LU87069A1 - SOLUBLE TAPE AND SOLUBLE FILM - Google Patents

Description

v ^ -3-20 ·; 8 * 1 Ύ \ P ~ Ù «jR- ^ N '.’.- rVTHF. DE LUXEMBOURG / V W ï - · 'Monsieur le Ministre ciu IC âécembre 1987, 2 ^ -5. de l'Economie et de * Classes Moyennes

Titre délivré, Service de la Propriété Intellectuelle

____! —LUXEMBOURG

Demande de Brevet d’invention I. Requête

Waterford Research S Development Limited., ....... Cork ...... Road, Water-. 2l ford, Irlande / représentée parMonsieur Jean Waxweiler, 55 rue · des Bruyères, Howald, agissant en qualité de mandataire Λ dépose! nti ce dix décembre mil .neuf, cent quatre-vingt-sept t à 15.0 0 heures, au Ministère de l'Économie et des Classes Moyennes, à Luxembourg: 1. la présente requête pour l'obtention d'un brevet d 'invention concernant: soluble tape and more soluble. Movie...... ............................... ............ .. s 5- 2. la description en langue allemande de l'invention en trois exemplaires: 3. / planches de dessin, en trois exemplaires: 4. la quittance des taxes versées au Bureau de l'Enregistrement à Luxembourg, le 1.0 » .12 .1987 5. la délégation de pouvoir, datée de Waterford ......................] e 27 .11.1987 6.le document d'avant cause ( authorization): déclarant) en assumant la responsabilité de cette déclaration, que l '(es) inventeurs) est (sont ι it> -

Lutz R. Weinhold, Ballyscanlon, ...... Fenor-Tramore, Co. Waterford,

Irlandeet John ...... Desmond McDonough, Knoçkavon, Dunmore Road,

Waterford, Irlande revendique! Nti pour la susdite demande de brevet la priorité d'une (des) demande! S) de ι brevet ............ déposée! s) en (8) Irlande le (9j 21 may 1987 sous le N "(10) 1336/87 ..... ...............

au nom de (il i Waterford Research & Development Limited élit! élisent) domicile pour lui (elle) et. si désigné, pour son mandataire, à Luxembourg ............

55 rue des Bruyères, Howald ................... (r.

sollicite (nt) la délivrance d'un brevet d'invention pour l’objet décrit et représenté dans les annexes susmentionnées, avec ajournement de cette délivrance% ’Λ _ .... / J ^ mois. * 13

Leld ^ oXKK mandataire: V ...................

II. Procès-verbal de Dépôt

The susdite demande de brevet d'invention a été déposée au Ministère de l'Écononut et des Ciasses Moyennes.

Service de la Propriété Intelleçpféïïe ^ CuSembourg. en date du: 10.12.1987 / y * '5 jf ^ ^ ^ C - Pr. le Ministre de l’Économie et des Classes Moyennes.

*. at 15.00 heures g | 5 _ï \ p. d.

U. U ,. '·; £ ·' Le chef du service de la propriété intellectuelle.

J ^ _ / LXPU '^ TIONS RELATIVES, AL FORN11XAIRi5l5c? Îm ~ ”J ps'u N üiitib''Demanat; dcceniiicaîdiidomonaubiçve: pnr »cipu: au denianor üc Dreve! rniicipa) V .......... du ...... ~ -'2 nsa-ur jê «· nr.rr pr-n.trr.

.idfUsve you öt’ITlundeur. iCrsque c £ iü.! - V ’es * Ui> particulier ou les, denommaîion sociale. forms lurjdiuut ;. address dusiepesociéî. lorsque le demandeur est une ρϊγμήιη mora. -? ir-.r. * ··

j PRIORITY STRESS

the patent application (η Ireland

From May 21, 1987 under No. 1336/87

DESCRIPTION

ON A PATENTED IDENTIFICATION IN

GRAND DUCHY OF LUXEMBOURG

WATERPORD RESEARCH & DEVELOPMENT LIMITED

Cork Road

Waterford

Ireland Soluble Tape and Soluble Film - 1-5 The invention relates to pressure sensitive adhesive tapes, films used in such tapes and the use of the tapes to cover selected areas of an object during high temperature treatment, particularly to cover selected areas of electronic components such as printed circuit boards during soldering -10 operations.

