JP2004006572A - Method for manufacturing element built-in substrate and element built-in substrate, and method for manufacturing printed wiring board and the printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing an element built-in substrate which can form a fine-pitch conductor pattern on an insulating layer with high precision while securing the size stability of the conductor pattern and to provide the element built-in substrate, and a method for manufacturing a printed wiring board and the printed wiring board. <P>SOLUTION: A transfer sheet 61 has a structure including two layers of a metal base material 62 and a dissolved metal layer 64 and the conductor pattern 55 is formed by electroplating on the dissolved metal layer 64. Then the transfer sheet 61 is removed through a process of separating the metal base material 62 from the dissolved metal layer 64 after sticking the transfer sheet 61 on which the conductor pattern 55 is laminated on a insulating base material 51 and a process of selectively dissolving the dissolved metal layer 64 away from the conductor pattern 55. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a device-embedded substrate and a device-embedded substrate, in which a conductive pattern is formed by a transfer method using a transfer sheet, and a method for manufacturing a printed wiring board and a printed wiring board. TECHNICAL FIELD The present invention relates to a method for manufacturing an element-embedded substrate and an element-embedded substrate that are excellent in forming a fine-pitch conductor pattern and a method for manufacturing a printed wiring board and a printed wiring board.
[0002]
[Prior art]
2. Description of the Related Art In recent years, as electronic devices such as mobile phones, PDAs (Personal Digital Assistants), and notebook personal computers have become smaller and more sophisticated, it has become indispensable to support high-density mounting of electronic components constituting these devices. Conventionally, high-density mounting of electronic components has been responded to by finer pitch of component terminals due to miniaturization of electronic components, finer conductive patterns on printed wiring boards on which electronic components are mounted, and the like.
[0003]
In recent years, a multilayer printed wiring board which enables three-dimensional wiring by stacking the printed wiring boards has been developed, and furthermore, a chip resistor or a chip has been developed for the multilayer printed wiring board. Development of a device-embedded board that further incorporates electronic components such as a capacitor or an electric device such as a semiconductor chip (hereinafter collectively referred to as “electric device”) to further improve the mounting efficiency has been promoted. I have.
[0004]
As a method of forming a conductor pattern of a printed wiring board, a transfer method using a transfer sheet has been conventionally known. The process of manufacturing a printed wiring board by this transfer method mainly includes a pattern forming step of forming a conductor pattern on one surface of the transfer sheet, and bonding the transfer sheet to the insulating layer via the formed conductor pattern, followed by transfer. And a pattern transfer step of removing the sheet.
[0005]
The printed wiring board manufactured by the transfer method can be easily multi-layered by forming vias for interlayer connection at arbitrary positions on the insulating layer.
[0006]
As a conventional technique of this kind, for example, Japanese Patent No. 3051700 discloses a method of manufacturing an element-containing substrate using a transfer method. Hereinafter, a conventional method for manufacturing a device-embedded substrate will be described with reference to FIG.
[0007]
13A to 13F are process cross-sectional views showing a conventional method for manufacturing a device-embedded substrate. In the insulating base material 31, a void portion 32 for accommodating the semiconductor chip 36 and a via penetrating body 33 for interlayer connection formed by filling a through-hole with a conductive paste are formed (FIG. 13 ( A)). On the other hand, on one surface of the transfer sheet 34, a conductor pattern 35 to be transferred onto the insulating base material 31 is formed (FIG. 13B).
[0008]
Here, the insulating substrate 31 is made of a semi-cured thermosetting resin, and the transfer sheet 34 is made of a resin film such as polyethylene terephthalate (PET). In addition, the conductor pattern 35 is formed by pattern-etching a conductor foil such as a copper foil that is previously adhered to the transfer sheet 34.
[0009]
Next, the semiconductor chip 36 is bonded to a predetermined portion of the conductor pattern 35 formed on the transfer sheet 34 (FIG. 13C). Then, the upper surface of the insulating base material 31 and the conductor pattern 35 side of the transfer sheet 34 are pressure-bonded to accommodate the semiconductor chip 36 in the gap 32 and connect the conductor pattern 35 to the via penetrator 33 (FIG. 13). (D)). The conductor pattern 35 is buried in the upper surface of the semi-cured insulating base material 31, and thereafter, only the transfer sheet 34 is removed from the insulating base material 31. Then, the insulating base material 31 is heat-treated and completely cured to complete the element built-in substrate 30 (FIG. 13E).
[0010]
Further, as shown in FIG. 13 (F), the multilayer wiring board 41 is formed by laminating the insulating base materials 39 and 40 on which the conductor patterns 37 and 38 are respectively formed on the device built-in substrate 30 in the same manner as described above. can get.
[0011]
[Problems to be solved by the invention]
However, in this conventional method for manufacturing a device-embedded substrate, since the transfer sheet 34 is mainly composed of a resin film, the pattern of the conductor pattern 34 to be transferred due to expansion and contraction or warpage of the transfer sheet 34 generated during handling. There is a problem that the shape is likely to be out of order. Therefore, it is very difficult for this conventional method for manufacturing a device-embedded substrate to cope with the miniaturization (fine pitch) of the conductor pattern, which is increasing more and more in the future.
[0012]
The conductor pattern 35 formed on the transfer sheet 34 is formed by pattern etching of a metal foil adhered on the transfer sheet 34 as disclosed in, for example, Japanese Patent Application Laid-Open No. 9-270578. Alternatively, for example, as disclosed in JP-A-10-335787, a metal layer directly formed on the transfer sheet 34 by a sputtering method or the like is formed by pattern etching. As the etching method, a wet etching method is applied.
[0013]
That is, in the conventional method of manufacturing a device-embedded substrate, since the wet etching method is used to form the conductor pattern 35, it is difficult to form a fine pitch pattern with high accuracy in the future. .
