DE3510529C2 - - Google Patents

Description

The invention relates to a method for producing a Prepregs with the following steps: precondensation of N, N'-bisimides of unsaturated dicarboxylic acids of the general Formula:

where D is a divalent organic radical which is a C-C- Contains double bond and A is a divalent organic Radical with at least two carbon atoms, with diamines the general formula:

H₂N-B-N₂

where B is a divalent organic residue with no more than 30 carbon atoms, and the molar ratio of Bisimide to diamine is between 1.2 and 50 in one  Solvent, applying the solution to a substrate and partially curing the resinous substrate; a Prepreg and the use of such a prepreg.

The invention relates to prepregs which are used for Production of laminates can be used, especially around such compositions and methods as for Manufacture of multilayer printed circuit boards are suitable.

For the production of multilayer boards with printed Circuits are often used with different epoxy resins has been the valuable properties, such as superior Adhesive properties, considerable resistance against chemicals, high mechanical resistance and have excellent dielectric properties. It but it has now been found that epoxy resins are not for the production of multilayer boards with printed Circuits with high packing density and modules are suitable because they are not sufficiently resistant to Are heat. In addition, they affect often due to possible resin leakage or heat expansion the reliability of the in the direction of the plate thickness Conductivity. To get around the above problems, heat-resistant polyimide resins are currently used and it has been found that they are for manufacture of printed circuits on multilayer boards satisfactory are.

In particular, very fine conductive lines can now be used trained and small holes with high accuracy, like they are indispensable when arranging high-level circuits are drilled. The heat expansion towards the thickness can be kept to a minimum.  This can increase the reliability of cables, the through holes lined with conductive material be formed, achieved.

Conductive coatings get a higher adhesion, while the bases of the printed circuit boards have greater hardness at elevated temperatures; their behavior when attaching modules improved; they now survive a continuous one Operation at elevated temperatures of around 200 ° C.

Such polyimide resins are already from Michael Bargain et al issued US-PS 35 62 223, the DE-OS 26 57 104, DE-OS 26 57 033 and DE-OS 26 26 837 as well the BE-PS 8 04 702 become known. These pamphlets give preferred material compositions for this Resins on, but do not give any indication of those to be observed Procedural conditions.

In the meantime there has been increasing miniaturization of large computers to use multi-layer plates for printed circuits with high mounting density which resulted in a much finer circuit pattern arrangement require and a much finer drilling of through Holes. Accordingly, the plates used for this higher dimensional stability for printed circuits, in particular the spread of the dimensional variance have superior adhesive properties.

This means that a dimensional variance of the plates Affect interlayer or interlayer entry can. Accordingly, the dimensional changes should be on one Minimum be kept; this is particularly important for the production of multilayer boards of larger dimensions.  

It is therefore preferred to use printed circuit boards with such a low pressure that the dimensional stability, in particular the spread of the dimensional variance, is not diminished. But it still remains the problem that the molding at such a low Pressure levels sometimes fail to be even Flow of the resin through the hardening plates leads or not all traces of solvent for the Impregnation used solvent are removed, causing unacceptable voids in the printed Circuits are formed. Regarding the adhesive properties is required for the manufacture of circuits higher packing density a correspondingly high Adhesive force, not only between the conductive layer and the connection layer, but also between the connection layer and base material or core of the plate; otherwise slight detachments in the intermediate layer between Connection layer and the base material during the Drilling of the small holes occur, such Detachments are unacceptable and should be avoided.

In view of the above, it is desirable that multilayer printed circuit boards for use in large computers much higher adhesive forces with much greater dimensional stability combine. In other words, should Prepolymers and the prepregs made therefrom for the production of multilayer plates for printed Circuits are used, much higher adhesive forces show and also the molding of the plates at such low Pressure allow dimensional stability, especially the spread of dimensional variance - without voids in the resulting plates - is not deteriorated.  Prior art prepolymers including in the above-referenced U.S. patent are known to they have excellent adhesive strength together with others possess remarkable features. Unfortunately them for the manufacture of multilayer printed Circuit boards of the type with a larger number Layers of a higher level of dimensional stability and still needs increased adhesive properties satisfactory. This means that polyimide prepolymers according to the state of the art, probably not under suffer sufficient adhesive properties if such multilayer printed circuit boards and also form disadvantageous voids if they at low pressure - in an attempt to Ensure dimensional stability - be molded.

