NL8301814A - METHOD FOR RELAXING POLYMERIC ARTICLES BY RADIATION - Google Patents

Description

-. —II · ^ Λ ~~ ^ "If · Ψ VO 4810 i

Method for relaxing polymeric objects by means of radiation.

The invention relates to a method of treating an object obtained by extrusion or molding of a polymer with radiation in order to release tension present in the polymer or to stabilize the polymer against cracks due to stress. More particularly, the invention relates to a method of rapidly relaxing an article comprising such a polymer or stabilizing such an article against cracking of the polymer due to stress in the manufacture of printed circuit boards.

It is well known that a large number of plastics can be electrolytically coated with metal, for example for decorative purposes, by chemically conditioning those plastics in strong oxidizing acids, for example chromic acid. Among the plastic materials that have been successfully coated are copolymers of acrylonitrile, butadiene and styrene (ABS), polyphenylene oxides (PPO), poly sulfones, polyether sulfones, polycarbonates and nylon. Some of these plastics cannot withstand the soldering temperature, namely a temperature of about 260 ° C. ABS, for example, has a bond strength at room temperature of only 1N / mm and a softening temperature of 80-100 ° C. As a result, a printed circuit board made of ABS is not resistant to soldering temperatures.

The use of thermoplastic polymers as substrates for dented wiring panels has had only limited application due to the marginal chemical compatibility of numerous inexpensive materials in the pretreatment solutions and metal plating baths used in circuit board manufacturing. In certain cases where the chemistry of the process cannot be considered a decomposing factor for the plastic, the stringent requirements of assembling parts and soldering have the following soldering cycles of solvent and / or detergent cleaning eliminate many competitive materials. A suitable thermoplastic material should be compatible with the chemical treatments used in the manufacture of circuit boards. In certain cases, where the chemistry of the process cannot be considered a decomposing factor for the plastic, the stringent requirements of assembling parts and soldering as well as soldering cycles following cleaning with solvent and / or detergent eliminate many competitive materials. A suitable thermoplastic material must be compatible with the chemical treatments used in the manufacture of circuit panels, be machined on existing equipment, be solderable and cleanable, and finally be a suitable dielectric material.

Numerous extrusion or molding films, sheets or articles of high temperature thermoplastic polymers require special treatment to relax them each time they have been mechanically machined. For example, flaking may be caused by drilling, machining, cutting, trimming, etc., or cracks may form in the polymeric material as a result of the stress that occurs therewith.

Base materials for printed circuits, consisting of a high temperature thermoplastic polymer, such as polyether-20 imide sheets laminated with copper foil, have been previously proposed, but have not been widely used due to the extremely great handling difficulties and the high cost of the resin system.

It is an object of the present invention to provide better methods for relaxing an extrusion or molding polymeric article, such as an article comprising a high temperature thermoplastic polymer with an aromatic backbone. Another object of this invention is to provide better methods of relaxing articles comprising an aromatic polyether polymer.

An object of this invention is to provide a better method for efficiently relaxing an article comprising such polymers, avoiding the need to gently anneal the polymer or fix it between support plates to maintain its shape during relaxation , or avoid physical deformation.

Another object of this invention is to provide 3301814 * 3 *. ψ of methods for relaxing articles, which include a surface layer of the polymers laminated to or adhered to a substrate.

Another object of this invention is to provide a method of manufacturing a starting material suitable for the manufacture of printed circuit boards, said starting material being a film, sheet or substrate of a high temperature thermoplastic polymer with a thickness of at least 75 µm.

Other objects and advantages of the invention will be described below or may be obtained in the practice of the invention.

By the term "aromatic polyether polymer" is meant a thermoplastic polymer, which is characterized by repeating aromatic and ether units in the polymer chain. Representative, but not limitative, examples thereof are polyetherimides and polyetherether ketones.

The term "high temperature thermoplastic polymer" is intended to refer to a polymer having an aromatic backbone that does not liquefy or decompose at that temperature. The polymer has a heat deflection temperature of 170 ° C higher.