[0014]
On the other hand, the transfer sheet may be made of a metal material such as stainless steel. In this case, the rigidity is higher than when the transfer sheet is made of a resin film, so that the dimensional stability of the conductor pattern is improved. However, in this case, if the rigidity of the insulating base material as the transfer destination is strong, it is difficult to remove the transfer sheet from the insulating base material, and there is a problem that the transfer operation of the conductor pattern cannot be performed properly.
[0015]
The present invention has been made in view of the above-described problems, and it is possible to form a fine-pitch conductive pattern on an insulating layer with high accuracy while securing the dimensional stability of the conductive pattern, and to appropriately remove a transfer sheet. It is an object of the present invention to provide a method of manufacturing a device-embedded substrate and a device-embedded substrate, and a method of manufacturing a printed wiring board and a printed wiring board.
[0016]
[Means for Solving the Problems]
In solving the above problems, in the present invention, the transfer sheet is made of metal, and by imparting conductivity to the transfer sheet, a fine pitch conductor pattern is formed with high precision using a pattern plating technique by an additive method. Is possible.
[0017]
When transferring the formed conductor pattern to the insulating layer, the transfer sheet and the insulating layer are attached to each other, and then the transfer sheet is removed from the insulating layer. In the present invention, since the transfer sheet is mainly composed of a metal material, there is almost no dimensional change during handling, and the dimensional stability of the transferred conductor pattern is ensured.
[0018]
In the present invention, the removal of the transfer sheet from the insulating layer is mainly intended to dissolve and remove the transfer sheet. Thereby, even when the rigidity of the insulating layer, which is the transfer destination, is strong, an appropriate transfer operation of the conductor pattern can be ensured.
[0019]
Here, the transfer sheet may be configured to include a metal base material and a metal layer to be melted which is formed so that the conductor pattern is formed and is separable from the metal base material. The metal base material occupies a major part of the total thickness of the transfer sheet and is mainly configured to have the mechanical or material properties required during handling. When the metal base material having such a configuration is separated and removed from the metal layer to be melted, the metal layer to be melted, which is a part of the transfer sheet, remains on the conductor pattern transferred onto the insulating layer. Therefore, the transfer sheet from the insulating layer is completely removed by dissolving and removing the metal layer to be dissolved. In this case, the time required for dissolving and removing the transfer sheet can be shortened, so that the transfer sheet removal processing is simplified.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
(First Embodiment)
1 to 5 show a configuration of a device-embedded substrate 50 according to the first embodiment of the present invention. In the insulating base material 51 constituting the insulating layer, a void 52 for accommodating a semiconductor chip 56 as an electric element and through holes (through holes) 53 for connecting the front and back surfaces of the insulating base material 51 are provided. Is formed. A conductive material 59 such as solder is filled in the through holes 53.
[0022]
In the present embodiment, the insulating base material 51 is composed of a resin base material mainly composed of a thermoplastic resin material, but is not limited to this, and is appropriately selected according to an application target, a use, or the like. For example, a glass fiber impregnated with an epoxy resin, a glass fiber impregnated with a polyimide resin, or a paper impregnated with a phenol resin is used. Further, a bismaleimide triazine resin, a benzocyclobutene resin, a liquid crystal polymer, or the like is also applicable.
[0023]
As the solder 59 filled in the through-hole 53, either a leaded or lead-free solder material may be used, but it is preferable to use a lead-free solder material from the viewpoint of environmental friendliness. As a lead-free solder material, an alloy obtained by adding Bi, In, Cu, Sb, or the like to a Sn-Ag system is typical. Further, as a conductive material other than the solder material, for example, a conductive paste obtained by mixing conductive particles such as silver powder and copper powder in a resin can be used.
[0024]
An adhesive material layer 54 made of a non-conductive adhesive is provided on the surface of the insulating base material 51, and a conductor pattern 55 patterned into a predetermined shape is adhered on the adhesive material layer 54. The conductor pattern 55 is formed of, for example, an electroplating film made of copper, and is electrically connected to the semiconductor chip 56 accommodated in the gap 52 and electrically connected to the solder 59 in the through hole 53. ing. In the present invention, as described later, the conductor pattern 55 is formed on the insulating base material 51 by a transfer method.
[0025]
The semiconductor chip 56 in the present embodiment is a bare chip, and gold or a bump (metal bump electrode) 57 whose surface is plated with gold is formed on an aluminum electrode pad portion provided on a bonding surface (active surface) thereof. Have been. The bump 57 is not limited to the illustrated ball bump, but may be a stud bump or a plated bump. The present invention is not limited to a semiconductor bare chip, but may be applied to a semiconductor package component having bumps formed in rows or areas on a mounting surface such as a BGA / CSP.
[0026]
An underfill resin layer 58 made of a thermosetting adhesive resin such as an epoxy resin is formed between the conductor pattern 55 and the semiconductor chip 56 inside the gap 52. The bonding state of the semiconductor chip 56 with the conductor pattern 55 is maintained by the underfill resin layer 58. The semiconductor chip 56 in the gap 52 may be completely sealed with the same resin material.
[0027]
The front side of the conductor pattern 55 is covered with a solder resist 60, and openings 60 a and 60 a are formed in portions corresponding to the through holes 53, exposing the conductor pattern 55 to the outside.
[0028]
According to the device-embedded substrate 50 of the present embodiment, since the conductor pattern 55 is formed of the electroplated layer, the conductor pattern 55 can be formed with a fine pitch, thereby further improving the mounting density. Can be planned.
