MXPA99010940A - Multilayer metalized composite on polymer film product and process - Google Patents

Abstract

A composite substrate material useful for fabricating printed circuits is provided comprising a polymeric film having at least one surface modified by plasma etching, a first thin metal nitride layer, a thin second metal nitride layer, and an electrically conductive third metal layer.

Description

PROCESS AND COMPOSITE PRODUCT METALIZED OF VARIOUS LAYERS IN POLYMERIC FILM BACKGROUND OF THE INVENTION 3L _? _ Field of Invention Traditionally, flexible, printed circuits have been used in place of pre-formed, discrete wiring for interconnecting components in electronic equipment applications where critical design objectives are three dimensional packaging efficiency, reduced weight and long-term flexural resistance. In this paper, flexible printed circuit designs are essentially flat wiring assemblies with connectors welded only to their terminations. However, more recently, this familiar role has been extended to include rigid-flexible, multilayer assemblies and so-called flexible-board circuit assemblies (COF), where active devices are attached. and passives to the body of the circuit by methods of welding or joining by thermocomprehension, such as they are in the assemblies of printed, rigid circuits. In this new design context, printed, flexible circuits are exposed to more rigorous manufacturing and assembly requirements, most notably at multiple and prolonged exposures to temperatures in the range of 180 to 250aC.

Recently, many printed, flexible circuits are manufactured from laminated products produced by adhesively bonding a copper sheet "preformed to a polyimide or polyester film in either a sheet or roll form base. extended use, these laminated, conventional products have limitations of well-known properties related to adhesive, which make them particularly unsatisfactory for COF and multilayer, fine line designs: poor dimensional stability after etching to high water; of retained moisture, high values of CTE, on the z axis, and excessive thickness.In addition, due to the fact that the normal test of the Institute for Printed Circuits (IPC, Institute for Printed Circuits) for resistance to thermal stress, IPC -TM-650, Method 2.4.9, method F, still carried out at 150 aC, designers using flexible circuits for the first time may not be aware Note that the bond strength of adhesive-based laminates, typically 8-9 pounds / inch after thermal cycling at 1502C, deteriorates by more than 50% when cycling is performed at 1802C (a rolling temperature). common for multilayer constructions) and falls to essentially zero at cycling temperatures above 200aC (the region of reflow solder and thermocompression bonding). These limitations have stimulated interest in a new family of substrate materials for flexible circuits, based on non-adhesive constructions. In one form, the polyimide resin is emptied onto a copper foil web and thermally cured to form a single-sided flexible flexible metal-dielectric composite product; this method, however, is not well suited for the production of two-sided constructions, an important category of products. In another form, the polyimide film is metallized directly by either chemical deposition methods (U.S. Patent Nos. 4,806,395; 4,725,504; 4,868,071) or vacuum deposition methods to produce constructions of one or more sides. However, bare copper itself does not bind directly to the polymeric film substrate in these constructions because it is well known that, while "initial, reasonably high values of resistance to detachment of 6-7 pounds can be achieved. / inch, the copper-polymer interface in directly bonded constructions, catastrophically fails (delaminates) when exposed to elevated temperature.This phenomenon is generally attributed to the propensity of copper to combine with oxygen or water driven from the core of the film during the heating process to form copper oxide, a structurally weak interface and not very passive. Two-sided constructions are essentially prone to failure by this mechanism because, as it is converted to a vapor phase, the moisture retained in the core of the film does not have an escape medium other than the path of the polymer interfaces. -metal It has also been determined in polyimide-based constructions that the cohesive strength of the surface of the polymeric film is catalytically degraded by the diffusion of copper in the polymer. Accordingly, in conventional practice, metals such as chromium or nickel or their alloys have been used, which form strong, self-passive oxides and readily bond to copper, in substrate materials, without adhesive, based on film to serve as a barrier to both oxygen transport and copper diffusion. Compared to directly plated copper, the proper thicknesses of these barrier layer metals improve the retained interfacial strength and bond after thermal exposure but, even so, commercially available, non-adhesive substrate materials are not completely satisfactory to this respect. Virtually all of these materials exhibit substantial loss, typically 40% or more, of the initial bond strength P941 even after thermal cycling at 1502C, a fact that is reflected in IPC-FC-241/18, the acceptability standard for materials of this class. One explanation for this phenomenon may be that these barrier metals form oxides that are stronger than copper oxide, but only in a relative sense. In the case of materials made by sputtering methods, however, a contributing factor can be really good in the industrial practice of exposing the surface of the polymeric film to a process called plasma etching prior to the deposition of the layer metal. of barrier. This process, which is typically performed in an argon-oxygen plasma, is generally considered to improve the adhesion of the barrier-polymer metal by cleaning the surface of the film to improve mechanical adhesion and enrich its oxygen content to promote chemical union. Although the final effect may be of some benefit, it is well known that argon-oxygen plasmas are essentially ablative in nature and as such create relatively smooth micro-profiles, as opposed to rough ones, which do not materially improve mechanical adhesion.

In this regard, it has been found by Ishii, M. et al.

(Proceedings of the Printed Circuit World Convention VI, San Francisco, CA, May 1-14, 1993) and others (U.S. Patent Nos. 4,337,279; 4,382,101; 4,597,828 and 5,413,687) that nitrogen-containing plasmas are more effective. In addition to being limited with respect to the retention of the bond strength after thermal cycling, the commercially available substrate-free adhesive materials employ sweeping layer metals making use of these materials, problematic with respect to the etching practices and plating circuits in the industry. Chromium, for example, can not be removed by any of the acidic or alkaline engravers commonly used in printed circuit operations to remove copper from the spaces between the trace patterns; The removal of the chromium barrier layer also presents a problem of waste disposal. Barrier layers of nickel or nickel alloy represent an improvement of genres since they can be removed in one step with commonly used acid etchers, but when the underlying copper layer is removed with any of the alkaline or ammoniacal recorders that predominate in current industrial practice, a separate engraving step is required. It has also been observed by Bergstresser, T. R., et al.

(Proceedings of Fourth Intl. Conference on Flex Circuits [Flexcon 97], Sunnyvale, CA, September 22-24, 1997) than when thin layers (less than 200 Angstroms) of metals P941 nickel barrier or nickel alloy are exposed to gold plating solutions of cyanide, dissolve preferentially. This phenomenon, which leads to the undercutting of copper traces and consequent loss of adhesion between metal-polymer, is especially problematic in the manufacture of very thin line designs with stroke / space geometries of less than 4 mils. Titanium is another well-known barrier layer metal that has been used in semiconductor manufacturing processes to improve the adhesion of plated copper to a spun layer of liquid polyimide. However, the titanium metal has not been used as a barrier layer in flexible circuit substrate constructions, without adhesive, because its removal requires a second etching process comprising specialized chemistry. As a means to address the issue of etching ability, it has been proposed in US Pat. No. 5,137,791 to form a composite product of polymeric-metal film, without adhesive, without the benefit of a conventional metal barrier layer. by first using an oxygen plasma which contains multiple metal electrodes to simultaneously treat the surface of the film and deposit a non-continuous, extremely thin layer of a metal oxide; then a second metal layer is deposited on the first layer P941 thicker such as copper. Although initial values of peel strength greater than 6 pounds / inches were reported for polyimide film-based constructions of this class, thermal cycling data were not provided; it has been found that when a composite material made by this process is subjected to thermal cycling, the peel strength of the metal-polymer bond rapidly degrades. U.S. Patent No. 5,372,848 proposes to provide etching capacity, alkaline, in a single step by depositing a copper nitride barrier layer directly on an untreated polyimide film surface. Although the composite products made by this process are alkaline recordable in one step, it has been found that their initially high adhesion values deteriorate significantly when exposed to high temperature. It has been proposed by Weber, A. et al. (Journal of the Electrochemical Society, Vol. 114, No. 3, March 1977) using chemical vapor deposition methods to deposit, on polymer-coated silicon wafers, a thin, sufficiently conductive titanium nitride barrier layer to allow direct electroplating of copper. It has been found that the thin tin barrier layers formed by sputtering methods are also resistant to achieve direct electroplating of copper and that even sputter-plated copper does not form a strong bond with tin due to its stoichiometry In this way, efforts to improve the initial / retained values of the release resistance and the chemical processing properties of the adhesive, non-adhesive substrate materials, based on film, have taken various forms but a completely satisfactory result has not emerged for the applications of printed circuits, flexible, nor the prior art has taken the specific form of the new system of materials proposed in this invention.