To achieve the objects described above, the present invention provides a method of relaxing a polymeric article or an article comprising such a polymer, which method comprises exposing said article to electromagnetic radiation selected from microwave, infrared and ultraviolet radiation at one or more frequency ranges, which can be absorbed by that object and are effective to release the stress, thus relax the object, practically without causing heat-induced softening or flow of the polymer, and the article is exposed to said electromagnetic radiation for a sufficient time to absorb sufficient energy to relax and / or stabilize the polymer against stress-induced cracks.

The article may be composed of a high temperature thermoplastic polymer and may, for example, be formed by extrusion or molding and it may be in the form of a sheet, an 8301814% w 4% untreated raw material, a film or any other geometric shape . Stress-induced cracking or cracking in the polymeric article may result from an extrusion, molding or metal coating step or from a mechanical treatment or from a swelling and etching treatment or other chemical treatment, as will be described below. discussed.

It has been found that relaxing the polymer by exposing it to infrared, ultraviolet and / or microwave radiation does not generate substantial heat and does not depend on it. Since no significant heat development occurs,. Also, the present method of relieving stress does not cause softening or flow of the polymeric material and thus does not alter its geometric shape or dimensions. The present relaxation can therefore be applied without using the support and clamping devices, etc., which have hitherto been used. generally used.

The present invention also relates to better methods of manufacturing the following materials: an untreated raw material, an insulating substrate to which a metal layer is laminated, a printed circuit panel and printed circuit panels manufactured by the aforementioned methods. The polymeric article can have a thickness of at least 75 µm and preferably has a thickness of less than about 6250 µm.

The present invention provides a simple and economical method of manufacturing an insulating substrate comprising a high temperature resistant thermoplastic polymer, for example an aromatic polyether polymer, having a surface capable of forming a layer or pattern of a electroless plating techniques applied to receive conductive metal. The method of manufacturing the polymeric insulating substrate or starting material for use in the manufacture of a printed circuit comprises exposing a polymeric film, sheet or substrate of the desired geometric shape to electromagnetic radiation at one or more frequency ranges capable of to be absorbed by the film, sheet or substrate and effective to relax the polymer substantially without causing heat-induced softening or flow of the polymer, for a sufficient time to absorb sufficient energy to release the stress and / or stabilize the polymer against stress cracking or cracking, the electromagnetic radiation being selected from microwave *, infrared and ultraviolet radiation; mechanical processing of the film, sheet or the substrate, to make holes therein, repeating the radiation treatment Long stage after the holes have been made or after any other mechanical machining stage; chemically treating the surface of the film, sheet, or substrate with a polar solvent capable of swelling the outer surface of the film, sheet, or substrate, and treating the surface of the film, sheet or the substrate with a strong oxidizing solution or other agent or with a plasma at a temperature and for a sufficient time to obtain places for chemically and / or mechanically bonding the surface to an attached metal layer.

The invention also relates to a method of manufacturing an assembly for use in the manufacture of printed circuit boards, which method comprises providing a polymeric film or sheet of substantially uniform thickness, preferably greater than 75 µm ; laminating the radiation-treated polymer film or sheet with a sheet of reinforced thermally cured material by applying an adhesive layer between the two materials or by applying heat and pressure or by using both; mechanically or otherwise machining the laminated assembly to provide one or more holes in the assembly; and exposing the assembly to said electromagnetic radiation at one or more frequency ranges that can be absorbed by the film or sheet of the assembly and effective to release the stress 30 substantially without heat-induced distortion as a result of softening or flowing of the polymer, for a sufficient time to absorb sufficient energy to release the stress and / or stabilize the polymer against stress-induced cracks or cracking. The film or sheet can be laminated with the thermally cured sheet by applying heat and pressure or by the action of an adhesive intermediate layer or by a combination of both.

