Multilayer printed wiring boards, multilayer metal-clad laminates, and resin-coated metal foils

Abstract

The present invention relates to a multilayer printed wiring board having one or more insulating layers 2 and formed by alternately laminating conductive layers 1 and insulating layers 2. Each of the one or more insulating layers 2 is formed only of a polyolefin resin layer 3, only of a liquid crystal polymer resin layer 4, or of a polyolefin resin layer 3 and a liquid crystal polymer resin layer 4. The liquid crystal polymer resin layer 4 accounts for 5 to 90% by volume relative to the total volume of the one or more insulating layers 2.

Description

[0001] The present application is a divisional application of an application having an international application date of January 5, 2016, an international application number of PCT / JP2016 / 000010, a national application number of 201680006150.0, and an invention title of “Multilayer printed wiring board, multilayer metal-clad laminate, and metal foil coated with resin”. Technical Field

[0002] The present invention generally relates to a multilayer printed wiring board, a multilayer metal-clad laminate, and a resin-coated metal foil, and particularly relates to a multilayer printed wiring board, a multilayer metal-clad laminate, and a resin-coated metal foil used in electronic equipment that processes high-speed signals. Background Art

[0003] In order to realize a ubiquitous society, the speed of information transmission has been continuously increasing faster and faster. Printed wiring boards such as fluororesin boards and polyphenylene ether (PPE) resin boards are currently used to process high-speed signals. For example, a material for a polyphenylene ether board is disclosed in JP 2006-516297 A (hereinafter referred to as "Document 1").

[0004] In addition, a multilayer printed wiring board that can be processed in the same manner as conventional printed wiring boards such as epoxy resin boards and polyimide resin boards has been proposed to reduce the transmission loss of high-speed signals and suppress disconnection of through-hole plating and the like due to improved heat shock resistance. For example, as disclosed in JP 2011-216841 A (hereinafter referred to as "Document 2"), the above printed wiring board comprises conductive layers and insulating layers alternately stacked, and the insulating layer comprises: one or more thermosetting resin layers prepared by impregnating glass cloth with a thermosetting resin containing an inorganic filler and a polyphenylene ether resin and curing it; and one or more liquid crystal polymer resin layers, which account for 5 to 80% by volume of the entire insulating layer. SUMMARY OF THE INVENTION

[0005] As described above, fluororesin boards and PPE resin boards are currently the mainstream of cutting-edge printed wiring boards for processing high-speed signals.

[0006] However, in the process of manufacturing fluororesin boards, the processing methods used for conventional printed wiring boards such as epoxy resin boards and polyimide resin boards cannot be adopted. Instead, a special processing method is required, which is problematic in terms of cost. In addition, because the fluororesin board has a large thermal expansion coefficient and low thermal shock resistance, problems such as through-hole plating disconnection may occur.

[0007] On the other hand, in manufacturing the PPE resin board as described in Document 1, processing methods used for conventional printed wiring boards such as epoxy resin boards and polyimide resin boards can be adopted. However, there is a problem that the PPE resin board is inferior to the fluororesin board in terms of transmission characteristics of high-speed signals.

[0008] For the multilayer printed wiring board of Document 2, since one or more liquid crystal polymer resin layers account for 5 to 80% by volume of the entire insulating layer, it is possible to reduce the transmission loss of high-speed signals. In addition, since the rest of the insulating layer other than the one or more liquid crystal polymer resin layers is reinforced with glass cloth and contains one or more thermosetting resin layers containing inorganic fillers, the thermal shock resistance is increased and disconnection of through-hole plating and the like can be suppressed.

[0009] However, since the insulating layer of the above multilayer printed wiring board includes one or more thermosetting resin layers reinforced with glass cloth, there is a problem that the above multilayer printed wiring board is not suitable for a substrate required to have flexibility.

[0010] The present invention has been made in view of the above circumstances, and the present invention is intended to provide a multilayer printed wiring board, a multilayer metal-clad laminate, and a resin-coated metal foil, which can be processed in the same manner as conventional printed wiring boards such as epoxy resin boards and polyimide resin boards, reduce the transmission loss of high-speed signals, and be used as a flexible material.

[0011] A multilayer printed wiring board according to the present invention comprises

[0012] One or more insulating layers and at least one conductive layer are alternately stacked,

[0013] The one or more insulating layers include at least one liquid crystal polymer resin layer, so that each of the one or more insulating layers includes at least one layer selected from the group consisting of at least one polyolefin resin layer and the at least one liquid crystal polymer resin layer, and

[0014] The volume percentage of the at least one liquid crystal polymer resin layer relative to the one or more insulating layers is in the range of 5 to 90%.

[0015] The multi-layer metal-clad laminate according to the present invention comprises:

[0016] One or more insulating layers and at least one conductive layer stacked alternately; and

[0017] at least one metal layer, the at least one metal layer serving as at least one of the opposing outermost layers of the multi-layer metal-clad laminate,

[0018] the one or more insulating layers include at least one liquid crystal polymer resin layer, so that each of the one or more insulating layers includes at least one layer selected from the group consisting of at least one polyolefin resin layer and the at least one liquid crystal polymer resin layer,

[0019] The volume percentage of the at least one liquid crystal polymer resin layer relative to the one or more insulating layers is in the range of 5 to 90%,

[0020] Each of the at least one polyolefin resin layer contains a component (A) representing a polyolefin-based elastomer and a component (B) representing a thermosetting resin, and

[0021] The weight percentage of the component (A) representing the polyolefin-based elastomer relative to the at least one polyolefin resin layer is in the range of 50 to 95%.

