CA1152226A - Process for the manufacture of printed circuits - Google Patents
Process for the manufacture of printed circuitsInfo
- Publication number
- CA1152226A CA1152226A CA000357874A CA357874A CA1152226A CA 1152226 A CA1152226 A CA 1152226A CA 000357874 A CA000357874 A CA 000357874A CA 357874 A CA357874 A CA 357874A CA 1152226 A CA1152226 A CA 1152226A
- Authority
- CA
- Canada
- Prior art keywords
- copper
- process according
- boreholes
- bath
- chemical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims abstract description 46
- 230000008569 process Effects 0.000 title claims abstract description 42
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 41
- 229910052802 copper Inorganic materials 0.000 claims abstract description 41
- 239000010949 copper Substances 0.000 claims abstract description 41
- 239000000126 substance Substances 0.000 claims abstract description 23
- 239000004020 conductor Substances 0.000 claims abstract description 18
- 230000009471 action Effects 0.000 claims abstract description 17
- 239000000758 substrate Substances 0.000 claims abstract description 17
- 239000004922 lacquer Substances 0.000 claims abstract description 15
- 239000000463 material Substances 0.000 claims abstract description 13
- 238000005476 soldering Methods 0.000 claims abstract description 9
- 238000003475 lamination Methods 0.000 claims abstract description 8
- 230000002829 reductive effect Effects 0.000 claims abstract description 6
- 239000002904 solvent Substances 0.000 claims abstract description 5
- 238000004080 punching Methods 0.000 claims abstract description 4
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 18
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 claims description 12
- 239000003513 alkali Substances 0.000 claims description 10
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 claims description 9
- 238000005530 etching Methods 0.000 claims description 8
- 229910000978 Pb alloy Inorganic materials 0.000 claims description 7
- 229910001128 Sn alloy Inorganic materials 0.000 claims description 7
- 230000002378 acidificating effect Effects 0.000 claims description 7
- 239000000470 constituent Substances 0.000 claims description 7
- WSFSSNUMVMOOMR-NJFSPNSNSA-N methanone Chemical compound O=[14CH2] WSFSSNUMVMOOMR-NJFSPNSNSA-N 0.000 claims description 7
- 150000001879 copper Chemical class 0.000 claims description 6
- 238000007650 screen-printing Methods 0.000 claims description 6
- 229940065287 selenium compound Drugs 0.000 claims description 6
- 150000003343 selenium compounds Chemical class 0.000 claims description 6
- 239000003381 stabilizer Substances 0.000 claims description 6
- 238000007639 printing Methods 0.000 claims description 5
- 238000000151 deposition Methods 0.000 claims description 4
- 230000008021 deposition Effects 0.000 claims description 4
- 239000004160 Ammonium persulphate Substances 0.000 claims description 3
- ROOXNKNUYICQNP-UHFFFAOYSA-N ammonium persulfate Chemical compound [NH4+].[NH4+].[O-]S(=O)(=O)OOS([O-])(=O)=O ROOXNKNUYICQNP-UHFFFAOYSA-N 0.000 claims description 3
- 235000019395 ammonium persulphate Nutrition 0.000 claims description 3
- KXZJHVJKXJLBKO-UHFFFAOYSA-N chembl1408157 Chemical compound N=1C2=CC=CC=C2C(C(=O)O)=CC=1C1=CC=C(O)C=C1 KXZJHVJKXJLBKO-UHFFFAOYSA-N 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 239000003960 organic solvent Substances 0.000 claims description 3
- UKLNMMHNWFDKNT-UHFFFAOYSA-M sodium chlorite Chemical compound [Na+].[O-]Cl=O UKLNMMHNWFDKNT-UHFFFAOYSA-M 0.000 claims description 3
- 229960002218 sodium chlorite Drugs 0.000 claims description 3
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims description 2
- 229910052783 alkali metal Inorganic materials 0.000 claims description 2
- -1 alkali metal seleno-cyanate Chemical class 0.000 claims description 2
- 239000000155 melt Substances 0.000 claims description 2
- 229940083608 sodium hydroxide Drugs 0.000 claims 1
- 235000011121 sodium hydroxide Nutrition 0.000 claims 1
- 239000000243 solution Substances 0.000 description 20
- 239000010410 layer Substances 0.000 description 7
- ICSNLGPSRYBMBD-UHFFFAOYSA-N 2-aminopyridine Chemical compound NC1=CC=CC=N1 ICSNLGPSRYBMBD-UHFFFAOYSA-N 0.000 description 4
- 238000005238 degreasing Methods 0.000 description 3
- 239000003822 epoxy resin Substances 0.000 description 3
- 229920000647 polyepoxide Polymers 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 239000000654 additive Substances 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 239000012670 alkaline solution Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 239000003638 chemical reducing agent Substances 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052708 sodium Inorganic materials 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- CHQMHPLRPQMAMX-UHFFFAOYSA-L sodium persulfate Chemical compound [Na+].[Na+].[O-]S(=O)(=O)OOS([O-])(=O)=O CHQMHPLRPQMAMX-UHFFFAOYSA-L 0.000 description 2
- 229910000679 solder Inorganic materials 0.000 description 2
- 239000001117 sulphuric acid Substances 0.000 description 2