Studies of these unsatisfactory results above when using polyimide prepolymers the prior art have shown that macromolecular Components with a molecular weight greater than 15,000 have a high viscosity, a larger amount of solvent need for impregnation and therefore a larger one Chance for inclusion of residual solvent in the printed circuit board when molding at low Provide pressure, creating the adverse voids in the Records are left. It is also typical of the above macromolecular components that they interact with one another Substrate that they connect to this touch, less sensitivity or activity have,  being this the reason for the lack of integral bonding with the substrate will be, resulting in less liability between the same leads. As can be seen from the above consideration, of polyimide prepolymers for the above purpose expects these less macromolecular components with a molecular weight of more than 15,000 than previous ones Own prepolymers. On the other hand, it is expected that Prepolymers with a larger proportion of components a molecular weight below 15,000 is preferred are. With this in mind, the inventors have the adaptability of polyimide prepolymers for the manufacture of multilayer printed circuits and other laminate products further examined.

It is therefore an object of the present invention, prepregs manufacture which has better dimensional stability for products made from these prepregs and at the same time increased mechanical strength of the same deliver as is especially for the production of Printed circuit boards is desired.

The object is achieved by a generic Process solved, which is characterized in that the partial curing is carried out such that the resin thereafter about 18 to 28% unreacted reactants, 55 to 70% components with a molecular weight between 400 and 15,000 and 7 to 10% components with a molecular weight has over 15,000.

The invention also relates to this method manufactured prepregs and the use of Prepregs for the production of a laminate by superimposing them  a predetermined number of prepregs, hang up of (one) metal foil (s) exposed to one or both Side (s) of the prepreg stack and curing of the laminate by applying elevated temperature and pressure.

The symbols A and B can be the same or different Have meaning and linear or branched alkyl groups with less than 13 carbon atoms, cycloalkylene groups with 5 or 6 carbon atoms in the ring, heterocyclic Groups with at least one of the atoms O, N and S or a phenylene or a polycyclic aromatic group be. These different groups can be substituents wear that itself no undesirable side reactions enter under operating conditions. The symbols A and B can also have several phenylene or alicyclic groups mean that directly or via a divalent atom or Group such as oxygen or sulfur, an alkylene group of 1-3 carbon atoms or one of the groups are connected:

where R₃, R₄ and Y each have an alkyl group of 1-4 Carbon atoms or a cycloalkyl group with 5 or 6 Carbon atoms in the ring, or a phenyl or a is polycyclic aromatic group, and X is a straight chain or branched alkylene group with less than 13 Carbon atoms, a cycloalkylene group with 5 or 6 Carbon atoms in the ring or a mono- or polycyclic Is arylene group.

Group D is derived from an ethylenically unsaturated Anhydride of the general formula from:

the maleic anhydride, citraconic anhydride, Tetrahydrophthalic anhydride, itaconic anhydride as well Products of the Diels-Alder reaction between a cyclodiene and can be one of these anhydrides.

Among the preferred N, N'bis-imides (I) can be used to call the following:

N, N'-ethylene-bis-maleimide,
N, N′-hexamethylene-bis-maleimide,
N, N′-m-phenylene-bis-maleimide,
N, N'-p-phenylene-bis-maleimide,
N, N'-4,4'-diphenylmethane-bis-maleinimide,
N, N'-4,4'-diphenylether-bis-maleinimide,
N, N'-4,4'-diphenylsulfone-bis-maleinimide,
N, N'-4,4'-dicyclohexylmethane-bis-maleinimide
N, N'- α , α -4,4'-dimethylenecyclohexane-bis-maleimide
N, N′-m-xylylene-bis-maleimide and
N, N'-4,4'-diphenylcyclohexane-bis-maleimide.

