Flex-rigid wiring board and method for manufacturing the same

[0084] Next, a description will be given of a rigid-flex circuit board and its manufacturing method according to an embodiment of the present invention.

[0085] Such as Figure 1A as well as Figure 1B As shown, the rigid-flex circuit board 10 of this embodiment roughly includes a first rigid substrate 11, a second rigid substrate 12, and a flexible substrate 13. The first rigid substrate 11 and the second rigid substrate 12 are opposed to each other via the flexible substrate 13. 地Configuration. In detail, the first rigid substrate 11 and the second rigid substrate 12 are arranged in the horizontal direction of the flexible substrate 13.

[0086] Arbitrary circuit patterns are respectively formed on the first rigid substrate 11 and the second rigid substrate 12. In addition, as necessary, for example, electronic components such as semiconductor chips are connected. On the other hand, a strip-shaped wiring pattern 13 a for connecting the circuit pattern of the first rigid substrate 11 and the circuit pattern of the second rigid substrate 12 is formed on the flexible substrate 13. The wiring pattern 13 a connects the circuit patterns of the rigid substrates 11 and 12.

[0087] Such as figure 2 As shown in the detailed structure of the flexible substrate 13, the flexible substrate 13 has a structure in which a base material 131, conductor layers 132 and 133, insulating layers 134 and 135, shielding layers 136 and 137, and covering layers 138 and 139 are laminated. .

[0088] The base material 131 is composed of an insulating flexible board. The insulating flexible board has a thickness of, for example, "20-50 μm". Preferably, the insulating flexible board is a polyimide board with a thickness of approximately "30 μm".

[0089] The conductor layers 132 and 133 are composed of, for example, a copper pattern having a thickness of about "5 to 15 μm", and are formed on the surface and back of the base material 131 to form the aforementioned striped wiring pattern 13a ( Figure 1B ).

[0090] The insulating layers 134 and 135 are made of a polyimide film or the like having a thickness of about "5-15 μm", and insulate the conductor layers 132 and 133 from the outside.

[0091] The shielding layers 136 and 137 are composed of a conductive layer, such as a cured film of silver paste (silverpaste), and prevent electromagnetic noise propagating from the external conductor layers 132 and 133 and electromagnetic noise propagating from the conductor layers 132 and 133 to the outside. shield.

[0092] The covering layers 138 and 139 are formed of an insulating film such as polyimide having a thickness of about “5-15 μm”, and insulate the entire flexible substrate 13 from the outside and protect the entire flexible substrate 13.

[0093] On the other hand, such as image 3 As shown, the rigid substrates 11 and 12 are all laminated by a rigid base material 112, a first insulating layer 111 and a second insulating layer 113, a first upper insulating layer 144 and a second upper insulating layer 114, a third upper insulating layer 145 and The fourth upper insulating layer 115, the fifth upper insulating layer 172, and the sixth upper insulating layer 173 are formed.

[0094] The rigid substrate 112 imparts rigidity to the rigid substrates 11 and 12, and the rigid substrate 112 is made of a rigid insulating material such as glass epoxy resin. The rigid base 112 is arranged separately from the flexible substrate 13 in the horizontal direction. The thickness of the rigid base 112 is approximately the same as the thickness of the flexible substrate 13. In addition, conductor patterns 112a and 112b made of copper, for example, are formed on the front and back surfaces of the rigid base 112, respectively. These conductor patterns 112a and 112b are respectively electrically connected to conductors (wirings) located above these conductor patterns 112a and 112b at predetermined positions.

[0095] The first insulating layer 111 and the second insulating layer 113 are formed by curing a prepreg. The thicknesses of the first insulating layer 111 and the second insulating layer 113 are respectively "50-100 μm", preferably about "50 μm". In addition, it is preferable that the resin of the prepreg resin cloth has low fluidity. After the epoxy resin is impregnated in the glass fiber cloth, the resin is thermally cured to accelerate the degree of curing in advance, thereby making it possible to produce such a prepreg resin cloth. However, prepreg resin cloth can be made by impregnating glass fiber cloth with resin with higher viscosity or impregnating glass fiber cloth with resin containing inorganic filler (such as silica filler) or reducing the resin impregnation amount of glass fiber cloth. .