[0029]
Next, FIG. 2 shows a device built-in multilayer substrate 65 in which a plurality of device built-in substrates 50 configured as described above are stacked. In this example, an embodiment is shown in which three element built-in substrates 50 having the above configuration are stacked and mounted on a base substrate 66. The electrical and mechanical connection between the layers of the device-embedded multilayer substrate 65 is made by solder 59 joined to the surface of the conductor pattern 55 via the opening 60 a of the solder resist 60.
[0030]
By connecting the layers with the solder 59 as described above, the connection can be made in a shorter time and the resistance can be reduced as compared with the case where the conductive paste is used.
[0031]
The base substrate 66 includes an insulating base material 67, an upper wiring layer 70 and a lower wiring layer 71 patterned and formed on the front and rear surfaces thereof, and a through-hole plating 68 for connecting the wiring layers 70 and 71 between layers. I have. The inside of the through-hole is filled with a filling body 69 made of a conductive material or a non-conductive material, thereby preventing a so-called popcorn phenomenon or improving heat radiation efficiency.
[0032]
The device built-in multilayer substrate 65 configured as described above has a form of a land grid array (LGA), and the lower wiring exposed to the outside through the openings 73a of the solder resist 73 when the mother substrate is mounted. External electrodes such as ball bumps are provided on the layer 71. Further, another electric element or electronic component may be mounted on the wiring layer (conductor pattern) 55 of the element-embedded substrate 50 located on the uppermost layer.
[0033]
Next, a method for manufacturing the device-embedded substrate 50 according to the present invention will be described with reference to FIGS.
[0034]
First, as shown in FIG. 3A, an insulating base material 51 having the above-described configuration is prepared, and an adhesive 54 for forming an adhesive material layer is applied to the surface thereof (FIG. 3B).
The adhesive 54 is for bonding the conductor pattern 55 to be transferred later to the insulating base material 51, and needs to be non-conductive. Further, in order to prevent the adhesive from flowing out into the gap portion 52 and the through hole 53 during the transfer of the conductor pattern 55, a material constituting the adhesive 54 has a low flow property and a high shape maintaining property. An example of such a material is “AS-3000” manufactured by Hitachi Chemical Co., Ltd.
[0035]
Next, as shown in FIG. 3C, a gap forming step of forming a gap 52 for accommodating an element and a through hole 53 for interlayer connection is performed on the insulating base material 51 (step S1). For forming the gap 52 and the through hole 53, for example, a known drilling technique such as processing using a drill or a router, a mold punch, or laser processing can be applied. Is also good. Note that the gap 52 needs to have an inner size larger than the outer shape of the semiconductor chip 56 to be accommodated.
[0036]
In parallel with the above-described step of preparing the insulating base material 51, a step of forming the conductor pattern 55 is performed as shown in FIGS. 3D to 3G (step S2). In the present embodiment, a transfer sheet 61 having a configuration shown in FIG. 5A is used to form the conductor pattern 55.
[0037]
The transfer sheet 61 includes a metal base material 62 made of copper having a thickness of, for example, about 100 μm, a conductive adhesive resin layer 63, and a melted metal layer 64 made of chromium (Cr) having a thickness of, for example, 5 μm or less. It has a layered structure. The metal base material 62 and the metal layer to be melted 64 are laminated via a conductive adhesive resin layer 63 so as to be separable (peelable) from each other.
[0038]
The metal base material 62 occupies a major part of the entire thickness of the transfer sheet 61, and is mainly configured to have mechanical or material properties required during handling. The conductive adhesive resin layer 63 is made of a material that can secure conduction between the metal base material 62 and the metal layer 64 to be melted and that can be separated and removed from each other. For example, a benzotriazole resin formed in a layer shape Is applied. The to-be-dissolved metal layer 64 is made of a metal foil or a metal plating layer, and is made of a metal material different from the conductor pattern 55 so that the conductor pattern 55 can be selectively etched.
[0039]
The configuration example for separating and removing the metal base material 62 and the melted metal layer 64 from each other is not limited to the above, and other configuration examples can be adopted, but the details will be described later.
[0040]
Now, referring to FIG. 3D, a photoresist film 72 is formed on the surface of the transfer sheet 61 having the above structure on the side of the metal layer 64 to be melted. The photoresist 72 may be either a dry film resist or a liquid resist. Then, exposure and development processes are performed on the formed photoresist film 72 to pattern the photoresist film 72 into a predetermined shape, thereby forming a plating resist 72A (FIG. 3E).
[0041]
Subsequently, the transfer sheet 61 is immersed together with the plating resist 72A in, for example, a copper electrolytic bath and connected to a cathode electrode (not shown) to deposit a copper electroplating layer 55A on the metal layer 64 to be melted (FIG. F)). After the formation of the electroplating layer 55A, the plating resist 72A is removed (FIG. 3G). As described above, the conductor pattern 55 including the electroplating layer 55A is formed on the surface of the transfer sheet 61.
The electroplating layer 55A is formed not only on the metal layer 64 of the transfer sheet 61 but also on the metal base material 62, but illustration thereof is omitted.
[0042]
In general, compared to a method in which an unnecessary portion of a conductor layer is removed by a wet etching method to form a conductor pattern (a subtractive method), a method of forming a conductor pattern by depositing a conductor layer only in a necessary portion by an electroplating method (additive method) According to the present embodiment, a conductor pattern having a fine pitch of L / S of, for example, 10 μm / 10 μm can be formed with high precision.
[0043]
If a conductor pattern with a fine pitch is not required, a conductor layer is further formed on the metal layer to be melted 64 by a method such as electroplating, and the conductor layer is pattern-etched to form the conductor pattern. It is also possible.
[0044]
Next, as shown in FIG. 3H, the transfer sheet 61 and the insulating base material 51 are bonded to each other via the formed conductive pattern 55, and the conductive pattern 55 is formed on the adhesive material layer 54 on the insulating layer 51. (Step S3).