- 235000011149 sulphuric acid Nutrition 0.000 description 2
- VDMJCVUEUHKGOY-JXMROGBWSA-N (1e)-4-fluoro-n-hydroxybenzenecarboximidoyl chloride Chemical compound O\N=C(\Cl)C1=CC=C(F)C=C1 VDMJCVUEUHKGOY-JXMROGBWSA-N 0.000 description 1
- FQRJWIRWWRZJAD-UHFFFAOYSA-N C(C)N(CC)B.[Na] Chemical compound C(C)N(CC)B.[Na] FQRJWIRWWRZJAD-UHFFFAOYSA-N 0.000 description 1
- 102100022183 E3 ubiquitin-protein ligase MIB1 Human genes 0.000 description 1
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- 101000973503 Homo sapiens E3 ubiquitin-protein ligase MIB1 Proteins 0.000 description 1
- 241001648341 Orites Species 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 239000012790 adhesive layer Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 230000001680 brushing effect Effects 0.000 description 1
- 238000005234 chemical deposition Methods 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 1
- 229910000366 copper(II) sulfate Inorganic materials 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000006735 deficit Effects 0.000 description 1
- 150000003959 diselenides Chemical class 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 230000005496 eutectics Effects 0.000 description 1
- UTVVREMVDJTZAC-UHFFFAOYSA-N furan-2-amine Chemical compound NC1=CC=CO1 UTVVREMVDJTZAC-UHFFFAOYSA-N 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000006864 oxidative decomposition reaction Methods 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- RFLFDJSIZCCYIP-UHFFFAOYSA-L palladium(2+);sulfate Chemical compound [Pd+2].[O-]S([O-])(=O)=O RFLFDJSIZCCYIP-UHFFFAOYSA-L 0.000 description 1
- JRKICGRDRMAZLK-UHFFFAOYSA-L persulfate group Chemical group S(=O)(=O)([O-])OOS(=O)(=O)[O-] JRKICGRDRMAZLK-UHFFFAOYSA-L 0.000 description 1
- 238000005554 pickling Methods 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- MNWBNISUBARLIT-UHFFFAOYSA-N sodium cyanide Chemical compound [Na+].N#[C-] MNWBNISUBARLIT-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
- H05K3/42—Plated through-holes or plated via connections
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/02—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding
- H05K3/06—Apparatus or processes for manufacturing printed circuits in which the conductive material is applied to the surface of the insulating support and is thereafter removed from such areas of the surface which are not intended for current conducting or shielding the conductive material being removed chemically or electrolytically, e.g. by photo-etch process
- H05K3/061—Etching masks
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
- H05K3/42—Plated through-holes or plated via connections
- H05K3/425—Plated through-holes or plated via connections characterised by the sequence of steps for plating the through-holes or via connections in relation to the conductive pattern
- H05K3/428—Plated through-holes or plated via connections characterised by the sequence of steps for plating the through-holes or via connections in relation to the conductive pattern initial plating of through-holes in substrates having a metal pattern
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
- H05K2203/05—Patterning and lithography; Masks; Details of resist
- H05K2203/0502—Patterning and lithography
- H05K2203/0542—Continuous temporary metal layer over metal pattern
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
- H05K2203/14—Related to the order of processing steps
- H05K2203/1423—Applying catalyst before etching, e.g. plating catalyst in holes before etching circuit
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K3/00—Apparatus or processes for manufacturing printed circuits
- H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
- H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
- H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
- H05K3/3452—Solder masks
Abstract
ABSTRACT OF THE DISCLOSURE
The resent invention provides a process for the manufacture of printed circuits using copper-laminated substrate material which, after boring or punching, is brushed, degreased, etched slightly, activated and reduced, characterised in that the substrate material prepared in such a manner is printed with an etch resist which covers the desired series of conductors, whereupon first of all the copper lamination is etched away and then the etch resist is removed by means of a solvent to bare the conductors, then either the lacquer layer is first applied, leaving the boreholes and soldering eyes uncovered, and these are then, to produce a conductive connection between the conductors and boreholes, provided with a layer of copper by the action of leaving the boreholes and soldering eyes uncovered, and these are then, to produce a conductive connection between the conductors and boreholes, provided with a layer of copper by the action of a chemical copper bath, or the entire surface is first coated with a layer of copper by the action of a chemical copper bath, then the lacquer layer is applied, leaving the boreholes and soldering eyes uncovered.