[0096] The rigid base 112 and the first insulating layer 111 and the second insulating layer 113 constitute the cores of the rigid substrates 11 and 12, support the rigid substrates 11 and 12, and support and fix the flexible substrate by sandwiching one end of the flexible substrate 13 13. Specifically, as in Figure 4 Zoom in Figure 1A The first insulating layer 111 and the second insulating layer 113 cover the rigid base 112 and the flexible substrate 13 from both sides of the surface and the back as in the region R11 (the junction of the first rigid substrate 11 and the flexible substrate 13) in the middle, and A part of the flexible substrate 13 is exposed. The first insulating layer 111 and the second insulating layer 113 described above overlap with the covering layers 138 and 139 provided on the surface of the flexible substrate 13.

[0097] In addition, the structure of the junction between the rigid substrate 12 and the flexible substrate 13 and the structure of the junction between the rigid substrate 11 and the flexible substrate 13 ( Figure 4 ) Is the same, therefore, detailed description of the bonding portion of the rigid substrate 12 is omitted here.

[0098] Such as Figure 4 As shown, the space defined by the rigid base 112, the flexible substrate 13, and the first insulating layer 111 and the second insulating layer 113 (a gap between these members) is filled with a resin 125. The resin 125 is, for example, resin exuded from the low-fluidity prepreg resin cloth constituting the first insulating layer 111 and the second insulating layer 113 during manufacture, and the resin 125 is cured integrally with the first insulating layer 111 and the second insulating layer 113 .

[0099] Via holes (contact holes) 141 and 113 are formed on the portions of the first insulating layer 111 and the second insulating layer 113 that are opposite to the connection pads (pads) 13b of the conductor layers 132 and 133 of the flexible substrate 13, respectively. 116. The portions of the flexible substrate 13 opposite to the via holes 141 and 116 (formed with Figure 1B The portion of the connection pad 13b shown) has the shielding layers 136 and 137 and the cover layers 138 and 139 of the flexible substrate 13 removed. The via holes 141 and 116 respectively penetrate through the insulating layers 134 and 135 of the flexible substrate 13 to expose the connection pads 13b composed of the conductor layers 132 and 133.

[0100] On the inner surfaces of the via holes 141 and 116, wiring patterns (conductor layers) 142, 117 made of copper plating or the like are formed, respectively. The plating films of these wiring patterns 142 and 117 are respectively connected to the connection pads 13b of the conductor layers 132 and 133 of the flexible substrate 13. In addition, the via holes 141 and 116 are respectively filled with resin. The resin in these via holes 141 and 116 is filled, for example, by extruding the resin of the upper insulating layer (upper insulating layers 144, 114) with a press. In addition, lead patterns 143 and 118 respectively connected to the wiring patterns 142 and 117 are formed on the upper surfaces of the first insulating layer 111 and the second insulating layer 113. These lead patterns 143 and 118 are respectively made of copper plating, for example. In addition, at the end of each of the first insulating layer 111 and the second insulating layer 113 on the flexible substrate 13 side, that is, at a position closer to the flexible substrate 13 side than the boundary between the flexible substrate 13 and the rigid base 112 Conductor patterns 151 and 124 insulated from other parts. These conductor patterns 151 and 124 can effectively dissipate the heat generated in the rigid substrate 11.

[0101] In this way, in the rigid-flex circuit board 10 of the present embodiment, the rigid boards 11 and 12 and the flexible board 13 are electrically connected without a connector. That is, the rigid substrates 11 and 12 are respectively entered (buried) through the flexible substrate 13, and the entry portion (buried portion) is used to electrically connect the flexible substrate 13 to each rigid substrate (see Figure 4 ). Therefore, even in the event of an impact due to a drop or the like, there will be no contact failure due to disconnection of the connector.

[0102] In addition, a part of the flexible substrate is embedded in the rigid substrate, so the rigid substrate is bonded to the surface and back of the position where the flexible substrate is electrically connected to the rigid substrate to strengthen it, even if the rigid flexible circuit board is dropped In the event of an impact or a change in the temperature environment and stresses due to the difference in CTE (Coefficient of Thermal Expansion) between the rigid substrate and the flexible substrate, the electrical connection between the flexible substrate and the rigid substrate can be ensured.