[0045]
At this time, since the transfer sheet 61 is made of metal, the transfer sheet 61 has higher strength than a transfer sheet made of a conventional resin film. The pattern 55 can be properly bonded onto the insulating base material 51 with high dimensional stability.
[0046]
Further, since the transfer sheet 61 can have a sufficient strength, it is possible to transfer a pattern with a higher load than in the past, and it is possible to reduce restrictions on the transfer process. In particular, local deformation of the transfer sheet during transfer is suppressed, so that deformation and breakage of the conductor pattern can be avoided.
[0047]
Subsequently, as shown in FIG. 4I, a step of accommodating the semiconductor chip 56 in the space 52 of the insulating base material 51 and joining the bump 57 formed on the active surface thereof to the conductor pattern 55 is performed. (Step S4). The mounting of the semiconductor chip 56 on the conductor pattern 55 is performed using, for example, a known mounter device.
[0048]
In this embodiment, since the bump 57 is formed of gold or the surface thereof is plated with gold, if the bump 57 is directly bonded to the conductor pattern (copper) 55, it becomes a connection between Au and Cu. Therefore, if a tin (Sn) -based metal film is further formed on the surface of the conductor pattern 55 formed on the transfer sheet 61 by electroplating or the like, the bonding step becomes Au-Sn bonding. The semiconductor chip 56 can be bonded at a lower temperature and a lower load than the bonding between Au and Cu. Examples of the Sn-based metal include Sn and Sn-based alloys (SnAg, SnBi, SnCu, etc.). Similar effects can be obtained by forming a NiP / Au film other than the Sn-based metal.
[0049]
On the other hand, instead of forming the bump 57 of the semiconductor chip 56 with Au, the bump 57 may be formed with a Sn-based metal. In this case, the bumps may be formed only with the Sn-based metal, or the surfaces of other metal balls or resin balls may be plated with the Sn-based metal. Examples of the Sn-based metal include Sn, SnAg, SnBi, SnCu, SnAgCu, SnAgBi, and SnAgBiCu.
[0050]
Now, after joining the semiconductor chip 56 to the conductor pattern 55, a thermosetting resin such as epoxy is injected into the space 52 to form an underfill resin layer 58 between the conductor pattern 55 and the semiconductor chip 56. The process is performed (FIG. 4 (I), step S5). Thus, the conductor pattern 55 is supported by both the transfer sheet 61 and the underfill resin layer 58.
[0051]
As described above, the step of joining the semiconductor chip 56 to the conductor pattern 55 and the step of forming the underfill resin layer 58 for sealing the joined semiconductor chip 56 inside the gap 52 provide the “element housing” according to the present invention. Step ”is configured.
[0052]
The bonding process of the semiconductor chip 56 is not limited to the above. The semiconductor chip 56 is bonded to the conductor pattern 55 on the transfer sheet 61 in advance, and the semiconductor chip 56 is bonded when the insulating base material 51 and the transfer sheet 61 are bonded. May be accommodated in the gap 52. In this case, since the transfer sheet 61 is made of metal, deformation of the transfer sheet 61 due to the weight of the semiconductor chip 56 can be suppressed.
[0053]
At this time, if an adhesive having a plating resist 72A is used, the plating resist 72A can be used as an underfill resin layer for the semiconductor chip 56 as shown in FIG. 12, for example. In this case, the thickness of the conductor pattern 55 may be a size that the bump 57 of the semiconductor chip 56 can reach.
[0054]
Next, a step of removing the transfer sheet 61 is performed. In the present embodiment, the transfer sheet 61 is removed by a step of separating and removing the metal base material 62 from the metal layer 64 to be dissolved (FIG. 4 (J)) and a step of dissolving and removing the metal layer 64 to be dissolved (FIG. 4 (K)).
[0055]
Referring to FIG. 4 (J), the step of separating and removing metal base material 62 from metal layer 64 to be melted is performed by peeling metal base material 62 from metal layer 64 to be melted via conductive adhesive resin layer 63. (Step S6).
In order to separate the conductive adhesive resin layer 63 from the metal layer 64 together with the metal base material 62, a release agent is applied to a predetermined portion of the surface on the metal layer 64 side. Is also good.
[0056]
The peeling process of the metal base material 62 can be easily performed by making a cut at the start of the peeling at the boundary between the metal base material 62 and the melted metal layer 64 at the edge of the transfer sheet 61. During the stripping process of the metal base material 62, the metal base material 62 and the metal layer 64 are supported by the adhesive material layer 54 and the underfill resin layer 58 via the conductor pattern 55. Can be properly separated and removed (FIG. 4 (K)).
[0057]
On the other hand, in the step of dissolving and removing the metal layer 64 to be dissolved, only the metal layer 64 to be dissolved is selectively removed using an etching solution that dissolves the metal layer 64 to be dissolved but does not dissolve the conductor pattern 55 (FIG. 4). (L), Step S7). In the present embodiment, since the conductor pattern 55 is formed of copper and the metal layer 64 to be dissolved is formed of chromium, only the metal layer 64 to be dissolved is left, for example, by using a hydrochloric acid-based etchant while leaving the conductor pattern 55. It can be dissolved and removed.
[0058]
As described above, the steps from the step of bonding the insulating base material 51 and the transfer sheet 61 (step S3) to the step of dissolving and removing the metal layer 64 to be melted (step S7) are described as the “pattern transfer step” in the embodiment of the present invention. Is constituted.