The resent invention provides a process for the manufacture of printed circuits using copper-laminated substrate material which, after boring or punching, is brushed, degreased, etched slightly, activated and reduced, characterised in that the substrate material prepared in such a manner is printed with an etch resist which covers the desired series of conductors, whereupon first of all the copper lamination is etched away and then the etch resist is removed by means of a solvent to bare the conductors, then either the lacquer layer is first applied, leaving the boreholes and soldering eyes uncovered, and these are then, to produce a conductive connection between the conductors and boreholes, provided with a layer of copper by the action of leaving the boreholes and soldering eyes uncovered, and these are then, to produce a conductive connection between the conductors and boreholes, provided with a layer of copper by the action of a chemical copper bath, or the entire surface is first coated with a layer of copper by the action of a chemical copper bath, then the lacquer layer is applied, leaving the boreholes and soldering eyes uncovered.
Description
~ZZZ6 The present invention relates to a process for the manufacture of ~rinted circuits using copper-laminated substrate material which, after boring or punching, is brushed, degreased, etchea slightly, activated and reduced in a conventional manner.
Processes for the manufacture of printed circuits are known, but these have certain disadvantages. A disadvantage of the so-called subtractive technique is, for example, that large quantities of the lamination of the substrate material have to be removed once the conductive pattern has been applied.
At the same time, under-cutting of the series of conductors occurs with all the known impairments which, the narrower the conductive paths and the distances between them, are all the more serious and, as a percentage, increase more quickly. llhese phenomena therefore preclude further miniaturisation by the subtractive technique. A disadvantage of the so-called additive techni~ue is that the substrate material used must be coated with an adhesion-imparting agent. The adhesion-imparting agent is, after chemical dissolution and activation have been carried out, the base for the selectively applied, chemically deposited copper ~0 and, after the wet treatment, has distinctly poorer electrical characteristics as compared with epoxy resin, as a result of which, similarly, narrow limits are placed on the use of tllls tecllni~ue for ~ro~ucinc3 miniaturis~d ciraults.
A furtller disadvantac3e of these processes is that ~o apply the series of conductors and the conductive connection between them and the boreholes, considerable quantities of copper bath solution are required.
The present invention provides a process which, whilst avoiding the disadvantages of the known processes, reaches possible the manufacture of printed circuits with very fine conductor series on a very narrow area with optimal electrical chdracteristics using very small ~uantities of copper bath solution.
~52~26 In accordance with the present invention in a process of the type described above the substrate material prepared in such a manner is printed, preferably by the positive process, advantageously using an alkali-soluble silk-screen printing ink, with an etch resist which covers the desired series of conductors, whereupon first of all the copper lamination is etched away and then the etch resist is removed by means of a solvent to bare the conductors, then either first of all the lacquer layer is applied, leaving the boreholes and soldering eyes uncovered, and these are then, to produce a conductive connection between the conductors and boreholes, provided with a layer of copper by the action of a chemical copper bath and subsequently, if desired, covered with a lead/tin alloy, or first of all the entire surface is coated with a layer of copper by the action of a chemical copper bath, then the lacquer layer is applied, leaving the boreholes and soldering eyes uncovered, and these are subsequently, if desired, provided with a covering of lead/tin alloy.
In preferred embodiments of this process:
(a) the copper lamination is etched away by means of an acidic etchin~ solution, advantagoously an clCidiC a~noniurn persulphate solution, or an ~lkaline etching solution, advantageously an ammoniacal solution o~ sodium chl.orite;
(b) the etch resist is removed by means of a 3 to 5%
sodium hydroxide solution or an organic solvent, advantageously methylene chloride;
(c) the lacquer used is a solder-blocking lacquer;
(d) a chemical copper bath is used, containing as the essential constituents a copper salt, a complex former, formaldehyde, as well as an alkali cyanide and optionally a selenium compound as stablilisers; and (e) a stabilised chemical copper bath is used;
1~2226 (f) the lead/tin alloy is applied in the form of a melt by the action of very hot air or by reductive deposition from a chemical tin bath.
The process according to the invention makes possible in a surprising manner, the manufacture of high-quality minia-turised circuits, especially by positive printing. The process produces fine conductors of a quality that can otherwise be obtained only by using photographic printing. The process furthermore has the great advantage that, starting from a cop-per-laminated substrate material, it is possible to produce the finest conductor paths in a width of less than 100 ~m with optimal insulation and surface resistance properties.