[0103] That is, the electrical connection of the rigid-flex circuit board 10 has higher reliability than the board to which the connector is connected.

[0104] In addition, the conductor layers 132, 133 of the flexible substrate 13 and the wiring patterns 142, 117 of the rigid substrates 11, 12 are connected by tapered vias, and thus pass through vias extending in a direction orthogonal to the substrate surface. Compared with the connection, the stress is dispersed when subjected to an impact, and cracks are less likely to occur. In addition, the conductor layers 132 and 133 and the wiring patterns 142 and 117 are connected by a plating film, so that the reliability of the connection portion is high. In addition, the via holes 141 and 116 are filled with resin, respectively, so that connection reliability can be improved.

[0105] A first upper insulating layer 144 and a second upper insulating layer 114 are laminated on the upper surfaces of the first insulating layer 111 and the second insulating layer 113, respectively. The first upper insulating layer 144 and the second upper insulating layer 114 are respectively formed with via holes (first upper via holes) 146 and 119 connected to the lead patterns 143 and 118 respectively. In addition, these via holes 146 and 119 are respectively filled with conductors 148 and 120 made of copper, for example. In addition, the first upper insulating layer 144 and the second upper insulating layer 114 are configured by curing, for example, a prepreg resin cloth obtained by impregnating a resin in a glass fiber cloth or the like.

[0106] A third upper insulating layer 145 and a fourth upper insulating layer 115 are laminated on the upper surfaces of the first upper insulating layer 144 and the second upper insulating layer 114, respectively. The third upper insulating layer 145 and the fourth upper insulating layer 115 are also formed by curing, for example, a prepreg resin cloth obtained by impregnating resin in a glass fiber cloth or the like. The third upper insulating layer 145 and the fourth upper insulating layer 115 are respectively formed with via holes (second upper via holes) 147 and 121 connected to the via holes 146 and 119 respectively. The via holes 147 and 121 are respectively filled with conductors 149 and 122 made of copper, and these conductors 149 and 122 are electrically connected to the conductors 148 and 120, respectively. In this way, filled build-up vias (filled build-up vias) are formed by the vias 146 and 147 and 119 and 121.

[0107] Conductor patterns (circuit patterns) 150 and 123 are formed on the upper surfaces of the third upper insulating layer 145 and the fourth upper insulating layer 115, respectively. Furthermore, via holes 147 and 121 are connected to predetermined positions of the conductor patterns 150 and 123, respectively, so that the conductor layer 133 and the conductor pattern 123 are electrically connected through the wiring pattern 117, the lead pattern 118, the conductor 120, and the conductor 122, and the conductor layer 132 and the conductor pattern 150 are electrically connected by the wiring pattern 142, the lead pattern 143, the conductor 148, and the conductor 49.

[0108] Such as image 3 As shown, a fifth upper insulating layer 172 and a sixth upper insulating layer 173 are laminated on the upper surfaces of the third upper insulating layer 145 and the fourth upper insulating layer 115, respectively. The fifth upper insulating layer 172 and the sixth upper insulating layer 173 are also formed by curing, for example, a prepreg resin cloth obtained by impregnating resin in a glass fiber cloth or the like.

[0109] The fifth upper insulating layer 172 and the sixth upper insulating layer 173 are respectively formed with via holes 174 and 175 respectively connected to the via holes 147 and 121. In addition, including these via holes 174 and 175, conductor patterns 176 and 177 made of copper are formed on the front and back surfaces of the substrate, respectively. These conductor patterns 176 and 177 are electrically connected to conductors 149 and 122, respectively. In addition, patterned solder resist layers 298 and 299 are respectively provided on the front and back surfaces of the substrate, and electrodes 178 and 179 are respectively formed on predetermined positions of the conductor patterns 176 and 177 by electroless gold plating, for example.

[0110] In addition, the surface of the rigid-flex circuit board 10, particularly the surface of the rigid substrate 12, is formed with a recess having a predetermined size (length, width, and depth), for example, a size that can accommodate electronic components such as IC (integrated circuit) chips. (Cavity) 300. By forming such a concave portion 300 on the surface of the substrate, a freely usable space is generated in the concave portion 300. In this space, for example, a component electrically connected to the rigid-flex circuit board 10 or a component electrically connected to another board can be arranged. Therefore, when the rigid-flex circuit board 10 is used as a substrate of a mobile phone, for example, it can contribute to the thinning and multifunctionalization of the phone body. However, the use of the space in the recess 300 is arbitrary, and for example, it may be used for other purposes such as positioning using a stepped surface.