[0059]
After the removal of the transfer sheet 61 is completed, as shown in FIG. 1, a conductor filling step of filling a solder 59 as a conductive material into the through hole 53 of the insulating base material 51 using a screen printing method or a dispensing method. Is performed, and a step of covering the surface of the conductor pattern 55 with a solder resist 60 excluding a portion corresponding to a portion where the through hole 53 is formed is performed (Step S8). In order to obtain the device-embedded multilayer substrate 65 shown in FIG. 2, a predetermined multilayering process is performed (Step S9).
[0060]
As described above, the device-embedded substrate 50 of the present embodiment is manufactured.
According to the present embodiment, since the transfer sheet 61 is made of metal, the conductor pattern 55 having a fine pitch can be formed with high precision by using a pattern plating technique based on an electroplating method. Further, since the transfer sheet 61 has predetermined mechanical strength and heat resistance, the dimensional change of the conductive pattern 55 to be transferred can be ensured with almost no dimensional change during handling or heating. .
[0061]
Further, since the transfer sheet 61 is finally removed by etching in the pattern transfer step, even if the rigidity of the insulating base material 51 is strong, the transfer function of the conductive pattern 55 can be properly performed. Can be secured.
[0062]
Further, according to the present embodiment, the transfer sheet 61 is configured to include the metal base material 62 and the metal layer to be melted 64 which is separably stacked on the metal base material 62, and Since the removal includes a step of separating and removing the metal base material 62 from the metal layer to be melted 64 and a step of melting and removing the metal layer 64 to be melted, the transfer sheet 61 can be easily removed. Is improved.
[0063]
(Second embodiment)
7 and 8 show a second embodiment of the present invention. In the present embodiment, a method for manufacturing a printed wiring board according to the present invention will be described.
[0064]
First, as shown in FIG. 7A, an insulating base material 81 is prepared, and an adhesive 84 for forming an adhesive material layer is applied to the surface thereof (FIG. 7B). The same material as the insulating base material 51 and the adhesive 54 described in the first embodiment is used for the insulating base material 81 and the adhesive 84 of the present embodiment.
[0065]
On the other hand, as in the first embodiment, the conductor pattern 85 transferred to the insulating base material 81 is formed on a metal transfer sheet 91 by electroplating as shown in FIGS. 7C to 7F. It is formed. The transfer sheet 91 has the same configuration as the transfer sheet 61 in the first embodiment without detailed description, and includes a metal base material 92 made of copper, a metal layer 94 to be melted made of chromium, A conductive adhesive resin layer (not shown) interposed therebetween.
[0066]
A plating resist 73A obtained by patterning the photoresist film 73 is formed on the metal layer 94 to be melted of the transfer sheet 91, and the conductor pattern 85 is formed by an electroplating layer (copper) 85A deposited in a region defined by the plating resist 73A. (FIG. 7E). After removing the plating resist 73A, the transfer sheet 91 on which the conductor pattern 85 is formed is attached on the insulating base material 81, so that the conductor pattern 85 is transferred onto the adhesive material layer 84 (FIG. 7 ( G)).
[0067]
Subsequently, as shown in FIGS. 8H to 8J, a step of removing the transfer sheet 91 attached on the insulating base material 81 is performed. As in the first embodiment, the transfer sheet 91 is removed by a step of separating and removing the metal base material 92 from the metal layer to be melted 94 and a step of melting and removing the metal layer 94 to be melted. In particular, for dissolving and removing the metal layer 94 to be dissolved, for example, a hydrochloric acid-based etchant that dissolves the metal layer (Cr) 94 but does not dissolve the conductor pattern (Cu) 85 is used.
[0068]
In the printed wiring board 80 manufactured as described above, as shown in FIG. 8J, a conductor pattern 85 formed by electroplating is bonded to an adhesive material layer 84 on an insulating base material 81. It is in the form shown.
[0069]
According to the present embodiment, since the transfer sheet 91 is made of metal, the conductor pattern 85 having a fine pitch can be formed with high precision by using a pattern plating technique based on an electroplating method. In addition, since the transfer sheet 91 has predetermined mechanical strength and heat resistance, dimensional changes during handling and heating can be substantially eliminated, and dimensional stability of the transferred conductor pattern 85 can be ensured. .
[0070]
Furthermore, since the transfer sheet 91 is finally removed by etching in the pattern transfer step, even if the rigidity of the insulating base material 81 is strong, the transfer function of the conductor pattern 85 can be properly performed. Can be secured.
[0071]
Further, according to the present embodiment, the transfer sheet 91 is configured to include the metal base material 92 and the metal layer 94 to be melted that is separably stacked on the metal base material 92, and the transfer sheet 91 is removed. However, since the steps of separating and removing the metal base material 92 from the melted metal layer 94 and the step of melting and removing the melted metal layer 94 are configured, the transfer sheet 91 can be easily removed, thereby improving the productivity. Is improved
[0072]
(Third embodiment)
FIG. 9 and FIG. 10 show a third embodiment of the present invention. In this embodiment, a method for manufacturing an element-embedded substrate according to the present invention will be described. In the drawings, the same reference numerals are given to portions corresponding to the above-described first embodiment, and detailed description thereof will be omitted.
[0073]
First, as shown in FIG. 9A, an insulating base material 51 is prepared, and an adhesive for forming an adhesive material layer 54 is applied to the surface thereof (FIG. 9B).
Next, as shown in FIG. 9C, a gap forming step of forming a gap 52 for element storage and a through hole 53 for interlayer connection is performed on the insulating base material 51.
[0074]
In parallel with the step of preparing the insulating base material 51, a step of forming the conductor pattern 55 is performed as shown in FIGS. 9 (D) to 9 (G).
In the present embodiment, a transfer sheet 61 having a configuration shown in FIG. 5A is used to form the conductor pattern 55. That is, it is composed of a metal base material 62 made of copper, a metal layer 64 to be melted made of chromium, and a conductive adhesive resin layer interposed therebetween (FIG. 9D).
