CS231896B1 - Laminated dielectric and method of its production - Google Patents

Description

BACKGROUND OF THE INVENTION The present invention relates to a laminated dielectric having ultrasonic or thermal energy-initiating adhesive properties, in particular for the production of printed wires. The invention further relates to a process for the manufacture of this layered dielectric.

Nowadays, so-called printed wires are increasingly used in interconnection technologies for electrical engineering. The essence of this progressive technology, unlike conventional printed circuit boards, is to create a signal conductive network on the motherboard from insulated conductors.

PCB technology is developed in several versions that differ from each other by connecting the wire to the terminal point. This connection can be provided by chemical forging, feeding the conductor to the terminal point or by gas-tight contact between the conductor and the terminal point.

For all versions of PCB technology, however, the problem of the wire motif remains a problem, both during its coordinate placement and during other PCB manufacturing operations, as well as on the finished product during its use.

This problem is of particular importance, especially in more demanding applications where a precise geometrical arrangement of the wire motif is required. Obviously, the fixation of PCB wires cannot be successfully ensured by the use of conventional PCB materials.

For this reason, a number of adhesives have recently been developed, some of which, due to their properties, are prerequisites for a very good solution to the problem of fixing the wire motif.

In particular, they are structurally rigid thermosetting adhesives with adhesive properties initiated by ultrasonic and / or thermal energy, synthesized by the reaction of a mixture of butadiene-acrylonitrile rubber carrying on its chain a reactive epoxy group, an epoxy resin, especially the palm type, and a suitable crosslinking agent.

However, the formulation of a suitable adhesive is only a partial solution to the entire problem of fixation.

In order for the above-mentioned adhesive mass to successfully fulfill its fixation function at all stages of production, even for a printed circuit board, it must be part of the self-supporting laminated material either in the form of an endless belt or laminate sheets. also in terms of dimensional stability in the assembled PCB.

Taking all these requirements into account, it can be said that the material that would simultaneously meet them is not yet known.

The layered dielectric with the adhesive properties initiated by the ultrasonic and / or thermal energy according to the invention contributes greatly to eliminating this drawback. This layered dielectric consists of a glass fabric which is impregnated with 5-15% by weight of epoxy resin (based on the original weight of the fabric) and further coated with a thermosetting adhesive on both sides.

The coating is asymmetrical - the face layer has a thickness of 0.10 - 0.25 mm, the backing layer is 0.03 - 0.15 mm. In addition, the facing layer is covered with a protective separating polyolefin film. In particular, the thermosetting adhesive is based on an acid-base catalyst catalyzed reaction product of a mixture of 10-90% by weight of butadiene-acrylonitrile rubber with an acrylonitrile content of 24-34% by weight carrying reactive epoxy functionalities on its chain and 90-10% by weight epoxy resin. especially of the palm type, preferably of an epoxy equivalent of 190-960, and a crosslinking agent, in particular based on polycarboxylic anhydrides.

The epoxidized butadiene-acrylonitrile rubber can furthermore be replaced up to 50% by weight in the reaction mixture described with a rubber based on polybutadlene or a butadiene-acrylonitrile copolymer which carries other reactive functional groups such as carboxyl on its chain and preferably has a weight average molecular weight range ΙΟ ³ - 10 ⁶ .

This thermosetting adhesive is further specified in terms of its adhesive properties for a period of 0.5-5 minutes at 170 ° C.

The essence of the process for the production of a layered dielectric according to the invention is to apply a 0.3-0.6 mm thick layer of thermosetting adhesive on a temporary separating substrate which is dried and precured at temperatures of 80 - 150 ° C for 4-9 minutes. .

A glass fabric which has been treated by epoxy resin impregnation followed by drying and pre-curing is laminated to the treated deposit by pressure and temperature.