A further important advantage is the saving of chemical copper bath solution, which is of special economic significance.
Of outstanding commercial importance, furthermore, is that by contrast with the additive technique, it is possible to dispense with an adhesive-coated or nuclear-catalysed substrate material so that the high requirements of the adhesive coating and the oxidative decomposition of the adhesive layer by means of chromosulphuric acid are inapplicable. The process accord-ing to the invention thus has an especially low pollution ef~ec~.
~ suitable sub~trate material is, ~or example, phenol resin-bonded paper, epoxy resin paper, and especially glass-fibre-reinforced epoxy resin.
The present invention will be further illustrated, by way of the accompanying drawings, in which:
Fig. 1 is a flow diagram of a process for the manu-facture of printed circuits according to one embodiment of the present invention; and Fig. 2 is a flow diagram of a process for the manu-facture of printed circuits according to allother embodiment of , ;, ~52~Z6 the present lnvention.
The process according to the invention is carried out, for example, after boring or punching, by brushing the plates in the conventional manner followed by alkaline degreas-ing. The surface is then etched slightly about 5 m~, which can be effected by the action of approximately 10~ sodium per-sulphate solution at 28-32C. After pickling, for example, with 10% sulphuric acid, the surface is then activated by means of an activator, preferably an aqueous alkaline solution of a palladium - 3a -~;2226 complex, especially palladium sulphate with 2-aminopyridine, wherein attention is to be paid to a high covering density especially on the borehole walls so as to ensure activation even after the later etching operation. Reduction is then carried out by the action of a reducing agent, for example sodium diethylaminoborane, and the surface is after-treated in the usual manner.
The desired wiring pattern is then positively applied thereto in accordance with the invention by silk-screen or photographic printing, which is effected by means of an etch resist, advantageously an alkali-soluble silk-screen printing ink, which covers the conductors, after which first of all the copper lamination is etched away, which can be carried out by the action either of an acidic etching solution, for example an acidic ammonium persulphate solution, or of an alkaline etching solution, for example an ammoniacal sodium chlorite solution.
Subsequent thorough rinsing of the boreholes or punched holes must be carried out.
After removing the etch resist by means of a solvent, for example by means of a 3 to 5% sodium hydroxide solution, or an organic solvent, such as methylene chloride, according to one embodiment of the process in accordAnG~ with ~he invention, a lacquer layer is th~n appli~, leavin~ tlle borehoJ.cs un~ovcred, for which purpose a solder-blocking lac~uer is especially suitable, this being applied as a mask print. After customary alkaline degreasing, chemical deposition of metal into the boreholes is then carried out to a layer thickness o preferably 15 to 25 m~ . This is advantageously effected with a stabilised chemical copper bath preferably containing, as the essential constituents, a copper ~alt, a complex former, formaldehyde, as well as an alkali cyanide and optionally a selenium compound as stabilisers.
The final partial application of a lead/tin alloy, ^`` ~1~i;2226 advantageously in a hot air process by the action of very hot air, guarantees a purely eutectic solder which, even after accelerated ageing, is satisfactorily solderable.
In accordance with another embodiment of the process according to the invention, after removing the etch resist the entire surface is copper-plated by the action of the above-described chemical copper bath, then the solder~blocking lacquer is applied leaving the boreholes uncovered, and finally, if desired, the mentioned hot-air tinning is carried out.
A chemical copper bath of the above-described composition is excellently suitable for carrying out the process according to the invention. A suitable alkali cyanide is especially sodium cyanide in c~centrations of 15 to 30 mg/litre.
Suitable selenium compounds are the organic, inorganic, and organic/inorganic monoselenides and diselenides and, of these, especially alkali metal selenocyanates, such as potassium selenocyanate, which are used in concentrations of, preferably, 0.1 to 0.3 mg/litre of bath liquid.
The following Example serves to illustrate the invention.
EXAMPLE
A substrate of ~lass-Eibre-reinEorcod epoxy rcsin which is copper-laminated on both sides is bored in the usual manner, mechanically cleaned (burred), and degreased by means of al]cali at approximately 80C with a treatment time of about 7 minutes. The substrate is then etched slightly (approximately 5 m~) by the action of a 10~ sodium persulphate solution at a temperature of approximately 28 to 32C within a period of 3 minutes. The substrate is subsequently pickled with sulphuric acid with a content of 10% by weight at room temperature and then activated with an aqueous alkaline solution ofpalladiumsulphatein 2-aminopyridine, whereupon it is reduced using sodium diethyl-.~5Z~226 aminofurane as reducing agent, then rinsed and dried.