8301814. 41 6

According to the invention there is also provided a method of manufacturing a multilayer printed circuit board which comprises the steps of providing a substrate with a printed pattern on at least one surface thereof; laminating a high temperature thermoplastic polymer film or sheet to its metal-coated surface; making one or more holes in the assembly thus formed; exposing the polymer film or polymer sheet to infrared or ultraviolet radiation at one or more frequency ranges, which can be absorbed by the film or sheet and effective to release the stress, substantially without heat-induced distortion due to softening or flowing the polymer for a time sufficient to release the stress and / or stabilize the polymer film or sheet against stress-induced cracks or cracking; treating the polymer surface with a solvent and an oxidizing agent to make the surface microporous and hydrophilic; repeating said radiation treatment step for a sufficient time to stabilize the polymer against stress-induced cracking or cracking; and applying a metal coating to the treated surface and to the walls of the hole or holes to form a second conduction pattern.

According to a preferred embodiment, the sheet or film of a thermoplastic polymer has a thickness of at least 75 µm.

The second conduction pattern may be formed by electroless deposition, followed or not by electrolytic deposition by any other known method.

Aromatic polyether polymers are high temperature thermoplastic polymers which have an aromatic backbone and do not liquefy or decompose at a temperature of about 245 ° C after being exposed to such temperature for 5 seconds. Aromatic polyether polymers suitable for the purpose of this invention include polyetherimide and polyetherether ketone.

It has been found that sheets and films of high temperature thermoplastic polymers are gently tempered for a long time to avoid cracking due to stress. For example, it is known that polyetherimide materials must be treated at 200 ° C for 2-4 hours after fabrication steps such as compounding. In addition, it has been found that materials of the aromatic polyether type "should be carefully tempered after the mechanical characteristics have been applied to the panel prior to the electroless metal deposition in order to avoid stress cracking in a solvent with a swelling effect. and an oxidizing solution. Tension is created in the 10 polymer sheets by drilling closely spaced holes as required for a "dual inline package", ie 7 to 20 holes 1mm in diameter spaced 2.54mm apart.

When the polymer sheets are exposed to a solvent having a swelling action, stress corrosion occurs, which can cause the sheet to crack or break in two or more pieces during the swelling. Residual stresses still present in the material in molded parts can similarly cause stress corrosion cracking. Even more stresses may be caused by rods and clamps used to hold the polymeric articles when a solvent having an expanding action acts on them. If the residual strength from the molding or from a mechanical operation is not removed before the action of the swelling solvent, the additional stress imposed by the rods or clamps will accelerate stress corrosion cracking.

It has been found that stress corrosion cracking is much stronger with thin sheets, for example, 0.4 mm thick polyetherimide, than with thick sheets, for example, 1.6 or 3.2 mm thick polyetherimide. Thin sheets will break and tear more easily due to stress corrosion cracking. Another form of stress cracking occurs in the form of thin surface cracks, which are discovered only after the metal is applied to the polymeric article.

These cracks are transferred into the metal layer, making it uneven for use as an electrical contact surface.

As noted above, prior art requires a gentle and slow annealing after machining the material before etching the surface for subsequent metal deposits. The advantages of using rigid molded aromatic polyethers are very important to those users who have stringent electrical requirements in high frequency applications. In those cases, the material is ideally suitable, but requires cumbersome annealing steps to be performed to make the material workable. As described herein, the relaxation by radiation treatment and the manufacture of the starting material and / or the laminate of this invention take place simultaneously in one step. It has been found that the above-mentioned polymeric films, sheets and compositions, as well as circuit panels of this invention, can be relaxed or stabilized against stress cracking over time in the order of minutes or less by exposure to predetermined ranges of frequencies of electromagnetic waves. This finding makes it unnecessary to employ the aforementioned cumbersome and time-consuming gentle annealing secondary stages of the prior art. The present invention is based on the finding that extruded or molded polymeric objects or materials, such as high temperature thermoplastic polymers, can be relaxed or stabilized against stress cracking in a short period of time and without any deformation or stresses occur in the material. This is accomplished by exposing the polymeric material to one or more microwave, ultraviolet, or infrared frequencies, which can be absorbed by the polymer and are effective to release the stresses, essentially without heat-induced softening or flow of cause the polymer. The polymeric material thus treated is stress-free and / or stabilized against stress-cracking so that it can be drilled or later introduced into the various oxidizing and swelling solutions, etc., without stress-cracking. In addition to rapidly relieving stress or stabilizing a polymer from stress cracking, another advantage of this invention is that the risk of deformation of the article is substantially nonexistent.

