DE10058822A1 - Process for treating a carrier film made from a plastic or polymer comprises applying a functional layer as conducting path on the film so that material parts enter recesses of the functional layer to anchor the layer in the foil - Google Patents

Abstract

Process for treating a carrier film made from a plastic or polymer comprises applying a functional layer as conducting path on the film so that material parts enter recesses of the functional layer to anchor the layer in the foil. Preferred Features: The shape and depth of the recesses are determined by radiating and etching conditions. The functional layer is passive or functional. Anchoring is carried out by allowing material parts of the functional layer to penetrate the recesses of the film. An adhesion promoter is provided between the layer and film to increase the adhesive strength. The functional layer is made from metal or non-metal and is conducting or non-conducting.

Description

State of the art

The invention is based on a method for processing a Carrier film made of plastic or polymer or a film as a carrier a functional layer according to the type of the main claim or of subsidiary claim 20.

In a known generic method (DE 42 10 486 C1 and EP 0 563 605 A1), solid bodies are irradiated, preferably of polymer films, with high energy Heavy ions with subsequent etching of the ion traces in order thereby continuous cylindrical micropores for the purpose of Manufacture of filters for ultrafiltration (pore diameters up to  50 nm) and microfiltration (pore sizes between 0.05 and 2 µm). Such filters with continuous micropores are called ion track membranes.

This method also enables the creation of further pore shapes along ion tracks in dielectric solids, preferably polyimides, by using the experimental knowledge that the ratio of the track etching rate ν _T (etching speed in the direction of the ion track) and the material etching rate ν _B (etching speed of the undisturbed material), the so-called selectivity, during the etching has a strong dependence on the pH of the etchant. Tapered and cylindrical pores as well as combinations of both geometries can be created, whereby in this application a very substantial, small fluctuation range of the pore diameters is achieved for the filter production. This known method is limited to use in the production of continuous pores. The change in the track etching rate takes place by changing the pH of the etching medium, the pore shapes being limited to cones, cylinders and their combination, and a conical channel on the surface of the film being widened. More complicated pore shapes are not feasible.

The invention and its advantages

The inventive method for processing carrier films with the characterizing features of the main claim or the Carrier film according to the invention with the characteristic features of subsidiary claim 20, in contrast, have the advantages that through the use of plastic carrier films or Polymer for layers of metallic, semiconducting or non-metallic material new fields of application especially on the Area of circuit board technology to be created, and here  a fast and material-saving process for generating the surface roughness required for the coating Carrier film is provided.

A method is known per se (DE 196 50 881 C2 and DE 33 37 049 A1), the creation of continuous pores (Micro holes) perpendicular to the surface (z direction) of plastic Enables foils and their filling with metallic threads, resulting in an anisotropic electrical conductivity of the film (electrically conductive in the z direction, i.e. perpendicular to the surface, but isolating in the x-y direction, d. H. parallel to the surface) becomes. This known method for filling microholes with metallic material through current-carrying galvanic However, deposition is only applicable to micro-channels (pores) that completely penetrate the film and cannot be used for Recesses that are designed as blind holes, that is end like a dead end in the film.

The advantage of the invention is particularly evident in a comparison with another known method for Connection of a functional layer with a carrier layer, the Coating of substrates using the additive process. With this The method is based on a base material filled with Pd seeds Adhesion promoter (acrylic adhesive with epoxy resin additive) and then one Galvanoresist mask (one by organic solvents developable dry film), which the desired conductor structure pretends to be upset. In those not covered by the mask Areas, the electroless catalyzed by the Pd nuclei occurs Copper deposition (35 µm in 20 h), with an adhesive strength of 1.8 to 2.4 N / mm is reached. The use of the adhesion promoter increases the number of process steps and complicates the process technological process. Therefore, as a further procedure So-called full additive process developed, which is a mechanical  Anchoring the copper layer on the substrate surface without Allows the use of an adhesion promoter. The procedure goes from standard, one-sided with a thickness of approx. 35 µm Copper lamination laminated circuit board substrates made from glass fiber reinforced epoxy. This copper layer will initially completely removed by etching. This will make the Outside of the laminate the micro-rough surface on the resin exposed by the roughness of the treatment side of the Copper lamination was created when pressing the laminate, so that sufficient adhesion in the subsequent copper plating of the metal on the base material is reached. The Conductor structures are also here by applying a Galvanoresists are produced, with 40-45 µm thick copper tracks grow the areas not covered by the resist. This known method has the disadvantage that an expensive Starting material, namely that completely laminated with copper Substrate, is used very ineffectively. The angry one The copper layer is completely removed in order to ensure that the Laminated micro-rough surface of the substrate for subsequent application of a new copper covering with the to be able to take advantage of the required adhesive strength. On untreated substrate has such a smooth surface that the necessary adhesive strength would not be guaranteed.

According to an advantageous embodiment relating to the method the invention is the shape and depth of the recesses the radiation and etching conditions determined.

According to a further advantageous embodiment of the invention the recesses do not penetrate the film.

According to a further advantageous embodiment of the invention the functional layer is passive or functional.  

According to a further advantageous embodiment of the invention anchoring the functional layer by intervening Material parts of the functional layer in the recesses of the film achieved.

According to an advantageous embodiment of the Invention increases the adhesive strength of the applied layer, by engaging the recesses in the carrier film are trained.