[0075]
The conductor pattern 55 shown in FIG. 9E is composed of an electroplating layer formed on the surface of the transfer sheet 61 on the side of the metal layer 64 to be melted, as in the first embodiment.
In the present embodiment, thereafter, a step of embedding an insulating film between the formed conductor patterns and flattening the surface of the transfer sheet 61 on the side of the metal layer 64 to be melted is performed.
[0076]
In this step, first, as shown in FIG. 9F, an insulating layer made of an insulating resin such as an epoxy resin is formed on the entire surface of the transfer sheet 61 on the side of the metal layer 64 to be melted from above the formed conductor pattern 55. The film 87 is applied and cured by, for example, a screen printing method.
Then, as shown in FIG. 9G, the cured insulating film 87 is polished to expose the surface of the conductor pattern 55 to the outside.
As a result, the insulating film 87 is embedded between the conductor patterns 55, and the surface of the transfer sheet 61 on the side of the metal layer 64 to be melted is flattened.
[0077]
Next, as shown in FIG. 9H, the transfer sheet 61 and the insulating base material 51 are bonded to each other via the formed conductive pattern 55, and the conductive pattern 55 is formed on the adhesive material layer 54 on the insulating layer 51. Paste to.
[0078]
At this time, since the transfer sheet 91 is made of metal, the strength is higher than that of a transfer sheet formed of a conventional resin film. The pattern 55 can be properly bonded onto the insulating base material 51 with high dimensional stability.
[0079]
Further, since the transfer sheet 61 can have a sufficient strength, it is possible to transfer a pattern with a higher load than in the past, and it is possible to reduce restrictions on the transfer process. In particular, local deformation of the transfer sheet during transfer is suppressed, so that deformation and breakage of the conductor pattern can be avoided.
[0080]
Furthermore, since the surface of the transfer sheet 61 on the side of the metal layer 64 to be melted is flattened by embedding the insulating film 87 between the conductor patterns 55, the adhesion to the adhesive material layer 54 on the insulating base material 51 is increased. Thus, the adhesive strength can be increased.
[0081]
Subsequently, as shown in FIG. 10I, a step of accommodating the semiconductor chip 56 in the void 52 of the insulating base material 51 and joining the bump 57 formed on the active surface thereof to the conductor pattern 55 is performed. Is
After bonding the semiconductor chip 56 to the conductor pattern 55, for example, an epoxy resin is injected into the gap 52 to form an underfill resin layer 58 between the conductor pattern 55 and the semiconductor chip 56. Thus, the conductor pattern 55 is supported by both the transfer sheet 61 and the underfill resin layer 58.
[0082]
Since the bumps of the semiconductor chip 56 are formed of gold or gold plated on the surface, it is necessary to form Sn-based metal or Ni / Au-based metal plating on the surface of the conductor pattern 55 made of copper. Accordingly, chip mounting in a low-temperature and low-load environment can be realized.
[0083]
In this case, in the present embodiment, since the insulating film 87 is buried between the conductor patterns 55, the bridge phenomenon between the patterns due to the isotropic growth of the metal plating can be avoided.
If the region corresponding to the chip connection land on the conductor pattern 55 is soft-etched prior to the formation of the metal plating, it is effective that the flatness of the transfer surface is not impaired by the formation of the metal plating. .
[0084]
Next, the transfer sheet 61 is removed. The transfer sheet 61 is removed by a step of separating and removing the metal base material 62 from the metal layer 64 to be melted (FIG. 10 (J)) and a step of melting and removing the metal layer 64 to be melted (FIG. 10 (K)). Be composed.
Since the transfer sheet 61 is removed by the same method as that described in the first embodiment, the description thereof is omitted here.
[0085]
After the removal of the transfer sheet 61 is completed, as shown in FIG. 10 (L), the solder 59 is filled as a conductive material into the through hole 53 of the insulating base material 51 using a screen printing method or a dispensing method. A step of covering the surface of the conductive pattern 55 with a solder resist 60 excluding a portion corresponding to a portion where the through hole 53 is formed is performed.
[0086]
As described above, the device-embedded substrate 50 'of the present embodiment is manufactured.
According to the present embodiment, the same effects as those of the above-described first embodiment can be obtained.
In particular, according to the present embodiment, since the conductor pattern 55 can be adhered to the insulating base material 51 with high adhesion, it is possible to obtain the element-containing substrate 50 ′ having excellent durability.
Further, when metal plating is formed in the chip mounting region of the conductor pattern 55, short-circuiting between the patterns can be prevented, so that it is possible to cope with mounting of a semiconductor chip having a narrow pad pitch.
[0087]
(Fourth embodiment)
Next, FIG. 11 shows a fourth embodiment of the present invention. In this embodiment, a method for manufacturing an element-embedded substrate according to the present invention will be described. In the drawings, the same reference numerals are given to portions corresponding to the above-described first embodiment, and detailed description thereof will be omitted.
[0088]
In the present embodiment, a plating resist 72A for electroplating (FIG. 11B) formed when depositing the conductor pattern 55 on the surface of the transfer sheet 61 on the metal layer 64 side shown in FIG. Are formed as the flattening insulating film 87 described in the third embodiment.
When the conductive pattern 55 is formed, the plating resist 72A fills the space between the conductive patterns 55 as shown in FIG.
[0089]
Therefore, after the formation of the conductor pattern 55, it is possible to bond the insulating layer 51 on the insulating base material 51 as shown in FIG. 11D without forming an additional insulating film for planarization. The same effect as that of the embodiment can be obtained.
If a material having adhesiveness is used for the plating resist 72A, the conductor pattern 55 can be attached onto the insulating base material 51 with higher adhesive strength.