The conductive pattern is then printed positively bysilk-screen printing using an alkali-soluble silk-screen printing ink. The printing can alternatively be carried out by the photographic method, wherein advantageously an alkali-soluble liquid resist may be used. The copper is then etched away, which may be effected by the action of an acidic etching solution, such as an acidic ammonium persulphate solution, or an alkaline etching solution, such as an ammoniacal solution of sodium chlorite.
The removal of the silk-screen printing ink is then effected by treating with a solvent, such as a 3 to 5% sodium hydroxide solution or methylene chloride, after which the substrate is thoroughly rinsed and dried. A solder-blocking lacquer is then applied, followed by alkaline degreasing. The boreholes are subsequently copper-plated by means of a stabilised chemical copper bath of the following composition:
g/l of copper sulphate CuSO4 5H2O
g/l of ethylenediaminetetraacetic acid g/l of sodium hydroxide NaOH
0.025 g/l of sodium cyanide NaCN
0.001 g/l o ~otassium seJ.~noa~anate KSe~N
4 ml o formal~ehyde, 37%.
The copper deposition is effected at a temperature of 65C and a treatment time of 20 hours at an average deposition speed of 1.5 ~m/hour. If desired, a selective hot-air tinning (so-called HOT-~IR-LEVELLING process) can then finally ~e carried out.
Alternatively, the solder-blocking lacquer can first be applied after copper-plating, whereupon finally, if desired, selective hot-air tinning is carried out.
The result is series of conductors in a layer thick-ness of ~pproximately 30 ~m with electrical characteristicsof at least 1 . 1012Q.
Processes for the manufacture of printed circuits are known, but these have certain disadvantages. A disadvantage of the so-called subtractive technique is, for example, that large quantities of the lamination of the substrate material have to be removed once the conductive pattern has been applied.
At the same time, under-cutting of the series of conductors occurs with all the known impairments which, the narrower the conductive paths and the distances between them, are all the more serious and, as a percentage, increase more quickly. llhese phenomena therefore preclude further miniaturisation by the subtractive technique. A disadvantage of the so-called additive techni~ue is that the substrate material used must be coated with an adhesion-imparting agent. The adhesion-imparting agent is, after chemical dissolution and activation have been carried out, the base for the selectively applied, chemically deposited copper ~0 and, after the wet treatment, has distinctly poorer electrical characteristics as compared with epoxy resin, as a result of which, similarly, narrow limits are placed on the use of tllls tecllni~ue for ~ro~ucinc3 miniaturis~d ciraults.
A furtller disadvantac3e of these processes is that ~o apply the series of conductors and the conductive connection between them and the boreholes, considerable quantities of copper bath solution are required.
The present invention provides a process which, whilst avoiding the disadvantages of the known processes, reaches possible the manufacture of printed circuits with very fine conductor series on a very narrow area with optimal electrical chdracteristics using very small ~uantities of copper bath solution.
~52~26 In accordance with the present invention in a process of the type described above the substrate material prepared in such a manner is printed, preferably by the positive process, advantageously using an alkali-soluble silk-screen printing ink, with an etch resist which covers the desired series of conductors, whereupon first of all the copper lamination is etched away and then the etch resist is removed by means of a solvent to bare the conductors, then either first of all the lacquer layer is applied, leaving the boreholes and soldering eyes uncovered, and these are then, to produce a conductive connection between the conductors and boreholes, provided with a layer of copper by the action of a chemical copper bath and subsequently, if desired, covered with a lead/tin alloy, or first of all the entire surface is coated with a layer of copper by the action of a chemical copper bath, then the lacquer layer is applied, leaving the boreholes and soldering eyes uncovered, and these are subsequently, if desired, provided with a covering of lead/tin alloy.
In preferred embodiments of this process:
(a) the copper lamination is etched away by means of an acidic etchin~ solution, advantagoously an clCidiC a~noniurn persulphate solution, or an ~lkaline etching solution, advantageously an ammoniacal solution o~ sodium chl.orite;
(b) the etch resist is removed by means of a 3 to 5%
sodium hydroxide solution or an organic solvent, advantageously methylene chloride;
(c) the lacquer used is a solder-blocking lacquer;
(d) a chemical copper bath is used, containing as the essential constituents a copper salt, a complex former, formaldehyde, as well as an alkali cyanide and optionally a selenium compound as stablilisers; and (e) a stabilised chemical copper bath is used;
1~2226 (f) the lead/tin alloy is applied in the form of a melt by the action of very hot air or by reductive deposition from a chemical tin bath.