According to a further advantageous embodiment of the invention to increase the adhesive strength between the layer and the carrier film Adhesion promoter provided, which makes one for many purposes suitable, particularly high adhesive strength of the layer results.

According to a further advantageous embodiment of the invention set the trace etch rate along the ion trace by the local Distribution of the energy introduced into the film by choosing the Entry energy of the heavy ions, based on the Bragg peak, is determined.

According to an advantageous embodiment of the Invention selectivity is defined as the ratio between Track etch rate and material etch rate, and thus the shape of the Recesses by the etching conditions, d. H. through the Composition of the etchant, by the concentration of the individual components of the etchant, by the etching time, by the pH of the etchant and the temperature during the etching process certainly.

According to a further advantageous embodiment of the invention the etching conditions are changed during the etching process,  on the one hand this creates the possibility of Adapt etching conditions to the material of the carrier film, and others this results in further possibilities, the form of the To design recesses.

According to a further advantageous embodiment of the invention are after the irradiation and before the etching of the carrier film Measures to sensitize the ion traces under Use of UV light, oxygen or Dimethylformamide (DMF) seized, which in particular the ratio the track etch rate to the material etch rate, d. H. the caustic effect in the area the ion trace is increased.

According to a further advantageous embodiment of the invention by varying the resulting selectivity, i.e. H. from the Ratio of track etch rate to material etch rate, the shape of the Recesses between the limit cases of a blunt etching cone and one that runs through the entire thickness of the carrier film Cylinders can be varied.

According to an advantageous embodiment of the Invention are towards the inside of the carrier film Bottle-shaped recesses can be produced.

According to a further advantageous embodiment of the invention ion bombardment several times with different energy, different ions and / or different Bullet points are carried out, so almost everyone Surface depth relief can be created. The term surface depth Relief means that the formation of the surface including the Volume to a predetermined depth leads to the fact that in formed the differences between surface and Volume can be blurred to a certain extent. The  resulting structure is reminiscent of a fractal structure created by a fractal dimension D is marked with 2 <D <3, where D is from the surface grows and in volume when reaching the not affected by the formation of the value 3 reached.

According to a further advantageous embodiment of the invention, the diameter of the recesses measured on the surface of the carrier film can be varied between 20 nm and several micrometers and the surface density of the pores determined by the ion current can be varied between 10 ⁵ and 10 ¹¹ cm ^-2 . This results in a great number of design options for the surface depth relief of the carrier film.

According to a further advantageous embodiment of the invention there are recesses of different sizes, shapes and orientations and / or areal density overlaid in the carrier film in such a way that there is a surface-depth-relief that the required Adhesion and functionality of the carrier film applied layer guaranteed.

According to a further advantageous embodiment of the invention can the conditions of irradiation and etching of the carrier film be chosen so that a surface Deep relief between the borderline cases of an almost undisturbed Surface with a low density of recesses and one strongly fissured surface with a high density itself overlapping, different recesses results, whereby the processed carrier film for many different Can adapt application purposes.

According to a further advantageous embodiment of the invention are in the carrier film with a strongly jagged surface structure  conical to improve their mechanical stability Recesses with a large (obtuse) opening angle generated.

According to a further advantageous embodiment of the invention the processed carrier film with the physical vapor deposition (PVD) processes, especially plasma or Sputtering process, chemical vapor deposition (CVD) process, electroless and / or galvanic deposition coated.

After an additional the carrier film according to secondary claim 20 relevant embodiment of the invention is that on the carrier film applied functional layer metallic.

According to a further advantageous embodiment, the is on the Carrier film applied non-metallic functional layer.

According to a further advantageous embodiment, the is on the Carrier film applied functional layer conductive.

According to a further advantageous embodiment, the is on the Carrier film applied semiconducting layer.

According to a further advantageous embodiment, the is on the Carrier film applied non-conductive functional layer.

According to a further advantageous embodiment of the invention the carrier film consists of polymers. These materials have as very suitable for use as carrier films for passive or functional layers.

According to a further advantageous embodiment of the invention the carrier film is made of polyethylene terephthalate (PETP).  

According to a further advantageous embodiment of the invention the carrier film is made of polyimide.

According to a further advantageous embodiment of the invention the carrier film is made of polycarbonate.

According to a further advantageous embodiment of the invention the carrier film is made of polypropylene.

Further advantages and advantageous configurations of the invention are the following description, the drawings and the Removable claims.

drawings

The prior art and some embodiments of the Invention are based on the drawings in more detail below described. Show it:

Fig. 1 shows the qualitative course of the transfer of energy per unit length to a carrier film,

Fig. 2, the energy transfer as a function of ion energy,

Fig. 3 can be generated in the carrier foil profiles of recesses,

Fig. 4 surface depth reliefs which can be produced by the method according to the invention and

Fig. 5 shows an arrangement for performing the method according to the invention.

Description of the embodiments

Within the scope of the method according to the invention Ion traces made by forming their Surface and, if necessary, their volume up to one any predetermined depth optimally to the to be applied Layer to be adjusted. The formation leads to the formation a special surface depth relief, the is visible by electron microscopy. The term ion trace foil denotes a polymer film that is exposed to radiation subjected to high energy heavy ions, being by the deposit of the kinetic energy of the ions in the environment of the ion trajectories are generated latent ion traces, which at Influence of an etchant can be extended to recesses. Both ion traces are possible, which completely cover the film penetrate and to continuous microchannels (as for Ion track membranes are typical) can be etched as even those that end in the film and so-called blind holes can be etched, creating an ion blind film. The amount of ion track foils includes ion track membranes, Ion blind hole films as well as combinations of both.