The following are examples of diamines that can be used call:

4,4′-diamino-dicyclohexylmethane,
1,4-diamino-cyclohexane,
2,6-diamino-pyridine
m-phenylenediamine,
p-phenylenediamine
4,4′-diamino-diphenylmethane,
2,2-bis (4-aminophenyl) propane
Benzidine
4,4'-diaminophenyl oxide,
4,4'-diaminodiphenyl sulfide
4,4'-diaminodiphenyl sulfone,
Bis (4-aminophenyl) diphenylsilane,
Bis- (4-aminophenyl) methylphosphine oxide,
Bis (3-aminophenyl) methylphosphine oxide,
Bis (4-aminopheny) phenylphosphine oxide,
Bis (4-aminophenyl) phenylamine,
1,5-diaminonaphthalene,
m-xylylenediamine,
p-xylylenediamine,
1,1-bis (p-aminophenyl) phthalate, and
Hexamethylenediamine.

The ratio of the individual components and unresponsive Reactants depends on the ratio of the referring to Known calibration curves determine peak areas, which the Ratio between molecular weight and that in one  Chromatography methods show certain retention time details will be explained below.

The ratio of unreacted reactants or unsaturated ones Bisimides and diamines in the prepolymer composition can be an indication of the reaction process and indicates if it is below 30%, that the reaction is too advanced and more undesirable components with a molecular weight of more than 15,000 manufactured to an unacceptable extent which reduces the adhesive force and then, if it is above 40%, indicates that the reaction has not progressed sufficiently to a sufficient amount of prepolymerized components form that for making a prepreg with proper Resin content is necessary. That is, without a sufficient amount of prepolymerized components the entire composition becomes too viscous is when in a polar diluent or solvent, such as N-methylpyrrolidone or dimethylacetamide is solved to a substrate for the manufacture of the Impregnating prepregs with it and means that none Prepreg can be made with the correct resin content. Under these circumstances it is hardly possible to Resin content of the prepolymer solution to increase the lack to compensate for viscosity since the does not react in of the prepolymer composition remaining bisimides in a low solubility in such a solvent have. A preferred level of unreacted reactants is between 35 and 39%.

The components with a molecular weight of between 400 to 15,000 show satisfactory properties for the manufacture of laminate products or the desired ones  multilayer printed circuit boards, i. H., that they have considerable adherence and a solution Form with suitable viscosity when in the solvent are solved, causing the substrate with the solution such can be impregnated that molding at low Printing without the appearance of faulty voids is possible. In this context, components with a Molecular weight of between 4500 and 15000 assumed that they prefer in the highest possible amount in the prepolymer compositions are to be used, however if an excess of such components is made is, this means that the reaction process accordingly continues to progress and correspondingly increasing Amount of unwanted macromolecular components forms a molecular weight of more than 15,000, wherein these components are kept to a minimum level should decrease the adhesive properties too prevent. From this point of view, it is preferred that the proportion of components with a molecular weight of between 400 and 15,000 does not exceed 65%. The lower limit for the amount of the above components it is determined to be 53% if it is below 53% more unreacted reactants remain, so that the prep polymer composition under the above shortcomings, such as lack of viscosity when dissolved in the solvent, would suffer.

The components with a molecular weight of more than 15,000 will be produced in larger quantities curing in the subsequent operation accelerate and shorten the curing time. Components above are undesirable components in the invention Prepolymer composition as it is for the occurrence defective voids in the molded end products  as well as for a loss of adhesive force, as already explained above, are responsible. The prepolymerization process cannot do without making such macromolecular components are carried out, d. H. such components are immediately after the start of Prepolymerization reaction produced. As a result macromolecular components that are inevitable in the Production of the prepolymers occur, preferably on a minimal but not negligible value. At the practical implementation is preferred, the amount limit these components to between 3.5% to 6.8%. The prepolymerization process would be below 3.5% not progress sufficiently so that the emerging prepolymeric composition when dissolved in Solvent suffers from a lack of viscosity, causing the Production of prepregs with a suitable resin content not possible. In contrast, above 6.8% in addition the prepolymer composition more undesirable Contain macromolecular components so that the solution of the prepolymer has too high a viscosity, which is the above reasons is not desired.