[0022] The resin-coated metal foil according to the present invention comprises:

[0023] Metal foil; and

[0024] a stack on the metal foil, the stack comprising a first insulating layer and a second insulating layer, the first insulating layer and the second insulating layer being arranged in this order starting from the metal foil,

[0025] The first insulating layer is: an insulating layer that does not include at least one polyolefin resin layer but includes at least one liquid crystal polymer resin layer; or an insulating layer that includes the at least one polyolefin resin layer and the at least one liquid crystal polymer resin layer,

[0026] The second insulating layer comprises at least one semi-cured polyolefin resin layer,

[0027] The percentage of the volume of the at least one liquid crystal polymer resin layer relative to the total volume of the first insulating layer and the second insulating layer is in the range of 5 to 90%,

[0028] Each of the at least one polyolefin resin layer and the at least one semi-cured polyolefin resin layer contains a component (A) representing a polyolefin-based elastomer and a component (B) representing a thermosetting resin, and

[0029] The percentage by weight of the component (A) representing the polyolefin-based elastomer relative to the total weight of the at least one polyolefin resin layer and the at least one semi-cured polyolefin resin layer is in the range of 50 to 95%. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a schematic cross-sectional view illustrating one example of a multilayer printed wiring board.

[0031] Figure 2 A is a schematic cross-sectional view illustrating another example of a multi-layer metal clad laminate. Figure 2 B is a schematic cross-sectional view of another example of a multi-layer metal-clad laminate.

[0032] Figure 3 A is a schematic cross-sectional view illustrating an example of a metal foil coated with a resin. Figure 3 B is a schematic cross-sectional view illustrating another example of the metal foil coated with the resin.

[0033] Figure 4 A is a schematic cross-sectional view illustrating one example of an insulating layer. Figure 4 B is a schematic cross-sectional view illustrating another example of the insulating layer. Figure 4 C is a schematic cross-sectional view illustrating another example of the insulating layer. Figure 4 D is a schematic cross-sectional view illustrating another example of the insulating layer. Figure 4 E is a schematic cross-sectional view illustrating another example of the insulating layer.

[0034] Figure 5 A is a schematic cross-sectional view illustrating an example of a metal clad laminate. Figure 5 B is a schematic cross-sectional view illustrating another example of a printed wiring board.

[0035] Implementation Description

[0036] Embodiments according to the present invention are described hereinafter.

[0037] <Multi-layer metal-clad laminate>

[0038] First, the multilayer metal clad laminate 20 of the present embodiment is explained. The multilayer metal clad laminate 20 can be used as a material for the multilayer printed wiring board 10 explained later. Figure 2 A illustrates an example of a multi-layer metal-clad laminate 20. The multi-layer metal-clad laminate 20 includes: one or more insulating layers 2 and at least one conductive layer 1 alternately stacked; at least one metal layer 5, which serves as at least one of the opposite outermost layers of the multi-layer metal-clad laminate 20. The at least one conductive layer 1 actually has one or more patterned conductors constituting a plurality of circuits; however, in Figure 2 At least one conductive layer 1 is shown in a simplified manner in A. At least one metal layer 5 is, for example, a layer formed by unfolding a metal plane. As explained, the multi-layer metal-clad laminate 20 includes at least one conductive layer 1 therein. Figure 2The multi-layer metal-clad laminate 20 shown in A has two insulating layers 2, one conductive layer 1, and two metal layers 5. However, the number of insulating layers 2, the number of conductive layers 1, and the number of metal layers 5 are not particularly limited. Figure 2 In the multilayer metal-clad laminate 20 shown in A, two insulating layers 2 are stacked with a conductive layer 1 therebetween, and two metal layers 5 are arranged as opposite outermost layers of the multilayer metal-clad laminate 20 in the thickness direction (stacked direction). The multilayer metal-clad laminate 20 can be manufactured by using the following: a printed wiring board 6 explained later; a polyolefin resin sheet and a liquid crystal polymer film that can be used to form one or more insulating layers 2; and a metal foil such as a copper foil that can be used to form at least one conductive layer 1 and at least one metal layer 5. The polyolefin resin sheet is made of a polyolefin resin and is used to form a polyolefin resin layer 3. The liquid crystal polymer film is made of a liquid crystal polymer resin and is used to form a liquid crystal polymer resin layer 4.

[0039] The one or more insulating layers 2 include at least one liquid crystal polymer resin layer, so that each of the one or more insulating layers 2 includes: (1) an insulating layer made by using at least one polyolefin resin layer 3 without using any liquid crystal polymer resin layer 4; (2) an insulating layer made by using at least one liquid crystal polymer resin layer 4 without using any polyolefin resin layer 3; or (3) an insulating layer made by using at least one polyolefin resin layer 3 and at least one liquid crystal polymer resin layer 4. Note that the insulating layer 2 made by using at least one polyolefin resin layer 3 and at least one liquid crystal polymer resin layer 4 can be interpreted as: an insulating layer 2 including at least one polyolefin resin layer 3 and at least one liquid crystal polymer resin layer 4. Since each of the one or more insulating layers 2 includes (1), (2) or (3) as explained above instead of the fluororesin layer requiring special processing, the multilayer metal clad laminate 20 can be processed in the same manner as conventional printed wiring boards such as epoxy resin boards and polyimide resin boards.