For forming the surface and the volume up to one predetermined depth, characterized by a when etching the Ion traces to recesses created relief, the Irradiation conditions and the etching conditions Requirements set according to and additional options such as Sensitization, tempering and aging by UV radiation created. It is essential that only through the combined Taking advantage of these factors the high flexibility in the formation is achieved, which is required for each base material (e.g. Polyethylene terephthalate (PETP), polyimide, polycarbonate, Polypropylene, etc.) and any type of coating and their  Function to create an optimal surface depth relief can.

The radiation conditions used to create this structure include:

• a) the type of heavy ions, characterized by the mass number and atomic number,
• b) the initial energy of the heavy ions (energy when entering the foil),
• c) the angle of incidence of the heavy ions in relation to the Surface normal of the film and
• d) the flux density of the ions, d. H. the number of on the Unit of area impinging ions.

To understand the interaction of factors (i) and (ii) make the physical basics of Interaction of high-energy heavy ions with solids, especially the relationship between the energy of a Schwerions and the energy transfer per unit length, dE / dx the solid body along the ion track and out of it resulting range of the ions in the solid (here in a Polymer film) described and explained using an example. The The effect of factors (iii) and (iv) is obvious, so that they only in the description of the Etching conditions are taken up again.

High-energy ions are passed through a Solid as a result of various interaction processes slowed down, their kinetic energy quasi-continuously reduced until they leave the solid or completely to Stand still and remain as a foreign atom in the solid. The kinetic energy is deposited in the solid. The essential interaction processes are with inelastic collisions  Electrons of the atoms of the solid. Only at very low Ion energies dominate inelastic collisions with the atomic nuclei itself. Through the energy absorbed during the impact process the electrons are raised to higher energy levels or into that brought energetic continuum, so completely from the atom Cut. This creates a region along the ion trajectory a radial expansion up to 10 nm chemically activated by the atoms located there are excited or ionized, chemical Bonds are broken and free radicals are generated. The at the high-energy free resulting from the interaction Electrons cause secondary ionization processes in the range down to 1 µm Distance from the trajectory, but this is here deposited energy density so low that these processes can be neglected. That due to the passage of ions structurally altered area is called a latent ion trace referred to, being the inner, highly excited and chemical activated area track core is called.

The qualitative course of the energy transfer per unit length log (dE / dx) from the ion to the target material as a function of the ion energy per nucleon E / M shown in FIG. 1 is, by a maximum, about 1 MeV / nucleon, the so-called Bragg peak 1 , caused by the interaction of the ion with the electrons of the solid, and a second maximum 2 at about 10 ^-3 MeV / nucleon, caused by the interaction of the ion with the atomic nuclei of the solid ("nuclear stopping"). The energy transfer caused by "nuclear stopping", which is overemphasized in FIG. 1 due to the logarithmic scale, is negligible compared to the contribution of the electronic interaction.

The exact quantitative course of this function is determined by Art of the respective lot, characterized by mass number,  Atomic number and effective charge, as well as by the type of Solid, here by the density and molecular weight of the polymer, certainly. It is determined experimentally, but can also, as well how the by integrating dE / dx with known Initial energy of the ion resulting range R of the ion in Solid, calculated with sufficient accuracy using computer programs with the relative error | ΔR / R | is below 10%.

Fig. 2 shows the operations in the electronic interaction energy transfer dE / dx as a function of ion energy E / M is calculated for the ion-material combination ⁸⁴ Kr ⁺ (krypton) in polyimide (Kapton). The energy transfer dE / dx passes through Bragg peak 1 here with an ion energy of about 2 MeV / nucleon.

The experimentally or theoretically determined dependence of the energy transfer on the ion energy per nucleon dE / dx = f (E / M) can be used to specifically influence the energy transfer to the polymer film along the ion track. As will be described further below, this enables a targeted setting of the trace etching rate ν _T and the shape of the pore shapes which arise in the subsequent etching.

Knowledge of the functional relationship dE / dx = f (E / M) for a selected ion-material combination makes it possible, for example, to realize an almost constant energy transfer in a film along an ion track. For this purpose, an entry energy of the ions is chosen which is sufficiently above the energy of the Bragg peak 1 , so that the energy loss of the ions when passing through the film is small compared to their entry energy, so that E / M and thus also dE / dx are practical remain constant. DE / dx can be varied by using different types of ions.

It is also possible to implement variable energy transfer along an ion track. For this purpose, an entry energy of the ions is selected in the area of the Bragg peak 1 , where the energy transfer dE / dx is very high and can no longer be neglected compared to the entry energy. In this area, the ions are braked very quickly, so that they come to rest within the film even in the case of relatively thin films and thereby generate ion traces which end in the film like a dead end. If the entry energy of the ions z. B. selected slightly above the Bragg peak 1 , when the ions in the film are decelerated, the energy transfer initially increases when the Bragg peak is approached, passes through a maximum and then drops rapidly to zero, so that in these conditions the Foil deposited kinetic energy of an ion is distributed unevenly along its ion track. A particularly high amount of energy is deposited in the track section in which the ion energy passes through the Bragg peak. The polymer structure is thus particularly changed and chemically activated.