Thereafter, the entire preform is laminated under pressure and temperature with the textile side into the backing of a thermosetting adhesive, applied at a thickness of 0.1-0.35 mra on a temporary release liner, dried and precured at temperatures of 80-150 ° C for 2-6 minutes.

The resulting formation is cooled and, after separating the temporary release liner with a facing layer, immediately laminating the protective polyolefin release liner therein and dseparating the temporary backing release liner is wound into a wrap.

Preferably, a temporary release liner is a silicone-coated polyester film or a silicone-coated release liner or polypropylene.

The main benefit of the laminated dielectric according to the invention is that, with the very good adhesive layer properties that determine its suitability for ultrasonic tool laying of insulated conductors, the above-specified multilayer construction also ensures optimal compliance with the requirements imposed on it during all handling operations during assembly PCB, as well as in finished product applications.

This essentially solves all the problems associated with the practical use of the previously formulated thermosetting adhesive in assembling printed wires.

From the foregoing, it is apparent that the essential properties of the layered dielectric according to the invention are the properties of the thermosetting adhesive layer. In this regard, it should be emphasized that the properties suitable for wire-laying conductor technology are more closely characterized by the adhesion of the surface of the dielectric adhesive layer lasting at a contact temperature of 170 ° C for 0.5-5 minutes.

That is, if the adhesive layer loses its tackiness in less than 0.5 minutes, it is too rigid and therefore unsuitable for precise wire placement. If, on the other hand, the adhesion of the surface of the adhesive layer lasts longer than 5 minutes, the adhesive is too soft and does not allow sufficient fixation of the conductors to be laid.

» _Z

The use of an impregnated glass fabric is necessary to achieve satisfactory electrical properties of the assembled printed circuit board. Indeed, impregnating the fabric with a pre-cured epoxy resin solution ensures uniform bonding of the individual fibers of the fabric with the binder so that the thermosetting adhesive itself is perfectly bonded to the adhesive, resulting in a higher insulation resistance.

Also the asymmetric coating of the impregnated glass fabric with a layer of thermosetting adhesive is necessary. This is because the thinner backing ensures good adhesion of the layered dielectric to the copper-clad base laminate, the larger thickness of the facing then serves, as already mentioned, for laying and fixing the conductors.

Its thickness can be selected in the above range according to the type of conductors used.

During the preparatory manipulation operations - rewinding, trimming, punching, lamination, the facing layer of the thermosetting adhesive is protected by a polyolefin-based release foil, which is removed immediately before the conductors are laid.

The following examples serve to illustrate the invention in greater detail, of which 1-4 describe various variants of the laminated dielectric according to the invention together with methods for their production, and 5. a process for assembling a printed circuit board using the laminated dielectric according to the invention.

He did

The glass fabric impregnation composition was prepared from the following components:

Dianbisglycidyl ether having an epoxy equivalent of 190-200 (e.g. epoxy resin CHS Epoxy 15, producer Association for Chemical and Metallurgical Production / 540 g

Phthalic anhydride 270 g

Toluene 1,620 g

Acetone 1,620 g

Triethanolamine 0,3 g

The preparation was carried out by placing the following components in a 6 L glass kettle equipped with a stirrer, reflux condenser, thermometer, and dosing tube: 540 g epoxy resin, 270 g phthalic anhydride and 270 g toluene.

The reactor contents were heated with stirring to 120 ° C and then 0.3 g of triethanolamine was added. This was followed by a 30 minute precondensation stage while maintaining the temperature at 120 ° C.

After cooling the mixture to 80 ° C, the remaining amount of toluene and 1620 g of acetone were added and homogenized with stirring until it cooled to room temperature.

The glass fabric was then impregnated with a silanized surface 2 of 0.11 kg / m @ 2. The impregnation was performed by immersing the glass fabric in the impregnation mixture, followed by squeezing between the squeezing rolls, evaporation of the solvents and precuring the epoxy adduct in a tunnel dryer at temperatures of 60-90 ° C for 6 minutes.

