CA1177973A - Printed circuit board and method of making the same - Google Patents
Printed circuit board and method of making the sameInfo
- Publication number
- CA1177973A CA1177973A CA000384488A CA384488A CA1177973A CA 1177973 A CA1177973 A CA 1177973A CA 000384488 A CA000384488 A CA 000384488A CA 384488 A CA384488 A CA 384488A CA 1177973 A CA1177973 A CA 1177973A
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- CA
- Canada
- Prior art keywords
- circuit board
- adhesive layer
- layer
- adhesive
- substrate
- 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
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Abstract
ABSTRACT
Adhesive is applied to a substrate for a printed circuit board in a pattern corresponding to that of the printed circuit. If the adhesive is of the type which contains a solvent, the substrate and adhesive are heated after application of the latter in order to drive off the solvent. Subsequently, a thin foil of a material which is capable of bonding to a chemically deposited metal is pressed onto the adhesive. The adhesive is then permitted to set which causes those portions of the foil in contact with the adhesive to adhere tightly to the latter. Once the adhesive has set, the foil is peeled from the adhesive. The portions of the foil which contact the adhesive remain bound to the adhesive thereby forming a base which is capable of receiving a chemically deposited metal. The thus-coated substrate is immersed in a bath where an electrically conductive metal for forming the printed circuit is chemically deposited in a pattern corresponding to that of the adhesive and, consequently, of the printed circuit.
Adhesive is applied to a substrate for a printed circuit board in a pattern corresponding to that of the printed circuit. If the adhesive is of the type which contains a solvent, the substrate and adhesive are heated after application of the latter in order to drive off the solvent. Subsequently, a thin foil of a material which is capable of bonding to a chemically deposited metal is pressed onto the adhesive. The adhesive is then permitted to set which causes those portions of the foil in contact with the adhesive to adhere tightly to the latter. Once the adhesive has set, the foil is peeled from the adhesive. The portions of the foil which contact the adhesive remain bound to the adhesive thereby forming a base which is capable of receiving a chemically deposited metal. The thus-coated substrate is immersed in a bath where an electrically conductive metal for forming the printed circuit is chemically deposited in a pattern corresponding to that of the adhesive and, consequently, of the printed circuit.
Description
7~973 The invention relates to printed circuit boards and methods of making the same.
A known printed circuit board has a printed circuit of electrically conductive material which is adhesively secured to a non-conductive substrate. The printed circuit is chemically deposited on the substrate in a thickness sufficient to carry the current which is supplied to the circuit board.
Printed circuit boards are manufactured in various ways. In the additive technique, an aluminum foil is coated with an adhesive, e.g. acrylonitrile, butadiene or a phenolic-based adhesive. After pressing, this carrier material constitutes a core catalyst on which copper may be chemically deposited. The core catalyst may also be cast or may be coated by immersion. This coating is dried at a temperature of 140C.
After cutting and drilling, etching is performed in a mixture of chronic and sulfuric acids. This is followed by the screen printing process and the further copper plating by chemical means.
Another method uses a base material which is laminated with a copper foil. Pressure is applied via the screen printing process. The areas which remain exposed are etched.
The methods used heretofore for the production of printed circuit boards require relatively complicated and expensive procedures. The production of a base core catalyst, in particular, is a very costly step.
The known methods for the production of printed circuit boards also have disadvantages aside from their high cost. Thus, they contribute strongly to environmental polution and require large amounts and material and labor.
According to the invention, a printed circuit board 3 ~77973 having a printed circuit of a predetermined pattern includes a substrate and an adhesive layer on the substrate conforming to the pattern. A base layer is provided on the adhesive layer and an electrically conductive layer is chemically deposited on and bonded to the base layer. In accordance with one feature of the invention, the adhesive layer is substantially free of solvent when the base layer is applied thereto.
me electrically conductive layer is deposited in a t~ickness sufficient to carry the current which is supplied to the printed circuit board.
The substrate which receives the adhesive layer is preferably non-conductive.
The invention further provides a method of ~aking a printed circuit bcard having a printed circuit of a predetermined pattern. m e method involves applying an adhesive layer to a substrate in conformance with the pattern and coating the adhesive layer with an electrically conductive layer.
