JP4805304B2 - Metal foil with carrier and method for producing multilayer coreless circuit board - Google Patents

Description

  The present invention relates to a copper foil with a carrier used in the production of a single-sided or two-layer multilayer board or an ultra-thin coreless substrate used for a printed wiring board.

A typical example of a multilayer laminate is a printed circuit board. In general, a printed circuit board has a basic configuration of a dielectric material called “prepreg” obtained by impregnating a synthetic resin into a base material such as a synthetic resin plate, a glass plate, a glass nonwoven fabric, or paper. Further, a sheet such as copper or copper alloy foil having electrical conductivity is bonded to the side facing the prepreg. The laminated body thus assembled is generally called a CCL (Copper Clad Laminate) material.
A foil made of aluminum, nickel, zinc or the like may be used instead of the copper or copper alloy foil. Their thickness is about 5 to 200 μm.

  For example, in a manufacturing process of a four-layer substrate using CAC (see Patent Document 1), a stainless-steel press plate having a thickness of 0.2 to 2 mm and a smooth press surface (commonly called “mirror plate”). ) On top of a copper foil, a predetermined number of prepregs, and then a printed circuit board on which a circuit is formed on a CCL material called an inner layer core, and then a prepreg, copper foil, and a mirror plate are stacked in this order. An assembly unit made of substrate material is completed. Next, these units (commonly called “pages”) are repeatedly stacked about 2 to 10 times to form a press assembly (commonly called “book”).

Then, the said book is set on the hot plate in a hot press machine, and a laminated board is manufactured by press-molding by predetermined temperature and pressure.
A substrate having four or more layers can be produced in the same process by increasing the number of inner core layers.
At this time, the CAC used is not coated with an adhesive between aluminum and copper foil, but is coated in a frame shape with a width of about 1 mm at a position of about 10 mm inside the four sides. Has been. For this reason, it is difficult to support a copper foil with aluminum over the entire surface, and wrinkles may occur in the copper foil during lamination.

In addition, when the surface of the copper foil of CAC is plated or etched, it cannot be put into a chemical solution. This is because the adhesive used in the CAC is not applied without a gap as described above, and there are gaps between the aluminum and the copper foil, so that the chemical solution enters from there.
Furthermore, the linear expansion coefficient of the aluminum plate (JIS # 5182) used for CAC is 23.8 × 10 ⁻⁶ / ° C., and the copper foil (16.5 × 10 ⁻⁶ / ° C) and the prepreg after polymerization (C stage: 12 to 18 × 10 ⁻⁶ / ° C.), the phenomenon that the substrate size before and after pressing differs from that during design (scaling change) occurs. This causes a positional shift of the circuit in the thickness direction, and there is a problem that contributes to a decrease in yield.

The linear expansion coefficients (room temperature) of various materials used for the printed wiring board are as follows. It can be seen that the linear expansion coefficient of the aluminum plate is prominently large.
Copper foil: 16.5 (× 10 ⁻⁶ / ° C)
SUS304: 17.3 × 10 ⁻⁶ / ° C
SUS301: 15.2 × 10 ⁻⁶ / ° C
・ SUS630: 11.6 × 10 ⁻⁶ / ° C
・ Prepreg (C stage): 12-18 × 10 ^-6 / ° C
Aluminum plate (JIS # 5182): 23.8 × 10 ⁻⁶ / ° C
Japanese Patent No. 3100833

The present invention has been made in view of these events, and relates to a carrier-attached copper foil used in the production of a single-sided or two-layer multilayer board or an ultra-thin coreless board used for printed wiring boards. .
More specifically, the present invention relates to a copper foil with a carrier used in the production of a laminated board, and its purpose is to use a resin as a support and to dispose easily peelable copper foil on one side or both sides of the print. It is an object to realize cost reduction by simplifying the substrate manufacturing process and increasing yield.

As a result of intensive studies to solve the above problems, the present inventors have found that it is effective to use a resin instead of the aluminum of CAC used in the production of a single-sided or double-sided multilayer laminate. Got.
Based on this knowledge, the present invention is based on 1) a synthetic resin plate carrier, and a metal foil with a carrier comprising a metal foil mechanically peelably adhered to at least one surface of the carrier. The metal foil with a carrier according to the above 1), characterized in that it is a prepreg, 3) the synthetic resin is a resin that has changed from a B stage (monomer) to a C stage (polymer) by polymerization of the resin. The metal foil with a carrier according to 1) or 2) 4) The metal foil with a carrier according to any one of 1) to 3) above, wherein the metal foil is a copper foil or a copper alloy foil. provide.