According to an aspect of this invention, an article 8301814 * 9, consisting of an aromatic palyether polymer, is exposed to 8 16 microwave frequencies above 1900 MHz, preferably between 10 and 10 Hz, in the space of a microwave oven to form the object. relax.

In contrast to the known methods, microwave treatment reduces the chance of heat distortion and it is also not necessary to fix the materials between metal plates, which is done in the case of gentle thermal annealing. The microwave treatment step is rather short, namely between 1 and 60 minutes and typically on the order of 30 minutes (for material with a thickness of 10 1.6 mm); that treatment stage varies depending on the thickness of the material. After treatment in a microwave oven, the relaxed polymeric materials can be processed and, in the case of fabrication, printed circuit boards drilled or punched for the prefabrication of holes.

The methods of this invention may also utilize microwave frequencies to achieve the same result as a second annealing fogging treatment, which is typically recommended according to previously known methods. The fabricated portion can be relaxed by exposure to microwave frequencies for a suitable period of time, for example, 30 minutes for a material 1.6 mm thick. The steps of the methods of this invention eliminate the long baking cycles of the previously described known methods, while making the polymeric part dimensionally stable and resistant to subsequent chemical and metallizing treatments.

In another aspect of this invention, infrared radiation, such as used for curing mask inks used in the fabrication of printed circuit boards, for example, can be used to relax polymeric materials.

The polymer can be exposed to infrared radiation in an infrared oven with transport facilities. In contrast to the known stress release methods, the infrared treatment cycle of the present invention, due to its short duration, reduces the potential for heat distortion and has found that when used, the materials do not need to be fixed between metal plates, which otherwise used in thermal relief 8301814 r 10. The infrared treatment step is performed by exposing the polymeric material to such radiation with a wavelength between 2/5 and 50 µm, preferably between 6 and 20 µm, for a period of time of at least 35 seconds (for material of thickness 5 of 1.6 mm).

The time period varies depending on the thickness of the polymeric material / whereby longer times are of course required for thicker materials.

In yet another aspect of this invention, an ultraviolet radiation source can be used to treat the polymer.

*

Although the radiation treatment of high temperature thermoplastic polymeric objects can generally be optionally performed with infrared, microwave or ultraviolet radiation according to this invention, there are exceptions.

According to a method of manufacturing printed circuit panels, the so-called "semi-additive" technique is applied. The starting insulating material of this invention is cut to size and exposed to microwave, infrared or ultraviolet radiation at a frequency that can be absorbed by the polymer. The holes are then made therein by drilling, punching or the like. According to an alternative method, the starting material can be molded in such a way that the holes are already therein. With a starting material formed in such a manner, it is not necessary to make holes in a mechanical manner later, nor does a relaxation-inducing irradiation step need to be performed prior to such a mechanical treatment step. After the holes are made, the starting material is exposed to microwave, infrared or ultraviolet radiation at a frequency that can be absorbed by the polymer. Then, the starting material is pretreated in a solution of dimethylformamide, for example, for 3-6 minutes and then etched in a strong oxidizing solution at about 55-65 ° G for, for example, 3 minutes. This changes the surface of the starting material from glossy to hazy, while providing sites for chemically and / or mechanically bonding the surface of the starting material with metal deposited thereon. A thin metal layer is then electrolessly deposited on the surface and on the hole wall (s) of the starting material. After this stair churn. the metal clad panel are printed with a desired circuit pattern by using a photoresist technique or by screen printing the negative of the desired circuit pattern. Copper or copper and another metal is electrolytically applied to the cartridge until a desired thickness is achieved. The pattern can then be coated with solder if desired. The reserve is removed and the thin layer of the exposed electroless metal thus etched away.

According to another method of manufacturing printed circuit panels using the radiation treatment of the present invention, a suitable insulating raw material is made from an aromatic polyether material.