The process according to the invention makes possible in a surprising manner, the manufacture of high-quality minia-turised circuits, especially by positive printing. The process produces fine conductors of a quality that can otherwise be obtained only by using photographic printing. The process furthermore has the great advantage that, starting from a cop-per-laminated substrate material, it is possible to produce the finest conductor paths in a width of less than 100 ~m with optimal insulation and surface resistance properties.
A further important advantage is the saving of chemical copper bath solution, which is of special economic significance.
Of outstanding commercial importance, furthermore, is that by contrast with the additive technique, it is possible to dispense with an adhesive-coated or nuclear-catalysed substrate material so that the high requirements of the adhesive coating and the oxidative decomposition of the adhesive layer by means of chromosulphuric acid are inapplicable. The process accord-ing to the invention thus has an especially low pollution ef~ec~.
~ suitable sub~trate material is, ~or example, phenol resin-bonded paper, epoxy resin paper, and especially glass-fibre-reinforced epoxy resin.
The present invention will be further illustrated, by way of the accompanying drawings, in which:
Fig. 1 is a flow diagram of a process for the manu-facture of printed circuits according to one embodiment of the present invention; and Fig. 2 is a flow diagram of a process for the manu-facture of printed circuits according to allother embodiment of , ;, ~52~Z6 the present lnvention.
The process according to the invention is carried out, for example, after boring or punching, by brushing the plates in the conventional manner followed by alkaline degreas-ing. The surface is then etched slightly about 5 m~, which can be effected by the action of approximately 10~ sodium per-sulphate solution at 28-32C. After pickling, for example, with 10% sulphuric acid, the surface is then activated by means of an activator, preferably an aqueous alkaline solution of a palladium - 3a -~;2226 complex, especially palladium sulphate with 2-aminopyridine, wherein attention is to be paid to a high covering density especially on the borehole walls so as to ensure activation even after the later etching operation. Reduction is then carried out by the action of a reducing agent, for example sodium diethylaminoborane, and the surface is after-treated in the usual manner.
The desired wiring pattern is then positively applied thereto in accordance with the invention by silk-screen or photographic printing, which is effected by means of an etch resist, advantageously an alkali-soluble silk-screen printing ink, which covers the conductors, after which first of all the copper lamination is etched away, which can be carried out by the action either of an acidic etching solution, for example an acidic ammonium persulphate solution, or of an alkaline etching solution, for example an ammoniacal sodium chlorite solution.
Subsequent thorough rinsing of the boreholes or punched holes must be carried out.
After removing the etch resist by means of a solvent, for example by means of a 3 to 5% sodium hydroxide solution, or an organic solvent, such as methylene chloride, according to one embodiment of the process in accordAnG~ with ~he invention, a lacquer layer is th~n appli~, leavin~ tlle borehoJ.cs un~ovcred, for which purpose a solder-blocking lac~uer is especially suitable, this being applied as a mask print. After customary alkaline degreasing, chemical deposition of metal into the boreholes is then carried out to a layer thickness o preferably 15 to 25 m~ . This is advantageously effected with a stabilised chemical copper bath preferably containing, as the essential constituents, a copper ~alt, a complex former, formaldehyde, as well as an alkali cyanide and optionally a selenium compound as stabilisers.
The final partial application of a lead/tin alloy, ^`` ~1~i;2226 advantageously in a hot air process by the action of very hot air, guarantees a purely eutectic solder which, even after accelerated ageing, is satisfactorily solderable.
In accordance with another embodiment of the process according to the invention, after removing the etch resist the entire surface is copper-plated by the action of the above-described chemical copper bath, then the solder~blocking lacquer is applied leaving the boreholes uncovered, and finally, if desired, the mentioned hot-air tinning is carried out.
A chemical copper bath of the above-described composition is excellently suitable for carrying out the process according to the invention. A suitable alkali cyanide is especially sodium cyanide in c~centrations of 15 to 30 mg/litre.
Suitable selenium compounds are the organic, inorganic, and organic/inorganic monoselenides and diselenides and, of these, especially alkali metal selenocyanates, such as potassium selenocyanate, which are used in concentrations of, preferably, 0.1 to 0.3 mg/litre of bath liquid.
The following Example serves to illustrate the invention.
EXAMPLE
A substrate of ~lass-Eibre-reinEorcod epoxy rcsin which is copper-laminated on both sides is bored in the usual manner, mechanically cleaned (burred), and degreased by means of al]cali at approximately 80C with a treatment time of about 7 minutes. The substrate is then etched slightly (approximately 5 m~) by the action of a 10~ sodium persulphate solution at a temperature of approximately 28 to 32C within a period of 3 minutes. The substrate is subsequently pickled with sulphuric acid with a content of 10% by weight at room temperature and then activated with an aqueous alkaline solution ofpalladiumsulphatein 2-aminopyridine, whereupon it is reduced using sodium diethyl-.~5Z~226 aminofurane as reducing agent, then rinsed and dried.