According to a preferred em~odiment of the method, the adhesive layer is pressed onto a non-conductive substrate in accordance with the predetermined pattern of the printed circuit and the solvent present in the adhesive layer is removed there-from. A foil oomposed of a material which is capable of bonding to a chemically deposited, electrically conductive substance is pressed onto the adhesive layer after removal of the solvent but before the adhesive layer has set or hardened. After the adhesive layer has set, the foil is peeled away in such a manner that the portions of the foil corresponding to the pattern of the printed circuit and the adhesive layer remain on the latter.
The portions of the foil which remain bound to the adhesive layer constitute a base or base layer for the electrically ~.s"~
~77973 conductive layer. The electrically conductive layer, which is advantageously metallic, is subsequently chemically desposited on the base layer in a predetermined thickness sufficient to carry the current which is supplied to the circuit board.
m e only pretreatment which the substrate requires is a degreasing, m e ninin~m di:stance of separation between the conducting strips of the printe circuit to be produced, as well as the fineness of the conducting strips, are deternuned by the particular manner in which pressure is applied.
m e base layer, which is capable of being chemically metallized and via which chemical metallization of the adhesive layer is effected, may be desposited in very precise thicknesses.
The base layer may be very thin (100-400 Angstroms) so that only small amounts of chemically metallizable material are required to produce the sante. m is makes it possible to form the b~se layer from expensive materials such as, for example, noble rltetals and valuable rare ear~ls t~;~ich ena~le good deposits of tile chem-ically deposited, electrically conductive layer to be achieved.
me invention does not require the substrate to be provided with a core catalyst or to be etched. Rather, only those areas corresponding to the electrically conductive layer, i.e. the conducting strips of the printed circuit, are coated with a layer which is capable of being chemically metallized and which forms the base for the metallic, electrically conduc-tive layer to be deposited by chemical means. me electrically conductive layer may be made of any metal which can be deposited via chemical metallization. Accordingly, the base layer may be deposited on the adhesive layer independently of the particular ~tetal which is selected fDr the electrically conductive layer or strips. A printed circuit board ~anufactured in accordance with ~ ~'77973 the invention is inexpensive as regards both the manufacturing operations and the basic materials to be used.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved printed circuit board itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.
Figure 1 is a cross-section through a degreased substrate;
Figure 2 is a cross-section through the substrate of Figure 1 illustrating the application of an adhesive layer to the substrate;
Figure 3 is a cross-section through the substrate of Figure 2 showing the application of a foil of a base metal to the adhesive layer of the substrate;
Figure 4 is a cross-section through the substrate of Figure 3 illustrating the removal of those portions of the foil which do not adhere to the adhesive layer of the substrate; and Figure 5 schematically illustrates an apparatus for manufacturing printed circuit boards in accordance with the invention.
Figure 1 illustrates a substrate 1 which is to be provided with electrically conductive strips or paths forming the printed circuit of a printed circuit board. The substrate 1 has been degreased in a known and non-illustrated manner.
As seen in Figure 5, which schematically illustrates an apparaius advantageously used for carrying out the method of the invention, the substrate l is placed in a non-illustrated supply vessel together with other similar substrates. In the illustrated embodiment, the substrate l and the other substrates are assumed to be in the form of individual sheets or wafers and are arranged in a stack. However, it is also possible for the substrate l and the other substrates to be supplied from a roll.
Referring to Figures 2 and 5, the substrate l is conveyed from the stack to a printing station 3 where a layer 4 of adhesive is applied to or imprinted upon the substrate l.
The adhesive layer 4 is applied to the substrate l in a pattern which corresponds to that of the printed circuit to be formed on the substrate l. In other words, the adhesive layer 4 is not applied to the substrate l uniformly but only in those areas where the conducting strips of the printed circuit are to be located. The adhesive layer 4 may be applied to the substrate l by means of the screen printing process or the intaglio process.
The adhesive used for the adhesive layer 4 will generally be a dry lamination adhesive which should be free of solvent at the time of lamination. As seen in Figure 5, a drying station 9 for careful drying of the adhesive layer 4 is located downstream of the printing station 3. All of the solvent contained in the adhesive layer 4 is driven out of the same in the drying station 9. Instead of using a solvent-containing adhesive for the adhesive layer 4, it is possible to use an adhesive which contains no solvent.