Certain zones of printed circuit boards, such as contact fingers, must be covered during the soldering operations (e.g. wave soldering or leveling under hot air) so that no solder metal 15 can penetrate the covered zones. This makes it necessary to cover the selected zones with a material that withstands the temperature of the soldering process, which in the case of wave soldering is in the range of 240 to 260 ° C., for a treatment time of 1 to 25 seconds. During this * 20 treatment, the masking material must not lift off the plate or shrink in any way, and it must form a complete barrier against the penetration of solder metal into the * covered areas. The masking material must be easily removable after the soldering process has been completed.

25th

Currently, this masking is mostly achieved using self-adhesive tapes based on high-temperature-resistant polyimide films or paper. These strips are removed from the circuit board after the soldering process. Apart from the work necessary for this removal, problems arise in the form of adhesive residues on the printed circuit board after the tape has been removed.

It is known to wash circuit boards after soldering 35 to remove flux residues. In certain cases water was used for this purpose. A water soluble 1. ' -2-.

* Tape for covering selected areas of circuit boards is commercially available. This tape is released from the circuit board during the washing process. However, washing with water is not considered sufficient on all sides to make a circuit board electronically "clean" - and adhesive residues can also remain. The use of fluorocarbon solvents, especially those based on trichlorotrifluoroethane, is preferred for this purpose. The washing can expediently be carried out in an ultrasonic bath filled with the solvent, followed by rinsing in the vapor of the solvent, or with the aid of a spray system in which the solvent is sprayed onto the printed circuit board in jets.

15

The applicants have now found a covering material which can be used effectively to cover selected zones of printed circuit boards during the soldering process, but which is completely dissolved by a fluorocarbon solvent during a washing process, as a result of which a special step for removing the tape is omitted and the problem of adhesive residue does not arise. Such a covering material can also be used in other applications

Areas in addition to the production of printed circuit boards when a cover is necessary during a high-temperature operation.

The present invention provides a pressure sensitive adhesive tape comprising a polymer film coated with a pressure sensitive adhesive, the film

qO

and the adhesive is resistant to temperatures up to 250 ° C for up to 5 seconds and both are soluble in a fluorocarbon solvent. The term "fluorocarbon solvent" used in this specification means a solvent q K ** which contains at least 50% by weight of a fluorocarbon. Preferably, the film and adhesive are resistant.

J * * resistant to temperatures up to 260 ° C for up to 25 seconds.

According to a further aspect, the present invention provides a pressure-sensitive adhesive tape which has a film made of polymethacrylate with the exception of polymethyl methacrylate, ethyl cellulose or polyvinylpyrrolidone, which is coated with a pressure-sensitive adhesive. The pressure sensitive adhesive is preferably one based on a polyacrylate.

10th

According to a further aspect, the present invention provides a self-supporting film avis polymethacrylate made from genonine polymethyl rethacrylate, ethyl cellulose or polyvinyl pyrrolidone. The term "self-supporting film" used in this specification means a film which can be pulled off a base and rolled up into a film roll without losing its integrity.

In another aspect, the present nn

Invention a covering material for electronic components

Available, which has a polymer material, which in one

Fluorocarbon solvent is soluble and resistant to temperatures up to 250 ° C for up to 5 seconds, the cover material being in the form of a continuous roll of tape, molded pieces, or a solution or dispersion. In the case of molded pieces, the pieces of polymeric material can conveniently be placed on a tape or laminate, e.g. made of a separating material. Preferably, the polymeric material is resistant to temperatures up to 260 ° C for up to 25 seconds.

In an additional aspect, the present invention provides a method for covering selected 35 zones of an electronic component, such as e.g. a circuit board during a high temperature operation, e.g. Soldering. The method includes applying the -4-.

1 cover material on the selected zone as defined above, performing the high temperature operation and washing the component in a fluorocarbon solvent that dissolves the cover material. The covering material 5 can expediently be applied in the form of a pressure-sensitive adhesive tape or shaped pieces, or it can be applied directly to the selected zones of the electronic component, e.g. by screen printing / brought.