[0111] When manufacturing such a rigid-flex circuit board 10, first, a flexible substrate 13 ( figure 2 ). Specifically, copper films are formed on both surfaces of the polyimide substrate 131 processed to a predetermined size. Next, the conductor layers 132 and 133 having the wiring pattern 13a and the connection pad 13b are formed by patterning the copper film. Then, insulating layers 134 and 135 made of polyimide, for example, are formed in a laminated manner on the surfaces of the conductor layers 132 and 133, respectively. Then, a silver paste is applied to the portions of the insulating layers 134 and 135 other than the ends of the flexible substrate 13 and the applied silver paste is cured to form the shielding layers 136 and 137. Next, covering layers 138 and 139 are formed so as to cover the respective surfaces of the aforementioned shielding layers 136 and 137. The shielding layers 136 and 137 and the covering layers 138 and 139 are formed so as to avoid the connection pad 13b.

[0112] After this series of processes, complete the previous figure 2 The laminated structure shown is a wafer. The sheet is used as a common material for multiple products. That is, as Figure 5 As shown, for example, a laser or the like is used to cut the sheet into a predetermined size, thereby obtaining a flexible substrate 13 of a predetermined size.

[0113] Next, the flexible substrate 13 manufactured in this way is bonded to each of the first rigid substrate 11 and the second rigid substrate 12. During the joining, for example Image 6 As shown, for example, a sheet shared by a plurality of products is cut by a laser or the like to prepare a first insulating layer 111 and a second insulating layer 113 of a predetermined size in advance. In addition, for example Figure 7 As shown, for example, a sheet common to a plurality of products is cut by a laser or the like to prepare a partition 291 of a predetermined size in advance.

[0114] In addition, for example Picture 8 As shown, the rigid substrate 112, which is the core of the rigid substrates 11 and 12, is also manufactured from a sheet 110 shared by multiple products. That is, after the conductor films 110a and 110b made of copper are formed on the surface and the back surface of the sheet 110, for example, through a predetermined photolithography process (pretreatment, lamination, exposure, development, etching, film peeling, inner layer inspection Etc.) to form the conductor patterns 112a and 112b by patterning the conductor films 110a and 110b, respectively. Next, a predetermined portion of the sheet 110 is removed by, for example, a laser or the like, so that the rigid base materials 112 of the rigid substrates 11 and 12 are obtained. After that, the surface of the conductor pattern of the rigid substrate 112 prepared in this way is processed to form a rough surface.

[0115] In addition, the rigid substrate 112 is composed of, for example, a glass epoxy substrate having a thickness of “50 to 150 μm”, preferably about “100 μm”, and the first insulating layer 111 and the second insulating layer 113 are composed of, for example, a thickness of “20 to 50 μm. ”Is composed of prepreg resin cloth. In addition, the separator 291 is composed of, for example, a cured prepreg resin cloth or a polyimide film. For example, in order to make the front and back surfaces of the rigid substrates 11 and 12 have a symmetrical structure, the thicknesses of the first insulating layer 111 and the second insulating layer 113 are set to the same thickness. The thickness of the spacer 291 is set to the same thickness as the thickness of the second insulating layer 113. In addition, it is preferable that the thickness of the rigid base 112 and the thickness of the flexible substrate 13 are substantially the same. Thereby, the resin 125 can be filled in the gap existing between the rigid base 112 and the covering layers 138 and 139, and the flexible substrate 13 and the rigid base 112 can be joined more reliably.

[0116] Next, right Figure 5 , Image 6 as well as Picture 8 The first insulating layer 111 and the second insulating layer 113, the rigid base material 112 and the flexible substrate 13 cut in the process of aligning, for example Figure 9A Configure as shown. At this time, the positions are aligned so that each end of the flexible substrate 13 is sandwiched between the first insulating layer 111 and the second insulating layer 113.