After leaving the drying station 9, the adhesive layer 4, which is now free of solvent, is brought into contact with a strip 18 consisting of a carrier 12 and a metallic foil lO.
~;"7~73 This is shown in Figures 3 and 5. As best seen in Figure 5, the strip 18 is produced by passing the carrier 12 through a vapor deposition station 13 in which the metallic foil 10 is vapor-deposited on the carrier 12~ The vapor deposition station 13 accommodates a metallic bath 15 and a heating unit 14. Both an electrical field and a vacuum are maintained in the vapor deposition station 13. The heating unit 14 heats the metallic bath 15 to such a high temperature that metal ions 16 are released from the bath 15 and, under the influence of the electrical field and the vacuum, travel upwards towards the carrier 12 and are deposited on the latter.
Referring again to Figure 3 in conjunction with Figure 5, the metallic foil 10 of the strip 18 is pressed against the adhesive layer 4 by a pair of rolls 11. The rolls 11 press the metallic foil 10 against the adhesive layer 4 in such a manner that the metallic foil 10 adheres to the adhesive layer 4 at all locations where the metallic foil 10 and adhesive layer 4 come into contact. The rolls 11 may be heated in order to achieve adhesion between the metallic foil 10 and the adhesive layer 4.
After being compressed by the rolls 11, the adhesive layer 4 sets or hardens while in engagement with the strip 18.
Once the adhesive layer 4 has set, the metallic foil 10 firmly adheres to the adhesive layer 4. The adhesion between the metallic foil 10 and the adhesive layer 4 is so great that, when the carrier 12 is peeled away, the portions of the metallic foil 10 which adhere to the adhesive layer 4 remain bound to the latter. The adhesion between the metallic foil 10 and the adhesive layer 4 is much greater than the cohesion between the metallic foil 10 and the carrier 12. It is only along the adhesive layer 4 that portions of the metallic foil 10 continue l~t77973 to adhere to the substrate 1 upon rem~val of the carrier 12.
me edges of those portions of the metallic foil 10 which remain on the adhesive layer 4 are well-defined.
Subsequent to setting of the adhesive layer 4, the carrier 12 may be readily removed from the substrate 1. As illustrated in Figure 4, those portions of the metallic foil 10 which do not contact the adhesive layer 4 continue to adhere to the carrier 12 when this is peeled away from the substrate 1.
After removal of the carrier 12, a pretreated, printed circuit board 19 is obtained as shown in Figure 5. The adhesive layer 4 of the pretreated board 19 has a metallic coating which is constituted by the portions of the metallic foil 10 left behind upon removal of the carrier 12 and which forms a base layer capa~le of bonding to a chemically deposited, electrically conductive metal. As illustrated in Figure 5, the pretreated board 19 is conveyed through a bath 17 in which a layer of an electri~lly conductive metal is chemically deposited on the base layer and is konded thereto. The chemical metallization which occurs in the bath 17 takes place in a known mEnner. The electrically conductive layer of the finished printed circuit board 20 emerging from the bath 17 has a thickness which is adjusted to the magnitude of the electrical current to be supplied to the printed circuit board 20.
As already mentioned, the substrate 1 may be in the form of a sheet or wafer. Such a sheet may be composed of a phenolic resin. It is also possible for the substrate 1 to be composed of paper, and epoxy web or woven epoxy sheet, epoxy paper or a non-woven epoxy sheet and phenolic resin paper or a sheet of non-woven phenolic resin. In addition, melanine resins have been found suitable for the substrate 1. Other materials .
1~t77973 which can be used for the substrate 1 are polyesters, polyimides, polycarbonates and polysulfanes. It is further p~ssible to use inexpensive papers which are coated or laminated with a poly-ester, a polyimide, a polycarbonate or a polysulfane.
me adhesive layer 4 may be composed of a reactive resin system. Fbr instance, a polyurethane may be used as an adhesive. m e adhesive may be hardenable by contact with atmospheric moisture or when exposed to electron beam radiation.