In connection with the above, the inventors have the components with a molecular weight above 50,000 separated and analyzed. They are believed that they are representative of the properties of the above macromolecular Components are. The separated components were dissolved in D-DMF (deuterated dimethylformamide) and analyzed in an NMR spectrometer. The analysis shows that the above components contain hardly any diamine and essentially consist of polymerized product, only bisimides, these products being known to: have less elasticity and less adhesive properties. This confirms that the amount is macromolecular  Components should be kept to a minimum.

In the present invention, the determination of the Molecular weight distribution of prepolymers and prepegs from a gel permeation chromatography (GPC) analysis, using a HLC-803 chromatograph (manufactured from Toya Soda Manufacturing Co., ltd.), which with a pair of chromatography columns Ad-803 / S (manufactured from Showa Denko K.K., Japan), 8.0 mm diameter × 250 mm length, packed with divinylbenzene styrene Copolymers with particle sizes in the micron range is. Dimethylformamide (DMF) was used as a diluent used. Each column corresponds to approximately 6000 theoretical ones Floors so that the above column system is effective of 12,000 theoretical soils.

A 100 microliter sample of a solution with a polymer content of 0.5 ± 0.2 percent by weight (resin content / DMF + solvent contained in the prepolymer or prepreg) was injected into the column at an elution rate of 1.0 ± 0 0.01 ml / min. A differential refractometer (128 x 10 ^-8 RI units) was used with a recorder at a paper speed of 5 mm / min and a paper log was recorded on paper with a uniform basis weight, a wave-shaped recording giving the eluate concentration. The refractometer was set to an output range of between 0 to 1V, corresponding to the selected input range of 0 to 10 mA of the recording device. For the determination of the molecular weights, 5 types of monodisperse polyethylene glycols with molecular weights of 20,000, 10,000, 6000, 4000 and 400 plus an ethylene glycol monomer with a molecular weight of 62 were used as comparative samples. The calculation of the molecular weights was carried out with a quadratic regression or calibration curve, which had been determined for each of the reference samples above, in order to obtain a relationship between the known retention time and the associated molecular weight, so that the molecular weights of the samples could be obtained by applying a corresponding retention time and one of the existing regression curves can be determined. The determination of the molecular weight distribution or in percentages of the constituents with different molecular weights to the total resin content of the sample in ratios in percentages was carried out by a so-called precipitation weighing method. Parts are cut from the uniform basis weight protocol paper described with the GPC recording or the chromatogram, each of which represents the proportion of certain components with a specific molecular weight range, each fraction being weighed to determine its ratio to the total amount of the weighed fractions . Before determining the above ratios, the index molecular weights were set at 15,000 and those for unreacted reactants which remain in the prepolymer or prepreg were determined for each molecular weight for which a corresponding retention time was obtained from the above calibration curves. The GPC paper protocol was then cut into the appropriate number of fraction areas under the GPC curve between the specific retention times representative of the above molecular weights. Each fraction was weighed precisely to determine its ratio to the total, the ratio indicating the ratio of the peak areas and approximately the weight fraction of certain components in the total resin content of the prepolymer or prepreg.

Alternatively, an integrator for a facilitated Fraction calculation by partial quadrature used with each fraction of the chromatogram in at least 200 steps for a reliable calculation should be divided.

Those remaining in the prepolymer composition above unreacted reactants are preferred at a molar ratio from bisimide to diamine from between 1.7 to 3.0 held. If the ratio is higher than 3.0, then shows the resulting prepolymer composition, if they have a solution or a prepreg with suitable Resin content disadvantageously forms a precipitate excess bisimids during its storage and, if the ratio is less than 1.7, one for curing the Prepolymers in the subsequent process step of prepreg production and / or end product manufacture essential Reduction of the reaction that the control of curing would be difficult.