[0040] Figure 4 A to Figure 4 E illustrates a specific example of the layered structure of the insulating layer 2 . Figure 4 A illustrates an insulating layer 2 comprising only a polyolefin resin layer 3, which can be formed by heating and curing one or more polyolefin resin sheets. In this case, one polyolefin sheet may be used, or a laminate of two or more polyolefin sheets may be used. Figure 4 B illustrates the insulating layer 2 including only the liquid crystal polymer resin layer 4, which may be formed of one or more liquid crystal polymer films. In this case, one liquid crystal polymer film may be used, or a stack of two or more liquid crystal polymer films may be used. Figure 4C illustrates an insulating layer 2 in which one polyolefin resin layer 3 is placed between two liquid crystal polymer resin layers 4, which can be formed by heating and curing a composite material sheet prepared by arranging two liquid crystal polymer films on opposite sides of one polyolefin resin sheet. Figure 4 D illustrates an insulating layer 2 in which a liquid crystal polymer resin layer 4 is placed between two polyolefin resin layers 3, which can be formed by heating and curing a composite material sheet prepared by arranging two polyolefin resin sheets on opposite sides of a liquid crystal polymer film. Figure 4 E illustrates an insulating layer 2 in which a polyolefin resin layer 3 and a liquid crystal polymer resin layer 4 are laminated, which can be formed by heating and curing a composite material sheet prepared by laminating a polyolefin resin sheet and a liquid crystal polymer film. Figure 4 A to Figure 4 In the case of E, one polyolefin sheet may be used, or a laminate of two or more polyolefin sheets may be used. Similarly, one liquid crystal polymer film may be used, or a laminate of two or more liquid crystal polymer films may be used.

[0041] Each of the at least one polyolefin resin layer 3 preferably contains a component (A) representing a polyolefin-based elastomer and a component (B) representing a thermosetting resin, and the weight percentage of the component (A) representing the polyolefin-based elastomer relative to the at least one polyolefin resin layer 3 is preferably in the range of 50 to 95%. In the case where the at least one polyolefin resin layer 3 contains a large amount of the component (A) representing the polyolefin-based elastomer, the multilayer metal-clad laminate 20 and the multilayer printed wiring board 10 manufactured by using the multilayer metal-clad laminate 20 can have increased flexibility and improved bendability.

[0042] Component (A) representing a polyolefin-based elastomer preferably contains one or more compounds selected from the group consisting of polystyrene-poly(ethylene / propylene) block-polystyrene copolymer; polystyrene-poly(ethylene-ethylene / propylene) block-polystyrene copolymer; polystyrene-poly(ethylene / butylene) block-polystyrene copolymer; polystyrene-polyisoprene block copolymer; hydrogenated polystyrene-polyisoprene-polybutadiene block copolymer; polystyrene-poly(butadiene / butylene) block-polystyrene copolymer; ethylene-glycidyl methacrylate copolymer; ethylene-glycidyl methacrylate-methyl acrylate copolymer; and ethylene-glycidyl methacrylate-vinyl acetate copolymer.

[0043] Component (B) representing a thermosetting resin preferably contains one or more compounds selected from the group consisting of epoxy resins, phenol resins, bismaleimide resins, and polyphenylene ether oligomers having vinyl groups at both ends.

[0044] Each of the at least one polyolefin resin layer 3 may further contain a component (C) representing a curing accelerator.

[0045] Each of the at least one polyolefin resin layer 3 may further contain a component (D) representing a filler.

[0046] On the other hand, each of the at least one liquid crystal polymer resin layer 4 may be a film made of a liquid crystal polymer (LCP) resin. Examples of the liquid crystal polymer resin may include: a polycondensate of ethylene terephthalate and p-hydroxybenzoic acid, a polycondensate of phenol and phthalic acid and p-hydroxybenzoic acid; and a polycondensate of 2,6-hydroxynaphthoic acid and p-hydroxybenzoic acid.

[0047] <Method for producing a multi-layer metal-clad laminate>

[0048] The multilayer metal-clad laminate 20 can be manufactured by, for example, the following method. First, a metal-clad laminate 60 is prepared. The metal-clad laminate 60 serves as a material for the multilayer metal-clad laminate 20. Examples of the metal-clad laminate 60 may include a laminate in which a metal foil is attached to a Figure 4 A to Figure 4 A single-sided metal-clad laminate having one surface of the insulating layer 2 shown in any one of E, and a metal foil attached to Figure 4 A to Figure 4 E is a double-sided metal laminate on both surfaces of the insulating layer 2 shown in any one of them. As one of these examples, Figure 5 A diagram shows the Figure 4 The metal-clad laminate 60 (double-sided metal-clad laminate) in which the metal layer 5 is provided on both surfaces of the insulating layer 2 shown in B. In this example, the insulating layer 2 is formed of the liquid crystal polymer resin layer 4 and the metal layer 5 is formed of a metal foil. Hereinafter, the metal-clad laminate 60 (refer to Figure 5 A) example; however, the present invention is not limited to this example. An unnecessary portion of one of the metal layers 5 of the metal-clad laminate 60 is removed to form the conductive layer 1. Thus, the metal-clad laminate 60 is transformed into Figure 5 B shows a printed wiring board 6. More specifically, Figure 5 In B, an unnecessary portion of one of the metal layers 5 corresponding to one of the opposite outermost layers of the metal-clad laminate 60 is removed by a method such as etching, and thereby a conductive layer 1 is formed. The other of the metal layers 5 remains as the other of the opposite outermost layers. Note that the conductive layer 1 actually has one or more patterned conductors constituting a plurality of circuits; however, in Figure 5 B shows the conductive layer 1 in a simplified manner. Figure 5As shown in FIG. 2B, when the conductive layer 1 includes a circuit for transmitting a high-speed signal or a circuit having a long transmission distance, it is preferable to form the conductive layer 1 so as to be in contact with the liquid crystal polymer resin layer 4. In this case, the transmission loss of the high-speed signal can be reduced. It is also preferable to form the conductive layer 1 so as to be in contact with the liquid crystal polymer resin layer 4 in terms of improving the heat resistance of the multi-layer metal-clad laminate 20 and the multi-layer printed wiring board 10 manufactured by using the same.

[0049] Subsequently, the printed wiring board 6 and at least one material selected from the group consisting of at least one polyolefin resin sheet and at least one liquid crystal polymer film are alternately laminated, and then heated and pressed to form a Figure 2 The multi-layer metal-clad laminate 20 shown in A is specifically prepared by laminating a polyolefin resin sheet for forming a polyolefin resin layer 3, a liquid crystal polymer film for forming a liquid crystal polymer resin layer 4, and a metal foil for forming a metal layer 5 in this order. Figure 5 B and then heating and pressing them, it is possible to manufacture Figure 2 A multi-layer metal-clad laminate 20 is shown in FIG. One of the insulating layers 2 is composed of two adjacent layers of a polyolefin resin layer 3 and a liquid crystal polymer resin layer 4 .