It is likewise possible to use an adhesive which sets or hardens under the influence of ultravîolet light. me adhesive may also be in the form of a multicomponent system. Thus, an isocyanate-containing resin may be used. It is further possible to utilize a hardenable ep~xy resin. In addition, an acrylic resin system may be used as an adhesive.
As mentioned earlier, the adhesive layer 4 may be applied to the substrate 1 of a printed circuit board, for example, by means of the screen printing process or the intagli~o process. me screen printing process has the advantage that the adhesive layer 4 may be produced more readily and cheaply.
The base layer which i5 capable of being chemically metallized may be composed of a non-ferrous metal. Thus, oopper or nickel may be used for producing the base layer. The base layer may also be composed of a noble meta] and, in particular, gold or silver. In addition, elements of the rare earths group which are capable of being chemically metallized may be used for the base layer. It is to be understood that the base layer need not be constituted by a metal but may be composed on any substance which is capable o~ banding to a chemically deposited metal~
The carrier 12 may be provided with a parting layer -~ ~77973 prior to vapor deposition of the material which is to form the base layer. The purpose of the parting layer is to facilitate disengagement of the material whichis to form the base layer from the carrier 12. m e parting layer must be such that it does not adhere to the material of the base layer under any circumstances. mus, the base layer must be absolutely clean so that the metallization in the chemical metallizing bath 17 takes place without difficulty. The parting layer may consist of wax which is firmly secured to the carrier 12. It is further possible for the parting layer to be composed of a silicone which firmly adheres to the carrier 12. A parting lacquer or varnish which releases more readily from the material of the base layer than from the carrier 12 may likewise be utilized for the parting layer.
Appropriate selection of the material of the carrier 12 is advantageous. Materials which may be used for the carrier 1~ include polypropylenes, polyesters and polycarb~nates.
m e coating of the adhesive layer 4 with a base layer which is capable of bonding to a chemically deposited metal may also be achieved by means of the known sputtering process.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by ~; applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptions should and are intended to be comprehended within the meaning and range of equivalents of the appended claims.
.
A known printed circuit board has a printed circuit of electrically conductive material which is adhesively secured to a non-conductive substrate. The printed circuit is chemically deposited on the substrate in a thickness sufficient to carry the current which is supplied to the circuit board.
Printed circuit boards are manufactured in various ways. In the additive technique, an aluminum foil is coated with an adhesive, e.g. acrylonitrile, butadiene or a phenolic-based adhesive. After pressing, this carrier material constitutes a core catalyst on which copper may be chemically deposited. The core catalyst may also be cast or may be coated by immersion. This coating is dried at a temperature of 140C.
After cutting and drilling, etching is performed in a mixture of chronic and sulfuric acids. This is followed by the screen printing process and the further copper plating by chemical means.
Another method uses a base material which is laminated with a copper foil. Pressure is applied via the screen printing process. The areas which remain exposed are etched.
The methods used heretofore for the production of printed circuit boards require relatively complicated and expensive procedures. The production of a base core catalyst, in particular, is a very costly step.
The known methods for the production of printed circuit boards also have disadvantages aside from their high cost. Thus, they contribute strongly to environmental polution and require large amounts and material and labor.
According to the invention, a printed circuit board 3 ~77973 having a printed circuit of a predetermined pattern includes a substrate and an adhesive layer on the substrate conforming to the pattern. A base layer is provided on the adhesive layer and an electrically conductive layer is chemically deposited on and bonded to the base layer. In accordance with one feature of the invention, the adhesive layer is substantially free of solvent when the base layer is applied thereto.
me electrically conductive layer is deposited in a t~ickness sufficient to carry the current which is supplied to the printed circuit board.
The substrate which receives the adhesive layer is preferably non-conductive.
The invention further provides a method of ~aking a printed circuit bcard having a printed circuit of a predetermined pattern. m e method involves applying an adhesive layer to a substrate in conformance with the pattern and coating the adhesive layer with an electrically conductive layer.