In fact, the inventors' investigation showed that the The above molecular ratio of the prepolymers according to the prior art the technology ranges between 3.5 and 4.1 moves, and that prepolymers according to the prior art Room temperature hardly dissolved in polar solvents and only when heated for the purpose of dissolution Preparation of the solution of a more suitable concentration of about 50 to 60% by weight, and further that the solution or the lacquer thus produced when heated suffers from bisimide failure during storage. In contrast to the above, for prepolymers according to the invention, in which unreacted reactants in one Bisimide to diamine molar ratio of between 1.7 and 3.0 are found to be essentially  no failure, not only during normal storage conditions at room temperature, but also when stored cold at a temperature of minus 5 ° C.

The above molecular ratio of unreacted reactants was calculated from the mole numbers by the following procedure. That is, the prepolymer was dissolved in acetonitrile, to dissolve selectively unreacted reactants in it and then the dissolved constituents in acetonitrile were analyzed to quantify the reactants and their number of moles by liquid chromatography using reverse phase distribution chromatography using a reverse phase distribution chromatography column 120 T (manufactured by Toyo Soda Manufacturing Co. ltd.), Whereby acetonitrile / - Water was used as a diluent. Before the above The procedure was a calibration curve for each of the reactants determined to give the ratio of mole number / peak area, and the calculation of the mole numbers of the corresponding reactants performed by measuring the measured peak value on the appropriate calibration curve was applied.

Before this determination, the acetonitrile was insoluble Components and therefore still remaining in the prepolymer Parts in DMF for analysis by gel permeation chromatography diluted, which showed no peak that the presence of unreacted reactants is indicated and therefore confirmed that unreacted reactants completely dissolved in and from acetonitrile had been extracted.

The prepolymer composition of the invention shows superior Adhesive forces on the substrate and an extraordinary Heat resistance. In contrast, were prepolymer compositions  according to the state of the art with the specific Component ratio not commercially available. Examination of commercially available prepolymers showed that these fewer components with a molecular weight contain between 400 and 15,000 and much more Components with a molecular weight of over 15,000, compared to the prepolymer composition according to the invention.

The prepolymer composition according to the invention can by Reaction of unsaturated bisimides with diamines in one polar diluent at a relatively low temperature below 95 ° C, preferably at a temperature between 60 and 90 ° C can be obtained. Procedure according to the State of the art for the production of polyimide prepolymers increase at elevated temperatures between 120 and 200 ° C in melt or solution normally as found the prepolymerization rate such that an excess of macromolecular components with a Molecular weight of over 15,000 was produced, though effectively reduced the amount of unreacted reactants has been. When trying the prepolymerization process to control such that the macromolecular components with a molecular weight of over 15,000 at one optimal ratio of between 3.5 and 6.8%, it was found that the prepolymerization reaction in the elevated temperature of 120 to 200 ° C to an insufficient Reaction process leads and consequently to an unnecessary higher amount of unreacted reactants that result in the Prepolymer composition remain. These Tendency that larger amounts of reactants remain unreacted, predominates when the prepolymerization reaction in the Melt is carried out at elevated temperature. Further leads to this prepolymerization reaction in the melt  an excess of macromolecular components with a Molecular weight over 15,000 and in addition to that unreacted reactants occur in excess, whereby an extreme shortage of molecular weight components results from between 400 and 5000 - these are, as already mentioned, the effective components for the Production of the prepregs and laminate end according to the invention Products.

The above prepolymerization reaction involving a solution a reduced temperature between 60 and 95 ° C for Preparation of the polyimide prepolymer according to the invention usually takes 2 to 10 hours, whereby the exact reaction time from the choice of the reactants, of the polar diluent, the concentration of the Solution and the reaction temperature is dependent and at certain conditions may differ from the above range.

The molar ratio of unsaturated bisimide to diamine in prepolymers according to the invention is preferred to between 1.7 and 2.5 set, given that, if it is below 1.7, macromolecular weight Components are manufactured in large quantities and at the same time the curing time is considerably reduced, so that handling or controlling the reaction process is difficult. If it is above 2.5, stay Reactants, especially unsaturated bisimide, unreacted and are in the resulting prepolymer composition Contained in larger amounts, which makes the unsaturated Bisimide during storage of the prepolymer solution Tends to fail. The above mole ratio was for the final solution of the prepolymer composition is determined, accordingly, both or each of the reactants can be used during the Prepolymerization process added at intervals  or it can be part of the same upon completion of the process, if necessary.