[0050] Note that you can Figure 2 The number of printed wiring boards 6, the number of polyolefin resin sheets, the number of liquid crystal polymer films and the number of metal foils are increased in the multilayer metal clad laminate 20 shown in A to increase the number of layers in the multilayer metal clad laminate 20. Therefore, further layering can be performed.

[0051] exist Figure 2The multilayer metal-clad laminate 20 shown in A has a structure in which the printed wiring board 6 is arranged on the outside of the multilayer metal-clad laminate 20. In this case, the conductive layer 1 serves as one of the opposite outermost layers of the printed wiring board 6 and the metal layer 5 serves as the other of the opposite outermost layers of the printed wiring board 6. The conductive layer 1 contains one or more patterned conductors constituting a plurality of circuits, and the metal layer 5 is, for example, a layer formed by unfolding a metal plane. When the multilayer metal-clad laminate 20 is manufactured, the printed wiring board 6 is arranged so that the conductive layer 1 is placed inside the multilayer metal-clad laminate 20 and the metal layer 5 is placed on the outside of the multilayer metal-clad laminate 20. On the other hand, when the multilayer metal-clad laminate 20 has a structure (not shown in the figure) in which the entire printed wiring board 6 is arranged inside the multilayer metal-clad laminate 20, the printed wiring board 6 in use has two conductive layers 1 serving as the two opposite outermost layers of the printed wiring board 6. The two conductive layers 1 are contained inside the multilayer metal-clad laminate 20.

[0052] Figure 2 B illustrates another example of a multi-layer metal-clad laminate 20. When manufacturing such a multi-layer metal-clad laminate 20, in addition to the printed wiring board 6 explained above, a single-sided metal-clad laminate can also be used. An example of a single-sided metal-clad laminate is one in which a plurality of metal-clad laminates are provided. Figure 4 A single-sided metal-clad laminate in which a metal layer 5 is provided on one surface of the insulating layer 2 shown in B. In this example, the insulating layer 2 is formed of a liquid crystal polymer resin layer 4 and the metal layer 5 is formed of a metal foil. Since liquid crystal polymers are generally thermoplastic resins, delamination can be easily performed by placing the insulating layer 2 of the above single-sided metal-clad laminate on a printed wiring board 6 and then heating and pressing them at a temperature high enough to melt the liquid crystal polymer.

[0053] One or more insulating layers 2 include at least one liquid crystal polymer resin layer 4, so that each of the one or more insulating layers 2 of the multilayer metal-clad laminate 20 includes: (1) an insulating layer made by using at least one polyolefin resin layer 3 without using any liquid crystal polymer resin layer 4; (2) an insulating layer made by using at least one liquid crystal polymer resin layer 4 without using any polyolefin resin layer 3; or (3) an insulating layer made by using at least one polyolefin resin layer 3 and at least one liquid crystal polymer resin layer 4. Therefore, the multilayer metal-clad laminate 20 can be processed in the same manner as conventional printed wiring boards such as epoxy resin boards and polyimide resin boards. The volume percentage of at least one liquid crystal polymer resin layer 4 relative to the one or more insulating layers 2 is in the range of 5 to 90%. Therefore, the transmission loss of high-speed signals can be reduced. In a specific example, in Figure 2The multilayer metal-clad laminate 20 shown in A has two insulating layers 2 and two liquid crystal polymer resin layers 4. Therefore, the volume percentage of the two liquid crystal polymer resin layers 4 relative to the two insulating layers 2 is in the range of 5 to 90%. The specifications such as thickness and quantity of the printed wiring board 6, the polyolefin resin sheet and the liquid crystal polymer film should be determined and adjusted in advance so as to meet the conditions explained above. In this case, it is also preferred to arrange a conductive layer 1 containing a circuit for transmitting a high-speed signal or a circuit with a long transmission distance so that the conductive layer 1 is in contact with the liquid crystal polymer resin layer 4. Therefore, the transmission loss of the high-speed signal can be reduced. In terms of improving the heat resistance of the multilayer metal-clad laminate 20, it is also preferred to form the conductive layer 1 so that the conductive layer 1 is in contact with the liquid crystal polymer resin layer 4 having high heat resistance.

[0054] Note that the layering may be performed once, twice, or more times. In addition, the number of layers is not particularly limited, but may be determined according to the desired design of the multi-layer metal-clad laminate 20 .

[0055] <Resin-coated metal foil>

[0056] Next, the resin-coated metal foil 30 according to the present embodiment is explained. The resin-coated metal foil 30 can be used as a material for the aforementioned multi-layer metal-clad laminate 20 and the multi-layer printed wiring board 10 explained later. Figure 3 A and Figure 3 B illustrates a specific example of the resin-coated metal foil 30. The resin-coated metal foil 30 includes a metal foil 50 and a laminate on the metal foil 50. The laminate includes a first insulating layer 21 and a second insulating layer 22, which are arranged in this order starting from the metal foil 50.