SUMMARY OF THE INVENTION According to this invention, a first composite product comprising an unsupported polymer film, in the form of a sheet or roll, a first thin layer of metal nitride, and a second layer of metal nitride, is provided, preferably electrically conductive, thin. The first composite product of this invention is useful in forming the second composite product of this invention comprising the first composite product of this invention coated with an electrically conductive metal layer in the second metal nitride layer. The second composite product of this invention is only suitable for the fabrication of thin-line flexible circuits for the reason that it has an initial, not only high, resistance to peeling, but does not degrade significantly in exposure to thermal stress but an individual stage engraving capability in alkaline engravers. In a first step of the process of this invention, one or both surfaces of an unsupported polymeric film substrate is subjected to a recording step to the plasma, preferably with a gas that is a source of nitrogen ions, such as nitrogen gas, in order to provide a rugged micro-profile, enriched with nitrogen-binding sites while substantially retaining the mechanical properties of the substrate. In a second step, a first layer of metal nitride is deposited on the etched film surfaces by sputtering. Interposed between the polymeric film substrate and a second layer of metal nitride, subsequently applied, the first layer of metal nitride provides a barrier layer which prevents the migration of moisture or oxygen from the polymer film to the second layer of nitride of metal and inhibits diffusion of the second layer of metal nitride or subsequently applied layers to the polymeric film. This first metal nitride layer comprises mainly a metal in the form of a metal nitride having a thickness between about 10 and about 200 Angstroms. A second layer of metal nitride, preferably an electrically conductive metal nitride such as copper nitride, is then deposited in the first metal nitride layer to form the first composite product of this invention. The metal nitride of the second layer may comprise the same metal or metal different from that used to form the first metal nitride layer. The second metal nitride layer generally has a thickness of about 25 to 1500 Angstroms and more usually between about 25 and about 500 Angstroms, to thereby form the first composite product of this invention. An electrically conductive metal layer, such as copper, is then applied by vacuum deposition or electrochemical methods to the total polymer-metal film nitride layers to form the second composite product of this invention. The polymeric film, treated with plasma, the metal nitride layers, and the metal layer cooperate to provide a composite product that has an initial peel strength in excess of 8.

P941 pounds / inch when measured by the IPC-TM-650 test method, Method B and more than 90% retention of initial peel strength when measured by IPC-TM-650, modified, Method F, using 180SC as upper limit. The composite product is capable of passing the weld flotation test, IPC-TM-650, Method 2.4.13, and is comprised of a metal multi-layered structure of metal nitride that can be removed either by acid etching chemicals or alkaline in one step. The process of this invention is capable of providing a variety of products and is particularly suitable for the production of printed, flexible circuits. In one aspect of this invention substrate materials of the composite product are provided, in which the metallization of several layers is applied to one or both sides of the polymeric film substrate. In another aspect, the process of this invention can be used with a pre-perforated polymeric film to provide a two-sided construction with metallized interconnections of through holes.

DETAILED DESCRIPTION OF SPECIFIC MODALITIES In accordance with this invention, a composite product structure of polymeric film-metal having a high initial resistance to P941 detachment between the metal and the surface of the polymer film that does not deteriorate significantly after thermal cycling, repeated, at high temperature. In the first step of the process of this invention, a plasma, preferably one containing a source of nitrogen ions, with sufficient energy; that is, an energy greater than about 20 Joules / cm2 to about 200 Joules / cm2, to roughen or create the micro profile on the polymeric film surface by etching with reactive ions. The pressure used in the plasma chamber is less than about 1500 mTorr and more usually between about 1 and about 50 mTorr. Nitrogen reactive ion plasma etching produces a surface microprofile with protuberances extending from the film surface, in contrast to the smooth corrugations characterizing the microprofile of a polymeric surface etched with a reactive ionic plasma containing oxygen. When plasma energies less than about 20 Joules / cm2 are used, insufficient surface roughness occurs; On the other hand, when plasma energies are used above about 200 Joules / cm2, mechanical degradation of the film surface occurs. It is believed that the improved properties of peel strength P941 of the composite products of this invention results from a combination of increased mechanical adhesion provided by the micro-profile of roughnesses of the film surface and the chemical bonding of the metal nitride subsequently applied to the nitrogen sites generated on the polymeric film surface. Although a variety of plasma gases may be used, the preferred plasma gas is a mixture consisting of a source of nitrogen ions, for example, nitrogen gas, ammonia, or various amines, or mixtures thereof, and a inert gas such as argon, neon, krypton, or xenon. The preferred energy source for the film etching plasma is an RF power supply but other lower frequency energy sources are also suitable. In the second step of the process of this invention, a plasma containing nitrogen is generated in the presence of one or more metallic electrodes or targets that, in the plasma, supply metal ions that react with the nitrogen ions in the plasma to form a first metal nitride layer on the surface of the polymer film. This first layer of metal nitride is formed at a thickness between about 10 to about 200 Angstroms, preferably between about 50 and 100 Angstroms, and serves both as a bonding layer and as a bonding layer.

P941 a barrier layer between the surface of the polymeric film and a second layer of metal nitride, subsequently applied. When this first layer of metal nitride is applied to these thicknesses, it is optically clear and the flexibility of the film is retained substantially. The metals used in the first metal nitride layer are those which can form strong bonds with a layer of electrically conductive metal nitride, applied subsequently. Representative metals suitable for forming this first layer of metal nitride include aluminum, titanium, chromium, nickel, zirconium, vanadium, iron, silicon, tantalum, tungsten, and alloys thereof, preferably titanium, zirconium, chromium, nickel or vanadium. The second metal nitride layer applied to the first metal nitride layer is preferably electrically conductive, but does not need to be, if it is deposited above it, a third electrically conductive layer. The metal nitride in this second layer is formed from copper, nickel, chromium, vanadium or alloys thereof, preferably copper. The second layer of metal nitride has a thickness between about 20 Angstroms and about 2000 Angstroms, preferably between about 100 Angstroms and about 1000 Angstroms, so that the P941 resulting composite product retains the flexibility of the polymer film substrate. The second layer of metal nitride is formed in a gaseous atmosphere that includes a source of nitrogen diluted with an inert gas; the volume percentage of nitrogen is typically between about 5 and about 100 volume percent. When copper is used as the metal, it is preferred to use an atmosphere containing between about 5 and about 50 volume percent nitrogen in order to produce an electrically conductive layer of copper nitride. Since the first and second metal nitride layers are completely thin and are deposited sequentially in the same plasma gas, it is believed that at the interface between the two layers, an intermediate layer or zone consisting of a mixture or alloy is formed. of the two layers. The plasma treatment of the film surface and the plasma deposition of the metal-nitrogen compounds in the film to form the metal nitride layers are carried out in a chamber that has been evacuated of unwanted gas so that it can be introduced the nitrogen-containing gas, desired. It is essential to remove the water from the polymeric film prior to the deposition of the metal nitride on the surface of the film, particularly in two-sided constructions.