The impregnated glass fabric, containing 13 g / m ² , i.e. 11.8% of its initial weight, of the precured epoxy adduct was then used to prepare a layered dielectric.

The thermosetting adhesive was prepared from the following mixture:

High molecular weight butadiene-acrylonitrile copolymer rubber containing, in 100 g, 0.07 carboxyl equivalent (type Hycar 1,472 from Goodrich)

500 g

Dianbisglycidyl ether having an epoxy equivalent of 190-200 (e.g. epoxy resin CHS Epoxy 15, producer Association for Chemical and Pharmaceutical Production / 1 OOO g

Phthalic anhydride 500 g

Triethanolamine 1 g

Methyl ethyl ketone 1300 sU.

Toluene 120 ml

Zirconium silicate 700 g

Silicic acid HDK 200, by Hacker 40 g

The preparation was carried out by pre-preparing a solution of the rubber component in methyl ethyl ketone in a 6 L glass kettle equipped with a stirrer, reflux condenser and thermometer and then adding a precondensate separately prepared by reacting 25% of the total amount of epoxy resin with suspended fillers and phthalic anhydride. , polycondensed in toluene with catalysis of triethanolamine at 120 ° C for 90 minutes.

The reactor temperature was then adjusted to 80 ° C and the mixture was maintained at this temperature with stirring for 3.5 hours. A precondensate, separately prepared by reacting the remaining amount, i.e. 75% epoxy resin with suspended fillers and phthalic anhydride, polycondensed in toluene under catalysis of triethanolamine at 120 ° C for 30 minutes was then carefully added to the reactor.

Finally, the mixture in the reactor was homogenized with vigorous stirring until cooling to room temperature.

The layered dielectric with adhesive properties of the invention was prepared as follows:

A silanized surface polyester film (Hostaphan HNTT 50 from Kalle) was coated with a 0.45 mm thick, thermosetting adhesive which was dried and precured in a tunnel dryer at temperatures of 80, 100, 130, 140 ° C. for 7 minutes.

An impregnated glass fabric was then laminated to the dried and precured deposit at 65 ° C under pressure of the pressure lamination roll and the obtained blank was wound into a wrap.

In another operation, a 0.25 mm thick thermosetting adhesive was applied to the silanized surface polyester film (Hostaphan HNTT 50), which was also dried and precured in a tunnel dryer at temperatures of 80, 100, 130, 140 ° C. for 5 minutes.

The blank obtained in the previous operation was laminated to the deposit at a temperature of 70 ° C under the pressure of the pressure laminating roller by the textile side into the deposit. ^x

After cooling, the polyester foil was separated from the face side and immediately thereafter a polyethylene foil having a thickness of 40 µm was laminated into the face layer at 65 ° C by pressure of a laminating roll.

After cooling again, the polyester foil was separated from the reverse side and the obtained material was wound into a wrap.

In this way, a layered dielectric was obtained with a face side covered with a protective release film having the following parameters:

Thickness of the reverse layer Thickness of the reverse layer Surface adhesion at 170 ° C Volatile content

190 fm 80 <om for 2 minutes 1.5 »

Example 2

The glass fabric impregnation mixture was prepared as in Example 1 and then additionally diluted with a 1: 1 mixture of toluene and acetone to 10% solids content.

Using this diluted mixture, the glass fabric was impregnated according to Example 2 to obtain an impregnated glass fabric containing 6 g / m, i.e. 5.5% of its initial weight, of a pre-cured epoxy adduct, which was then used to prepare the laminate. dielectrics.