[0057] The first insulating layer 21 is (1) an insulating layer that does not include at least one polyolefin resin layer 3 but includes at least one liquid crystal polymer resin layer 4 or (2) an insulating layer that includes at least one polyolefin resin layer 3 and at least one liquid crystal polymer resin layer 4. Figure 3 In the resin-coated metal foil 30 shown in A, the first insulating layer 21 includes at least one liquid crystal polymer resin layer 4 and does not include any polyolefin resin layer 3. Figure 3 In the resin-coated metal foil 30 shown in FIG. 1B , the first insulating layer 21 includes at least one polyolefin resin layer 3 and at least one liquid crystal polymer resin layer 4. Figure 3In B, the polyolefin resin layer 3 of the first insulating layer 21 is placed on the metal foil 50; however, the liquid crystal polymer resin layer 4 of the first insulating layer 21 can be placed on the metal foil 50. Incidentally, the liquid crystal polymer resin is generally a thermoplastic resin, and the polyolefin resin is generally a thermosetting resin. Therefore, in the case where the first insulating layer 21 includes at least one liquid crystal polymer resin layer 4 and does not include any polyolefin resin layer 3, the first insulating layer 21 is in a solid state at room temperature, melts when heated, and returns to its solid state when cooled. On the other hand, in the case where the first insulating layer 21 includes at least one polyolefin resin layer 3 and at least one liquid crystal polymer resin layer 4, the first insulating layer 21 is in a cured state or solid state at room temperature, and partially melts when heated, and the partially melted part returns to its solid state when cooled.

[0058] The second insulating layer 22 includes at least one semi-cured polyolefin resin layer 3. The semi-cured state is defined as an intermediate stage of the curing reaction, which is between the A stage of the varnish state and the C stage of the fully cured state. When the curing is carried out to the extent that no viscosity is observed at room temperature, the semi-cured polyolefin resin layer 3 is in a cured state. When heated, the semi-cured polyolefin resin layer 3 first melts and then fully cures to form the polyolefin resin layer 3 in the C stage.

[0059] The volume percentage of the at least one liquid crystal polymer resin layer 4 is in the range of 5 to 90% with respect to the total volume of the first insulating layer 21 and the second insulating layer 22. In this case, the transmission loss of the high-speed signal can be reduced.

[0060] Each of the at least one polyolefin resin layer 3 of the first insulating layer 21 and the at least one semi-cured polyolefin resin layer 3 of the second insulating layer 22 contains a component (A) representing a polyolefin-based elastomer and a component (B) representing a thermosetting resin. In the case where the first insulating layer 21 includes at least one liquid crystal polymer resin layer 4 and does not include any polyolefin resin layer 3, the at least one semi-cured polyolefin resin layer 3 of the second insulating layer 22 contains a component (A) representing a polyolefin-based elastomer and a component (B) representing a thermosetting resin.

[0061] The weight percentage of the component (A) representing the polyolefin-based elastomer relative to the total weight of at least one polyolefin resin layer 3 of the first insulating layer 21 and at least one semi-cured polyolefin resin layer 3 of the second insulating layer 22 is in the range of 50 to 95%. In the case where the first insulating layer 21 includes at least one liquid crystal polymer resin layer 4 and does not include any polyolefin resin layer 3, the weight percentage of the component (A) representing the polyolefin-based elastomer relative to the weight of at least one semi-cured polyolefin resin layer 3 of the second insulating layer 22 is in the range of 50 to 95%. When one or more polyolefin resin layers 3 in the resin-coated metal foil 30 contain a large amount of the component (A) representing the polyolefin-based elastomer, the multi-layer metal-clad laminate 20 and the multi-layer printed wiring board 10 manufactured by using the same can have increased flexibility, resulting in improved bendability.

[0062] The metal foil 30 coated with resin can be manufactured by, for example, the following method. First, a resin sheet or a resin film is placed on the surface of the metal foil 50, which is then heated and pressed to form the first insulating layer 21. Examples of resin sheets may include polyolefin resin sheets, and examples of resin films may include liquid crystal polymer films. There is no substantial conceptual difference between sheets and films. Subsequently, a resin varnish is applied to the surface of the first insulating layer 21 and then dried. Examples of resin varnishes may include polyolefin resin varnishes. Thus, a second insulating layer 22 is formed, and thereby a metal foil 30 coated with resin is obtained. In the metal foil 30 coated with resin, the second insulating layer 22 is in a semi-cured state.

[0063] Specifically, in manufacturing Figure 3 In the process of forming the metal foil 30 coated with the resin shown in A, a liquid crystal polymer film is placed on the surface of the metal foil 50, which is then heated and pressed to form the first insulating layer 21 made of the liquid crystal polymer resin layer 4. Subsequently, a polyolefin resin varnish is applied on the surface of the first insulating layer 21 and then dried. Thus, the second insulating layer 22 made of the semi-cured polyolefin resin layer 3 is formed, and thus the second insulating layer 22 made of the semi-cured polyolefin resin layer 3 is obtained. Figure 3 A shows a metal foil 30 coated with resin.

[0064] In manufacturing Figure 3 In the process of forming the metal foil 30 coated with the resin shown in B, a polyolefin resin sheet and a liquid crystal polymer film are stacked on the surface of the metal foil 50 in the order of the polyolefin resin sheet and the liquid crystal polymer film, which are then heated and pressed to form a first insulating layer 21 including a polyolefin resin layer 3 and a liquid crystal polymer resin layer 4. Subsequently, a polyolefin resin varnish is applied on the surface of the first insulating layer 21 and then dried. Thus, a second insulating layer 22 made of the semi-cured polyolefin resin layer 3 is formed, and thereby a second insulating layer 22 made of the semi-cured polyolefin resin layer 3 is manufactured as in Figure 3B shows a metal foil 30 coated with resin.