In this case, when the wiring density of the conductor pattern 55 is relatively low, the adhesive material layer 54 on the insulating base material 51 can be made unnecessary.
[0090]
Note that the chip mounting step (FIG. 11E) and the transfer sheet removing step (FIG. 11F) after attaching the conductor pattern 55 are the same as those in the first embodiment described above. Description is omitted.
[0091]
Although the embodiments of the present invention have been described above, the present invention is, of course, not limited thereto, and various modifications can be made based on the technical idea of the present invention.
[0092]
For example, in each of the above embodiments, as the transfer sheets 61 and 91, the conductive adhesive resin layer 63 is provided between the metal base members 61 and 91 and the metal layers 64 and 94 to be melted as shown in FIG. The metal base members 61 and 91 and the meltable metal layers 64 and 94 are configured to be separable from each other with the interposition of, but the configuration of the transfer sheets 61 and 91 is not limited thereto. Any configuration may be used as long as the configuration can be separated from each other.
[0093]
For example, in a transfer sheet 101 whose cross-sectional structure is shown in FIG. 5B, an intermediate layer 103 made of chromium plating is interposed between a metal base material 102 made of copper and a metal layer 104 to be melted made of nickel. Then, the metal layer to be melted (Ni) 104 and the intermediate layer (Cr) 103 are separated at the interface by utilizing a difference in plating stress. In the step of dissolving and removing the to-be-dissolved metal layer (Ni) 104 after the removal of the metal base material 102 and the intermediate layer 103, when the conductor pattern to be transferred is copper, for example, a sulfated hydrogen peroxide aqueous etching solution may be used. .
[0094]
In FIG. 5B, if the intermediate layer 103 is formed by chromium plating and the metal layer to be melted 104 is formed by nickel-cobalt alloy plating, the layers 103 and 104 can be easily separated at the interface. In this case, in the step of dissolving and removing the metal layer to be dissolved (Ni / Co) 104, when the conductor pattern to be transferred is copper, for example, a soft etching agent based on a sulfated hydrogen peroxide solution can be applied.
[0095]
Further, in each of the above embodiments, an example has been described in which the transfer sheets 61 and 91 are removed by the steps of peeling and removing the metal base members 62 and 92 and the steps of dissolving and removing the metal layers 64 and 94 to be dissolved. However, instead of this, the entire transfer sheet may be dissolved and removed. In this case, the transfer sheet may be made of the same kind of metal, or may be made of a laminate of different kinds of metal. In particular, in the latter case, each metal layer may be selectively etched using a different etching solution.
[0096]
For example, FIG. 5C shows a configuration of a transfer sheet 111 including first and second metal layers 112 and 114 different from each other. Here, in the case where the first metal layer 112 is made of copper and the second metal layer 114 is made of nickel, only the first metal layer (Cu) 112 can be etched by using an alkali etchant. Similarly, when copper is used for the first metal layer 112 and aluminum is used for the second metal layer 114, only the first metal layer (Cu) 112 can be etched by using hot sulfuric acid as an etchant. Other examples of the combination of the first and second metal layers 112 and 114 include nickel and gold, copper and chromium, and the like.
[0097]
Further, the combination examples of these dissimilar metals can also be applied as a combination example between the constituent metal of the metal layer to be melted (64, 94) and the constituent metal of the conductor pattern (55, 85).
[0098]
Further, the transfer sheet may be composed of two layers, a metal base material and a metal layer to be melted, and these layers may be separated from each other by a difference in thermal expansion coefficient between the layers. Alternatively, as in a transfer sheet 121 shown in FIG. 5D, a thermal foam layer 123 is interposed between a metal base material 122 and a metal layer 124 to be melted, and the thermal foam layer 123 is foamed by heat treatment to a predetermined temperature. Thus, the metal base material 122 and the metal layer to be melted 124 may be separated.
[0099]
【The invention's effect】
As described above, according to the method for manufacturing a device-embedded substrate and the method for manufacturing a printed wiring board of the present invention, since a metal sheet is used as a transfer sheet, a fine-pitch conductor pattern can be formed with high precision. And transfer to the insulating layer while ensuring the dimensional stability of the formed conductor pattern. Further, since the transfer sheet is finally removed by dissolving and removing the transfer sheet, it is possible to ensure a proper transfer operation of the conductor pattern.
[0100]
Further, the transfer sheet includes a metal base material and a metal layer to be melted that is separably stacked on the metal base material, and removing the transfer sheet separates and removes the metal base material from the metal layer to be melted. By comprising the step and the step of dissolving and removing the metal layer to be dissolved, the time cost required for the step of removing the transfer sheet can be reduced, and the productivity can be improved.
[0101]
Furthermore, according to the device-embedded substrate and the printed wiring board of the present invention, since the conductor pattern formed on the insulating layer is constituted by the electroplating layer, the conductor pattern can be finely pitched, and the mounting density can be reduced. Can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a configuration of a device-embedded substrate according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a state in which the device-embedded substrate shown in FIG. 1 is multilayered.
FIGS. 3A to 3H are process cross-sectional views illustrating a method for manufacturing a device-embedded substrate according to the first embodiment of the present invention, and FIGS. , (D) to (G) show a pattern forming step, and (H) shows a part of a pattern transfer step.
4A to 4L are process cross-sectional views illustrating a method for manufacturing a device-embedded substrate according to the first embodiment of the present invention, wherein FIG. 4I is a device accommodating process, and FIG. (L) shows the step of removing the transfer sheet.
FIG. 5A is a cross-sectional view schematically illustrating a configuration of a transfer sheet applied to the first embodiment of the present invention, and FIGS. 5B to 5D illustrate modified examples thereof. It is sectional drawing.