Holes with a distance between their centers of 2.5 mm or less are made in preselected locations in the starting material. Before making the holes, the starting material is exposed to microwave, infrared or ultraviolet radiation as previously described and the surface of the starting material, including the wall (s) of the hole or holes, is pretreated to be hydrophilic and micro - make it porous. The surface, including the hole wall (s), is completely coated with an aqueous ultraviolet-reducible copper complex and dried according to the technique described in Dutch Patent Specification 171,383 or in Dutch Patent Applications 25 72.10534, 75.08354, 72.10532 or 75.08355. A photo image is formed by projection or contact printing onto the sensitized substrate, the unexposed photo-reducible coating is washed away, and the image is fixed by briefly exposing it to an electroless copper plating bath.

A metal such as copper is electrolessly deposited on the pattern thus formed, including the hole wall (s), for a period sufficient to achieve the desired thickness, for example, 25-125 µm.

The starting material of the present invention may alternatively be catalytic in its entirety, namely comprising suitable materials distributed or processed throughout 8301814 12 during extrusion of the thermoplastic film surface of the starting material; starting materials and / or laminates of this invention are the polymers as previously defined.

According to an embodiment of the invention, support materials which can be provided with a surface layer of a thermoplastic material according to this invention contain inorganic and organic substances, such as glass, ceramic, porcelain, resins, paper, fabric and the like. For printed circuits, materials used as such a carrier include insulating thermosetting resins, thermoplastic resins and mixtures thereof, including glass fibers, impregnated paper and the like.

The invention is described in more detail below with reference to the figures of the accompanying drawing, which show certain embodiments of this invention.

Figures 1-3 show processes that can be used for manufacturing printed circuit boards from insulating starting materials made in accordance with the teachings of this invention.

Fig. IA shows an insulating catalytic starting material 10 consisting of an aromatic polyether polymer, such as a poly-20 etherimide or a polyether ether ketone. The polymeric starting material 10 is catalytic to receive electroless deposits. Before drilling holes, the starting material 10 is exposed to microwave radiation at a frequency above 1960 MHz for 30 minutes.

In Fig. 1B, holes 16 and 18 are shown in the starting material 10.

After the holes are made, the starting material 10 is exposed to microwave radiation as previously described. The starting material 10 is then dipped in a solvent, followed by a chemical treatment in a solution with 20 g / l CrO 2, 500 mg / l HjSO 2, 25 g / l NaF and at a temperature between 45 and 65 ° C , in order to expose the catalyst and make the surface hydrophilic and microporous (Fig. 1C).

A permanent photo reserve 24 is applied to the surface of the stock 10 to mask areas not coated with copper 35 (Fig. 1D).

Then, by known methods, copper is electrolessly deposited on the walls of the holes 16 and 18 and on the exposed surface areas of the starting material 10, thereby forming the conduction pattern 22 (Fig. IE) -

A register solder mask 30 can be applied as shown in Fig. 1F.

Figures 2Ά - E show the use of a fully additive method for manufacturing a printed circuit board, wherein Figure 2A shows the insulating starting material 10, which consists of a polymer sheet of polyetherimide.

In Fig. 2Ξ, a hole 16 is shown in the starting material. Before and again after the hole 16 is made, the starting material is exposed to a microwave radiation as previously described in connection with Fig. 1 and for a period of 1-25 minutes, depending on the mass of the starting material and the frequency of the radiation in order to release the stress from the raw material, substantially without generating heat, which would cause deformation or liquefaction of the sulfone polymer. The starting material 10 and the walls of the hole 16 undergo surface pretreatment as previously described and are then completely coated with an ultraviolet-reducible copper complex 20 and dried (Fig.

2C).

An ultraviolet light photo image is formed on the thus photosensitive surface by short projection or contact printing. Then, the unexposed photo-reducible coating 20 is washed away and the image 22 is fixed by briefly exposing 25 to an electroless copper bath (Fig. 20).

Copper is then electrolessly deposited on the formed copper pattern, including the wall of the hole 16, until the circuit pattern 28 is built up to the desired thickness.