In summary, it can be stated that the properties of the latent ion traces, which were produced by the irradiation of the polymer films with high-energy heavy ions, are determined in the following manner by the irradiation conditions:
The type of heavy ions, characterized by their mass number, atomic number and effective charge, determines the functional dependence of the energy transfer dE / dx on the ion energy per nucleon E / M for a polymer film of a given density. The entry energy of a given type of heavy ions into a polymer film of a given density determines the range of the ions and the lateral distribution of the transferred energy along the ion track. The direction of the ion traces is determined by the direction of incidence of the heavy ions, any orientation being possible. Relative to one level through the surface normal of the film z. B. by two successive radiation cycles at the angles α and -α two sets of symmetrical to the surface normal inclined ion traces. There is also the possibility of generating ion traces with a continuous angular distribution between two critical angles α _min and α _max by z. B. guided over a roll and exposed to a divergent ion beam. The surface density of the ion traces in the polymer film is determined by the total ion flow per unit area and can be varied over several orders of magnitude.

The untreated ion traces are called latent ion traces referred to as having no additional measures electron microscopic, diffractometric and spectroscopic methods are difficult to make visible. They are characterized by structural changes that result from electronic excitation (interaction of the heavy ions with the electrons of the target material). In an area with radial expansion up to 10 nm along the ion track, the highly excited and chemically activated trace core dominates breaking down the macromolecules of the polymer into short, reactive ones Fragments with free radicals, "dangling bonds" etc. on it then an area with a through cross-connections between neighboring ones Macromolecule stabilized polymer structure observed, the in polyimide extends up to 35 nm from the ion track. With The structure approaches a growing distance from the ion trace that of the non-irradiated material. The through the Ion irradiation achieved activation of the material can appropriate storage over any period be preserved.  

When exposed to an etchant, the latent ion traces are preferably attacked and expanded into recesses compared to the undisturbed material, the shape of which is determined by the conditions of the previous irradiation and by the etching conditions. The influence of the irradiation conditions is expressed in the functional dependence of the selectivity S, defined as the ratio between the track etching rate ν _T and the material etching rate ν _B , from the energy transfer dE / dx to the target material along the ion track. During the etching of organic plastics, an etching rate ν _{T is} achieved in the region of the track core, which significantly exceeds that of the unaffected material ν _B , in some cases by three orders of magnitude, so that selectivities S <1000 are possible. If the etching conditions remain unchanged, S proves to be approximately proportional to the energy dE / dx deposited in the track core per unit length, which is set by the irradiation conditions. In order to be able to use the dependence S = f (dE / dx) technologically, it has to be determined experimentally for the ion-material combinations in question. The typical shape of the recesses that occurs during the etching of the latent ion traces is a cone, the half opening angle α of which is given by α = arctan (ν _B / ν _T ) = arctan ( 1 / S). By adjusting the selectivity, its shape can be set between the limit cases of the blunt etching cone (at S <1) and the cylinder completely penetrating the film (at S → ∞), the limit case of the cylinder at S = 1000 (α = 0.06 °) can be considered as achieved. The possibilities for varying S are not limited to the irradiation conditions, but also, as explained below, extend to the etching conditions (e.g. the type of etchant and its pH). However, what is essential for potential applications is the possibility given by the specific setting of the irradiation conditions to vary the energy transfer dE / dx and thus the selectivity S along a track. In the particularly highly activated region of the ion trace, which is created when a heavy ion passes through the Bragg peak, a higher etching rate is achieved than in the upper and lower sections of the trace. This makes it possible to realize special geometries of the recesses, for example blind holes which are flared like a bottle, especially if the heavy ion does not pass through the Bragg peak until it has already penetrated the film a bit.

The targeted variation of the energy transfer dE / dx is only one the possibilities for setting the selectivity S. Very important are also the etching conditions (type, pH, temperature and Concentration of the etchant). Its principal effect is known. Increases in concentration and temperature lead to a Increase in both the track etching rate and the material etching rate however i. generally do not run proportionally, so that a Variation of the selectivity S is achieved.

Since the qualitative knowledge of these conditions is not sufficient for technological applications, they were determined quantitatively for a number of materials and published or patented in the specialist literature. For example, for the material polyimide in the patent DE 42 10 486 cited above, an increase in the pH of the etching solution from 9 to 12 results in a reduction in the selectivity S from 10 to 3, since in the range mentioned the material etching rate ν _B of 0 , 05 µm / h to 0.6 µm / h (by a factor of 12), while the trace etching rate ν _{T increases} from 0.5 µm / h to 1.8 µm / h (only by a factor of 3.6) , The selectivity can therefore be set very precisely by these measures, although only a limited interval is accessible. It is only through the solution according to the invention specified here, ie through the combined setting of the irradiation and etching conditions and through additional measures to sensitize the surface during the etching, that for the realization of the desired different recess profiles and for the realization of the resulting surface depth Reliefs required range of selectivity obtained.

The sensitization is to be understood as an additional activation of the already highly excited and chemically activated trace core area, whereby a substantial increase in the trace etching rate ν _{T is} achieved. This is possible, among other things, through the three measures mentioned below, which are most effectively used in combination:

• - irradiation with UV light,
• - exposure to oxygen,
• - Treatment with dimethylformamide (DMF).