10 The polymer film is preferably cast from a solution or dispersion of the polymer. However, an extruded film of the polymer can also be used. The polymer material is preferably cast onto a carrier, such as a tape or a laminate, from a separating material.

15

Preferred materials for the polymer film are polymethacrylate with the exception of polymethyl methacrylate. The preferred polymers .thacrylates are polymers of butyl methacrylate, i-butyl methacrylate or copolymers thereof, with one another or with methylraethacrylate 20 or with a compatible further

Monomers, especially a plasticizing monomer, which is advantageously present in an amount of 0 to 30 percent by weight. Alternatively, or in addition, the poly-25 methyl acrylate can be plasticized by adding a soft acrylic polymer such as polybutyl acrylate in an amount up to 90 weight percent, preferably 50 weight percent, based on the polymethacrylic lat. In the case of an acrylic plasticizer, the most preferred range is up to 40 Ge-30% by weight, whereas for a non-acrylic plasticizer the preferred range is up to 20% by weight. Suitable polymethacrylates usually have a molecular weight in the range from 50,000 to 500,000 and are commercially available as a solid, solution or dispersion and are available from suppliers such as Roehm GmbH, E.I. du pont de

Nemours & Co. Inc. or Rohm & Haas Company. Although the polymer * -5-- 1 material can soften under the chosen high temperature conditions, it must not flow to any appreciable extent.

Other polymeric film materials that have the required combination of properties include ethyl cellulose and polyvinyl pyrrolidone with a molecular weight in the range of 50,000 to 500,000. PVC is commercially available under the trademark "Luviskol" from BASF or from GAF Corporation. Ethyl cellulose can be obtained from Hercules Corporation or from Dow Chemical Company.

The self-adhesive layer suitably contains a polyacrylate, such as butyl acrylate or a copolymer thereof, preferably with a molecular weight in the range from 400,000 15 to 3,000,000, which has been tackified with a suitable resin, such as an alkylphenol type, and which in an amount of 0 to 90 percent by weight, based on the polyacrylate, may be present. Other adhesive compositions which can withstand temperatures of 240 to 260 ° C (i.e., which retain their tack and remain thermoplastic at 20 such temperatures) and which are soluble in a selected fluorocarbon solvent can also be used. A rubber resin in the form of a solution or a latex or a silicone type 25 adhesive may e.g. be suitable.

A release material is usually attached to the self-adhesive layer. This release material may conveniently be a tape or a laminate, e.g. a silicone material, such as a siliconized film made of polyethylene terephthalate (P.E.T.P.) or siliconized paper, or it can also consist of a non-siliconized material. The release material can optionally be in the form of a solution or dispersion which is applied to the opposite side of the polymer film from the self-adhesive layer if the tape is to be brought into the form of a self-winding roll.

- 6 - 1 The masking material may be colored to make it visible on the electronic component. For example, a pigment or dye may be included in the polymer film material or in the adhesive. The covering material 5 can be transparent or opaque.

In the preferred embodiment of the invention, the polymer film is applied as a polymer solution to the release film or release paper made of siliconized P.E.T.P. or siliconized Pa-10 pier applied. The most preferred polymeric material is polybutyl methacrylate, which is plasticized with 0 to 50 weight percent polybutyl acrylate based on the methacrylate. Polybutyl methacrylate is a medium-hard polymer that gives a brittle, colorless film that is soluble in chlorinated hydrocarbons. Polybutyl acrylate is a soft polymer that gives the film flexibility and toughness, and is also soluble in chlorinated hydrocarbons. The preferred solvent is trichlorethylene. However, other organic solvents, especially other chlorinated hydrocarbons, such as methylene chloride, can also be used.

··

The cast film is expediently dried at 80 to 160 ° C. for 2 to 10 minutes. Film thicknesses of 0.005 mm to 25 0.250 mm are suitable, in particular those of 0.01 to 0.075 mm if the film is intended to cover printed circuit boards.