In addition, the present invention
5) The metal foil with a carrier according to any one of 1) to 4) above, wherein the metal foil is an electrolytic foil having a thickness of 5 to 120 μm. 6) The metal foil has a thickness of 5 to 120 μm. A metal foil with a carrier according to any one of claims 1) to 4), wherein the peel strength between the plate-like carrier and the metal foil is 1 g / cm or more and 1 kg / cm. The metal foil with a carrier according to any one of 1) to 6) above, wherein the peeling surface is a boundary between the plate-like carrier and the metal. 8) The coefficient of thermal expansion of the plate-like carrier is metal. The metal foil with a carrier according to any one of 1) to 7) above, which is within + 10% and −30% of the thermal expansion coefficient of the foil.

The present invention is a metal foil with a carrier by sticking a metal foil to at least one surface made of a plate-shaped synthetic resin (Resin), and supports the copper foil over the entire surface with the synthetic resin. Generation of wrinkles on the copper foil during lamination can be prevented. Further, in this metal foil with a carrier, since the metal foil and the synthetic resin are in close contact with each other, when the surface of the metal foil is plated or etched, it can be put into a chemical solution for plating or etching. .
Furthermore, since the linear expansion coefficient of the synthetic resin is at the same level as the copper foil that is a constituent material of the substrate and the prepreg after polymerization, the circuit does not cause a position shift, so that the occurrence of defective products is reduced. It has the outstanding effect that a yield can be improved.

Generally, a printed circuit board uses a dielectric material called “prepreg” obtained by impregnating a synthetic resin into a base material such as a synthetic resin plate, a glass plate, a glass nonwoven fabric, and paper, and sandwiches the prepreg therebetween. Thus, a sheet of copper or copper alloy foil having electrical conductivity is joined. The laminated body thus assembled is generally called a CCL (Copper Clad Laminate) material.
This commonly used CCL (Copper Clad Laminate) material is shown in FIG. Instead of the copper or copper alloy foil, a foil of aluminum, nickel, zinc or the like may be used. Their thickness is about 5 to 200 μm.

The metal foil with a carrier of the present invention is shown in FIG. The metal foil with a carrier is composed of a synthetic resin plate-shaped carrier and a metal foil which is in close contact with at least one surface of the carrier so as to be mechanically peelable. FIG. 2 shows a metal foil with a carrier in which a metal foil is in close contact with both sides of a plate-shaped carrier made of synthetic resin.
The structure is similar to the CCL material shown in FIG. 1, but the metal foil with a carrier of the present invention is a structure in which the metal foil and the resin are finally separated and can be easily separated mechanically. Have In this respect, since the CCL material is not peeled off, the structure and function are completely different.

As the metal foil, copper or copper alloy foil is typical, but foils of aluminum, nickel, zinc and the like can also be used. In the case of copper or copper alloy foil, electrolytic foil or rolled foil having a thickness of 5 to 120 μm can be used.
As the synthetic resin serving as the plate-like carrier, phenol resin, polyimide resin, epoxy resin, or the like can be used. Moreover, the said prepreg can also be used. In particular, a resin in which the synthetic resin is changed from the B stage (monomer) to the C stage (polymer) by polymerization of the resin can be used. As described above, the present invention is a (CRC) having a structure of copper (Cu) -resin (Regin) -copper (Cu) instead of the conventional CAC.
In addition, about the said prepreg, the same thing may be used for the peelable prepreg used for copper foil with a carrier, and the prepreg which comprises a circuit board, and a different prepreg may be used. The peelability and adhesion between the prepreg and the copper foil can be arbitrarily adjusted by the state of the interface with the copper foil and the treatment.