The UV radiation causes ionization in the trace core existing free radicals, creating active centers that react intensively with basic etching agents (especially NaOH). In Oxygen acts in a similar way Trace nucleus are formed by oxidation molecular groups that also preferably react with NaOH. Liquid sensitization by DMF is particularly suitable for polyester films.

These measures result in a significant increase in the track etching rate ν _T , while the undisturbed material is hardly influenced, so that the material etching rate ν _B remains practically unchanged. As a result, the selectivity S is increased to values <100, which makes it possible to produce cylindrical recesses.

Schematic representations of possible recess profiles are shown in Fig. 3. The top row shows profiles that arise when etching with a given selectivity that is constant along the ion track. With a selectivity S <1, a blunt etching cone 3 is obtained . With S = 1, an etching cone 4 with an opening angle of 90 ° results. If the film is etched on both sides, two cones are formed which grow together into a double cone 5 after a certain etching time. A sharp etching cone 6 results when S <1. In the case of etching on both sides, a double cone 7 is also possible here. If the selectivity on one side of the film is increased by additional sensitization (in the example chosen here on the back of the film), this results in a continuous channel 8 with a conical extension on one side. With a very high selectivity of S → ∞, this can be regarded as achieved with S = 1000 and an opening angle α ≈ 0.06 °, an almost cylindrical channel 9 results. If the ion energy is set so that the heavy ion does not penetrate the film, but comes to rest at a certain depth, and if the subsequent etching process is supported by additional sensitization, a cylindrical blind hole 10 results.

The recess profiles can be modified by specifically setting and coordinating the irradiation conditions and the etching conditions according to the invention. This makes it possible in particular to produce the recesses with a bottle-shaped extension 11-19 .

Fig. 3 shows only the basic forms of the realizable in an ion track film Ausnehmungsprofile. The size and the angle of inclination of the recesses relative to the surface normal of the sheet are set by the etching time and the angle of incidence of heavy ions in the required manner.

It should also be noted that the sharp edges and tips contained in the schematic representations of FIG. 3 are more or less rounded off in reality during the etching process.

The desired surface depth relief is created by the more or less pronounced overlay of the recesses by the diameter of the recesses (resulting from Etching time and etching speed), the recess profile (resulting from the selectivity), the distribution of the Angle of inclination of the recesses (resulting from the Angle of incidence of the heavy ions) and the density of the recesses (resulting from the areal density of the ion traces) become.

The electron micrographs of FIG. 4 show some basic forms of the surface depth reliefs that can be produced reproducibly (taking into account the statistical distribution of the bullets).

In Fig. 4a is a moderate-formed surface is shown. Area density and diameter of the recesses were set so that isolated recesses dominate. As a result of the vertical radiation, the cross section of the recess is circular. The recesses can be both cylindrical and conical, or they can have extensions hidden inside the film.

FIG. 4b shows a more was formed by increasing the surface density and / or the diameter of the recessed surface, obtained by perpendicular irradiation. Overlaps of two or more recesses often occur. Here, too, the recesses can be cylindrical or conical and have hidden structures. In the case of cylindrical recesses, the maximum proportion of the changed surface is limited by the stability of the film.

Fig. 4c shows the surface of a strongly formed film that was irradiated at different angles.

Fig. 4d shows a strongly-formed sheet having a rugged surface, wherein in each case the intaglio is taken into account. In order to maintain the mechanical stability of the film, conical recesses with an obtuse opening angle must be realized by working with low selectivity.

In Fig. 4e, the fracture surface of a film is shown having a typical intaglio, in which two sets of cylindrical recesses overlap with different angles of inclination.

After the ion trace in the for the application of each desired metallic, semiconducting or non-metallic passive or functional layer required manner the process of layer deposition follows, for which a variety of known methods are available from which are the most commonly used procedures below to be discribed:

Vacuum coating technology

Vacuum coating techniques can be used to to completely fill the formed relief structures of the ion track foils or, e.g. B. in the case of functional layers, the deposition perform that the required functionality of layer to be applied is reached. The vacuum coating encompasses various processes that are related to physical vapor  deposition (PVD) and chemical vapor deposition (CVD) processes have it divided. All procedures have the same basic principle Task to solve: The coating process must be under Taking into account the physical and chemical Laws governing the above procedures will be realized. It must be ensured that the layers with the required adhesive strength and functionality are applied. Are z. B. Fill up recesses, it must first be checked whether the recess profile and the surface-depth relief allow, with the help of vacuum coating, the entire surface, d. H. also shaded areas and areas hidden in the film Cavities to achieve.

Application of metallic conductive layers in the nanometer range (Starting layers) and subsequent coating by galvanic deposition

In many cases, it has proven to be advantageous to apply a conductive starting layer to the surface depth relief of the ion trace foils, which must have an average layer thickness in the nanometer range, in order then to carry out the actual coating by means of electrodeposition. This layer is referred to as the starting layer because it serves both as an electrode in the electrodeposition and as the layer on which the electrodeposition process "starts". Various methods can be used to generate starting layers, e.g. B .:

• - Creation of the starting layer by vacuum coating technologies,
• - Generation of the starting layer by chemical means, e.g. B. that Application of conductive polymer layers,
• - Generation of the starting layer mechanically, e.g. B. that Applying conductive silver varnish using screen printing,  
• - Generation of the starting layer by deposition from colloidal Solutions, e.g. B. the deposition of conductive Graphite layers.