The self-adhesive layer can expediently be applied directly as a solution to the polymer film and dried for 3 to 5 minutes at about 120 ° C. Suitable layer thicknesses for the self-adhesive layer are in the range from 0.005 mm to 0.050 mm.

35 A protective layer of release material is applied to the adhesive layer and the release material onto which the polymer material - 7 - 1 was poured can be removed. During continuous coating on production lines, the polymer film can be cast onto a substrate that has two surfaces provided with release material (e.g. siliconized 5 PETP film on both sides), the release material also having a spool on the sticky one during the winding of the tape Surface is transferred and thus acts as a protective layer.

Preferred solvents for washing an article, such as a printed circuit board, and for releasing the adhesive tape of the present invention are solvents based on trichlorotrifluoroethane, as are commercially available under the trademark "FREON" from E.I. du Pont De Nemours Inc. or under the trademark "ARKLONE" from Imperial Chemical 15 Industries PLC. Such solvents contain mixtures of trichlorotrifluoroethane with up to 50% of another solvent, such as isopropanol, ethanol, methanol, methylene chloride, acetone and / or stabilizing agents and surfactants.

The object provided with the covering material is expediently washed in an ultrasound bath containing the fluorocarbon solvent for 2 to 4 minutes at a temperature of 33 to 38 ° C. After washing, the article is rinsed in the steam of the washing solution over a period of 30 seconds to 5 minutes. The washing process can optionally be effected by jet spraying with the fluorocarbon solvent. The washing process should result in a complete dissolution of the covering material by the washing solution, with no residue of the adhesive tape 30 (neither from the polymer film nor from the adhesive) remaining on the article.

The invention is illustrated by the following examples.

The polybutyl methacrylate used in Example 1 was the 35 resin available from Roehm GmbH under the trademark "PLEXIGUM P24", with a. Molecular weight from 100,000 - 81 to 200,000. Another suitable material is the resin available under the trademark "PLEXIGUM P675". Other suitable materials include resins under the trademark "ELVACITE" from E.I. du Pont de Nemours & Co. Inc. and 5 the trademark "ACRYLOID" from Rohm & Haas Company.

(

Example 1 A. Polymer Film 10 A solution was prepared from the following ingredients:

% By weight

Polybutyl methacrylate (powder) 35 15 Polybutyl acrylate (25 percent solution

Weight / weight in light petrol) 20

Trichlorethylene ^ 45 ’··

A clear, colorless film with a layer thickness of 0.03 mm was obtained by applying this solution to siliconized P.E.T.P.-20 release film and drying at 100 ° C. for 3 minutes. Samples of this film were made from the P.E.T.P. release film ».

removed and proved to be a self-supporting film that could be wound into a roll.

25 B. Adhesives

A solution was made as follows:

% By weight 30

Polybutyl acrylate (25% solution weight /

Weight in light petrol) 92

Tackifying alkylphenol resin (PA 103 from Hoechst AG) 8 35 - 9- · 1 By applying this solution to polymer film A and drying at 120 ° C for 3 minutes, a clear sticky surface was formed in a layer thickness of 0.010 mm.

5

A protective layer of siliconized P.E.T.P. film was applied to the adhesive layer and the P.E.T.P. to which the polymer film a was applied was removed.

Test procedure 10

Strips of the 19 mm wide tape prepared as above were applied to a clean, unsoldered circuit board. The plate was subjected to a wave bath soldering while being brought into direct contact with 15 molten solder metal at a temperature of 250 ° C. for 3 seconds. This process was immediately repeated with the same plate still carrying the same strip of tape.

20th

Within the zones covered with tape, no solder penetrated the board surface during soldering. No tape shrinkage occurred. The tape was still intact and had not lifted off the plate.

25th

The circuit board was immersed in an ultrasonic bath containing a mixture of 94.3% trichlorotrifluoroethane and 5.7% anhydrous methanol. The temperature of the solution was 33 ° C.

30th

After 3 minutes the plate was removed from the bath and rinsed in the steam of the same solution, which was at boiling temperature, i.e. 39 ° C. Rinsing time: 1 minute. The plate was removed and assessed.