P941 When a polyimide film is used, satisfactory drying can be carried out at a temperature between about 50 ° C and about 400 SC for a time between about 2 hours and about 1 minute, respectively. After the polymeric film has been plasma etched with the nitrogen-containing plasma and subsequently coated with the first and second metal nitride layers, a third layer comprising a conductive metal can be deposited in the resulting composite product by a variety of methods, including: sputtering, evaporation, deposits without electrodes, and electrolytic deposit, alone or in combination. This third layer of conductive metal has a thickness greater than about 1000 Angstroms so that the resulting composite product can be used to form printed circuits, protective materials, and the like. When a relatively large current carrying capacity of the printed circuits manufactured from these composite products is required, conductive metal layers having a thickness of at least about 2.5 μm and typically between about 5 μm and about 35 μm are used. The metal layers in this thickness range are preferably formed by electroplating and the metal can be copper, P941 nickel, chromium or vanadium. The substrates that can be coated according to the present invention are organic polymeric substrates and include synthetic polymers such as polyesters, polyamides, polyimides, polyimide precursors, polyepoxides, polyetherimides, fluoropolymers, and other materials, such as polyaramides, are capable of being formed in structures in the form of frames, non-woven. While the substrates may be relatively rigid or flexible depending on their thickness and modulus, the process is carried out more easily when the substrate is flexible enough to be handled in a continuous, roll-shaped process. Once the metal layer (s) are formed, a wiring board can be made, printed by forming a pattern of conductive lines and spaces in the metal on the substrate. The pattern can be formed by a simple "print and engrave" process or by a semi-additive "pattern deposit" process that is more suitable for the production of fine line circuitry. In a printing and etching process, a etch resistant pattern is formed on the surface (s) of the third layer of the substrate material of this invention either by the screen printing of a liquid protective layer or by the lamination, exposure and development of a P941 dry film protective photolayer; the third layer in this case is relatively thick, typically 2 μm to 35 μm. The materials marked with the pattern of the protective layer are then transported through the spray engraving machines where the unprotected copper metal is removed from the bare film to create the spaces in the pattern. The subsequent removal of the protective layer that protects the lines produces the desired pattern of the circuit. In the semi-additive technique, the surface of the third layer (s) of the substrate material of this invention, which is chosen in this case is relatively thin (typically 2 μm to 9 μm), It is laminated with a protective layer of plating which is then exposed through a photomask and is developed to create a positive image of the circuit pattern desired in exposed copper. Subsequent immersion in an electroplating bath accumulates the copper in the exposed areas of the standard to a thickness typically in the range of 9 μm to 35 μm. When the protective plating layer is removed, the thin copper dissolves with a light etching step that reduces the consumption of the engraver, minimizes the generation of waste, and is a pattern of well-defined line circuit lines with side walls , straight. To evaluate the adaptability of the composite substrates of this invention for the requirements of P941 chemical processing of the manufacture of flexible circuits, sample materials produced by the preferred processes described above were used to form printed circuit test patterns by different processing techniques. A sample sheet was imaged with a photoprotective layer and etched in a typical peroxide / sulfuric acid recorder to produce a fine line circuit pattern with a line / space geometry of 5 mils; the resulting traces of the circuit were recorded cleanly in an individual pass through the etching bath and exhibited no evidence of scour. A second sample sheet was also imaged with a photoprotective layer and etched with a typical ferric chloride acid with the same results. A third sample sheet was imaged with the photoprotective layer and recorded in a typical ammoniacal copper chloride recorder; again, the resulting traces of the circuit were clearly recorded in an individual pass through the engraving magneal and exhibited no evidence of scour. XPS analysis of the exposed film area in each of the three sample sheets detected only a light trace of titanium, indicating that the titanium nitride was completely removed from the etching process. It is believed that the barrier layer of titanium nitride forms P941 alloys with the underlying copper nitride layer, and when exposed to strong oxidizing agents in the recorders, it is converted to titanium oxide; Both titanium oxide and copper nitride dissolve easily in the chemistries of the engraver commonly used in printed circuit manufacturing work. On the other hand, protected by the copper covered with the protective layer, plated over the trace areas, the titanium nitride retains its chemical state which is highly resistant to the scouring of the engraver. The exposed film also passed the IPC-TM650 surface resistance test, method 2.5.17, as well as the IPC-TM650 moisture resistance and insulation test, Method 2.6.3.2. These results indicate that any residual ionic contamination on the surface of the film was too low to be measurable in these test procedures. Thus, there are several advantages to manufacturing printed circuits, particularly those comprising high density designs of very fine lines, from the composite materials of this invention: (1) greater assurance that, due to the values of resistance to detachment, retained, unusually high, exhibited by these materials, traces and circuit pads will not delaminate from the P941 underlying polymer film during assembly or re-locking processes or at high temperature, especially those that comprise multiple exposures to welding and bonding processes by thercompression; (2) no scouring of copper traces / pads, which improves circuit fabrication / assembly performance and improves long-term circuit reliability, especially in dynamic bending applications; (3) individual stage recording in ammonia recorders, which avoids an extra process step, which includes special chemical products and simplifies the waste treatment procedures. The equipment used to carry out the experiments shown in the following examples was a custom-built combination plasma treater and a metal sputtering machine that can fit polymer film sheets as large as 16"by 16". The film sheets are mounted on a steel plate that is mounted on a chain-driven rail system; an external speed controller is used to vary the time that the sample is exposed to the etch and metal sputter plasma zones in a central vacuum chamber which is maintained at a pressure of about 1-4 mTorr. The machine has three separate vacuum chambers; an introductory camera P941 sample and a sample outlet chamber, both isolated from the central pneumatic bombardment chamber by sliding gate valves. Samples of the test film are pre-dried in an external oven to dehydrate them, then they are mounted on the steel plate that is placed in the sample introduction chamber. When a vacuum is created in this chamber, as in the central chamber, the gate valve opens and the sample plate is transported to the combined plasma ionization and plasma treatment chamber. At the end of the metallization protocol, the sample plate is transported to the exit chamber through the opening of the gate valve and closing it after the plate is completely inside. The gate valve arrangement prevents the main treatment chamber, which has a larger volume than the two satellite chambers, from having to be generated empty each time a sample is introduced for processing. The amount of energy applied to the sample in Watt-seconds or Joules / cm2 can be controlled by the energy of the plasma and by the time of exposure of the sample in the plasma zones. The central sputtering chamber is equipped to provide multiple metal targets. By sliding the sample back into the rail system, the metal can be applied in one or P941 multiple layers to accumulate to any desired thickness. Since this sheeting machine has no cooling capacity, certain time intervals between the passes under the metallization plasma were necessary, to avoid excessive heat accumulation in the sheets. In each of the following examples, a composite structure consisting of a thin barrier / tie layer of about 100 Angstroms was first deposited on a polymeric film substrate, etched with plasma. A second layer of approximately 100 Angstroms then sputtered on the first layer and a third layer of approximately 1000 Angstroms of copper sputtered in the second layer. The sputter-plated sheets were then mounted on stainless steel reservoir frames for subsequent electrolytic copper deposition to a thickness of 35 μm (1.4 mils or 1 oz / ft2) for the adhesion test per standard IPC-TM650, Method 2.4.9. German wheel method. Additional tests performed on each sheet included a modified 180a T-strain shear test, a weld flotation test, thermal cycling at various temperatures, and a moisture exposure test. The results are reported in the following examples.

P941 Sample sheets plated at various copper thicknesses were subsequently manufactured into printed circuit patterns by conventional imaging and etching methods using standard copper engravers such as copper cupric acid ethers, peroxide / sulfuric acid, persulfate, chloride ferric, etc., and a recorder called alkaline which is ammoniacal copper chloride. The entire metal layer was etched cleanly to the film without visual evidence of residual titanium nitride (which is transparent in any case and highly dielectric). Subsequent ESCA analysis of the exposed film area in the revealed circuits indicated no significant residual titanium, thus indicating that the titanium nitride alloyed with the copper nitride recorded clearly on all conventional copper etchings. In addition, the engraving of the patterns of the test samples produced fine, very clear lines without evidence of scour. Exposure of composite materials to a variety of solvents by the chemical stability test Method 2.3.2, IPC-TM-650, normal, for substrate materials and flexible circuits did not affect the bond strength. The following examples illustrate the present invention and are not intended to limit the same.

P941 EXAMPLE 1 To evaluate the effect that different gaseous mixtures in the plasma etching process may have on adhesion, samples were prepared using the common barrier layer metals that have been reported in the literature to bind well in polyimide films , either supported (for example, coated on a wafer substrate) or not supported. Each of the metallized film samples was made by cutting 14 x 16 inch sheets from a commercial roll of polyimide film, type E, 1 mil Kapton mark; the film sheets were then dehydrated in an oven at 1802C for 16 hours. Each sheet was then recorded with plasma in a vacuum of 4 mTorr at approximately 10-20 J / cm2 for 15 minutes. Four different gaseous plasma gas mixtures were evaluated: 100% Ar; Ar / 02 50/50; Ar / N, 50/50; Ar / 0, / N, 50/25/25 The metals evaluated were copper, chromium, nickel, titanium and aluminum. Each barrier metal candidate was deposited by ion bombardment at approximately 100 Angstroms in 100% Ar, then subjected to ion over-bombardment with approximately 1000 Angstroms of copper in 100% Ar, one side of the film at a time. After both sides of the sample sheet were metallized in this manner, they were electrolytically deposited with copper at 35 ° C.

P941 μm for the detachment test. The sheets were then tested for shedding by the German wheel release test method E of 902, Method 2.4.9, IPC-TM650, normal (cut 1/2 inch strips) and evaluated for initial shedding strength. . Seperate strips of 1/2 inch, cut, were exposed to three consecutive thermal cycles consisting of an oven that bakes at 1802C for 1 hour, followed by final and environmental cooling for 1 hour, after thermal cycling, these tests were evaluated for the retained resistance to peel at 902. All the peel results discussed later in Table 1 are the average of at least three peel strips. The results presented in Table 1 show that, in spite of the plasma gas mixture used to pretreat the surface of the film, copper and aluminum are completely ineffective as barrier layers; after exposure to thermal cycling, their initially high release values deteriorate to essentially zero. On the other hand, chromium, nickel and titanium exhibit all the typical barrier properties cited in the numerous preferences of the literature. Of the three, titanium averaged the highest retained values in all gas mixtures (63%), followed by chromium (59%), then nickel (54%). Based on the P941 results achieved by each of these metals in the four categories of gas mixtures, the most effective gas mixtures for plasma etching are Ar / N2 50/50 and Ar at 100%; the other two mixtures are noticeably less effective. The combination of the titanium metal with a plasma recorder of Ar / N2 50/50 produced the highest required peel strength and the only value of more than 6.0.