According to a preferred em~odiment of the method, the adhesive layer is pressed onto a non-conductive substrate in accordance with the predetermined pattern of the printed circuit and the solvent present in the adhesive layer is removed there-from. A foil oomposed of a material which is capable of bonding to a chemically deposited, electrically conductive substance is pressed onto the adhesive layer after removal of the solvent but before the adhesive layer has set or hardened. After the adhesive layer has set, the foil is peeled away in such a manner that the portions of the foil corresponding to the pattern of the printed circuit and the adhesive layer remain on the latter.
The portions of the foil which remain bound to the adhesive layer constitute a base or base layer for the electrically ~.s"~
~77973 conductive layer. The electrically conductive layer, which is advantageously metallic, is subsequently chemically desposited on the base layer in a predetermined thickness sufficient to carry the current which is supplied to the circuit board.
m e only pretreatment which the substrate requires is a degreasing, m e ninin~m di:stance of separation between the conducting strips of the printe circuit to be produced, as well as the fineness of the conducting strips, are deternuned by the particular manner in which pressure is applied.
m e base layer, which is capable of being chemically metallized and via which chemical metallization of the adhesive layer is effected, may be desposited in very precise thicknesses.
The base layer may be very thin (100-400 Angstroms) so that only small amounts of chemically metallizable material are required to produce the sante. m is makes it possible to form the b~se layer from expensive materials such as, for example, noble rltetals and valuable rare ear~ls t~;~ich ena~le good deposits of tile chem-ically deposited, electrically conductive layer to be achieved.
me invention does not require the substrate to be provided with a core catalyst or to be etched. Rather, only those areas corresponding to the electrically conductive layer, i.e. the conducting strips of the printed circuit, are coated with a layer which is capable of being chemically metallized and which forms the base for the metallic, electrically conduc-tive layer to be deposited by chemical means. me electrically conductive layer may be made of any metal which can be deposited via chemical metallization. Accordingly, the base layer may be deposited on the adhesive layer independently of the particular ~tetal which is selected fDr the electrically conductive layer or strips. A printed circuit board ~anufactured in accordance with ~ ~'77973 the invention is inexpensive as regards both the manufacturing operations and the basic materials to be used.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved printed circuit board itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.
Figure 1 is a cross-section through a degreased substrate;
Figure 2 is a cross-section through the substrate of Figure 1 illustrating the application of an adhesive layer to the substrate;
Figure 3 is a cross-section through the substrate of Figure 2 showing the application of a foil of a base metal to the adhesive layer of the substrate;
Figure 4 is a cross-section through the substrate of Figure 3 illustrating the removal of those portions of the foil which do not adhere to the adhesive layer of the substrate; and Figure 5 schematically illustrates an apparatus for manufacturing printed circuit boards in accordance with the invention.
Figure 1 illustrates a substrate 1 which is to be provided with electrically conductive strips or paths forming the printed circuit of a printed circuit board. The substrate 1 has been degreased in a known and non-illustrated manner.
As seen in Figure 5, which schematically illustrates an apparaius advantageously used for carrying out the method of the invention, the substrate l is placed in a non-illustrated supply vessel together with other similar substrates. In the illustrated embodiment, the substrate l and the other substrates are assumed to be in the form of individual sheets or wafers and are arranged in a stack. However, it is also possible for the substrate l and the other substrates to be supplied from a roll.
Referring to Figures 2 and 5, the substrate l is conveyed from the stack to a printing station 3 where a layer 4 of adhesive is applied to or imprinted upon the substrate l.
The adhesive layer 4 is applied to the substrate l in a pattern which corresponds to that of the printed circuit to be formed on the substrate l. In other words, the adhesive layer 4 is not applied to the substrate l uniformly but only in those areas where the conducting strips of the printed circuit are to be located. The adhesive layer 4 may be applied to the substrate l by means of the screen printing process or the intaglio process.
The adhesive used for the adhesive layer 4 will generally be a dry lamination adhesive which should be free of solvent at the time of lamination. As seen in Figure 5, a drying station 9 for careful drying of the adhesive layer 4 is located downstream of the printing station 3. All of the solvent contained in the adhesive layer 4 is driven out of the same in the drying station 9. Instead of using a solvent-containing adhesive for the adhesive layer 4, it is possible to use an adhesive which contains no solvent.