[0117] And, for example Figure 9B Shown in Figure 7 The spacers 291 and the second insulating layer 113 cut in the process of the above are arranged on one side surface (for example, the upper surface) of the portion of the flexible substrate 13 exposed between the rigid substrate 11 and the rigid substrate 12. On the outer side (front and back) of the spacer 291, for example, conductive films 161 and 162 made of copper are arranged. For example, an adhesive is used to fix the partition 291. With this structure, since the spacer 291 supports the conductor film 162, it is possible to prevent or suppress problems such as the plating solution from penetrating into the gap between the flexible substrate 13 and the conductor film 162 and breaking the copper foil.

[0118] Then, in this alignment state ( Figure 9B ),E.g Figure 9C As shown, the structure is pressurized. At this time, the resin 125 is respectively extruded from the prepreg resin cloths constituting the first insulating layer 111 and the second insulating layer 113, as described above Figure 4 As shown, the resin 125 is used to fill the gap between the rigid substrate 112 and the flexible substrate 13. In this way, by filling the resin 125 in the void, the flexible substrate 13 and the rigid base 112 are reliably bonded. For example, using a hydropress device, the pressurization is performed under the conditions of a temperature of "200 degrees Celsius", a pressure of "40kgf", and a pressurizing time of "3hr".

[0119] Next, the whole is heated or the like to cure the prepreg resin cloth and the resin 125 constituting the first insulating layer 111 and the second insulating layer 113 to be integrated. At this time, the covering layers 138 and 139 of the flexible substrate 13 ( Figure 4 ) Overlap with the resin of the first insulating layer 111 and the second insulating layer 113. By overlapping with the resin of the insulating layers 111 and 113, the surroundings of the via holes 141 and 116 (formed in a subsequent process) are fixed with resin, and the via holes 141 and the conductor layer 132 (or the via holes 116 and the conductor layer 133 ) Connection reliability of each connection part.

[0120] Then, for example, after pre-processing is specified, for example from CO 2 Laser processing device irradiates CO 2 Laser, like this Figure 9D The through hole 163 is formed as shown. At this time, a flexible substrate 13 ( Figure 4 ) The conductor layer 133 is connected to the rigid substrate 11, 12 through the via 116 and the flexible substrate 13 ( Figure 4 A via hole 141 (for example, IVH (Interstitial Via Hole: Interstitial Via Hole)) connecting the conductor layer 132 of the rigid substrates 11 and 12).

[0121] Then, for example Figure 9E As shown, after performing desmear treatment (drill smear removal) and soft etching, PN plating (such as electroless copper plating and copper electroplating) is performed to perform copper plating on the entire surface of the structure. The copper produced by this copper plating process is integrated with the existing conductor films 161 and 162, thereby forming a copper film 171 on the surface of the entire substrate including the through holes 116 and 141 and the through hole 163. At this time, the flexible substrate 13 is covered by the conductive films 161 and 162 so as not to directly contact the plating solution. Therefore, the flexible substrate 13 is not damaged by the plating solution.

[0122] Then, like Figure 9F As shown, for example, through a predetermined photolithography process (pretreatment, lamination, exposure, development, etching, film stripping, inner layer inspection, etc.), the copper film 17 on the surface of the substrate is patterned. Thus, the flexible substrate 13 ( Figure 4 The wiring patterns 142, 117, the lead patterns 143, 118, and the conductor patterns 151, 124 connected to the conductor layers 132, 133 of ). At this time, the copper foil remains at each end of the first insulating layer 111 and the second insulating layer 113 on the flexible substrate 13 side. After that, the surface of the copper foil is processed to form a rough surface.

[0123] Then, for example Figure 10A As shown, the first upper insulating layer 144 and the second upper insulating layer 114 are respectively arranged on the surface and the back surface of the result, and the outer side of the first upper insulating layer 144 and the second upper insulating layer 114 is made of copper, for example. The conductor films 114a, 144a. Then, like Figure 10B As shown, the structure is pressurized. At this time, the via holes 141 and 116 are filled with resin from the respective prepreg resin cloths constituting the first upper insulating layer 144 and the second upper insulating layer 114. Thereafter, the resin in the prepreg resin cloth and the via holes is cured by, for example, heat treatment or the like, so that the first upper insulating layer 144 and the second upper insulating layer 114 are cured.