TABLE I Plasma Layer Resistance to Detachment Treatment Barrier121 to 902 (pounds / inches) "' No. of Movie111 100 Á 1000 Á Initial After% of Sample 3 TC131 Retention 1 Ar (100%) Cu Cu 4.5 0.0 0 2 Ar (100%) Cr Cu 6.5 4.5 69 3 Ar (100%) Ni Cu 6.3 3.7 59 4 Ar (100%) Ti Cu 6.5 4.0 62 Ar (100%) Al Cu 10.5 0.0 0 6 Ar / 02 Cu Cu 6.0 0.0 0 (50/50) 7 Ar / 02 Cu Cu 8.0 4.2 53 (50/50) 8 Ar / 02 Ni Cu 7.5 3.5 49 (50/50) 9 Ar / 02 Ti Cu 8.6 8.6 61 (50/50) 10 Ar / 02 Al Cu 11.8 0.0 0 (50/50) P941 Layer Plasma of Resistance to Detachment Treatment Barrier121 to 90a (pounds / inches) 141 No. of from Film111 100 to 1000 A Initial After% of Sample 3 TC131 Retention 11 Ar / N2 Cu Cu 6.5 1.5 23 (50/50) 12 Ar / N2 Cr Cu 8.5 5.3 62 (50/50) 13 Ar / N2 Ni Cu 8.9 5.5 62 (50/50) 14 Ar / N2 Ti Cu 8.7 6.2 71 (50/50) 15 Ar / N2 At Cu 10.6 0.0 0 (50/50) 16 Ar / 02 / N2 Cu Cu 6.5.0 0.0 (50/25/25) 17 Ar / 02 / N2 Cr Cu 9.2 4.8 52 ( 50/25/25) 18 Ar / 02 / N2 Ni Cu 7.5 3.5 47 (50/25/25) 19 Ar / 02 / N2 Ti Cu 8.4 4.8 57 (50/25/25) 20 Ar / 02 / N2 Al Cu 11.8 0.0 0 (50/25/25) (1) All samples, above the 1-mil polypropylene Kapton® brand film, type E. < 2 > The barrier layer was applied using 100% Ar plasma with pure Cu, Cr, Ni, Ti and Al metal targets. 1) TC indicates a thermal cycle exposure of 1 hour to 1802C.

P941 All detachment tests are detachments at 90a in 1/2 inch cut strips (Method B) of IPC-TM650, Method 2.4.9.

EXAMPLE 2 It has been reported that certain metals are more effective as a barrier layer when deposited in an oxide or nitride form. Accordingly, a series of samples were prepared where five different barrier layer metals were deposited in the same plasma gas mixture as the pretreatment. In this way, the barrier layers in the first five samples were oxide compounds from the five selected metals, the second five samples had metal nitride barrier layers, and the last five samples had oxide / nitride barrier layers. metal. Since copper, chromium and nickel do not form stoichiometric nitrides, the amount of nitrogen that actually co-deposited with them as an interstitial impurity in the metallic crystalline screen will vary, but the thickness of the metal nitride deposit (as determined by an optical densimeter) It was about 100 Angstroms. Titanium and aluminum form stoichiometric nitrides, as does zirconium and other metals not evaluated in this example. To finish the composite structures evaluated in this For example, the gas was then changed to pure argon and 1000 Angstroms of pure copper was deposited by sputtering in the barrier layer. All sample sheets were electrodeposited subsequently to 35 μm copper, exposed to three thermal cycles at 180 ° C for 1 hour, then subjected to the same 90 ° German release test, IPC-TM650-Method 2.4.9. All the detachment results set forth in Table II below are the average of at least three strips of detachment. This summary of data shows that, while compounds containing copper oxide are completely ineffective as barrier layers (zero detachment resistance, retained), copper nitride is reasonably effective (58% retention). In contrast, chromium and nickel are not only reasonably effective in the form of oxide-containing compounds, but completely remarkable (90% retention) in the form of nitride. Aluminum is reasonably effective in the oxide form, but not in all nitride-containing compounds. Titanium is reasonably effective in oxide-containing compounds but fails completely in the form of nitride. Visual observation of sample 9 indicated complete release of the copper layer from the substrate and analysis by XPS confirmed P941 that the titanium nitride was still present on the surface of the film. Similarly, copper easily peeled off the AIN layer in sample 10. These findings reflect the fact that copper metal can adhere to non-stoichiometric nitrides of Cu, Cr, and Ni, but not to Ti nitrides and Al with which it can not form a metallic alloy.

TABLE II Barrier Layer Plasma Detachment Resistance Treatment of a 90a (pounds / inches) 111 Film No.111 100 A 1000 A Initial After% Sample 3 tc131 Retention Ar / 02 CuO. Cu 4.5 0.0 (50/50) Ar / 02 Cr.O Cu 9.5 3.1 33 (50/50) Ar / 02 Ni / O Cu 8.2 2.5 30 (50/50) Ar / 02 UNC, Cu 8.3 5.0 60 (50 / 50) Ar / 02 A1203 Cu 8.1 4.5 55 (50/50) Ar / N2 Cu N. Cu 7.1 4.1 58 (50/50) Ar / N2 Cr2N and Cu 10.9 9.8 90 (50/50) Ar / N2 NI N Cu 10.7 9.7 91 (50/50) Ar / N2 TiN Cu 10.4 0.0 0 (50/50) P941 Barrier Layer Plasma Loss Resistance Treatment at 90a (pounds / inches) 111 No. 100 A 1000 A Initial After% Sample 3 TC131 Retention Ar / N2 AIN Cu 11.3 0.3 3 (50/50) 11 Ar / 02 / N2 CuO x N and Cu 5.0 0.0 0 (50/25/25) 12 Ar / 02 / N2 CrO? Ny Cu 8.9 4.7 53 (50 / 25/25) 13 Ar / 02 / N2 NiOxNy Cu 8.1 3.8 47 (50/25/25) 14 Ar / 02 / N2 TiO? Ny Cu 9.4 4.5 48 (50/25/25) 15 Ar / 02 / N2 AlOxNy Cu 10.0 1.2 12 (50/25/25) > All samples, above the 1-mil polypropylene Kapton® brand film, type E. (2) After 3 thermal cycles the copper layer was released from the TiN layer with 0 shedding strength TC indicates a thermal cycle exposure of 1 hour to 180aC All peeling tests are landslides at 902 in 1/2 inch cut strips (Method B) of IPC-TM650, Method 2.4.9.

P941 EXAMPLE 3 It is believed that the copper failure to bind to the stoichiometric barrier layer compounds could be prevented by inserting a layer of the same metal used to form the barrier layer compound, so that the metal layer inserted is It will bond your compound from the barrier layer below and a layer of copper metal from above. In this way, the samples evaluated in this example were prepared by using three different gas samples for plasma pre-treatment. Within each group of gas mixtures, five different metals were used to form thick barrier layer compounds of 100 Angstroms which were then over-bombarded ionically with 100 Angstroms of the same metal in a 100% Ar plasma; 1000 Angstroms of copper then sputtered into the intermediate metal layer in a 100% Ar plasma. As in the previous examples, all the sample sheets were electrodeposited subsequently to 35 μm of copper, exposed to three thermal cycles at 1802C for 1 hour, then subjected to the 90a German wheel detachment test, IPC-TM650- Method 2.4.9. All of the release results discussed later in Table III are the average of at least three strips of release. With respect to the compounds of the layer of P941 - - - - - metal oxide barrier, the three-layer approach significantly improved the results of the retained resistance to release for chromium, nickel and titanium, but had no effect on the previous results for copper and aluminum ( complete failure). Essentially, no improvement was found in the results achieved by the oxide-nitride barrier layer compounds. For the nitride barrier layer compounds, none of the previous results was markedly improved except for titanium, which was transformed from full failure to the highest percent retention, recorded, 93%. Unfortunately, this remarkable result does not translate into a flexible, successful substrate and circuit material, because the titanium metal can only be removed with special chemistries not routinely available in printed circuit board sizes. Likewise, the results achieved with the intercaps of chromium and nickel are also unsatisfactory since when the copper coating moves with the conventional, alkaline engravers, a second etching operation with specific chemistry to these metals is required. An interesting aspect of the AIN sample (# 10) was that the strips shed after the thermal exposure showed no evidence of the 100 Angstrom aluminum metal interlayer, apparently because the thin aluminum diffused P941 in copper and lost its binding integrity. When the thickness of the aluminum metal interlayer was increased to 500 Angstroms, good linear retention was achieved after the thermal cycling, but this result does not result in a flexible circuit substrate material, satisfactory because the traces of the circuits Subsequent elaborations in this construction were severely undermined by the engraver.