Figures 3A-F show an electroplating method, wherein Figure 3A shows a starting insulating material 10 consisting of a polyether ether ketone. Both before and after the holes are made, the starting material is exposed to infrared radiation at a frequency between 2.5 and 40 µm for a time period of the order of 1 minute or less, depending on the mass of the starting material, in order to reduce the voltage virtually without heat generation which would cause deformation or liquefaction of the polymer. The starting material is then continued. pre-treated in a solution of dimethylformamide for about 3-6 minutes and in a strong oxidizing solution or in an oxidizing atmosphere for about 3 minutes at 35-70 ° C. As a result, the surface of the starting material 10 is changed from glossy to hazy, while providing sites for chemically and mechanically bonding that surface with metal deposited thereon. The starting material 10 thus treated is made susceptible to electroless metal deposition by solution immersion consisting of the reaction product of SnCl 2 and PdCl 2 at room temperature for 1-3 minutes. During that immersion, catalytic sites 20 are deposited over the entire starting material, including the hole wall (s) or holes (not shown) (Fig. 3B).

A layer of electroless metal 22 is deposited on the surface and holes (not shown) of the starting material 10 (FIG. 30) using a known electroless metal deposition method. A desired circuit pattern is achieved by of a photoresist technique printed on the metal coating 22 of the starting material 10. A photosensitive coating 20 24 is applied to the entire surface of the starting material 10. After exposure of the coating 24 with ultraviolet light, a mask 26 is formed, the areas correspondingly remain free with the circuit pattern to be reproduced (fig. 3D).

Copper 28 is electrolytically applied to those areas in the desired thickness (Fig. 3e).

The backup mask is then stripped and the electrolessly deposited copper film released therefrom is removed by etching (Fig. 3F).

Some applications of the present invention are illustrated in the examples below.

Example I

An extruded sheet of a 1 mm thick polyetheretherketone (PEEK) was treated as follows: (1) 2 mounting holes were drilled to provide means to secure the sheet during the treatment; (2) the sheet was exposed to microwave radiation at 2450 MHz for 1 minute in a microwave oven; 8301814 f »t '»

IS

(3) the sheet was dipped in an aqueous solution of dimethylformamide (s.g. 0/955 - 0/965) for 3-6 minutes; (4) the sheet was dipped in a hot aqueous solution of 0.1% of an anionic surfactant, a nonylphenylpolyethoxyphosphate (GAFAG RE-610) at 35-45 ° C for 5-60 seconds; (5) the sheet was dipped in an aqueous solution of phosphoric acid 100 cc / l / sulfuric acid 600 cc / l and 0.05% of an anionic per-fluoroalkyl sulfonate at 55 ° C for 5 minutes; (6) the sheet was treated for 5 minutes in a solution of 10 400 g / l CrO 2, 250 cm3 / l HjSt 4, 50 cm3 / l HjPO 4 and 0.5 g / l of an anionic perfluoroalkyl sulfonate at 70 ° C and rinsed in calm water; (7) the sheet was donated in a solution of 40 ml of 35% hydrogen peroxide and 10 ml of 96% sulfuric acid and rinsed in water; (8) the sheet was dipped in an alkaline cleaning solution R! TM ^ 15 (ALTREX) and rinsed again in water; (9) the sheet was successively dipped in a pre-immersion solution of tin (II) chloride sodium, an activator solution consisting of tin (II) chloride palladium chloride, a water rinse bath and as an accelerator in 5% fluoroboric acid; 20 (10) copper was electrolessly deposited on the sheet in a thickness of 2.5 µm; (11) the copper clad sheet was rinsed with water and dried at 125 ° C for 10 minutes to obtain a copper clad extruded sheet as shown in Fig. 3C.

The copper-coated sheet was electrolytically coated in a copper sulfate coating bath to obtain a thickness of 35 µm. A peel strength of 2.6 N / mm was measured. After a soldering flux test at 288 ° C for 20 seconds, no exfoliation or delamination was observed.

Example II

The procedure described in Example I was repeated, but instead of the 1 mm thick sheet of polyether ether ketone, a 1.6 mm thick extruded sheet of polyetherimide was used. The peel strength. of the copper was found to be iN / mm. The sample was resistant to a solder flux test at 260 ° C for 10 seconds.

Example III

Molded raw materials of poly 8301814

V ·· V

4 16 etherimide resin were prepared. The molding resin contained 0.12% titanium dioxide pigment to make the starting materials opaque. Some of the starting materials were formed with 10% glass fiber filler and some with glass fiber filler plus mineral filler for reinforcement. The formed starting materials were treated according to the procedure described in Example 1, steps (2) to (8), except that the adhesion promoting step (6) was carried out for 3 minutes.