The new prepreg created according to the invention was created by Impregnate a suitable substrate with the solution of a polyimide produced by an addition reaction Prepolymer made in the above manner had been produced, followed by partial or Semi-curing the prepolymer as well as by evaporation of the solvent such that the resin content of the same between Is 18 and 28% of the unreacted reactants, 55 to 70% of the components having a molecular weight of own between 400 and 15,000 and 7 to 15% of the components have a molecular weight of over 15,000. The Prepreg with this specific component ratio can only from the above polyimide prepolymer composition are produced according to the invention and can be used alone successful shaping of certain laminate products ensure a low pressure level without Voids remain in the final laminate product. If the ratio of the unreacted reactants to less is reduced as 18% and that of components with a molecular weight between 400 and 15,000 70% exceeds and that of components with a molecular weight of more than 15,000 exceeds 15%, the latter macromolecular components are predominant, so that they Unnecessarily increase the viscosity of the resin, causing safe voids in the laminates when manufactured by a low pressure molding process arise. Among the above The subsequent curing for the conditions would Laminate manufacture completed in too short a time as that successful fabrication of laminates is larger Dimension would be possible. If the percentage is unconverted Reactants is above 28%, that of components with a  Molecular weight of between 400 and 15,000 under 55% and that of components with a molecular weight above 15,000 is less than 7%, a larger amount of resin emerged from the substrate in the subsequent molding process, resulting in severe thickness variance in the resulting Laminate leads, in addition, a larger remains Amount of solvent in the substrate, causing bubbles leads in the resulting laminates. The components with a molecular weight above 15,000 are preferred for the same reasons as for the prepolymer composition discussed, kept at a minimum.

As already mentioned, the prepolymers contain after State of the art larger quantities of components with one Molecular weight of over 15,000 than that of the invention Prepolymer composition and therefore cannot Deliver prepreg with the above component ratios, regardless of which curing conditions are selected.

The substrate that can be used to make the prepregs includes glass fabrics, inorganic fabrics such as quartz fibers and other heat-resistant fabrics such as Kevlar (trademark the DuPont for polyaramid fibers).

The above semi-hardening process for prepreg production can preferably at a temperature between 30 and 155 ° C be carried out at temperatures above 155 ° C the reaction is accelerated so that it is larger Amounts of unwanted macromolecular components produced and at a temperature below 130 ° C the prepreg can still be produced effectively. The laminate products are producible by making any number of such prepreg according to the invention  Layers of conductive layers made of metal foil, such as copper or nickel, followed by whole Hardening by exposure to heat and pressure. Because of the superior properties of the aforementioned prepregs, which is the production of laminate products with 50 × 50 cm² Size and even larger dimensions in the plane at one allows low pressure of less than 147.1 N / m² without that there are any voids in the final product this differs from the commercially available prepregs, a higher one to prevent cavitation Need pressure levels of over 392.3 N / m², the Laminate products produced according to the invention have a high Dimensional stability in addition to superior adhesive properties have, as with the invention above prepolymer composition. As a result can manufacture laminate products according to the invention of multilayer boards for printed circuits be suitable that a very compact circuit and module arrangement.

The following examples serve to explain the present invention.

example

Tables 1 and 2 include Examples 1 to 6, which representative of the compositions according to the invention are, as well as Comparative Examples 7 to 11, for comparison purposes are listed. In the comparative examples Examples 7 to 10 correspond to prepolymer compositions the above-mentioned US-PS 35 62 223 and that Example 11 shows a polyamide bismaleimide prepolymer commercially available type under the trademark Kelimid 601 distributed by Rhone Poulenc, France  becomes.