[0124] Next, for example, by half etching, the conductor films 114a and 144a are each thinned to a predetermined thickness. Then, after a predetermined pretreatment, for example, a laser is used to form via holes 146 on the first upper insulating layer 144, and via holes 119 and tangent lines 292 are formed on the second upper insulating layer 114, and then a desmear process is performed. (Drill dirt removal), after soft etching, for example Figure 10C As shown, by performing PN plating treatment (for example, electroless copper plating treatment and copper electroplating treatment), conductors are formed in these via holes 146 and 119 and the cut line 292. The conductor can also be formed by printing a conductive paste (for example, a thermosetting resin with conductive particles), for example, by a screen printing method.

[0125] Next, for example, by half etching, the conductor film on the surface of the substrate is thinned to a predetermined thickness, and then, as Figure 10D As shown, the conductive film on the surface of the substrate is patterned after a predetermined photolithography process (pretreatment, lamination, exposure, development, etching, film stripping, inner layer inspection, etc.). Thus, conductors 148 and 120 are formed. In addition, the conductor in the cut line 292 is removed by etching. Next, after removing the inner conductor of the tangent line 292, the surface of the conductor is processed to form a rough surface.

[0126] Here, before describing the next step, the steps performed before the next step will be described. That is, as Picture 11 As shown, before the next process, for example, a sheet shared by multiple products is cut using a laser or the like, and a third upper insulating layer 145 and a fourth upper insulating layer 115 of a predetermined size are formed in advance. In addition, such as Picture 12 As shown, for example, a sheet shared by a plurality of products is cut using a laser or the like, and a partition 293 of a predetermined size is formed in advance. The partition 293 is composed of, for example, a cured prepreg resin cloth, a polyimide film, or the like.

[0127] Then like Figure 13A As shown, in the subsequent process, on the surface and back of the substrate Picture 11 as well as Picture 12 The third upper insulating layer 145, the fourth upper insulating layer 115 and the spacer 293 cut in the process of, and then on the outer side (front and back) of the conductor film 145a, 115a made of copper. Thereafter, for example, heating or the like is performed to cure the third upper insulating layer 145 and the fourth upper insulating layer 115. The third upper insulating layer 145 and the fourth upper insulating layer 115 are each composed of a general prepreg resin cloth, which is formed by impregnating a glass fiber cloth with resin, for example.

[0128] Then, like Figure 13B As shown, the resultant is pressurized. Thereafter, the conductor films 145a and 115a are each thinned to a predetermined thickness by, for example, half etching. Then, after a predetermined pretreatment, via holes 147 and 121 are formed on the third upper insulating layer 145 and the fourth upper insulating layer 115, respectively, using a laser, and then performing desmear treatment (drill smear removal) and soft etching. After that, for example Figure 13C As shown, the through holes 147 and 121 are filled with conductors by performing PN plating treatment (such as electroless copper plating treatment and electroplating copper treatment). In this way, the same conductive paste material is filled in the via holes 147 and 121, thereby improving the connection reliability when thermal stress is generated in the via holes 147 and 121. The conductor can also be formed by printing a conductive paste (for example, a thermosetting resin with conductive particles), for example, by a screen printing method.

[0129] Then, like Figure 13D As shown, for example, by half-etching, the conductor film on the surface of the substrate is thinned to a predetermined thickness, and then the predetermined photolithography process (pretreatment, lamination, exposure, development, etching, film stripping, inner layer inspection, etc.) , Pattern formation of the copper film on the surface of the substrate. Thus, the conductors 149 and 122 and the conductor patterns 150 and 123 are formed. After that, the resultant is blackened.

[0130] Then, like Figure 14A As shown, the fifth upper insulating layer 172 and the sixth upper insulating layer 173 are arranged on the front and back surfaces of the resultant, and conductor films 172a and 173a made of copper, for example, are arranged on the outer sides (surface and back). The fifth upper insulating layer 172 and the sixth upper insulating layer 173 are each made of a prepreg resin cloth, which is made of, for example, a glass fiber cloth impregnated with resin.