A printed wiring pattern was applied to the starting materials by the process of Dutch patent application 75.08354 and coated in an electroless copper plating bath with copper at a thickness of 35 µm. The starting materials were dried at 160 ° C for 1 hour. The following peel strength values were found:

Form compound Peel strength polyetherimide + 0.12% TiOj Ir75 N / mm 15 polyetherimide + 0.12% TiO2 + 10% glass fiber 1.40 N / mm polyetherimide + 0.12% TiO ^ + 10% glass fiber + mineral filler 1.20 N / mm

Example IV

Printed wiring was produced on an extruded polyetherimide sheet using the semi-additive technique. The starting material was cut to the desired size, relaxed according to the present invention and provided with a hole pattern. It was then treated according to the procedure of Example I, steps (2) - (11). Then the starting material was provided with a printed plating mask and electrolytically coated with copper; after the mask was removed, the thin electrolytically formed copper deposit released thereby was removed, thereby obtaining a conductive copper printed circuit pattern, also plating the hole walls. The peel strength of the copper conductor to the base material was determined to be a value of iN / mm. Example V

The top and bottom of an epoxy glass-35 laminate panel were coated with a 35 µm thick copper foil. A printed 8301814 * Jr-17 4 guide pattern was formed according to the well-known dent and etch technique.

A polyetherimide adhesive was prepared by dissolving pellets of polyetherimide resin in methylene chloride. A 75 µm-thick polyetherimide film was coated with the adhesive and laminated in a rotary laminating press with a hot silicone rubber roller at 75 ° C using the panel pressure of 15N / mm width, the panel passing through the rotary laminator. at a speed of 20 mm / minute.

. Holes with walls to be metallized were made in the panel by drilling and the drill bits were removed by brushing. Before and after the holes were made, the starting materials were relaxed by exposure to infrared radiation at a frequency of 2.5 - 40 mm for a duration of 35 seconds in an infrared melting furnace. The panel was processed into a multilayer printed circuit board according to the procedure described in Example I, except that the time for the. treatment to promote adhesion was only 2 minutes.

8301814

Claims (17)

