously cleaned with nitric acid to 500 thick copper film, a 35 pm thick polyimide from 3,3 ', 4 "4 ^I -Diphenylsulfontetracarbonsäuredianhydrid and 4» 4'-diaminodiphenyl sulfide is then placed and "vnn at a temperature of 34O ⁰ C and a specific pressure of 10 kgf / cm, which brings about the intimate bonding of the individual layers, between two iron sheets for 5 minutes in e: te-heatable plate press pressed cf. the peel strength ASTM D 1781-62 of the copper foil on the as adhesion promoters.. The polyimide film used, measured on a 25 mm wide strip, is 2.5 kp / 25 mm. The peel strength of the polyimide outer layer on the adhesion promoter is 1.8 kp / 25 mm.

Example 2

A 0.2 mm thick iron frame with an outer surface dimension of 200 × 200 mm and an inner surface dimension of 100 × 100 mm is placed on a 200 200 mm large and 0.5 thick titanium foil. In the middle of the frame is a polyimide powder, obtained from a condensate, from 3,3 ', 4,4'-Diphenylsulfontetracarbonsäuredianhydrid and 50 mol- $ 4,4 ^I -Diaminodiplienylsulfid and 4,4'-Di ™ aminobenzophenon with a bed height "brought mm from about 0.7 to 0 ₅ 8 the powder has a leervolnHöen of about 70 $ _e on the bed is placed a further titanium film. Between two iron blocks is at 420 ⁰ C and a pressure of 200 kp / cm

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Pressed for 5 minutes.
The composite obtained shows a peel strength of 2.2 kgf / 25 mm.

Example 3

Between two 3 mm thick glass plates cleaned with chromosulfuric acid, a 100 μτα thick polyimide film made of 50 mol- $ 3.3 ^l H-, 4 ^t ~ Mphenylsulfonetetracarboxylic acid dianhydride and 50 mol- # 3.3 ^l H-, 4 ^r -benzophenonetetracarboxylic acid diarihydride and 4 »4'-Diaminodiphenylsulfid placed and pressed at a temperature of 360 C- and a pressure of about 1 kp / cm. The result is a bond with a peel strength of 1.2 kp / 25 mm.

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Claims (3)

'- 8 - ° · ζ · 2T 248 claims 1. Laminates with high temperature resistance and high bond strength of layers of an inorganic material and / or a high temperature resistant polyimide and a connecting or adhesive layer, characterized in that the connecting or adhesive layer consists of a polyimide which is composed of aromatic tetracarboxylic acid diarihydride sulfones general formula - SO ₂ and diaminoaryl sulfides of the general formula II H ₂ K - [Ar - S ~ | - Ar - MH _p where η is 1, 2 or 3 in each case, this polyimide optionally condensing in from 1 to 50 percent by weight of other polyimides may contain. 2. A method for manufacturing laminates according to claim 1, characterized in that the layers pressed under a pressure of 1 to 100 kgf / cm and at a temperature of 300 to 45O ⁰ G with one another. 3. A method for producing laminates according to claim 1, characterized in that the inorganic material used is glass, ceramic and metal, in particular copper. Badische Anilin- & Soda-Fabrik AG 209828/1044