[0065] It is also possible to manufacture the following method using the metal foil 30 coated with the resin. Figure 2 The multi-layer metal-clad laminate 20 shown in A can be Figure 3 The second insulating layer 22 of the metal foil 30 coated with resin shown in A is placed Figure 5 The conductive layer 1 of the printed wiring board 6 shown in B is then heated and pressed to produce Figure 2 The multilayer metal-clad laminate 20 shown in A. When the second insulating layer 22 of the metal foil 30 coated with resin is changed from a semi-cured state to a fully cured state, the printed wiring board 6 and the metal foil 30 coated with resin adhere to each other. Two adjacent layers of the first insulating layer 21 and the second insulating layer 22 (polyolefin resin layer 3 after curing) form an insulating layer 2. Therefore, the second insulating layer 22 (semi-cured polyolefin resin layer 3) of the metal foil 30 coated with resin acts as an adhesive layer. Because the melting point of the semi-cured polyolefin resin is much smaller than the melting point of the liquid crystal polymer resin, the metal foil 30 coated with resin according to the present embodiment can be formed under milder conditions, resulting in excellent processability. Therefore, the metal foil 30 coated with resin is suitable for the material of the multilayer metal-clad laminate 20 and the multilayer printed wiring board 10.

[0066] <Multilayer printed wiring board>

[0067] Next, the multilayer printed wiring board 10 according to the present embodiment is explained. The multilayer printed wiring board 10 is manufactured by forming the conductive layer 1 on the multilayer metal-clad laminate 20. The conductive layer 1 is manufactured by removing unnecessary portions of the metal layer 5 serving as one of the opposite outermost layers of the multilayer metal-clad laminate 20 by etching. Figure 1 An example of a multilayer printed wiring board 10 according to the present embodiment is shown. The multilayer printed wiring board 10 includes one or more insulating layers 2 and at least one conductive layer 1 which are alternately stacked. Figure 1 The multilayer printed wiring board 10 shown in FIG. 1 includes two insulating layers 2 and three conductive layers 1; however, the number of insulating layers 2 and the number of conductive layers 1 are not particularly limited. Figure 1In the multilayer printed wiring board 10 shown in , conductive layers 1 and insulating layers 2 are alternately stacked, and two of the conductive layers 1 serve as opposite outermost layers of the multilayer printed wiring board 10 in the thickness direction (stacked direction). For example, one or more conductive layers 1 of the multilayer printed wiring board 10 can be manufactured by removing unnecessary portions of one or both of the metal layers 5 serving as opposite outermost layers of the multilayer metal-clad laminate 20 by etching. The conductive layer 1 may include, for example, a signal layer, a power supply layer, and a ground layer. Note that the conductive layer 1 of an actual multilayer printed wiring board 10 has one or more patterned conductors constituting a plurality of circuits; however, in Figure 1 The conductive layer 1 is shown in a simplified manner in FIG. The metal layer 5 is, for example, a layer formed by spreading a metal plane. Figure 1 The figure shows a conductor such as a through-hole plating layer for electrically connecting two or more different conductive layers 1.

[0068] Because at least one conductive layer 1 and one or more insulating layers 2 are alternately stacked and one or more insulating layers 2 contain at least one liquid crystal polymer resin layer 4 so that each of the one or more insulating layers 2 contains at least one layer selected from the group consisting of at least one polyolefin resin layer 3 and at least one liquid crystal polymer resin layer 4, instead of containing a fluororesin layer that requires special processing, the multilayer printed wiring board 10 can be processed in the same manner as conventional printed wiring boards such as epoxy resin boards and polyimide resin boards. In addition, because the volume percentage of at least one liquid crystal polymer resin layer 4 relative to the one or more insulating layers 2 is in the range of 5 to 90%, the transmission loss of high-speed signals can be reduced. In addition, because the multilayer printed wiring board 10 does not contain any thermosetting resin layer reinforced with glass cloth but contains at least one polyolefin resin layer 3, the multilayer printed wiring board 10 can be used as a bendable material. In particular, each of the at least one polyolefin resin layer 3 preferably has a temperature range of 25 to 150° C. after being treated at 180° C. for 60 minutes. 5 Up to 10 8 The storage modulus is within the range of 200 Å to 100 Å Pa. In this case, in the multilayer printed wiring board 10 , thermal shock resistance can be increased and disconnection of through-hole plating and the like can be suppressed, further resulting in improved resistance to soldering heat during reflow.

[0069] If the volume percentage of at least one liquid crystal polymer resin layer 4 relative to one or more insulating layers 2 is less than 5%, the transmission loss of the high-speed signal transmitted through the at least one conductive layer 1 cannot be sufficiently reduced, and sufficient heat resistance cannot be ensured. If the volume percentage of at least one liquid crystal polymer resin layer 4 relative to one or more insulating layers 2 exceeds 90%, the thermal expansion coefficient (z-CTE) of the multilayer printed wiring board 10 in the thickness direction (stack-up direction) increases, resulting in low thermal shock resistance, causing lower suppression of disconnection of through-hole plating and the like.

[0070] As explained above, in the present embodiment, since one or more insulating layers 2 include at least one liquid crystal polymer resin layer 4 so that each of the one or more insulating layers 2 includes at least one layer selected from the group consisting of at least one polyolefin resin layer 3 and at least one liquid crystal polymer resin layer 4, the multilayer printed wiring board 10, the multilayer metal-clad laminate 20, and the metal foil 30 coated with resin can be processed in the same manner as conventional printed wiring boards such as epoxy resin boards and polyimide resin boards. In addition, since the volume percentage of at least one liquid crystal polymer resin layer 4 relative to the one or more insulating layers 2 is in the range of 5 to 90%, the transmission loss of high-speed signals can be reduced. In addition, since the multilayer printed wiring board 10, the multilayer metal-clad laminate 20, and the metal foil 30 coated with resin do not include any thermosetting resin layer reinforced with glass cloth, the multilayer printed wiring board 10, the multilayer metal-clad laminate 20, and the metal foil 30 coated with resin can be used as a bendable material. Example

[0071] Hereinafter, the present invention is explained in further detail based on examples.