The thermosetting adhesive was prepared as described in Example 1 from the following mixture:

High molecular weight butadiene-acrylonitrile copolymer rubber containing, in 100 g, 0.07 carboxylic equivalents (Hycar type 1,472 by Goodrich) / 500 g

Low molecular weight polybutadiene rubber terminated with carboxyl groups / type Hycar CTB 2 000 X 162, by Goodrich / 100 g

Epoxy resin - unmodified dian type of mol. weight 910-1 050 / CHS Epoxy 1/16, producer Association for Chemical and Metallurgical Production / 1 090 g

Phthalic anhydride 110 g

Triethanolamine 1 g

Methyl ethyl ketone 1300 ml

Toluene 120 ml

Titanium white / type RKB 2, Bayer / 450 g

The layered dielectric having the adhesive properties of the invention was then prepared as follows:

Silicone-coated release paper (Multicast 449 from Wiggins) was coated with a 0.3 mm thick thermosetting adhesive, dried and precured in a tunnel dryer at temperatures of 90, 100, 140, 150 ° C for 5 hours. minutes.

The impregnated glass fabric was then laminated into the dried and precured coating and wound into the wrapping. In a further operation, a backing of 0.15 mm thick thermosetting adhesive was applied to the silicone-coated release paper / Multicast 449 /, which was also dried and precured at temperatures in each of the sections 90,

100, 140, 150 ° C for 3 minutes.

The blank obtained in the previous operation was laminated to the deposit at a temperature of the backing roll of 90 [deg.] C. by pressing the pressure laminating roller with the textile side into the deposit.

After cooling, the release paper was separated from the face side and immediately thereafter a 30 .mu.m thick polypropylene film was laminated into the face layer at 65 [deg.] C. by pressing a laminating roller.

After cooling again, the release paper was separated from the reverse side and the obtained material was wound into a wrap.

In this way, a layered dielectric having a face-side covered with a protective release film having the following parameters was obtained:

Thickness of the reverse layer Thickness of the reverse layer Surface adhesion at 170 Volatile content

130 µm 50 (wt for 3 minutes 2.0%

Example 3

The glass fabric was impregnated as in Example 1. A thermosetting adhesive was also prepared by the same procedure as in Example 1 from the following mixture:

high molecular weight butadiene-acrylonitrile copolymer rubber containing, in 100 g, 0.07 carboxyl equivalent (type Hycar 1,472, Goodrich) / 660 g

Dianbisglycidylether with an epoxy equivalent of 455-525 (e.g. epoxy resin

CHS Epoxy 1/33, producer Association for chemical and metallurgical production / 600 g

Phthalic anhydride 120 g

Triethanolamine 0,5 g

Methyl ethyl ketone 2120 ml

Toluene 120 ml

Titanium white / type RKB 2, by Bayer / 140 g

The layered dielectric having the adhesive properties of the invention was then prepared according to the procedure of Example 2 using a polypropylene surface separation paper. In this way, a layered dielectric having a face-side covered with a protective release film having the following parameters was obtained:

Thickness of the reverse layer Thickness of the reverse layer Surface tack at 170 ° C Volatile matter content

130 µm 50 µm for 3.5 minutes 2.3%

Example 4

The glass fabric was impregnated as in Example 1. A thermosetting adhesive was also prepared by the same procedure as in Example 1 from the following mixture:

High molecular weight butadiene-acrylonitrile copolymer rubber, containing in 100 g 0.07 carboxyl equivalent (type Hycar 1,472 from Goodrich)

880 g

231896 8

Diapbisglycidyl ether of epoxy equivalent weight 910-1 050 / e.g. epoxy resin CHS Epoxy 1/16, producer Association for chemical and metallurgical production / 200 g

Phthalic anhydride 20 g

Triethanolamine 0,2 g

Methyl ethyl ketone 2800 ml

Toluene 60 ml

Zirconium silicate 100 g

Silicic acid gel / type HDK 200 from Wacker / 20 g

The layered adhesive dielectric according to the invention was prepared according to the procedure of Example 1 and had the following parameters:

Thickness of the reverse layer Thickness of the reverse layer Surface adhesion at 170 ° C Volatile content

200 (tons 85 (um for 2.5 minutes 1.8%)

Example 5

The base laminate (1 mm thick double-sided clad with 35 tons of SEC-type copper foil, manufactured by Gumon Bratislava) with etched conductive motif for grounding was coated on both sides with a layered dielectric prepared according to Example 1 or 2.