TABLE III Detachment Resistance Plasma Treatment Barrier Layer 'at 90a (pounds / inches) "' No. of Film111 100 A 1000 A 100 A Initial After% Sample of 3 TC131 Retention 1 Ar / 02 CuO Cu Cu 7.7 0.0 0 (50/50) 2 Ar / 02 Cr O Cr Cu 10.5 5.5 52 (50/50) 3 Ar / 0 NiO Ni Cu 8.3 4.7 57 (50/50) 4 Ar / 02 UNCLE, T Cu 8.9 6.1 69 (50750) Ar / 02 A1203 At Cu 11.4 0.0 (50/50) Ar / N2 CuN, Cu Cu 7.0 4.2 60 (50/50) Ar / N2 Cr2N and Cr Cu 9.2 8.5 92 (50 / 50) Ar / N2 NixNy Ni Cu 10.0 9.1 91 (50/50) P941 Loose Resistance Plasma Treatment Barrier Layer "1 to 90a (pounds / inches) '" No. of Film111 100 A 1000 A 100 A Initial After% Sample of 3 TC131 Retention 9 Ar / N, TiN '"Ti Cu 10.4 9.8 93 (50/50) 10 Ar / N2 A1N Al Cu 9.5 0.8 (50/50) 11 Ar / 02 / N2 Cu Cu Cu 6.2 0.0 (50/25/25) 12 Ar / 02 / N2 CrON Cr Cu 9.0 4.9 54 (50/25/25) 13 Ar / 0, / N "NiON Ni Cu 7.9 3.7 47 (50/25/25) 14 Ar / 02 / N2 TiOSJ Ti Cu 8.3 4.8 58 (50/25/25) 15 Ar / 02 / N2 AlOxNy Al Cu 10.1 0.0 (50/25/25) (1> All samples, above the 1-mil polypropylene Kapton® brand film, Type E. <2> All peeling tests are landslides at 902 in 1/2 inch cut strips (Method B) of IPC-TM650, Method 2.4.9. (3) TC indicates a thermal cycle exposure from 1 hour to 1802C.

P941 EXAMPLE 4 Based on the superior results achieved in Example 2 and 3 with nitrogen-based processes, an evaluation was made of a new three-layer system based on a substrate of plasma-recorded polyimide film in a gaseous mixture of Ar / N2 50/50 to approximately 20 J / cm2. In this case, the three-layer construction consisted of a wider variety of metal nitride barrier layers of 100 Angstroms in thickness, followed by a copper nitride interlayer 100 Angstroms thick, both sputter-plated in a plasma of Ar / N2 50/50; a third layer of pure copper metal of 1000 Angstroms in thickness was deposited in a 100% Ar plasma. As in the previous examples, all the sample sheets were electrodeposited subsequently to 35 μm of copper, were exposed to three thermal cycles at 180 aC for 1 hour, then subjected to the 90a German wheel detachment test, IPC-TM650-Method 2.4.9. All of the release results discussed later in Table IV are the average of at least three strips of release. Visual examination of the stripping strips both initial and after thermal cycling indicated that adhesion failure was due to cohesive fracture in the upper layer of the P941 polymer film substrate. This was subsequently confirmed by an XPS analysis of both the surface of the film and the top of the copper that broke off, showing very slight traces of metal left in the film and a significant amount of carbon and nitrogen present at the top of copper. The excellent results achieved with respect to both the initial release values and the percent retention after three thermal cycles demonstrated the effectiveness of this composition for virtually every selected metal, but particularly the first five. As candidates for the barrier layer, an advantage of both Ti and Zr is that their nitrides are stoichiometric and are likely to be more stable in terms of long-term use than non-stoichiometric nitrides of chromium, vanadium, and nickel. TiN and ZrN are also optically transparent at 100 Angstroms thickness while CrN VN and NiN have a dark appearance in their thickness and are more difficult to remove with the coating copper in a single step using alkaline etching chemistry.

P941 TABLE IV Barrier Layer Plasma 'Peel Resistance Treatment at 90a (pounds / inches)' 1 Film No.11 100 A 1000 A 100 A Initial After% of Sample of 3 TC131 Retention 1 Ar / N2 TiN Cu? Ny Cu 9.2 9.0 98 (50/50) '11 2 Ar / N2 ZrN CuN Cu 8.8 8.1 95 (50/50) 3 Ar / N2 Cr N CuN. Cu 9.4 8.7 93 (50/50) 4 Ar / N2 VN CuN Cu 8.9 8.0 90 (50/50) 5 Ar / N2 NixNy CuxNy Cu 10.0 8.5 85 (50/50) 6 Ar / N2 WN CuN Cu 10.2 8.2 80 ( 50/50) 7 Ar / N2 FeN CuN Cu 9.1 7.0 77 (50/50) 8 Ar / N2 FeSiN CuN. Cu 11.4 7.0 62 (50/50) 9 Ar / N2 Cu N Cu N Cu 7.1 4.1 58 (50/50) u: 10 Ar / N2 MoN CuxNy Cu 7.1 3.7 52 (50/50) 11 Ar / N2 A1N CuN Cu 10.6 4.4 42 (50/50) 12 Ar / N2 TaN CuN. Cu 8.0 3.2 40 (50/50) C1J All samples, above the 1-mil polypropylene Kapton® film, type AND.

All peeling tests are landslides at 90a in 1/2 inch cut strips (Method B) of IPC-TM650, Method 2.4.9. < 3) TC indicates a thermal cycle exposure of 1 hour at 1802C. > Example of the United States Patent No. ,372,848.

EXAMPLE 5 It has been observed that the plasmas of several noble gases such as helium, neon, argon, krypton and xenon, can produce different results on polymeric substrates due to the effect that the relative sizes of the atoms of these noble gases, and therefore their kinetic energy in the impact, can have in the different atoms in the polymer structure. To evaluate the possibility that the bond strength could be influenced by the choice of the plasma gas mixture, films of polyimide film, type E, Kapton mark of 1 mil, were etched into the plasma with several gas mixtures that contain nitrogen at approximately 20 J / cm2; all gas mixtures used were 50/50, except for two samples that were 100% nitrogen. These samples were then metallized in a three-layer construction consisting of a thick barrier layer of 100 P941 Angstroms of either nickel or titanium nitride plating on the surface of the film, followed by a layer of coarse copper nitride, 100 Angstroms, followed by a pure, thick copper layer of 1000 Angstroms; in the gas mixtures for the first two layers were the same as those used for the pre-treatment of each sample, but the copper layer was sputtered in 100% argon. As in the previous examples, all the sample sheets were electrodeposited subsequently to 35 μm of copper, exposed to three thermal sites at 1802C for 1 hour, then subjected to the 90a German wheel detachment test, IPC-TM650- Method 2.4.9. All the stripping results set forth in Table V below are the average of at least three strips of stripping. Based on the results presented in Table V, it seems that, at comparable energy levels in this particular polymeric substrate, the gases evaluated produced comparable results. Since it is well known that ammonia is readily degraded in a plasma to hydrogen and active nitrogen species, the surprising of the 50/50 argon / ammonia gas mixture in sample 4 produced essentially the same result as in sample 3 , a mixture of Ar / N2. Even a 100% nitrogen plasma (samples 9 and 10) achieved results comparable to those obtained with neon, helium and argon which suggests that a noble gas is not essential. However, with a noble gas present, a plasma can be started at lower energy levels; consequently, Ar / N2 is the preferred gas mixture for an efficient source of nitrogen ion energy.

TABLE V Barrier Layer Plasma Tear Resistance: Treatment111 to 90a (pounds / inches) 141 Film No.141 100 A 1000 A 100 A Initial After% of Sample of 3 TC131 Retention: 1 Ar / N2 Ni? Ny Cu? Ny Cu 9.3 7.6 82 2 Ar / N2 TiN Cu? Ny Cu 10.5 8.8 84 3 Ar / NHj TiN Cu? Ny Cu 9.5 8.9 87 4 He / N2 Ni? and CuNy Cu 10.5 9.4 89 He / N2 TiN C? Ny Cu 9.8 8.1 83 6 Ne / N2 Ni? Ny Cu? Ny Cu 8.9 8.8 99 7 Ne / N2 TiN CuxNy Cu 8.8 8.4 84 8 N2 (100%) Ni? Ny CuxNy Cu 8.4 6.3 75 9 N2 (100%) TiN CuNy Cu 9.2 8.4 91 (1) All samples, above the 1-mil polypropylene Kapton® brand, type E. All peeling tests are 90a peelings on 1/2 inch cut strips (Method B) of IPC-TM650 , Method 2.4.9. P941 131 TC indicates a thermal cycle exposure of 1 hour at 180 aC. ) All plasma gas mixtures for film pretreatment and the first two barrier layers were 50/50, except for samples 8 and 9 with 100% N2.