[0072] For each of Examples 1 to 5 and Comparative Example 1, the Figure 1 The three-layer printed wiring board shown in . For easier explanation, the three conductive layers 1 are distinguished by naming them L1 to L3 in the order of L1 to L3 starting from one of the opposite outermost layers (also used to refer to the copper foil in which the patterned conductor has not yet been formed). Note that the "PCB construction" in Table 1 means the layered structure of the three-layer printed wiring board. In addition, hereinafter, for example, "L1 / L2 copper-clad laminate (or printed wiring board)" means a copper-clad laminate (or printed wiring board) comprising L1 and L2 representing the conductive layer 1, and "L1-L3 three-layer printed wiring board" means a three-layer printed wiring board comprising L1 to L3 representing all three conductive layers 1. Tables 2 and 3 show the resin compositions used to form the polyolefin resin sheets for Examples 1 to 5 and Comparative Example 1.

[0073] (Examples 1-(1) to 1-(11))

[0074] A copper foil having a thickness of 18 μm was laminated on both surfaces of a liquid crystal polymer film having a thickness of 50 μm ("Vecstar" available from KURARAY CO., LTD.), which was then heated and pressed at 310° C. for 10 minutes to prepare an L1 / L2 liquid crystal polymer copper clad laminate. Similarly, a copper foil having a thickness of 18 μm was placed on one surface of the same liquid crystal polymer film as used above, which was then heated and pressed under the same conditions as above to prepare an L3 liquid crystal polymer copper clad laminate.

[0075] Subsequently, L2 of the L1 / L2 liquid crystal polymer copper clad laminate is processed to have a signal layer, and thereby an L1-L2 liquid crystal polymer printed wiring board is obtained.

[0076] The polyolefin resin sheet with a thickness of 25 μm is made from each of the resin compositions (1) to (11) as shown in Table 2. Two polyolefin resin sheets made of the same resin composition are stacked to form an adhesive sheet with a thickness of 50 μm. The adhesive sheet is placed between the L1-L2 printed wiring board and the L3 copper-clad laminate, which is then heated and pressed at 180°C for 60 minutes, and thereby a three-layer metal-clad laminate is prepared. Table 3 shows the product name and manufacturer of the components contained in each of the resin compositions shown in Table 2.

[0077] Subsequently, L1 and L3 of the three-layer metal clad laminate are processed to have a ground layer, and thereby a three-layer printed wiring board is obtained.

[0078] (Examples 2-(1) to 2-(11))

[0079] A three-layer printed wiring board was prepared in the same manner as in Example 1, except that a metal foil having a thickness of 12 μm was used and a polyolefin resin sheet having a thickness of 25 μm was used as an adhesive sheet.

[0080] (Examples 3-(1) to 2-(11))

[0081] A three-layer printed wiring board was prepared in the same manner as in Example 2, except that a liquid crystal polymer film having a thickness of 25 μm was used and eight polyolefin resin sheets having a thickness of 50 μm were used as an adhesive sheet having a thickness of 400 μm.

[0082] (Examples 4-(1) to 4-(11))

[0083] A copper foil having a thickness of 12 μm was stacked on both surfaces of a liquid crystal polymer film having a thickness of 25 μm ("Vecstar" available from KURARAY CO., LTD.), which was then heated and pressed at 310°C for 10 minutes to prepare an L1 / L2 liquid crystal polymer copper-clad laminate. Similarly, a copper foil having a thickness of 12 μm was placed on one surface of the same liquid crystal polymer film as used above, which was then heated and pressed under the same conditions as above to prepare an L3 liquid crystal polymer copper-clad laminate. Subsequently, as a polyolefin resin, each of the resin compositions (1) to (11) shown in Table 2 was coated on the liquid crystal polymer resin layer of the L3 liquid crystal polymer copper-clad laminate and then dried to form a polyolefin resin layer having a thickness of 25 μm. Thus, a liquid crystal polymer single-sided metal-clad laminate was prepared.

[0084] Thereafter, L2 of the L1 / L2 liquid crystal polymer copper clad laminate is processed to have a signal layer, and thereby an L1-L2 liquid crystal polymer printed wiring board is obtained.

[0085] The L1-L2 liquid crystal polymer printed wiring board and the L3 liquid crystal polymer single-sided metal-clad laminate were stacked, and then heated and pressed at 180° C. for 60 minutes. Thus, a three-layer metal-clad laminate was prepared.

[0086] Subsequently, L1 and L3 of the three-layer metal clad laminate are processed to have a ground layer, and thereby a three-layer printed wiring board is obtained.

[0087] (Example 5)

[0088] A three-layer printed wiring board was prepared in the same manner as in Example 1, except that a polyolefin resin sheet having a thickness of 25 μm formed of the resin composition (12) shown in Table 2 was used as the polyolefin resin sheet.

[0089] (Comparative Example 1)

[0090] A three-layer printed wiring board was prepared in the same manner as in Example 1, except that a glass cloth-reinforced polyphenylene ether resin prepreg (prepreg reinforced with glass cloth and containing a polyphenylene ether resin) having a thickness of 100 μm was used as the adhesive sheet.

[0091] The following evaluations were performed on each of Examples and Comparative Examples.

[0092] (Transmission loss)

[0093] The transmission loss in the signal layer of L2 at 5 GHz was measured for the three-layer printed wiring board of each of the embodiment and the comparative example.

[0094] (Flexibility)

[0095] For the three-layer printed wiring board of each of the examples and comparative examples, a patterned conductor of L(line) / S(space)=1 / 1 mm was formed in L1, and the bendability was measured by the MIT method (JIS P 8115).

[0096] (Heat resistance)

[0097] For each of the three-layer printed wiring boards of the embodiment and the comparative example, a 25 mm 2 The heat resistance (JIS C 5012 10.4.1) in solder float was measured under normal conditions (30°C or less, 60%Rh or less) and under wet conditions (60°C, 60%Rh, 120H). The results are shown in Table 1.

[0098]

[0099]

[0100]

[0101]

[0102] In each of Examples 1 to 4, the results of the evaluation conducted on the three-layer printed wiring boards prepared by using the 11 kinds of resin compositions appeared to be the same.