Table 1 follows:

In Examples 1, 36 and Comparative Examples 1-3, 5-10 each set of starting materials (weight in Grams) in Table 1 into a 3 liter four-necked flask Mixing introduced. After inserting a stirrer, Thermometer and cooling device in the flask was put through a side neck of nitrogen passed to the flask Thereby exchanging the atmosphere in the piston. Subsequently the mixture was placed in an oil bath on a table 1 listed temperature heated, and until the beginning Dissolution stirred. After stirring over one in Table 1 listed time, the resulting solution was in one Water bath cooled to room temperature in 15 minutes and provided a blackish-red prepolymer solution.

In Example 2, a total of 911 g bisimide in 2 Partial quantities added in the time interval. First, 828 g Bisimid used to implement a mixture like above, after which 83 g of the remaining bisimide at a temperature of 90 ° C until complete dissolution was added. The resulting product was then cooled to obtain a prepolymer solution.

In Comparative Example 4, N, N'-methylene-bis (N-phenyl maleimide) and 4,4'-diamino-diphenylmethane in the prescribed amounts evenly in portions within in a heated reaction vessel for one minute stainless steel introduced by an electrical Heating had been sufficiently heated. Then was the melted mixture stirred and 8 minutes at one Temperature maintained at 16 ° C. After that, the resulting Product in a thin layer on a steel plate spread out, which had been cooled sufficiently and gave a yellowish solid product. The product was grind with a mortar and then in a heated to 40 ° C  N-methylpyrrolidone dissolved, after which the solution Room temperature to obtain a dark red prepolymer solution was cooled.

In Comparative Example 11, the specified amount of kerimide 601, a polyamide bismaleimide prepolymer, in the specified Amount of N-methylparrolidone at a temperature of 50 ° C or below, obtaining a dark red prepolymer solution resolved.

Those according to Examples 1 to 6 above and Comparative Examples 1-11 prepared prepolymer solutions show analytically determined values, the component ratios and other specific properties as in Table 2 specified.

From the results given in Tables 1 and 2 it can be seen that the comparative examples 1 to 11 die Prepolymer solution with advantageous component ratios, as specific to the present invention are not able to hire, whereby it can be assumed that the reason for this is the incorrect combination of Reaction temperature and time is.

Table 2 follows:

Below are the ones using the above Prepolymer solutions available with reference to prepolymer solutions explained in Table 3.

Surface treated glass cloth with a specific gravity of 105 g / m² was impregnated with each of the prepolymer solutions of Examples 1 to 5 above and Comparative Examples 2 and 11. The resin-impregnated glass fabric was then partially hardened in a drying oven so that a prepreg with a resin content of 47 to 50% was obtained. The specific properties of each of the prepregs produced in this way are listed in Table 3, from which it can be seen that the prepreg according to the invention with a specific component ratio cannot be produced using the prepolymers of the comparative examples.

The following are the laminate products available from the above prepregs explained. Four square pieces of 12 × 12 cm² were at an angle of 45 ° to the glass fiber longitudinal direction from each prepreg of Examples 10 and 11 as well of Comparative Examples 2, 14 and 15 listed in Table 3, cut out and then between a pair of 1.6 mm thicker size plates stacked on top of each other and between this at a temperature of 165 ° C at a pressure of 981 kN / m² cured to a laminate over 10 minutes. The resin flowability of each of the so produced Laminates are listed in Table 4, the resin flowability the weight ratio (%) of resin poured out of the prepregs when hardening to weight of the prepregs before Indicates curing.

Table 4

As can be seen from the table, from the laminates of Examples 13, 14 and 15 claims that they are due to suitable resin flowability of the prepreg used have a suitable resin content, as well as a low one Dimensional variance related to their thickness, compared with the laminates of the comparative examples.

Table 5 below shows test results of laminates made from the prepregs prepared as above.

Manufacture of double-sided printed circuits

5 plates of 50 × 50 cm² square specimens were made each of the prepregs of Examples 7 to 11 and Comparative Examples 12 to 16 manufactured and superimposed, to form a core. The core was then with a pair of surface treated copper foils on both Sides between a pair of 1.6 mm thick finishing plates placed, heated to a temperature of 130 ° C and immediately then subjected to a pressure of 5 kg / cm² and 20 minutes kept under this condition.