[0131] Then, like Figure 14B As shown, pressurize. After that, for example, by half etching, the conductor films 172a and 173a are thinned to a predetermined thickness. Then, after a predetermined pretreatment, via holes 174 and 175 are formed on the fifth upper insulating layer 172 and the sixth upper insulating layer 173, respectively, using a laser or the like, and Figure 14C Shown, removed Figure 14B The insulating layer of each part shown by the dotted line, that is, the end of the partition 291 (the boundary between the second insulating layer 113 and the partition 291) and the end of the partition 293 (the boundary between the fourth upper insulating layer 115 and the partition 293) Part) of the insulating layer, forming cut lines (notches) 294a to 294c, 295a, and 295b. At this time, for example, the cut lines 294a to 294c are formed (cut out) by using the conductor patterns 151 and 124 as stoppers. In addition, for example, the cut lines 295a and 295b are formed using the conductor pattern 123 as a stopper film. At this time, it is also possible to cut the conductor patterns 123, 124, and 151 serving as stop films to some extent by adjusting energy or irradiation time.

[0132] Next, by performing PN plating treatment (for example, electroless copper plating treatment and copper electroplating treatment), conductors are formed on the surface of the entire substrate including the via holes 174 and 175. Next, for example, by half etching, the conductor film on the surface of the substrate is thinned to a predetermined thickness, and then, for example, through a predetermined photolithography process (pretreatment, lamination, exposure, development, etching, peeling, etc.), the substrate surface The copper foil is patterned. Like this Figure 14D As shown, conductor patterns 176 and 177 are formed. Then, after the pattern is formed, the pattern is checked.

[0133] Then, for example, by screen printing, a solder resist layer is formed on the entire surface of the substrate, such as Figure 14E As shown, the solder resist layer is patterned after a predetermined photolithography process. Thereafter, heating or the like is performed to cure the solder resist layers 298 and 299 after pattern formation.

[0134] Next, at the end of the spacer 291 and the end of the spacer 293 (refer to Figure 14B The dotted line in), etc. after drilling and shape processing, such as Figure 15A As shown, the structures 301 to 303 are peeled and removed from the flexible substrate 13. At this time, since partitions 291 and 293 are arranged, separation is easy. In addition, when separating (removing) the structures 301 to 303 from other parts, only the conductor pattern 151 is pressed onto the cover layers 138 and 139 of the flexible substrate 13 with a press machine without fixing (refer to Figure 9C ), therefore, a part of the conductor pattern 151 (the part in contact with the flexible substrate 13) is also removed together with the structures 301 to 303.

[0135] In this way, by exposing the central portion of the flexible substrate 13, spaces (regions R1 and R2) for the flexible substrate 13 to bend (bend) are formed on the front and back surfaces of the flexible substrate 13 (the stacking direction of the insulating layer). As a result, the rigid-flex circuit board 10 can be bent or the like in the portion of the flexible substrate 13.

[0136] In addition, a concave portion (cavity) 300 is formed on the surface of the rigid-flex circuit board 10, particularly on the surface of the rigid substrate 12, in the partition 293 (region R3). As described above, the recess 300 can be used, for example, to accommodate electronic components.

[0137] E.g Figure 15B As shown by the dotted lines in the middle, the conductor patterns 124 and 151 and the conductor pattern 123 remain at the front end portions of the removed portions (regions R1 to R3) facing the respective insulating layers. Such as Figure 15C As shown, the remaining copper is removed, for example, by mask etching (pretreatment, lamination, exposure, development, etching, film stripping, etc.) as needed.

[0138] Next, the electrodes 178 and 179 are formed by, for example, electroless gold plating. After that, the shape processing, warpage correction, energization inspection, appearance inspection, and final inspection are performed to complete the previous image 3 Rigid-flex circuit board 10 is shown. As described above, the rigid-flex circuit board 10 has a structure in which the end of the flexible substrate 13 is sandwiched between the cores (the first insulating layer 111 and the second insulating layer 113) of the rigid substrates 11 and 12, and The connection pads of the rigid substrates 11 and 12 and the connection pads of the flexible substrate 13 are respectively connected by plating films. In addition, a recess 300 is formed on the surface of the rigid-flex circuit board 10.

[0139] As mentioned above, although the rigid-flex circuit board 10 which concerns on one embodiment of this invention was demonstrated, this invention is not limited to the said embodiment.