EXAMPLE 6 Although it was determined that Ar / N2 is the most effective gas mixture in the previous example, an additional experiment was undertaken to determine the sensitivity of the adhesion of the metal-nitride barrier layer to the gas nitrogen content of plasma. Accordingly, films of polyimide film, E-type, Kapton 1-mil mark, were etched to the plasma at about 20 J / cm 2 with gaseous mixtures having different nitrogen to argon ratios. These samples were then metallized in a three-layer construction consisting of a 100 Angstroms thick barrier layer of titanium nitride formed in the same plasma gas mixture used for the pre-treatment step, followed by 100 Angstroms of the nitride of copper formed in the same plasma gas mixture, followed by a thick pure copper layer of 1000 Angstroms sizzled in 100% argon. As in the previous examples, all the sheets of P941 sample were electodeposited subsequently to 35 μm copper, exposed to three thermal cycles at 1802C for 1 hour, then subjected to the 90a German wheel detachment test, IPC-TM650-Method 2.4.9. All the release results discussed later in Table VI are the average of at least three strips of release. From the results summarized in Table VI, it appears that above about 5% nitrogen content, the effectiveness of the Ar / N2 mixtures for both the plasma pre-treatment process and the ion bombardment process of the Barrier layer is relatively insensitive to nitrogen content. However, below some minimum amount, probably 5% or less in volume, insufficient nitrogen in the plasma will cause the titanium to deposit on the surface of the polymeric film as the free metal, rendering it unsuitable for applications of interest for this invention.

P941 TABLE VI Resistance to Release Plasma Treatment Barrier Layer121 90a (pounds / inches) 141 Film No.111 Initial After% 100 A 100 A 1000 A Sample 3 TC131 Retention 1 N2 (100) Tin Cu N Cu 8.9 8.1 91 2 Ar / N2 Tin CuN. Cu 9.2 9.0 98 (50/50) Ar / N2 Tin CuA Cu 8.5 8.2 97 (75/25) Ar / N2 Tin Cu N Cu 9.5 8.4 88 (88/12) Ar / N2 Tin CuN, Cu 9.3 8.9 96 (94 / 6) Ar / N7 Tin (2) CuN. Cu 7.5 5.5 73 (98/2) < - > All samples, above the 1-mil polypropylene Kapton® brand, type E. All peeling tests are 90a detachments on 1/2 inch cut strips (Method B) of IPC-TM650, Method 2.4 .9. TC indicates a thermal cycle exposure of 1 hour at 1802C. < _ > Sample No. 6 made with 2% N2 does not produce Tin deposit in the film and free Ti metal was observed.

P941 EXAMPLE 7 It is well known that the plasma energy level can have a significant effect on the adhesion of the barrier layer. To investigate this relationshippolyimide film sheets, type E, of the Kapton 1 mil mark, will be etched into the plasma in a 50/50 Ar / N2 gas mixture using different energy levels. The energy levels were calculated from the watts of RF energy absorbed by the plasma in the sample area and by varying the exposure time and the pressure in the vacuum chamber varied from 2 to 200 J / cm2. In this example, the samples were metallized in a three-layer construction consisting of a 100 Angstroms thick barrier layer of nickel nitride formed in the same plasma gas mixture used for the pretreatment step, followed by 100 Angstroms of copper nitride formed in the same plasma gas mixture, followed by a layer of 1000 Angstroms thick pure copper sputtered in 100% argon. As in the previous examples, all the sample sheets were electrodeposited subsequently to 35 μm copper, exposed to three thermal cycles at 1802C for 1 hour, then subjected to the 90a Roman wheel release test, IPC-TM650-Method 2.4.9. All the results shown in Table VII are the average of P941 minus three strips of detachment. The results presented in Table VII show that, for samples based on polyimide film, low energy levels produce low levels of initial and retained adhesion. As plasma energy is increased to the range of 20-50 J / cm2, adhesion, initial and retained values are dramatically improved. Beyond this level of energy, however, both categories of adhesion fall to the point where, at the level of 200 J / cm2, the bond strength at the polymer film-barrier layer interface is at most marginal. Atomic force microscopy (AFM) confirmed that an increasing degree of atomic level rugosity of the microprofiles of the films recorded to the plasma achieved the increase in energy levels up to approximately 50 J / cm2; beyond this point, the microprofile of the film decreased and showed evidence of polymer degradation. The effect that the level of plasma energy has on the release resistance is also fully observable when different polyimide film structures are recorded; those with a higher modulus and more rigid "structures" require higher energy levels than the more typical, more flexible polyimides with ether bonds that are more easily cleaved.

P941 TABLE VII Energy Time Res: Dessert Attendance Sample Exposure Total Pressure141 to 90a (pounds / inches) to'2'51 No. (Min.) (Μ) J / cm2 Initial After 3 TC131% of Rett 1 2 4 2 4.2 1.5 36 2 15 4 10 6.8 4.2 62 3 30 4 20 12.1 9.0 74 4 60 4 40 12.0 9.1 76 30 1 50 9.9 8.7 88 6 15 1 100 5.0 3.5 70 7 2 1 200 4.8 1.2 25 All samples, above the polyimide film brand KaptonR 1 mil of an inch, type E.

All peeling tests are landslides at 90a in 1/2 inch cut strips (Method B) of IPC-TM650, Method 2.4.9. TC indicates a thermal cycle exposure of 1 hour to 180aC > Assume that the total exposed energy is cumulative over time. (51 All previous samples were treated with plasma with Ar / N2 gas mixture 50/50 under the time and pressure conditions shown were metallized with NixNy 100A / Cu 100A / Cu 100A and then electrodeposited at 35μm of Cu thickness for the detachment test.

P941 EXAMPLE VIII To examine the effect that the thickness of the barrier layer can have on the peel strength, initially and most importantly, after thermal exposure, five samples were prepared using polyimide film sheets of the E type, of Kapton of 1 thousandth of an inch. All the film samples were pretreated with approximately 10 J / cm2 of energy in a 50/50 Ar / N2 gas mixture. The samples were then metallized in a three-layer construction consisting of a 100 Angstroms thick barrier layer of nickel nitride formed in the same plasma gas mixture used for the pre-treatment step, followed by 100 Angstroms of copper nitride formed in the same plasma gas mixture, followed by a pure, thick copper layer of 1000 Angstroms sizzled in 100% argon. As in the previous examples, all the sample sheets were electrodeposited subsequently to 35 μm copper, exposed to three thermal cycles at 180 aC for 1 hour, then subjected to the 90a German wheel detachment test, IPC-TM650- Method 2.4.9. All the release results discussed later in Table VIII are the average of at least three strips of release.

P941 To reveal the data presented in Table VIII, the thickness of the nickel nitride barrier layer was varied in scales from 100 Angstroms down to approximately 6 Angstroms by varying the current to the nickel target. The thicknesses of the barrier layer in each step were measured by an optical densimeter. The results show that nickel nitride provides an effective barrier layer in sputter-coated coatings as thin as about 50 Angstroms, but below this level its effectiveness as measured by the resistance to detached detachment falls in a completely significant way. Other tests indicate that the thickening of the nickel nitride above 100 Angstroms does not materially improve its effectiveness as a barrier layer beyond 500 Angstroms is observed a deterioration of the initial values of detachment. These tests, therefore, establish that a metallic nitride plated in a range of thickness of 50-100 Angstroms produces an optically clear, continuous coating that performs effectively with a barrier to the migration of oxygen and water to the copper layers of coating and, equally important in the construction of the polyimide film, prevents the diffusion of copper in the film where it can oxidize and catalytically degrade the polymer structure.