[0103] As indicated by Table 1, each of Examples 1 to 5 exhibited better bendability than Comparative Example 1. Since the glass cloth-reinforced polyphenylene ether resin prepreg was used in Comparative Example 1, Comparative Example 1 did not exhibit any bendability.

[0104] Furthermore, each of Examples 1 to 4 is more excellent in bendability than Example 5, and also exhibits better resistance to soldering heat after moisture absorption than Example 5. Since each of Examples 1 to 4 contains more elastomer than Example 5, each of Examples 1 to 4 is more excellent in flexibility, resulting in better bendability. Furthermore, since the resin used has a large mechanical strength, Examples 1 to 4 exhibit better heat resistance.

Claims

1. A multilayer printed circuit board, comprising: a plurality of insulating layers disposed in a thickness direction; and A plurality of conductive layers arranged in a thickness direction; Disposing at least one of the plurality of insulating layers between any two conductive layers adjacent to each other in the thickness direction of the plurality of conductive layers; one or more of the plurality of insulating layers are polyolefin resin layers, and the remaining layers of the plurality of insulating layers are liquid crystal polymer resin layers, The volume percentage of the entire liquid crystal polymer resin layer relative to the entire plurality of insulating layers is in a range of 67 to 90%.

2. The multilayer printed wiring board according to claim 1, wherein: Two or more of the plurality of insulating layers are disposed between two of the plurality of conductive layers adjacent in the thickness direction.

3. The multilayer printed wiring board of claim 1, wherein: The plurality of conductive layers include a signal layer, a power layer or a ground layer.

4. The multilayer printed wiring board according to claim 3, wherein: The plurality of conductive layers include a signal layer.

5. The multilayer printed wiring board according to claim 4, wherein: The signal layer is in contact with one of the liquid crystal polymer resin layers.

6. The multilayer printed wiring board of claim 4, wherein: The signal layer is disposed between two insulating layers among the plurality of insulating layers.

7. The multilayer printed wiring board of claim 4, wherein: The signal layer includes circuits for transmitting high-speed signals.

8. The multilayer printed wiring board of claim 1, wherein: One or two of the plurality of conductive layers are disposed on the outermost sides in the thickness direction.

9. The multilayer printed wiring board of claim 8, wherein: The one or both conductive layers are arranged to be ground layers.

10. The multilayer printed wiring board of claim 1, wherein: Each of the plurality of insulating layers does not contain glass cloth.

11. The multilayer printed wiring board of claim 1, wherein: Each of the polyolefin resin layers contains a component (A) representing a polyolefin-based elastomer and a component (B) representing a thermosetting resin.

12. The multilayer printed wiring board of claim 11, wherein: The weight percentage of the component (A) representing the polyolefin-based elastomer relative to the entire polyolefin resin layer is in the range of 50 to 95%.

13. The multilayer printed wiring board according to claim 11, wherein The component (A) representing the polyolefin-based elastomer contains one or more compounds selected from the group consisting of polystyrene-poly(ethylene / propylene) block-polystyrene copolymer; polystyrene-poly(ethylene-ethylene / propylene) block-polystyrene copolymer; polystyrene-poly(ethylene / butylene) block-polystyrene copolymer; polystyrene-polyisoprene block copolymer; hydrogenated polystyrene-polyisoprene-polybutadiene block copolymer; polystyrene-poly(butadiene butylene) block-polystyrene copolymer; ethylene-glycidyl methacrylate copolymer; ethylene-glycidyl methacrylate-methyl acrylate copolymer; and ethylene-glycidyl methacrylate-vinyl acetate copolymer.

14. The multilayer printed wiring board according to claim 11, wherein The component (B) representing the thermosetting resin contains one or more compounds selected from the group consisting of epoxy resins, phenol resins, bismaleimide resins, and polyphenylene ether oligomers having vinyl groups at both ends.

15. The multilayer printed wiring board according to claim 11, wherein Each of the polyolefin resin layers further contains a component (C) representing a curing accelerator.

16. The multilayer printed wiring board according to claim 11, wherein Each of the polyolefin resin layers further contains a component (D) representing a filler.

17. The multilayer printed wiring board according to claim 1, wherein The polyolefin resin layers each have a strength of 100 % at a temperature range of 25 to 150° C. after being treated at 180° C. for 60 minutes. 5 Up to 10 8 The storage modulus is in the range of Pa.

18. A multi-layer metal-clad laminate, comprising: a plurality of insulating layers disposed in a thickness direction; and A plurality of conductive layers arranged in a thickness direction; Disposing at least one of the plurality of insulating layers between any two conductive layers adjacent to each other in the thickness direction of the plurality of conductive layers; one or more of the plurality of insulating layers are polyolefin resin layers, and the remaining layers of the plurality of insulating layers are liquid crystal polymer resin layers, The volume percentage of the liquid crystal polymer resin layer as a whole relative to the plurality of insulating layers as a whole is in a range of 67 to 90%, One or two of the plurality of conductive layers are disposed at the outermost sides in the thickness direction, and the one or two conductive layers are metal layers each extending in a plane perpendicular to the thickness direction.

19. A resin-coated metal foil, the resin-coated metal foil comprising: metal foil; A liquid crystal polymer resin layer provided on one surface of the metal foil; and a polyolefin resin layer provided on the side of the liquid crystal polymer resin layer opposite to the metal foil, The polyolefin resin layer is semi-cured, The volume percentage of the liquid crystal polymer resin layer relative to the sum of the polyolefin resin layer and the polyolefin resin layer is in the range of 67 to 90%.

20. The resin-coated metal foil according to claim 19, wherein: The polyolefin resin layer is a first polyolefin resin layer, and the resin-coated metal foil further includes a second polyolefin resin layer provided between the liquid crystal polymer resin layer and the first polyolefin resin layer.

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