35 Λ - lö - '1 results

No adhesive or film residue remained on the plate. A complete solution of the tape had taken place 5 and there were no tape residues in the bath solution.

Example 2

A polymer film formulation was prepared as follows: 10

% By weight

Polyvinylpyrrolidone 40 (GAF Corporation, New York)

Polyethylene glycol 300 4 15 methanol 56

This formulation was poured onto siliconized P.E.T.P. film and dried at 100 ° C for 3 minutes. A clear self-supporting film with a layer thickness of 0.03 mm 20 was obtained.

The film was coated with a self-adhesive layer as described in Example 1 and applied in the form of a tape to a printed circuit board. The tape was successfully tested for heat resistance in an oven at 250 ° C for 2 minutes. Solubility was tested in a bath of 94.3% trichlorotrifluoroethane and 5.7% anhydrous methanol.

The tape came off completely in less than 2 minutes.

These tests demonstrate the usefulness of the tape as a covering material according to the invention.

Example 3

Example 2 was repeated with a formulation consisting of 35 consisting of a 15 percent solution (weight / weight) of ethyl cellulose (available from. Dow Chemical Company under the trade name "ETHOCEL") in trichlorethylene. A self-supporting film was again obtained. The film was coated with a self-adhesive layer as described in Example 1 and applied to a printed circuit board in the form of a tape. This tape behaved satisfactorily in the tests described in Example 2 and thus proved to be useful for use as a masking material in accordance with the invention.

Example 4 10 Example 1 was repeated using fine-grained acrylic resin from Roehm GmbH, known under the trademark PLEXIGUM P675: this is a polybutyl methacrylate resin with a molecular weight in the range from 100,000-200,000.

The following proportions were used in making the polymeric film.

Parts by weight of PLEXIGUM P675 (powder) 30 ~

Polybutyl acrylate (25% solution

Weight / weight in light petrol) 25 20 dye 0.15

Trichlorethylene 44.85

The resulting film contained 17.2% plasticizer. A tape was made as in Example 1 and passed the tests described in Example 2 satisfactorily.

25 30 35

Claims (10)

1. Pressure-sensitive adhesive tape, comprising a polymer film coated with a pressure-sensitive adhesive, characterized in that the film and the adhesive are resistant to temperatures up to 250 ° C for a period of up to 5 seconds and both are soluble in a fluorocarbon solvent . 2. Adhesive tape according to claim 1, characterized in that the film and the adhesive are resistant to temperatures up to 260 ° C for a period up to 25 seconds. 3. Adhesive tape according to claims 1 or 2, characterized in that the polymer film contains polymethycrylate except polymethyl methacrylate, ethyl cellulose or polyvinylpyrrot- rr ee lidon. <* 4. Adhesive tape according to one of claims 1 to 3, characterized in that the pressure-sensitive adhesive is a polyacrylate. - 13 - 5. Adhesive tape according to claim 3, characterized in that the polymer film contains a polymethacrylate which is selected from the polymers of butyl methacrylate or i-butyl methacrylate or their copolymers with one another or with another compatible monomer. io 6. Adhesive tape according to one of claims 1 to 5, characterized by a protective layer applied to the adhesive layer from a release material. 7. covering material for electronic components, characterized in that it contains a polymeric material which is soluble in a fluorocarbon solvent and is resistant to temperatures up to 250 ° C for a period of up to 5 seconds and the said Cover material in the form of a) a continuous roll of tape, b) shaped pieces or * c) a solution or dispersion. 25th 8. Covering material according to claim 7, characterized in that the shaped pieces are applied to a base made of separating material. 9. A method for covering a selected zone of an electronic component during a high-temperature operation, comprising applying the masking material to the selected zone of the electronic component, performing the high-temperature operation and subsequent washing of the component, characterized in that one The covering material used in claim 7 is used as covering material, and the washing process is carried out with a fluorocarbon solvent which dissolves the covering material. 10. Self-supporting film made of polymethacrylate with the exception of polymethyl methacrylate, ethyl cellulose or polyvinyl pyrrolidone. 10 15 20 25 30 35