P941 TABLE VIII Amp. In Thickness (A) 90a Release Resistance Target sample NIA (pounds / inches) No. of Initial Initial After 3 tc131% of Withholding 1 4.00 100 11.2 9.7 87 2 2.00 50 11.3 10.2 90 3 1.00 25 10.9 6.4 59 4 0.50 12 9.8 3.7 38 5 0.25 6 8.5 0.9 11 > All samples, above the 1-mil polpylene Kapton® brand film, type E. (2> All peel tests are 90a peelings on 1/2 inch cut strips (Method B) "from IPC -TM650, Method 2.4.9. < 3 > TC indicates a thermal cycle exposure of 1 hour at 180 ° C. w Plasma pre-treatment gas mixture was Ar / N2 50/50. (5 > Gas of sample plasma used to deposit variable thickness of NixNy then CuxNy 100 Á then 1000 Á of Cu in only Ar plasma before electroplating at 35 μm for the detachment test.

P941 EXAMPLE 9 Three samples were independently prepared to reproduce the process of this invention and confirm the findings of the previous examples. The three sheets were made using an E-grade polyimide film, 2-mil Kapton that was pre-treated with plasma with a 50/50 Ar / N2 plasma followed by the 100 Angstrom sputtering deposition of titanium nitride. in a gas plasma of Ar / N2 94/6, followed by the deposition by sputtering of 100 Angstroms of copper nitride in a plasma gas of Ar / N2 94/6, followed by the sputter deposition of 1000 Angstroms of copper in a plasma of 100% Ar gas. As in the previous examples, all the sample sheets were electrodeposited subsequently to 35 μm of copper, exposed to three thermal cycles at 1802C for 1 hour, then subjected to the 90a German wheel detachment test, IPC-TM650- Method 2.4.9. All of the release results discussed later in Tables IX-A and IX-B are the average of at least three strips of shedding. The test results summarized in Table IX-A show a remarkable degree of reproducibility. This can be explained by the fact that the values of resistance to detachment, both initial and P941 retained correspond to the cohesive failure values reported in the literature for the E-grade polyimide film, Kapton, of 2 thousandths of an inch. In other words, because the interfacial bond strength provided by the process of this invention exceeds the cohesive strength of the film itself, these test results are actually measures of the film properties, not the metallization properties per se. However, it is clear from these results that the process of this invention is capable of producing a flexible circuit substrate material, composed with interlaminar adhesion properties, which has exceptional resistance to thermal stress.

TABLE IX-A Shows Barrier Layer Resistance to Release No (1.2) and Metalization 902 (pounds / inches) '5 > Initial'31 Initial After% of 3 TC Retention 1 100 Á TiN / 100 Á 9.2 9.0 98 Cux / Ny 2 - 1000 A Cu 9.3 9.2 99 3 9.2 8.8 96 Average 9.2 9.0 98 C1 'All samples, above the KaptonR polyimide film, 2 mils, type AND.

P941 (2) The film was prepared with a gas plasma of Ar / N2 50/50, 15 minutes / 4 μm (J / cm2). < 3 > Metallization of TiN 100 Á initial and barrier layer Cu $ y of 100 Á was in a plasma of Ar / N2 94/6 followed by Cu of 1000 Á and 100% Ar plasma 44) Previous sputter metalized film samples were subsequently electrodeposited with copper at 35 μm for the release test. < 5 > All peel tests are on 90a peel off on 1/2 inch cut strips (Method B) of the IPC-TM650, Method 2.4.9 and are averages of 3 strips for each value.

The long-term bonding durability of two-sided metallized film composite products is especially important in many high temperature, such as automotive and aerospace printed circuit applications below the cab. The 200SC thermal exposure data presented in Table IX-B illustrate the unique and remarkable results obtained with the metallized film composite products using the multilayer constructions of this invention.

P941 TABLE IX-B Release Values at 90! % Retained (lxhras / inch) (2) Initial 9.2 (1) NO After Thermal Exposure 0.5 hours 8.9 97 1.0 hours 9.0 98 2.0 hours 9.2 100 4.0 hours 9.0 98 8.0 hours 8.9 97 24.0 hours 7.6 83 to? All test strips are from sample sheet No. 1 above (see also notes 1, 2 and 3 above).

() See also notes 4 and 5 above. (3> Thermal exposures were in 1/2 inch cut strips in air with air heated by convection to 2002C for the indicated times.

To evaluate the suitability of these composite products for the chemical processing requirements of flexible circuit manufacturing, each of the three previous sheets was used to form printed circuit test patterns by different processing techniques. Sheet number 1 was imaged, revealed, and recorded on a peroxide / acid etchant Sulfuric P941, typical for producing a fine-line circuit pattern with 5-mil / inch tracing / space geometry; the traces of the resulting circuit were recorded cleanly and exhibited no evidence of scour. Sheet number 2 was also image-formed, revealed and recorded in a copper, ammoniacal, typical recorder with similar results. Sample number 3 was also imaged and etched in a typical ferric chloride acid etchant with the same excellent results. The XPS analysis of the exposed film area in each of these three sheets detected only a slight trace of titanium, indicating that the titanium nitride was completely removed in the etching process. It is believed that the titanium nitride barrier layer forms alloy with the coating copper nitride layer and when it is exposed to strong oxidizing agents in the engravers, it is converted to titanium oxide. Both titanium oxide and copper nitride dissolve easily in the chemistries of the engraver commonly used in printed circuit manufacturing work. On the other hand, protected by copper covered with a protective layer plated over the trace areas, the titanium nitride retains its chemical state which is highly resistant to scouring by engravers. The exposed film also passed the endurance test Surface P941 of IPC-TM650, Method 2.5.17, as well as the moisture resistance and insulation test of IPC-TM650, Method 2.6.3.2. These results indicate that any residual residual contamination on the surface of the film was also too low to be measurable in these test procedures.

EXAMPLE 10 In this example, the application of the metallization process described in this invention to other polymeric films typically used to make printed circuits was evaluated. Each sample was prepared with a pretreatment of Ar / N2 50/50 followed by the sputtering of 100 Angstroms of nickel nitride in a gaseous plasma of Ar / N2 94/6, followed by the sputter deposition of 100 Angstroms of copper nitride in a gas plasma of Ar / N2 94/6, followed by the sputter depression of 1000 Angstroms of copper in a plasma of 100% Ar gas. As the previous examples, all the sample sheets were electrodeposited subsequently to 35 μm of copper. With the exception of samples 7 (Ulte) and 8 (PEN), all samples were exposed to three thermal cycles at 802C for 1 hour, and then subjected to the 90a German wheel detachment test, IPC-TM650- Method 2.4.9. Samples 7 and 8 P941 are subjected to a thermal cycle test at 180 aC because this temperature exceeds the thermal limits of the films; these samples were therefore tested at 1502C, the normal IPC test condition. The results of these Tse tests are presented in Table X. Compared to reference samples 1 and 2, samples 3-6, which are based on polyimine films with different chemical formulations, achieved comparable detachment test results. However, no significant release values could be observed in the remaining samples due to the fracture of the internal film. This is that the metal-polymer interface remained intact during the peel test, but the film itself cohesively failed at extremely low strength levels (typically less than 2 pounds / inch). Samples 3-6 were also subjected to a so-called "pressure oven" test where the material is dispersed above boiling water in a pressure oven to simulate, under accelerated conditions, the effect of long-term exposure to conditions of high humidity. In all cases, the interlaminar integrity of the composite product was not affected. Similarly, when subjected to the IPC-TM650, Method 2.3.2, samples 3-6 proved to be highly resistant to degradation by P941 any of the various chemical reagents used in this test method.

TABLE X Release Resistance at 90a (pounds / inches) 14.51 Initial No. After Sample% Film Substrate111 of 3 TC Retention Polymer of 1 thousandth of 9.9 7.7 78 inch - Kapton V Polyimide of 1 thousandth of 13.4 9.5 71 inch - Kapton E Polyimide of 2 thousandths of 9.2 9.0 98 inch - Kapton Polyimide of 1 thousandth of 9.8 7.2 74 inch - Apical AV Polyimide of 2 thousandths of 9.0 8.5 to 94 inches - Apical NP Polyimide of 2 thousandths of 7.7 6.2 81 inches - Upilex S Polyetherimide of 2 thousand (7) (7) inches - Ultem 1000 Pqlietilene-naphthalate (PEN) (7) (7) of 2 thousandths of an inch (PBl) Polybenzimidazole of 2 (7) (7) thousandths of an inch (PBI) (S > 10 Polyarylene-ether-benzimidazole (7) (7) (PAEBI or PABI) of 2 thousandths of an inch 11 Polytetrafluoroethylene ( 7) (7) (PTFE) 3 mils P941 Release Resistance at 90a (pounds / inches) 14'51 Do not . Initial After Sample% 3-C film substrate Retention 12 Liquid crystal polymer (7) (7) of 2 mil polyester (Vectra) < S) 13 Non-woven paper polyaramide- (7) (7) Nomex 1.5 mils All the above film samples were subjected to a plasma pre-treatment in an Ar / N2 gas mixture of 50/50 at a pressure of 4 μm for 15 minutes (10 J / cm2). All peeling tests are detachments at 90a in 1/2 inch cut strips (Method B) of IPC-TM650, Method 2.4.9 TC indicates a thermal cycle expression of 1 hour at 180a composition. A TiN barrier layer of 100 Á / CuxNy of 100 Á was applied to the same plasma gas and then Cu of 100 Á was deposited in 100% Ar plasma. Subsequently, all samples were electrodeposited to 35 μm copper thickness by the peel test. Samples 9 and 10 were development films obtained from NASA / Langley Sample 12 was a development film obtained from Foster-Mi11er P941 Samples 7-13; metal-polymer release resistance values per se were not obtained for these constructions because the cohesive fracture occurred in the polymer substrate itself when the attempt was made to detach the metal from the structure, ie, the polymer-interface was stronger than the cohesive resistance that the film itself.