As the starting layers during the electroplating process as Electrode, they must have a sufficiently high conductivity to make it suitable for this type of galvanization can build up the necessary electrical field.

The electrodeposition can be done with different electrolytes be carried out so that it is possible to use a number of metallic Elements such as B. Cu, Ni, Au, Ag and others to deposit. At the Foil, which is connected as a cathode by the metallic Starting layer a negative potential is applied, the discharge Cations of the electrolysis bath and separate on the surface and in the deep relief (recesses).

With the help of galvanic deposition, it succeeds very well Molding the surface depth relief of ion trace foils, replenish and create compact metallic layers. At the same time it ensures this process, the layers like this to bring up that their desired functionality is realized.

Introduction of germs and subsequent electroless separation

Germs are introduced into and onto the polymer material, which act as catalysts in the subsequent electroless deposition. Electroless deposition is also a very good way of molding the surface depth relief of ion trace foils, filling them up and creating compact metal surfaces. The depth relief and the size of the pores present must be designed so that the crystallization process occurring during electroless deposition can take place, ie the openings of the profile or of pores must not be smaller than the dimensions of the microcrystallites that form. Is z. B. a copper deposition is desired, palladium nuclei are introduced, which are either pressed during the manufacture of the film with the starting material and exposed during the etching (and thereby activated) or only after the etching by chemical deposition from a solution onto the already formed surface be applied. Under the action of formaldehyde, the catalytic Pd nuclei are reduced by Cu ²⁺ ions to metallic Cu, which grows on the surface of the nuclei. Due to the even distribution of the germs, this process produces a compact copper layer with very good homogeneity.

Apply metallic and non-metallic layers printing techniques

To apply non-metallic, non-conductive, but in some Cases also conductive (e.g. conductive silver varnish, conductive silver paste) Coatings are preferably different printing processes used. Worth mentioning are screen printing, pad printing and the Offset printing, but also printing techniques used in commercial Office technology has entered, such as B. inkjet printing and the injection pressure. In this way, z. B. paints, Apply epoxy resins, etc., which can then by UV radiation or Annealing to be hardened. Especially in the phase in which Varnishes or epoxy resins are not yet cured introduce functional layers through subsequent processes.

For the production of such layer combinations are the Ion track foils thanks to their precisely tunable surface depth Relief well suited.  

A suitable radiation source for generating the required Heavy ion is the cyclotron since it is the generation of heavy ions with high current density and defined ion energy, which over several orders of magnitude can be allowed. to Ensuring very high ion current densities at comparatively low ion energies (near the Bragg peak) that are required in particular for the production of blind hole films, it makes sense to use a so-called RFQ source (radio frequency quadrupole).

Embodiment 1 Ion trace foil as a carrier foil of an adhesive layer made of copper for use as a starting material for flexible printed circuit boards

FIG. 5 shows a polyester film 20 (polyethylene terephthalate, PETP) with a thickness of 50 μm, which is subjected to irradiation with an ⁸⁴ Kr ⁺ (Krypton) ion beam 21 . For this purpose, the starting material, which is in the form of a roll (width 50 cm), is guided through the ion beam 21 via a roll system of 5 rolls. The symmetrically constructed roll system contains a take-off roll 22 with the polyester film 20 and a take-up roll 23 for the polyester film 20 after the irradiation has taken place. In between are a first fixing roller 24 , a deflection roller 25 and a second fixing roller 26 . The ion beam 21 sweeps over the area between the two fixing rollers 24 and 26 , it being possible for a partial area of the ion beam 21 to be masked out by a diaphragm 27 . The deflection roller 25 is displaceably arranged on a rail 28 parallel to the direction of the ion beam 21 and thereby makes it possible to vary the angle of incidence of the ions between -70 ° and + 70 ° relative to the surface normal.

In the present exemplary embodiment, an angle of incidence of 45 ° is set. For this purpose, the partial area in which the deflection roller 25 is located is hidden from the ion beam 21 . As a result, only two bundles of rays, to which the angles of incidence -45 ° and + 45 ° can be assigned, come into effect. At the angles mentioned, these generate two groups of latent ion traces. The total radiation density is 5.10 ⁷ cm ^-2 . The entry energy of the ions is 1.2 MeV / nucleon, which leads to an average range of 20 µm.

The irradiated foils are then subjected to a 10 to 30 minute etching with 3N NaOH solution at a temperature of 80 ° C. This results in an etching of the latent ion traces into cylindrical blind hole recesses with a diameter of 1 µm and a length of approx. 18-19 µm. This length is somewhat less than the penetration depth of the ions, since at the end of the ion trace the energy transfer to the polyester film 20 becomes so small that the trace can no longer be etched. The length of this non-etchable section is approximately 5-10% of the total length of the ion trace.

To create the functional layer, first a Starting layer with a thickness of 0.2 to 0.4 µm, consisting of copper Sputtering (vacuum coating) applied. The real one Copper layer with a thickness of 5 to 140 µm is then galvanized deposited. The copper-coated polyester film produced in this way is characterized by a high adhesive strength of the top layer (<< 10 N / cm), achieved by mechanically anchoring them in the pores of the basic material. It is used as a flexible printed circuit board well suited with high mechanical alternating loads.  