The conductive pattern is then printed positively bysilk-screen printing using an alkali-soluble silk-screen printing ink. The printing can alternatively be carried out by the photographic method, wherein advantageously an alkali-soluble liquid resist may be used. The copper is then etched away, which may be effected by the action of an acidic etching solution, such as an acidic ammonium persulphate solution, or an alkaline etching solution, such as an ammoniacal solution of sodium chlorite.
The removal of the silk-screen printing ink is then effected by treating with a solvent, such as a 3 to 5% sodium hydroxide solution or methylene chloride, after which the substrate is thoroughly rinsed and dried. A solder-blocking lacquer is then applied, followed by alkaline degreasing. The boreholes are subsequently copper-plated by means of a stabilised chemical copper bath of the following composition:
g/l of copper sulphate CuSO4 5H2O
g/l of ethylenediaminetetraacetic acid g/l of sodium hydroxide NaOH
0.025 g/l of sodium cyanide NaCN
0.001 g/l o ~otassium seJ.~noa~anate KSe~N
4 ml o formal~ehyde, 37%.
The copper deposition is effected at a temperature of 65C and a treatment time of 20 hours at an average deposition speed of 1.5 ~m/hour. If desired, a selective hot-air tinning (so-called HOT-~IR-LEVELLING process) can then finally ~e carried out.
Alternatively, the solder-blocking lacquer can first be applied after copper-plating, whereupon finally, if desired, selective hot-air tinning is carried out.
The result is series of conductors in a layer thick-ness of ~pproximately 30 ~m with electrical characteristicsof at least 1 . 1012Q.
Claims (18)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the manufacture of printed circuits using copper-laminated substrate material which, after boring or punching, is brushed, degreased, etched slightly, activated and reduced, in which the substrate material prepared in such a manner is printed, with an etch resist which covers the de-sired series of conductors, whereupon first of all the copper lamination is etched away and then the etch resist is removed by means of a solvent to bare the conductors, then applying a lacquer layer to said substrate leaving the boreholes and solder-ing eyes uncovered and providing a layer of copper by the action of a chemical copper bath on said boreholes and soldering eyes to produce a conductive connection between the conductors and the boreholes.
2. A process according to claim 1, in which the lacquer layer is first applied, leaving the boreholes and soldering eyes uncovered, and these are then, to produce a con-ductive connection between the conductors and boreholes, pro-vided with a layer of copper by the action of a chemical copper bath.
3. A process according to claim 1, in which the entire surface is first coated with a layer of copper by the action of a chemical copper bath, then the lacquer layer is applied, leaving the boreholes and soldering eyes uncovered.
4. A process according to claim 1, 2 or 3, in which the copper lamination is etched away by means of an acidic etching solution or an alkaline etching solution.
5. A process according to claim 1, 2 or 3, in which the copper lamination is etched away by means of an acidic ammonium persulphate solution or an ammoniacal solution of sodium chlorite.
6. A process according to claim 1, 2 or 3, in which the substrate material is printed by a positive process.
7. A process according to claim 1, 2 or 3, in which the substrate material is printed by a positive printing process using an alkali soluble silk-screen printing ink.
8. A process according to claim 1, 2 or 3, in which the product obtained is provided with a covering of a lead/tin alloy.
9. A process according to claim 1, in which the etch resist is removed by means of a 3 to 5% sodium hydrox-ide solution or an organic solvent.
10. A process according to claim 9, in which the etch resist is removed by means of methylene chloride.
11. A process according to claim 1, 2 or 3, in which the lacquer is a solder-blocking lacquer.
12. A process according to claim 1, 2 or 3, in which a stabilised chemical copper bath is used.
13. A process according to claim 1, 2 or 3, in which a chemical copper bath is used, containing as the essential constituents a copper salt, a complex former, formaldehyde, and an alkali cyanide as stabiliser.
14. A process according to claim 1, 2 or 3, in which a chemical copper bath is used, containing as the essential constituents a copper salt, a complex former, formaldehyde, and an alkali cyanide as stabiliser and a selenium compound.
15. A process according to claim 1, 2 or 3, in which the product obtained is provided with a covering of a lead/tin alloy, the lead/tin alloy being applied in the form of a melt by the action of very hot air or by reductive deposition from a chemical tin bath.
16. A process according to claim 1, 2 or 3, in which a chemical copper bath is used, containing as the essential constituents a copper salt, a complex former, formaldehyde, and an alkali cyanide as stabiliser and an alkali metal seleno-cyanate.