Furthermore, it is desirable that the thermal expansion coefficient of the synthetic resin is within + 10% and −30% of the thermal expansion coefficient of the metal foil. As a result, it is possible to effectively prevent circuit misalignment due to the difference in thermal expansion between the metal foil and the synthetic resin, reduce the occurrence of defective products, and improve the yield.
The plate-like carrier and the metal foil must have appropriate adhesion in a process such as plating or etching. However, since they will be peeled off mechanically, the peel strength of both is 1 g / cm or more, 1 kg / It is desirable that it is cm or less. Furthermore, it is desirable that the peeling surface is the boundary between the plate-like carrier and the metal, and it is necessary to avoid that the residue of the counterpart material remains between them because a removal process is required and the process becomes complicated. Don't be.

  Next, specific examples of the present invention will be described. The following examples are intended to facilitate understanding of the present invention and are not limited thereto. That is, modifications, embodiments, and other examples based on the technical idea of the present invention are included in the present invention.

Example 1
A prepreg produced from an epoxy resin was used as the resin material. A copper foil was bonded to the front and back of the prepreg to obtain a copper foil with a carrier. On this copper foil with a carrier, a desired number of prepregs, then a two-layer printed circuit board called an inner layer core, then a prepreg, and then a copper foil with a carrier are sequentially stacked to form a set of four-layer board material assembly units. Completed.
Next, this unit (commonly called “page”) was repeated about 10 times to form a press assembly (commonly called “book”).

  Thereafter, this book was set in a hot press machine, and a four-layer substrate was manufactured by pressure molding at a predetermined temperature and pressure. In general, a substrate having four or more layers can be produced in the same process by increasing the number of inner core layers. The material thus produced is sandwiched between upper and lower stainless steel hot plates of a press machine and pressed to obtain a laminated plate. Usually, a thick plate of about 50 mm is used as the hot plate, but the thickness is not limited.

  A printed circuit board having a multilayer structure having a prepreg produced in this way forms a circuit through a plating process and / or an etching process, and further peels and separates between the carrier resin and the copper foil to become a finished product. Since the copper foil was supported over the entire surface by the synthetic resin carrier, no wrinkles were observed on the copper foil during the lamination.

Further, in this metal foil with a carrier, the metal foil and the synthetic resin were in close contact with each other without any gap, so that when the surface of the metal foil was plated or etched, it could be put into the plating or etching chemical.
Furthermore, the linear expansion coefficient of the synthetic resin is almost the same level as that of the copper foil as the constituent material of the substrate and the prepreg after polymerization, so that the circuit is not displaced. Therefore, compared with the case where a conventional CAC is used, the generation of defective products is reduced, and the yield can be improved.

(Example 2)
Next, an example of manufacturing an ultrathin substrate will be described with reference to FIGS. In these figures, prepregs are arranged on both sides of a copper foil with a carrier, a copper circuit is formed on the prepreg surface, and a carrier made of resin is further peeled to produce two substrates simultaneously. FIG. As in Example 1, a prepreg made of a phenol resin was used as a resin material to be a carrier. Copper foil was bonded to the front and back of this prepreg to obtain a copper foil with a carrier.

By plating the copper foil with carrier or etching the copper foil about half, L1 (first layer) was formed on both sides of the product of the present invention as shown in FIG.
Next, as shown in FIG. 5, a copper foil layer of L2 (second layer) is formed by stacking a desired number of prepregs and then a copper foil on the front and back of the copper foil with a carrier, and further hot pressing this. Formed. Further, L2 was completed by further circuit formation. Thereafter, L3 (third layer) and the like can be formed in the same manner as necessary. “× n” shown in FIGS. 3 to 7 means a multilayer (n = 1, 2, 3,... N).

After stacking a predetermined number of layers, the copper foil with a carrier was peeled from the interface between the prepreg and the copper foil. This is shown in FIG. Two upper and lower two-layer CCLs are formed.
Next, the entire surface of the peeled surface was etched to form a circuit exposed on the surface. As a result, as shown in FIG. 7, a multilayer ultra-thin coreless substrate could be produced. In addition, in this case, two substrates can be produced simultaneously from the two front and back surfaces of the substrate material formed on a single copper foil with a carrier, so that the production efficiency is improved. Similarly to the above, L2, L3, and so on can be formed in the same manner, so that it is easy to produce a multi-layer ultra-thin coreless substrate.