Embodiment 2 Ion trace foil as carrier foil of a copper layer on both sides high Adhesive strength for the substitution of copper foils

In the arrangement according to FIG. 5, a polycarbonate film 29 with a thickness of 75 μm is subjected to irradiation with ⁴⁰ Ar ⁺ (argon) ions 21 . For this purpose, the starting material in roll form (width 50 cm) is guided over the roller system 24 , 25 and 26 according to FIG. 5.

In embodiment 2, by shifting the deflection roller 25 to the height of the fixing rollers 24 and 26, a perpendicular incidence of the ion beam 30 on the polycarbonate film 29 is set, the total radiation density being 1 .10 ⁷ cm ^-2 . The entry energy of the ions is set at 5.4 MeV / nucleon, which leads to an average range of 80 μm, so that the film 29 is completely penetrated and a latent ion trace is formed which can be etched over its entire length.

In preparation for the etching, the surface of the irradiated film 29 is sensitized by the action of UV light on both sides. Thereafter, the film 29 is subjected to a 20- to 40-minute etching with 4N NaOH solution at a temperature of 60 ° C., whereby the latent ion traces are etched into cylindrical channels with a diameter of 1 μm, which penetrate the film 29 vertically , This results in a porosity of 8%.

To produce the functional layer, the film 29 is first wetted on both sides with a solution which contains palladium complexes, which form a starting layer on the surface and in the continuous channels. By electroless deposition, a copper layer with a thickness of 200-300 nm is then applied to the surface of the film 29 and to the walls of the channels etched into the film 29 with a diameter of 1 μm. Cylindrical cavities with a diameter of 400-600 nm remain in the center of these channels and are not yet filled with copper. In the subsequent galvanic deposition, a compact copper layer is applied to the film 29 , the thickness of which can be varied between 5 and 100 μm, the remaining free cavities in the channels also being completely filled with compact copper. The polycarbonate film 29 produced in this way, coated on both sides with copper, is distinguished by a high adhesive strength of the cover layers, achieved by mechanically anchoring them in the channels of the film 29 . The adhesive strength achieved is greater than 10 N / cm. The coated foil 29 can be used as a replacement for copper foils.

Embodiment 3 Ion track foil with a high specific surface as a carrier aluminum coating

A polyester film 20 (polyethylene terephthalate, PETP) with a thickness of 23 μm is subjected to irradiation with ⁴⁰ Ar ⁺ ions 21 . For this purpose, the starting material in roll form (width 50 cm) is guided over the roller system described in application example 1 .

In the present case, the angle of incidence is set to ± 30 °, ie the radiation is carried out successively at the angles + 30 ° and -30 ° relative to the surface normal of the film 20 , the total radiation density being 5 .10 ⁷ cm ^-2 . The entry energy of the ions is set to 0.11 MeV / nucleon, which results in latent ion traces, the effective (etchable) length of which is approximately 7 µm.

The surface of the irradiated film is then subjected to a 6-8 minute etching with 5N NaOH solution at a temperature of 90 ° C., which causes the latent ion traces to form conical blind holes with a depth of approximately 7 μm, resulting from the above-mentioned effective Length to be etched. The diameter of the (due to the steep shot angle) almost circular recess openings on the surface is 1.9-2.1 µm, which corresponds to an area of approximately 3 µm ² = 3.10 ^-8 cm ² . The total area covered by recesses, which is given by the product of the recess area and the total radiation density, is thus approximately 1.5 cm ² per unit area of 1 cm, corresponding to a theoretical area share of approximately 150%. The etching process is continued here until the area covered by recesses arithmetically exceeds the available area by about 50%. This process is called overetching and is characterized by a strong mutual overlap / overlap of the recesses. The result of this formation is a film with a very rugged, mountainous surface and a pronounced depth relief. A typical example is shown in Fig. 4d. The film has an extremely high specific surface. Their mechanical stability is retained because the thickness of the formed area is only about a third of their total thickness.

The foil thus formed is vaporized with aluminum at a working pressure of ≦ 5.10 ^-2 mbar. The duration of vapor deposition required to achieve a certain layer thickness must be determined experimentally. In contrast to conventional aluminum-coated foils, the aluminum layer deposited in this way is not only bound adhesively to the substrate, but is also mechanically anchored in the recesses of the same.

Many practical applications of such Al-coated polymer films require a subsequent oxidation of the surface, mechanical stresses occurring in the Al ₂ O ₃ -Al _x O _y -Al-polymer system. (Al _x O _y denotes a non-stoichiometric transition layer between the metal and the oxide, which is characterized by a continuous change in the oxygen content.) The oxide-transition layer-metal system is very adhesive, however, the mechanical stresses on the metal-polymer composite transfer. In conventional films, this leads to the layer peeling off the substrate (polymer). Due to the mechanical anchoring implemented here, the adhesive strength of the layer is increased so much that peeling due to surface oxidation is avoided. Likewise, the flexural strength of the coated film is improved so that it can be wound into a roll with a very small inner radius of curvature.

Such films are Al-vapor-coated and oxidized on the surface as a raw material for the production of Electrolytic capacitors can be used.