After leaving the drying station 9, the adhesive layer 4, which is now free of solvent, is brought into contact with a strip 18 consisting of a carrier 12 and a metallic foil lO.
~;"7~73 This is shown in Figures 3 and 5. As best seen in Figure 5, the strip 18 is produced by passing the carrier 12 through a vapor deposition station 13 in which the metallic foil 10 is vapor-deposited on the carrier 12~ The vapor deposition station 13 accommodates a metallic bath 15 and a heating unit 14. Both an electrical field and a vacuum are maintained in the vapor deposition station 13. The heating unit 14 heats the metallic bath 15 to such a high temperature that metal ions 16 are released from the bath 15 and, under the influence of the electrical field and the vacuum, travel upwards towards the carrier 12 and are deposited on the latter.
Referring again to Figure 3 in conjunction with Figure 5, the metallic foil 10 of the strip 18 is pressed against the adhesive layer 4 by a pair of rolls 11. The rolls 11 press the metallic foil 10 against the adhesive layer 4 in such a manner that the metallic foil 10 adheres to the adhesive layer 4 at all locations where the metallic foil 10 and adhesive layer 4 come into contact. The rolls 11 may be heated in order to achieve adhesion between the metallic foil 10 and the adhesive layer 4.
After being compressed by the rolls 11, the adhesive layer 4 sets or hardens while in engagement with the strip 18.
Once the adhesive layer 4 has set, the metallic foil 10 firmly adheres to the adhesive layer 4. The adhesion between the metallic foil 10 and the adhesive layer 4 is so great that, when the carrier 12 is peeled away, the portions of the metallic foil 10 which adhere to the adhesive layer 4 remain bound to the latter. The adhesion between the metallic foil 10 and the adhesive layer 4 is much greater than the cohesion between the metallic foil 10 and the carrier 12. It is only along the adhesive layer 4 that portions of the metallic foil 10 continue l~t77973 to adhere to the substrate 1 upon rem~val of the carrier 12.
me edges of those portions of the metallic foil 10 which remain on the adhesive layer 4 are well-defined.
Subsequent to setting of the adhesive layer 4, the carrier 12 may be readily removed from the substrate 1. As illustrated in Figure 4, those portions of the metallic foil 10 which do not contact the adhesive layer 4 continue to adhere to the carrier 12 when this is peeled away from the substrate 1.
After removal of the carrier 12, a pretreated, printed circuit board 19 is obtained as shown in Figure 5. The adhesive layer 4 of the pretreated board 19 has a metallic coating which is constituted by the portions of the metallic foil 10 left behind upon removal of the carrier 12 and which forms a base layer capa~le of bonding to a chemically deposited, electrically conductive metal. As illustrated in Figure 5, the pretreated board 19 is conveyed through a bath 17 in which a layer of an electri~lly conductive metal is chemically deposited on the base layer and is konded thereto. The chemical metallization which occurs in the bath 17 takes place in a known mEnner. The electrically conductive layer of the finished printed circuit board 20 emerging from the bath 17 has a thickness which is adjusted to the magnitude of the electrical current to be supplied to the printed circuit board 20.
As already mentioned, the substrate 1 may be in the form of a sheet or wafer. Such a sheet may be composed of a phenolic resin. It is also possible for the substrate 1 to be composed of paper, and epoxy web or woven epoxy sheet, epoxy paper or a non-woven epoxy sheet and phenolic resin paper or a sheet of non-woven phenolic resin. In addition, melanine resins have been found suitable for the substrate 1. Other materials .
1~t77973 which can be used for the substrate 1 are polyesters, polyimides, polycarbonates and polysulfanes. It is further p~ssible to use inexpensive papers which are coated or laminated with a poly-ester, a polyimide, a polycarbonate or a polysulfane.
me adhesive layer 4 may be composed of a reactive resin system. Fbr instance, a polyurethane may be used as an adhesive. m e adhesive may be hardenable by contact with atmospheric moisture or when exposed to electron beam radiation.
It is likewise possible to use an adhesive which sets or hardens under the influence of ultravîolet light. me adhesive may also be in the form of a multicomponent system. Thus, an isocyanate-containing resin may be used. It is further possible to utilize a hardenable ep~xy resin. In addition, an acrylic resin system may be used as an adhesive.