Method for relaxing a polymeric object or an object comprising such a polymer / characterized in that the object is exposed to electromagnetic radiation selected from microwave, infrared and ultraviolet radiation at one or 5 more frequency ranges, which are article can be absorbed and effective to release the stress substantially without causing heat-induced softening or flow of the polymer, and for a sufficient time to absorb enough energy to relax and / or stabilize the polymer. against stress-induced cracks. 2. A method according to claim 1, characterized in that the polymeric article is an extrusion or molding article comprising a high temperature thermoplastic polymer with an aromatic backbone that does not liquefy or decompose at a temperature of about 245 ° C, after being exposed to that temperature for 5 seconds. A method according to claim 2, characterized in that the object obtained by extrusion or molding comprises an aromatic polyether polymer. Process according to claim 3, characterized in that the polymer is selected from polyetherimides and polyetheretherketones. A method according to claims 1-4 for manufacturing a starting material for use in making a printed circuit board, characterized in that a polymeric film, sheet 25 'or substrate of a desired geometric shape comprising a high temperature thermoplastic polymer with an aromatic backbone, which does not liquefy or decompose at a temperature of about 245 ° C, after being exposed to that temperature for 5 seconds, is exposed to electromagnetic radiation at one or more frequency ranges, which can be absorbed by the film, sheet or substrate and effective to release the stress substantially without causing heat-induced softening or flow of the polymer for a period of time sufficient to absorb enough energy to absorb the stress and / or to stabilize the poly- 8301814 * * ψ more against cracks or cracks as a result of s panning, where the radiation is selected from microwave, infrared and ultraviolet radiation; the film, sheet or substrate is mechanically treated to make holes therein; the radiation treatment step is repeated; the film, sheet or substrate is chemically treated with a polar solvent capable of swelling the outer surface of the film, sheet or substrate; and the surface of the film, sheet or substrate is treated with a strong oxidizing solution or other agent or with a plasma 10 at a temperature and for a time sufficient to provide sites for the chemical and / or mechanical joining the surface with a metal layer, which is attached to it » 6. A method according to claims 1-4, for producing an assembly suitable for use in the manufacture of printed circuit panels, characterized in that a polymeric film or sheet is provided consisting of a high temperature thermoplastic polymer with an aromatic backbone that does not liquefy or decompose at a temperature of about 245 ° C after being exposed to that temperature for 5 seconds; the film or sheet is exposed to electromagnetic radiation at one or more frequencies that are able to be absorbed by the film or sheet and effective to release the stress substantially without heat-induced distortion; and the radiation-treated polymer film or sheet is laminated to a sheet of a reinforced thermally cured material; and treating the laminated assembly mechanically or otherwise, thereby providing one or more holes therein; and the assembly is exposed to the electromagnetic radiation at one or more frequency ranges that can be absorbed by the film or sheet of the assembly, for a period of time sufficient to absorb enough energy to release the voltage and / or stabilize polymer against cracking or cracking due to stress. A method according to claim 6, characterized in that the film or sheet has a thickness of more than 75 µm. A method according to claim 6 or 7, characterized in that the film or sheet is laminated to the thermally cured material by applying heat and pressure. Method according to claims 6-8 / characterized in that the film or sheet is laminated to the thermally cured material using an adhesive layer between the film or sheet 5 and the thermally cured material. A method according to claims 1-4, characterized in that the polymeric article is an injection molding article of a high temperature thermoplastic polymer, the article containing one or more holes therein. A method according to claims 1-4 for manufacturing a multilayer printed circuit board, characterized in that a substrate with a circuit pattern is provided on at least one surface thereof; a high temperature thermoplastic polymeric film or sheet is laminated to the metal coated substrate; The assembly thus formed is provided with one or more holes; the polymer film or sheet is exposed to infrared or ultraviolet radiation at one or more frequency ranges passing through the. film or sheet can be absorbed and effective to release the stress, substantially without heat-induced distortion due to polymer softening or flow, for a time sufficient to release the stress and / or to stabilize the polymer film or sheet against cracking or cracking due to stress; the polymer surface is treated with a solvent and an oxidizing agent to make the surface microporous and hydrophilic; the radiation treatment step is repeated for a time sufficient to stabilize the polymer against cracking or cracking due to stresses; and the treated surface and the walls of the holes are provided with a metal coating to form a second circuit pattern. A method according to claim 11, characterized in that the film or sheet has a thickness of more than 75 µm. Method according to claim 2 or 3, characterized in that the radiation is infrared radiation with a wavelength between 2.5 and 40 µm and the exposure time is less than 1 minute. Method according to claim 2 or 3, characterized in that the radiation is microwave radiation with a frequency of about 8301814 V 1960 MHz. 15. A method of metal-coating a polymeric article consisting of a high temperature thermoplastic polymer with an aromatic backbone that does not liquefy or decomposes at a temperature of about 245 ° C after 5 seconds at that temperature exposed, characterized in that the polymeric object is exposed to electromagnetic radiation at one or more frequency ranges that are capable of being absorbed by the object and effective to release the stress, essentially without heat-induced distortion by softening or liquefaction of the polymer, for a period of time sufficient to absorb enough energy to release the stress and / or stabilize the article against stress cracking or cracking, the radiation being selected from microwave , infra-15 red and ultraviolet trailing; the surface of the polymeric article is chemically treated with a polar solvent capable of swelling the outer surface of the article to promote adhesion of etched metal to its surface after an etching step; the surface is treated in a strong oxidizing agent, providing sites for chemical and / or mechanical bonding of the surface to the metal; and a metal layer is deposited on at least part of the surface of the object. A method according to claim 15, characterized in that the article is an article of an aromatic polyether polymer. A method according to claim 5, 11 or 15, characterized in that the metal attached to the starting material, film, sheet or object, consisting of or comprising the radiation sensitive treated polymer, is formed by electroless metal deposition, whether or not followed by electrolytic metal deposition. 8301814