All in the description, in the following claims and in the features shown in the drawings can be both individually and be essential to the invention with one another in any form.  

LIST OF REFERENCE NUMBERS

1

Bragg peak

2

second maximum by "nuclear stopping"

3

Profile of a blunt etching cone

4

Profile of a right-angle etching cone

5

Profile of the connection of two rectangular etching cones to a double cone

6

Profile of a pointed etching cone

7

Profile of the connection of two pointed etching cones to a double cone

8th

Profile of a continuous channel with a conical extension on one side

9

Profile of a cylindrical etching cone (etching channel)

10

Profile of a cylindrical blind hole

11-19

different types of recess profiles with bottle-shaped extensions

20

polyester film

21 ⁸⁴

Kr ⁺

ion beam

22

withdrawal roller

23

up roll

24

first fixing roller

25

idler pulley

26

second fixing roller

27

cover

28

rail

29

Polycarbonate film, film

30 ⁴⁰

Ar ⁺

ion beam

Claims (30)

1. Process for processing carrier films or the like. made of plastic or polymer by bombarding them with heavy ions and then etching the ion traces in order to achieve recesses in the film, characterized in that
that on the slide or the like. a functional layer as a conductor track or the like. is applied and
that material parts of the functional layer reach into the recesses during application, so that the functional layer is anchored in the film. 2. The method according to claim 1, characterized in that the Shape and depth of the recesses due to the radiation and etching conditions is determined. 3. The method according to claim 1, characterized in that the Recesses or the like. do not penetrate. 4. The method according to any one of the preceding claims, characterized characterized in that the functional layer is passive or is functional. 5. The method according to any one of the preceding claims, characterized characterized in that the anchoring by intervention of Material parts of the functional layer in the recesses of the Foil is achieved. 6. The method according to claim 5, characterized in that the Recesses formed in the backing film increase the adhesive strength of the applied layer increase. 7. The method according to claim 1 or 5, characterized in that that an adhesion promoter is provided between the film and the layer to increase the adhesive strength. 8. The method according to claim 1 or 2, characterized in that the local distribution of the introduced into the film Energy by choosing the entry energy of the heavy ions, based on the Bragg peak, and thus the Track etching rate is set along the ion track. 9. The method according to claim 8, characterized in that the Shape of the recesses by adjusting the ratio  the track etching rate to the material etching rate is achieved, namely by Change in pH, temperature, concentration and / or the composition of the etchant. 10. The method according to claim 9, characterized in that the Etching conditions are changed during the etching. 11. The method according to any one of the preceding claims, characterized characterized in that the ion trace sensitizes before the etching is caused by UV light, oxygen and / or dimethylformamide (DMF). 12. The method according to claim 9 or 10, characterized in that by varying the track etch rate to material etch rate Shape of the recesses between the blunt cone and Cylinder that runs through the entire carrier film is adjusted. 13. The method according to claim 10, characterized in that by changing the ratio of trace etch rate to Material etching rate bottle-shaped recesses are producible. 14. The method according to any one of the preceding claims, characterized characterized in that the ion bombardment several times with different energy, different ions and / or various shooting devices is carried out and almost any surface depth relief can be generated. 15. The method according to any one of claims 8 to 14, characterized in that the diameter of the recesses measured on the surface of the carrier film between 20 nm and several micrometers and the surface density of the recesses determined by the ion current can be varied between 10 ⁵ and 10 ¹¹ cm ^-2 are. 16. The method according to claim 14 or 15, characterized in that that recesses of different sizes, shapes, orientations and / or surface density in the carrier film itself overlapping that a surface depth Relief shows which the required adhesive strength and Functionality of the layer to be applied to the carrier film guaranteed. 17. The method according to any one of claims 9 to 16, characterized characterized in that the conditions of irradiation and Etching of the carrier film can be chosen so that on the Carrier film a surface depth relief between the Limit cases of an almost undisturbed surface with less Density of the recesses and a strongly jagged Surface with a high density of overlapping, different recesses results. 18. The method according to claim 17, characterized in that in the carrier film with a strongly jagged surface structure Improve their conical mechanical stability Recesses with a large (obtuse) opening angle be generated. 19. The method according to claim 1, characterized in that the processed carrier film after the physical vapor deposition (PVD) processes, especially plasma or Sputtering process, chemical vapor deposition (CVD) Method and / or the method of currentless and / or galvanic deposition is coated.   20. Foil or the like made of plastic or polymer, which as a carrier Functional layer (conductor track or the like.) Which serves on the film is arranged, characterized in that between Functional layer and film a mechanical anchor is available. 21. A film according to claim 20, characterized in that the Functional layer consists of metal. 22. A film according to claim 20, characterized in that the Functional layer consists of non-metal. 23. A film according to claim 20, characterized in that the Functional layer is conductive. 24. A film according to claim 20, characterized in that the Functional layer is semiconducting. 25. A film according to claim 20, characterized in that the Functional layer is not conductive. 26. A film according to claim 20, characterized in that the film consists of polymers. 27. A film according to claim 20, characterized in that the film consists of polyethylene terephthalate (PETP). 28. Film according to claim 20, characterized in that the film consists of polyimide. 29. A film according to claim 20, characterized in that the film consists of polycarbonate.   30. A film according to claim 20 or 26, characterized in that the film is made of polypropylene.