17. A process according to claim 1, 2 or 3, in which a chemical copper bath is used, containing as the essential constituents a copper salt, a complex former, formaldehyde, and an alkali cyanide as stabiliser and a selenium compound, the selenium compound being present in an amount of from 0.1 to 0.3 mg/litre of a bath liquid.
18. A process according to claim 1, 2 or 3, in which a chemical copper bath is used, containing as the essential constituents a copper salt, a complex former, formaldehyde, and an alkali cyanide as stabiliser, the alkali cyanide being sodium cyanide present in an amount of from 15 to 30 mg/litre.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP2932536.8 | 1979-08-09 | ||
| DE19792932536 DE2932536A1 (en) | 1979-08-09 | 1979-08-09 | METHOD FOR PRODUCING PRINTED CIRCUITS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1152226A true CA1152226A (en) | 1983-08-16 |
Family
ID=6078196
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000357874A Expired CA1152226A (en) | 1979-08-09 | 1980-08-08 | Process for the manufacture of printed circuits |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS5629395A (en) |
| CA (1) | CA1152226A (en) |
| CH (1) | CH647372A5 (en) |
| DE (1) | DE2932536A1 (en) |
| FR (1) | FR2463569B1 (en) |
| GB (1) | GB2057774B (en) |
| IE (1) | IE49971B1 (en) |
| IT (1) | IT1131716B (en) |
| NL (1) | NL8003939A (en) |
| SE (1) | SE454476B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0090900B1 (en) * | 1982-04-05 | 1987-02-11 | Kanto Kasei Co., Ltd. | Process of manufacturing printed wiring boards and printed wiring boards manufactured by the same |
| FI88241C (en) * | 1990-10-30 | 1993-04-13 | Nokia Mobile Phones Ltd | FOERFARANDE FOER FRAMSTAELLNING AV KRETSKORT |
| US5358602A (en) * | 1993-12-06 | 1994-10-25 | Enthone-Omi Inc. | Method for manufacture of printed circuit boards |
| US5620612A (en) * | 1995-08-22 | 1997-04-15 | Macdermid, Incorporated | Method for the manufacture of printed circuit boards |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1378154A (en) * | 1962-09-24 | 1964-11-13 | North American Aviation Inc | Electrical interconnections for printed circuit boards |
| US3269861A (en) * | 1963-06-21 | 1966-08-30 | Day Company | Method for electroless copper plating |
| DE1690224B1 (en) * | 1967-08-29 | 1971-03-25 | Standard Elek K Lorenz Ag | BATHROOM FOR ELECTRONIC COPPER PLATING OF PLASTIC PANELS |
| FR2128355A1 (en) * | 1971-03-01 | 1972-10-20 | Fernseh Gmbh | |
| JPS5489276A (en) * | 1977-12-27 | 1979-07-16 | Fujitsu Ltd | Method of producing printed board |
-
1979
- 1979-08-09 DE DE19792932536 patent/DE2932536A1/en not_active Withdrawn
-
1980
- 1980-07-08 NL NL8003939A patent/NL8003939A/en not_active Application Discontinuation
- 1980-07-17 CH CH5489/80A patent/CH647372A5/en not_active IP Right Cessation
- 1980-07-18 IT IT23530/80A patent/IT1131716B/en active
- 1980-07-29 SE SE8005443A patent/SE454476B/en not_active IP Right Cessation
- 1980-08-07 FR FR8017460A patent/FR2463569B1/en not_active Expired
- 1980-08-08 CA CA000357874A patent/CA1152226A/en not_active Expired
- 1980-08-08 IE IE1669/80A patent/IE49971B1/en unknown
- 1980-08-08 GB GB8025868A patent/GB2057774B/en not_active Expired
- 1980-08-08 JP JP10841080A patent/JPS5629395A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| IE49971B1 (en) | 1986-01-22 |
| SE454476B (en) | 1988-05-02 |
| DE2932536A1 (en) | 1981-02-26 |
| JPS5629395A (en) | 1981-03-24 |
| FR2463569A1 (en) | 1981-02-20 |
| IT1131716B (en) | 1986-06-25 |
| IE801669L (en) | 1981-02-09 |
| SE8005443L (en) | 1981-02-10 |
| NL8003939A (en) | 1981-02-11 |
| IT8023530A0 (en) | 1980-07-18 |
| GB2057774B (en) | 1983-09-07 |
| FR2463569B1 (en) | 1985-09-20 |
| CH647372A5 (en) | 1985-01-15 |
| GB2057774A (en) | 1981-04-01 |
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