Claims (47)

1. CLAIMS 1. A composite product comprising a polymeric substrate having at least one surface modified by plasma etching to form a micro-rough substrate surface, a layer on the surface of micro-rough substrate comprising a first layer of metal nitride , a second non-stoichiometric layer of metal nitride on the first metal nitride layer, the first metal nitride layer and the second non-stoichiometric layer of metal nitride are capable of dissolving in an alkaline etchant composition and a third layer of metal nitride. electrically conductive metal in the non-stoichiometric layer of metal nitride.
2. 2. The composite product according to claim 1, wherein the second non-stoichiometric layer of metal nitride is electrically conductive.
3. 3. The composite product according to claim 1, wherein the substrate has perforations through its thickness.
4. 4. The composite product according to claim 1, wherein the composite product retains at least about 60% of its initial resistance to peeling after. which is exposed to three thermal cycles consisting of 1 hour at room temperature P941 followed by 1 hour at 1802C.
5. The composite product according to claim 3, wherein the composite product retains at least about 60% of its initial peel strength after it is exposed to three thermal cycles consisting of 1 hour at room temperature followed by 1 hour at 1802C.
6. 6. The composite product according to claim 1, wherein the second non-stoichiometric layer of metal nitride is a copper nitride.
7. 7. The composite product according to claim 1, wherein the metal layer is copper.
8. 8. The composite product according to claim 6, wherein the metal layer is copper.
9. The composite product according to any of claims 1, 2, 4, 5, 6, 7 or 8, wherein the first metal nitride is selected from the group consisting of titanium nitride, zirconium nitride, nitride chrome, nickel nitride and vanadium nitride.
10. 10. The composite product according to any of claims 1, 2, 3, 4, 5, 6, 7 or 8, wherein the polymeric substrate is a polyimide film.
11. 11. The composite product according to claim 9, wherein the polymeric substrate is a polyimide film. P941
12. 12. The compound product according to claim 10, wherein the first metal nitride is selected from the group consisting of titanium nitride, zirconium nitride, chromium nitride, nickel nitride and vanadium nitride.
13. 13. The composite product according to any of claims 1, 2, 3, 4, 5, 6, 7 or 8, wherein the polymeric substrate is a polyether film.
14. The composite product according to claim 13, wherein the first metal nitride is selected from the group consisting of titanium nitride, zirconium nitride, chromium nitride, nickel nitride, and vanadium nitride.
15. 15. The composite product according to any of claims 1, 2, 3, 4, 5, 6, 7 or 8, wherein the polymeric substrate is a polyester film.
16. 16. The composite product according to claim 15, wherein the first metal nitride is selected from the group consisting of titanium nitride, zirconium nitride, chromium nitride, nickel nitride, and vanadium nitride.
17. 17. The composite product according to any of claims 1, 2, 3, 4, 5, 6, 7 or 8, wherein the polymer substrate is a fluoropolymer film.
18. 18. A composite product in accordance with P941 claim 17, wherein the first metal nitride is selected from the group consisting of titanium nitride, zirconium nitride, chromium nitride, nickel nitride, and vanadium nitride.
19. 19. A composite product comprising a polymeric substrate comprising at least one surface modified with a plasma containing nitrogen ions to form a micro-rough substrate surface, a layer on the substrate surface made micro-rough comprising a first layer of metal nitride, a second layer of metal nitride, non-stoichiometric in the first 'layer of metal nitride, the first layer of metal nitride and the second layer of metal nitride, non-stoichiometric, are capable of dissolving in a recording composition, alkaline and a third metal layer, electrically conductive in the metal nitride layer, non-stoichiometric.
20. The composite product according to claim 19, wherein the second non-stoichiometric metal nitride layer is a copper nitride.
21. 21. The composite product according to claim 19, wherein the substrate has perforations through its thickness.
22. 22. The composite product according to claim 19, wherein the composite product retains P941 at least about 60% of its initial resistance to peeling after being exposed to three thermal cycles consisting of 1 hour at room temperature followed by 1 hour at 1802.
23. 23. The composite product according to claim 19, wherein the product compound retains at least about 60% of its initial resistance to peeling after being exposed to three thermal cycles consisting of 1 hour at room temperature followed by 1 hour at 1802C.
24. 24. The composite product according to claim 19, wherein the second non-stoichiometric metal nitride layer is a copper nitride.
25. 25. The composite product according to claim 19, wherein the metal layer is copper.
26. 26. The composite product according to claim 24, wherein the metal layer is copper.
27. 27. The composite product according to any of claims 19, 20, 21, 22, 23, 25 or 26 wherein the first metal nitride is selected from the group consisting of titanium nitride, zirconium nitride, chromium nitride , nickel nitride and vanadium nitride.
28. 28. The composite product according to any of claims 19, 20, 21, 22, 23, 25 or 26, wherein the polymeric substrate is a polyimide film. P941
29. 29. The composite product according to claim 27, wherein the polymer substrate is a polyimide film.
30. 30. The composite product according to claim 28, wherein the first metal nitride is selected from the group consisting of titanium nitride, zirconium nitride, chromium nitride, nickel nitride, and vanadium nitride.
31. 31. The composite product according to any of claims 19, 20, 21, 22, 23, 25 or 26, wherein the polymeric substrate is a polyetherimide film.
32. 32. The composite product according to claim 31, wherein the first metal nitride is selected from the group of titanium nitride, zirconium nitride, chromium nitride, nickel nitride and vanadium nitride.
33. 33. The composite product according to any of claims 19, 20, 21, 22, 23, 24 or 25, wherein the polymeric substrate is a polyester film.
34. 34. A composite product according to claim 33, wherein the first metal nitride is selected from the group consisting of titanium nitride, zirconium nitride, chromium nitride, nickel nitride, and vanadium nitride.
35. 35. The composite product according to any of P941 claims 19, 20, 21, 22, 23, 25 or 26, wherein the polymer substrate is a fluoropolymer film.
36. 36. A composite product according to claim 25, wherein the first metal nitride is selected from the group consisting of titanium nitride, zirconium nitride, chromium nitride, nickel nitride, and vanadium nitride.
37. 37. The process for forming a composite product suitable for making a printed circuit comprising plasma-etching a polymer film in a nitrogen-containing plasma to micro-roughened at least one surface of the film, depositing a first thin layer of nitride metal having a thickness of 50 to 500 Angstroms, depositing a second layer of metal nitride, preferably electrically conductive, on the first layer of metal nitride, depositing an electrically conductive metal on the second layer of metal nitride.
38. 38. The process according to claim 37, wherein the first metal nitride layer is selected from the group consisting of titanium nitride, zirconium nitride, chromium nitride and vanadium nitride.
39. 39. The process according to claim 38, wherein the second metal nitride is a copper nitride.
40. 40. The process according to claim 39, in P941 where the second metal nitride is a copper nitride.
41. The process according to any of claims 37, 38, 39, 40, wherein the metal is copper.
42. 42. The process according to claim 41, wherein the copper is deposited by sputtering, evaporation or anelectrolytically or electrolytically.
43. 43. The composite product according to any of claims 1, 3, 4, 5, 7, 8, 19, 21, 22, 24, 25, 26 wherein the third layer of electrically conductive metal is patterned.
44. 44. The composite product according to any of claims 1, 2, 3, 4, 5, 6, 7, or 8, wherein the polymeric substrate is a non-woven paper of a round polyara.
45. 45. The composite product according to any of claims 19, 20, 21, 22, 23, 24, 26 or 27, wherein the polymer substrate is non-woven polyaramide paper.
46. 46. The composite product according to claim 9, wherein the polymeric substrate is non-woven polyaramide paper.
47. 47. The composite product according to claim 27, wherein the polymeric substrate is non-woven polyaramide paper. P941