As mentioned earlier, the adhesive layer 4 may be applied to the substrate 1 of a printed circuit board, for example, by means of the screen printing process or the intagli~o process. me screen printing process has the advantage that the adhesive layer 4 may be produced more readily and cheaply.
The base layer which i5 capable of being chemically metallized may be composed of a non-ferrous metal. Thus, oopper or nickel may be used for producing the base layer. The base layer may also be composed of a noble meta] and, in particular, gold or silver. In addition, elements of the rare earths group which are capable of being chemically metallized may be used for the base layer. It is to be understood that the base layer need not be constituted by a metal but may be composed on any substance which is capable o~ banding to a chemically deposited metal~
The carrier 12 may be provided with a parting layer -~ ~77973 prior to vapor deposition of the material which is to form the base layer. The purpose of the parting layer is to facilitate disengagement of the material whichis to form the base layer from the carrier 12. m e parting layer must be such that it does not adhere to the material of the base layer under any circumstances. mus, the base layer must be absolutely clean so that the metallization in the chemical metallizing bath 17 takes place without difficulty. The parting layer may consist of wax which is firmly secured to the carrier 12. It is further possible for the parting layer to be composed of a silicone which firmly adheres to the carrier 12. A parting lacquer or varnish which releases more readily from the material of the base layer than from the carrier 12 may likewise be utilized for the parting layer.
Appropriate selection of the material of the carrier 12 is advantageous. Materials which may be used for the carrier 1~ include polypropylenes, polyesters and polycarb~nates.
m e coating of the adhesive layer 4 with a base layer which is capable of bonding to a chemically deposited metal may also be achieved by means of the known sputtering process.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by ~; applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptions should and are intended to be comprehended within the meaning and range of equivalents of the appended claims.
.
Claims (51)
1. A printed circuit board having a printed circuit of a predetermined pattern, said circuit board ccmprising:
(a) a substrate;
(b) an a adhesive layer on said substrate having said pattern;
(c) a metal foil base layer on said adhesive layer, said adhesive layer having been substantially free of solvent when said base layer was applied thereto; and (d) an electrically conductive layer chemically deposited on and bonded to said base layer.
(a) a substrate;
(b) an a adhesive layer on said substrate having said pattern;
(c) a metal foil base layer on said adhesive layer, said adhesive layer having been substantially free of solvent when said base layer was applied thereto; and (d) an electrically conductive layer chemically deposited on and bonded to said base layer.
2. The circuit board of claim 1, wherein said substrate is substantially non-conductive.
3. The circuit board of claim 2, wherein said circuit board is designed for a predetermined electrical current and said conductive layer has a thickness sufficient to carry the current.