[0140] E.g Figure 16 As shown, the connection terminals 180 for mounting electronic components are formed in the recess 300, thereby making it easy to mount the electronic components. In front of e.g. Figure 10C , Figure 10D In the illustrated process, the connection terminal 180 is formed together with the conductor 120. in Figure 16 In the illustrated example, the electronic component 500 (IC chip) is mounted by so-called flip-chip connection. In detail, the Au bump 502 provided on the electrode 501 of the electronic component 500 and the connection terminal 180 are electrically connected with the conductive adhesive 503, and the connection portion is covered with the insulating resin 504.

[0141] In addition, the materials of electrodes and wiring used for mounting such electronic components are arbitrary. E.g Figure 17 As shown, an ACF (Anisotropic Conductive Film) containing conductive particles 503a may also be used to electrically connect the electronic component 500 and the connection terminal 180. If this type of ACF connection is adopted, the alignment can be easily performed. In addition, for example, an Au-Au connection may be used to mount electronic components. If the Au-Au connection is used, a corrosion-resistant connection can be formed.

[0142] In addition, the connection method is not limited to flip-chip connection but is arbitrary. E.g Figure 18A As shown, it is also possible to mount electronic components using wire bonding technology through wires 503b. In addition, for example Figure 18B As shown, electronic components can also be mounted via the spring 503c. Alternatively, electronic components may be mounted through connectors.

[0143] In addition, for example Figure 19A As shown, not only the concave portion is formed on the surface of the rigid substrate 12, but also the concave portion 300a may be formed on the surface of the rigid substrate 11. In addition, such as Figure 19B As shown, in addition to the concave portion 300a on the surface of the rigid substrate 11 (one end surface of the insulating layer in the stacking direction), the concave portion 300, 300b can also be formed on the surface and back of the rigid substrate 12 (both ends in the stacking direction of the insulating layer), respectively. . And like Figure 19C As shown, in addition to the concave portion 300 on the surface of the rigid substrate 12 and the concave portion 300b on the back surface, the concave portions 300a and 300c may be formed on the surface and the back surface of the rigid substrate 11, respectively.

[0144] Not only by the method of using the above-mentioned spacer 293, but also by selective etching or the like removing the portion (region R3) corresponding to the space of the recess (pit) to form the recess (pit). However, by using the partition 293, even a deep recess (pit) can be easily formed.

[0145] In the above-mentioned embodiment, the material, size, number of layers, etc. of each layer can be arbitrarily changed. For example, RCF (Resin Coated Cupper Foil: Resin Coated Cupper Foil) can be used instead of prepreg resin cloth.

[0146] In addition, for example Figure 20 As shown, the rigid substrate 11 may have a conductor (wiring layer) only on one surface of the core surface or the back surface (the same applies to the rigid substrate 12).

[0147] In addition, three or more rigid substrates may be connected through a flexible substrate. E.g Figure 21A or Figure 21B As shown, as a group of rigid substrates (relatively rigid substrates) arranged opposite to each other via flexible substrates 104 and 105, it may include a relatively rigid substrate 1001 composed of a rigid substrate 101 and a rigid substrate 102, and a rigid substrate 101 and The structure of the rigid substrate 103 is relatively rigid substrate 1002. The rigid substrates 102 and 103 are arranged opposite to the common rigid substrate 101. in Figure 21A In the example of, the relatively rigid substrate 1001 and the relatively rigid substrate 1002 are arranged at an angle of "90°" to each other. in Figure 21B In the example of, the relatively rigid substrate 1001 and the relatively rigid substrate 1002 are arranged at an angle of "180°" to each other. In the rigid-flex circuit board having such a structure, it is also possible to provide the same effect as the above by providing at least one recess on the main surface or both the front and back surfaces of at least one of the three rigid substrates 101 to 103. effect. In addition, it may be a structure having three or more sets of relatively rigid substrates.

[0148] In the foregoing, the embodiments of the present invention have been described, but it should be understood that various modifications and combinations required due to design needs or other reasons are included in the invention described in the "claims" and the "embodiments of the invention". The specific examples described are within the scope of the corresponding invention.

[0149] This application is based on the US Patent Provisional Application No. 61/084685 filed on July 30, 2008. Refer to the entire specification, claims, and drawings of U.S. Patent Provisional Application No. 61/084685 and cited in this specification.

[0150] Industrial availability

[0151] The present invention can be applied to a flexible rigid-flex circuit board that is partially composed of a flexible substrate.