This operation was performed on the laminator under pressure and temperature. A copper wire motif of 100 or 160 µm diameter with a double insulation based on polyimidester was then placed on the preform prepared by means of an ultrasonic tool.

After the mutual overlap of the blank wire of the printed circuit connections two milliamperes adhesive sheet / thickness of 0.1 mm, the SEC / L Bratislava Gumon manufacturer and / dielectric laminate according to Example 3 or 4 was laminated in this packet press under conditions dvoutlakového mode with the following parameters T ₃ = 13 ° C, ρ Ο Ο, Ι MPa, txx10 min and T ₂ = 170 ° C, p ₂ s = J, 2 MPa at a 50 min.

After completion of the lamination cycle, the board was cooled, followed by its coordinate drilling with carbide drills with a diameter of 0.8-1.3 mm with regard to its fitting with electronic components and their interconnection.

The plate thus prepared was activated for chemical plating with a 700 g CrOg / l solution of chromosulphuric acid. 10 ml H ₂ SO _4/1 for 10 minutes at 25 ° C. After rinsing and neutralizing the hexavalent chromium residues, the plate surface, including the holes, was copper-plated to a thickness of 1 mm using a chemical copper treatment process, which is commercially available · (manufactured by Lachema Brno).

The blank prepared in this way was processed by conventional technology for the production of double-layer printed circuits with forged holes into the resulting printed circuit board.

The layered dielectric according to the invention has applications both as a base material for printed wires and in the plastics industry, taking advantage of the above properties.

Claims (3)

Laminated dielectric with ultrasonic and / or thermal energy-initiating adhesive properties, in particular for the production of printed wires, characterized in that it consists of a glass fabric impregnated with 5 to 15% by weight of epoxy resin, based on the original weight of the fabric, and backed a layer of 0.03 to 0.15 mm thickness and a face layer of 0.10 to 0.25 mm thickness of a thermosetting adhesive, in particular based on an acid-base catalyst catalyzed reaction product of a blend of 10 to 90 wt.% butadiene-acrylonitrile rubber with an acrylonitrile content of 24 to 34 wt. %, which carries reactive epoxy functional groups on its chain, alone or in combination with up to 50% by weight of polybutadiene or butadiene-acrylonitrile rubber, preferably having a weight average molecular weight in the range 10 ³ to 10 ®, to which other reactive chains are attached Functional group other than epoxy, e.g., carboxyl, and 90 to 10% by weight of an epoxy resin, in particular of the palm type, preferably of an epoxy equivalent of 190 to 960, and a crosslinking agent, in particular based on polycarboxylic anhydrides, the facing layer of the thermosetting adhesive; which is preferably specified in more detail by the surface tack of 170 ° C for 0.5 to 5 minutes, is covered with a protective polyolefin release film. 2. A method according to claim 1, characterized in that a temporary deposit of a thermosetting adhesive is applied to a temporary separating substrate in a thickness of 0.3 to 0.6 mm, after which it is dried and precured at temperatures of 80 to 150 ° C. For 4 to 9 minutes, the glass fabric laminated by epoxy resin impregnation followed by drying and pre-curing is laminated under pressure and temperature, and then the laminate 2a is laminated under pressure and temperature with a textile side to the backing of the thermosetting adhesive 0.1 to 0.35 mm thick on a temporary release liner, dried and pre-cured at 80 to 150 ° C for 2 to 6 minutes, cooled and after separation of the temporary release liner from the face deposit by immediate lamination of the protective polyolefin release liner foil into it and separating it The backing pads are wound into the wrapping. 3. Method according to claim 2, characterized in that a silicone-coated polyester foil or a silicone-coated release liner or polypropylene is used as a temporary release liner.