4. The circuit board of claim 1, wherein said adhesive layer is hardenable by contact with moisture.
5. The circuit board of claim 1, wherein said adhesive layer is hardenable by irradiation with an electron beam.
6. The circuit board of claim 1, wherein said adhesive layer is hardenable by irradiation with ultraviolet light.
7. The circuit board of claim 1, wherein said adhesive layer comprises a reactive resin.
8. The circuit board of claim 1, wherein said adhesive layer is a multicomponent system.
9. The circuit board of claim 1, wherein said adhesive layer comprises an isonate-containing resin.
10. The circuit board of claim 1, wherein said adhesive layer comprises a hardenable epoxy resin.
11. The circuit board of claim 1, wherein said adhesive layer comprises an acrylic resin.
12. The circuit board of claim 1, wherein said adhesive layer comprises a polyurethane.
13. The circuit board of claim 1, wherein said base layer comprises a non-ferrous metal.
14. The circuit board of claim 13, wherein said metal is copper.
15. The circuit board of claim 13, wherein said metal is nickel.
16. The circuit board of claim 1, wherein said base layer comprises a noble metal.
17. The circuit board of claim 16, wherein said metal is gold.
18. The circuit board of claim 16, wherein said metal is silver.
19. The circuit board of claim 1, wherein said base layer comprises a rare earth.
20. The circuit board of claim 1, wherein said substrate comprises a phenolic resin.
21. The circuit board of claim 20, wherein said substrate comprises a non-woven sheet of phenolic resin.
22. The circuit board of claim 1, wherein said substrate comprises a non-woven sheet of an epoxy resin.
23. The circuit board of claim 1, wherein said substrate comprises a woven sheet of an epoxy resin.
24. The circuit board of claim 1, wherein said substrate comprises a melamine resin.
25. The circuit board of claim 1, wherein said substrate comprises a polyester.
26. The circuit board of claim 1, wherein said substrate comprises a polyimide.
27. The circuit board of claim 1, wherein said substrate comprises a polycarbonate.
28. The circuit board of claim 1, wherein said substrate comprises a polysulfane.
29. The circuit board of claim 1, wherein said substrate comprises paper.
30. The circuit board of claim 29, wherein said paper is coated with a polyester.
31. The circuit board of claim 29, wherein said paper is coated with a polyimide.
32. The circuit board of claim 29, wherein said paper is coated with a polycarbonate.
33. The circuit board of claim 29, wherein said paper is coated with a polysulfane.
34. The circuit board of claim 1, wherein said electrically conductive layer is metallic.
35. A method of making a printed circuit board having a printed circuit of a predetermined pattern, said method comprising the steps of:
(a) applying an adhesive to a substrate in said predetermined pattern to form an adhesive layer substantially free of solvent:
(b) adhering a metal foil base layer to said adhesive layer; and (c) chemically depositing an electricallly conductive layer on said base layer.
(a) applying an adhesive to a substrate in said predetermined pattern to form an adhesive layer substantially free of solvent:
(b) adhering a metal foil base layer to said adhesive layer; and (c) chemically depositing an electricallly conductive layer on said base layer.
36. The method of claim 35, wherein said adhesive includes a solvent; and further comprising removing said solvent from said adhesive to form said adhesive layer.
37. The method of claim 35, wherein the adhering step comprises contacting said adhesive layer with a metal foil of said base layer and thereafter dis-engaging said foil from said adhesive layer in such a manner that the portions of said foil corresponding to said pattern remain secured to said adhesive layer.
38. The method of claim 37, comprising vapor-depositing said foil on a carrier prior to the adhering step; and wherein the disengaging step com-prises peeling said carrier from said adhesive layer.
39. The method of claim 38, comprising applying a parting layer to said carrier prior to the vapor-depositing step, said parting layer adhering to said carrier subsequent to the disengaging step.
40. The method of claim 39, wherein said parting layer comprises a wax.
41. The method of claim 39, wherein said parting layer comprises a silicone.
42. The method of claim 39, wherein said part-ing layer comprises a lacquer.
43. The method of claim 38, wherein said carrier comprises a polypropylene.
44. The method of claim 38, wherein said carrier comprises a polyester.
45. The method of claim 38, wherein said carrier comprises a polycarbonate.
46. The method of claim 37, comprising harden-ing said adhesive layer prior to the disengaging step.
47. The method of claim 46, said circuit board being designed for a predetermined electrical current, and said electrically conductive layer being metallic and deposited in a thickness sufficient to carry said current, said substrate being substantially non-conductive: and wherein said adhesive layer includes a solvent and the solvent is removed from said adhesive layer prior to the adhering step.
48. The method of claim 35, wherein said electrically conductive layer is metallic.
49. The method of claim 35, wherein said sub-strate is substantially non-conductive.
50. The method of claim 35, wherein the apply-ing step is performed using a screen printing process.
51. The method of claim 35, wherein the apply-ing step is performed using an intaglio process.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000384488A CA1177973A (en) | 1981-08-24 | 1981-08-24 | Printed circuit board and method of making the same |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000384488A CA1177973A (en) | 1981-08-24 | 1981-08-24 | Printed circuit board and method of making the same |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1177973A true CA1177973A (en) | 1984-11-13 |
Family
ID=4120782
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000384488A Expired CA1177973A (en) | 1981-08-24 | 1981-08-24 | Printed circuit board and method of making the same |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1177973A (en) |
-
1981
- 1981-08-24 CA CA000384488A patent/CA1177973A/en not_active Expired
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