Each laminate was then run for 90 minutes at one in Table 5 specified pressure heated to a temperature of 170 ° C. and then cooled to room temperature while the pressure was kept at the same pressure level a printed circuit with glued on both sides of the same To create copper foil. The resulting printed circuit became one 120-minute post-curing treatment at room temperature Subjected to 200 ° C and then by training conductive lines in the copper layer according to a known Etching process converted into a circuit and then examined for shape characteristics and cohesive forces, which is the force needed to around a layer of copper foil from the core through a vertical to create the surface of the Schicolie. The resulting one printed circuit was a 120 minute Post-curing treatment at a temperature of 200 ° C subjected and then conductive by training Lines in the copper layer using a known etching process converted into a circuit and then on Shape characteristics and cohesive forces examined, which is the force needed to around a layer of copper foil from the core through a vertical To release tensile force exerted on the surface of the layer: the results are shown in Table 5.

Production of a multilayer printed circuit

Square 25 × 25 cm² sample plates obtained from each of the prepregs were the same on both sides with copper foil Size (0.0305125 g / cm²) coated and under the same Conditions as above for using a first laminate  Copper foil coating processed.

Subsequently, index holes were made in every first laminate drilled approximately 200 mm in one direction and accurate distance measurements between the index holes taken. After that, the copper foil was on both sides the first laminate with a known etching process removed and two-layer prepregs of the same type and Dimension placed on each surface of the first laminate, a 0.0305 g / cm² copper foil being the same Size was applied. The resulting laminate was under a pressure of 3923 kN / m² and a temperature of Cured at 170 ° C for 90 minutes, followed by post-curing at a temperature of 200 ° C for 120 minutes to a final laminate product with copper coating on both sides to obtain. After that, the outer copper foil layer or the newly applied layer mechanically at the points removed the index holes in the original Copper foil correspond to turn the exact distance between the index holes after the laminate product has been formed to eat. The measurement result of the end products was compared with the corresponding measurement results that were previously with compared to the first laminate the dimensional variance of the product before and after insertion to assess additional conductive layers, whereby the result is shown in Table 5.

From Table 5 it can be seen that Examples 16 to 20, which use the prepreg according to the invention and at molded a lower pressure, a higher cohesion than the comparative examples and also have one smaller dimensional variance show what surely the Requirements for multilayer printed circuits corresponds.  

It is noteworthy that, although the invention Prepolymer composition especially for manufacturing of laminate products are suitable, of course also as Molding material used in other electrical applications can be; for example, the prepolymer, provided with suitable filling material, serve semiconductors to seal, supports for high electrical modules mechanical resistance and superior elasticity to form chips on their mounting base too glue and around pastes for the manufacture of circuits to fabricate. When using the method according to the invention can the products available from this with a remarkable resilience and high Cohesiveness with good elastic Behavior.

Claims (5)

1. Method for producing a prepreg with the following steps:
Precondensation of N, N'-bis-imides of unsaturated dicarboxylic acids of the general formula where D is a divalent organic radical which contains a CC double bond and A is a divalent organic radical with at least two carbon atoms, with diamines of the general formula: H₂N-B-NH₂, where B is a divalent organic radical with no more than 30 carbon atoms, and the molar ratio of bisimide to diamine is between 1.2 and 50, in a solvent, applying the solution to a substrate, and partially curing the resinous substrate; characterized in that the partial curing is carried out such that the resin thereafter has 18 to 28% unreacted reactants, 55 to 70% components with a molecular weight between 400 and 15,000 and 7 to 10% components with a molecular weight over 15,000. 2. The method according to claim 1, characterized in that that the molar ratio of unreacted bis-imide to not reacted diamine is between 1.7 and 3.0. 3. The method according to any one of claims 1 or 2, characterized in that the partial curing of the prepreg at a temperature below 95 ° C, preferred between 60 and 90 ° C, is carried out. 4. Prepreg, producible according to one of the preceding Expectations. 5. Use of a prepreg according to claim 4 for Production of a laminate by superimposing one predetermined number of prepregs. Hang up (one) Metal foil (s) on one or both exposed sides of the Stack of prepregs and cure the laminate by applying of increased temperature and pressure.