  The present invention is a metal foil with a carrier by sticking a metal foil to at least one surface made of a plate-shaped synthetic resin (Resin), and supports the copper foil over the entire surface with the synthetic resin. Generation of wrinkles on the copper foil during lamination can be prevented. Further, in this metal foil with a carrier, since the metal foil and the synthetic resin are in close contact with each other, when the surface of the metal foil is plated or etched, it can be put into a chemical solution for plating or etching. . Furthermore, since the linear expansion coefficient of the synthetic resin is at the same level as the copper foil that is a constituent material of the substrate and the prepreg after polymerization, the circuit does not cause a position shift, so that the occurrence of defective products is reduced. Since it has the excellent effect that the yield can be improved, the merit of the metal foil with a carrier obtained by the present invention is great, and is particularly useful for the production of a printed circuit board.

It is a conceptual explanatory view of a CCL material in which a copper foil, a prepreg, and a copper foil are sequentially stacked and adhered. It is explanatory drawing of the copper foil with a carrier of this invention by which copper foil was affixed on both surfaces of the resin substrate. It is explanatory drawing which shows the mode before press molding which piled up the prepreg on the copper foil with a carrier of this invention on the lamination metal mold | die. It is explanatory drawing which shows a mode that L1 was created on both surfaces by plating a copper foil with a carrier or etching a copper foil about half. A plurality of prepregs and then a copper foil are stacked on the front and back of the copper foil with a carrier, and further hot-pressed to form a copper foil layer of L2, and further, a circuit is formed on the copper foil layer to form L2 It is explanatory drawing which shows a mode that it produced. It is explanatory drawing which shows a mode that it peeled from the prepreg of copper foil with a carrier, and the interface of copper foil, and formed two upper and lower two-layer CCL, after piled up a predetermined number of layers. It is explanatory drawing which shows a mode that the circuit exposed to this surface was formed by etching the peeling surface entirely, and the multilayer ultra-thin coreless board | substrate was created.

Claims (10)

A plate-like carrier made of a prepreg and a metal foil with a carrier made of a copper foil or a copper alloy foil mechanically and peelably adhered to at least one surface of the carrier.   2. The metal foil with a carrier according to claim 1, wherein the peel strength between the plate-like carrier and the metal foil is 1 g / cm or more and 1 kg / cm or less, and the peel surface is a boundary between the plate-like carrier and the metal. . The metal foil with a carrier according to claim 1 or 2 , wherein the thermal expansion coefficient of the plate-like carrier is within + 10% and -30% of the thermal expansion coefficient of the metal foil. The metal foil with a carrier according to any one of claims 1 to 3 , wherein the metal foil is an electrolytic foil or a rolled foil having a thickness of 5 to 120 µm.   A circuit is formed by etching a plate-like carrier made of prepreg and a metal foil with a carrier made of metal foil that is mechanically peelably adhered to at least one surface of the carrier, or by etching about half the thickness of the metal foil or metal foil. Next, a step of forming a new metal foil layer by hot pressing the prepreg and metal foil on the circuit, then forming a circuit on the new metal foil layer, After a predetermined number of layers have been stacked, the multilayer coreless circuit board is manufactured by peeling from the interface between the prepreg and metal foil of the metal foil with a plate-like carrier and further etching the peeled surface to expose the circuit. Method. 6. The method for producing a multilayer coreless circuit board according to claim 5 , wherein the metal foil with a carrier is formed by attaching a metal foil to both sides of a plate-like carrier and forming a circuit in advance on both metal foil layers. 7. The method for producing a multilayer coreless circuit board according to claim 5 , wherein the metal foil is a copper foil or a copper alloy foil. Plate carrier and peel strength between the metal foil 1 g / cm or more and 1 kg / cm or less, in any one of claims 5-7 in which the release surface is characterized in that it is a boundary between the prepreg and the metal The manufacturing method of the multilayer coreless circuit board of description. The method for producing a multilayer coreless circuit board according to any one of claims 5 to 8 , wherein the thermal expansion coefficient of the plate carrier is within + 10% and -30% of the thermal expansion coefficient of the metal foil. The method for producing a multilayer coreless circuit board according to any one of claims 5 to 9 , wherein the metal foil is an electrolytic foil or a rolled foil having a thickness of 5 to 120 µm.