FIG. 6 is a process flow chart for explaining a method of manufacturing the device-embedded substrate according to the first embodiment of the present invention.
FIGS. 7A to 7G are process cross-sectional views illustrating a method for manufacturing a printed wiring board according to a second embodiment of the present invention, and in particular, FIGS. Step (G) shows a part of the pattern transfer step.
8 (H) to 8 (J) are cross-sectional views illustrating a method for manufacturing a printed wiring board according to the second embodiment of the present invention, and particularly show a step of removing a transfer sheet.
FIGS. 9A to 9H are process cross-sectional views illustrating a method for manufacturing an element-embedded substrate according to a third embodiment of the present invention.
FIGS. 10A to 10L are process cross-sectional views illustrating a method for manufacturing an element-embedded substrate according to a third embodiment of the present invention.
FIGS. 11A to 11F are process cross-sectional views illustrating a method for manufacturing an element-embedded substrate according to a fourth embodiment of the present invention.
FIG. 12 is a fragmentary cross-sectional view for explaining a modification of the chip mounting step according to the first embodiment of the present invention.
13A to 13F are process cross-sectional views illustrating a conventional method for manufacturing a device-embedded substrate.
[Explanation of symbols]
50, 50 ': Device built-in substrate, 51, 81: Insulating base material, 53: Through hole, 54, 84: Adhesive material layer, 55, 85: Conductor pattern, 55A, 85A: Electroplating layer, 56: Semiconductor chip ( 58, underfill resin layer, 59, solder (conductive material), 61, 91, transfer sheet, 62, 92, metal base material, 63, conductive adhesive resin layer, 64, 94, metal layer to be melted , 65: Multi-layer substrate with built-in element, 72A: Plating resist, 80: Printed wiring board, 87: Insulating film.

Claims (23)

An electric element electrically connected to the conductor pattern on the insulating layer, wherein the method for manufacturing an element-containing substrate is accommodated in a void formed in the insulating layer,
A gap forming step of forming the gap with respect to the insulating layer,
A pattern forming step of forming the conductor pattern on one surface of a metal transfer sheet,
After bonding the transfer sheet and the insulating layer to each other via the formed conductor pattern, a pattern transfer step of removing the transfer sheet,
An element accommodating step of accommodating the electric element bonded to the formed conductor pattern in the void portion,
The method for manufacturing a substrate with a built-in element, wherein the removal of the transfer sheet includes a step of dissolving and removing at least a part of the transfer sheet. The transfer sheet comprises a metal base material, and a metal layer to be melted which is formed so that the conductor pattern is formed and is separable from the metal base material.
2. The device built-in device according to claim 1, wherein the removal of the transfer sheet includes a step of separating and removing the metal base material from the metal layer to be melted, and a step of melting and removing the metal layer to be melted. 3. Substrate manufacturing method. The method according to claim 1, wherein the pattern forming step is performed by an electroplating method. The pattern forming step includes a step of forming a conductor pattern on one surface of the transfer sheet, and a step of flattening one surface of the transfer sheet by embedding an insulating material between the formed conductor patterns. The method for manufacturing an element-embedded substrate according to claim 1. 2. The method according to claim 1, wherein in the pattern transfer step, an adhesive is applied to an upper surface of the insulating layer in advance. 3. 2. The method according to claim 1, wherein the element accommodating step is performed after the transfer sheet and the insulating layer are bonded to each other and before the transfer sheet is removed. 3. The element accommodating step includes a step of accommodating the electric element in the gap and electrically connecting the electric element to the conductor pattern, and a step of injecting a sealing resin between the conductor pattern and the electric element. The method for manufacturing an element-embedded substrate according to claim 1, wherein: The dissolving metal layer and the conductor pattern are made of different metal materials, and the step of dissolving and removing the dissolving metal layer uses an etching solution that dissolves the dissolving metal layer but does not dissolve the conductor pattern. The method according to claim 2, wherein the method is performed. In the gap forming step, a through hole for connecting the front and back surfaces of the insulating layer with the gap is formed,
2. The method according to claim 1, further comprising a conductor filling step of filling the through hole with a conductive material. 10. The method for manufacturing a device-embedded substrate according to claim 9, further comprising: after the conductor filling process, laminating the manufactured device-embedded substrate in multiple layers with electrical connection in the through hole. Method. In a device built-in substrate in which an electric element housed in a void formed in the insulating layer is electrically joined to a conductor pattern on the insulating layer,
The substrate with a built-in element, wherein the conductive pattern comprises an electroplating layer adhered to an upper surface of the insulating layer. The device-embedded substrate according to claim 11, wherein the conductor pattern is a transfer film of a pattern plating film deposited on a metal transfer sheet. 12. The device built-in substrate according to claim 11, wherein an insulating material is buried between the conductor patterns bonded to the upper surface of the insulating layer, and the upper surface of the insulating layer is flattened. 14. The device-embedded substrate according to claim 13, wherein the insulating material is a plating resist. The device-embedded substrate according to claim 11, further comprising an underfill resin layer between the electric element and the conductor pattern. The device-embedded substrate according to claim 11, wherein a plurality of insulating layers on which the conductor pattern is formed are laminated. Printed wiring, comprising: a pattern forming step of forming a conductor pattern on one surface of a transfer sheet; and a pattern transfer step of removing the transfer sheet after attaching the transfer sheet to an insulating layer via the formed conductor pattern. In the method of manufacturing a plate,
The transfer sheet is made of metal,
The method for manufacturing a printed wiring board, wherein the step of removing the transfer sheet includes a step of dissolving and removing at least a part of the transfer sheet. The transfer sheet comprises a metal base material, and a metal layer to be melted which is formed so that the conductor pattern is formed and is separable from the metal base material.
18. The printed wiring according to claim 17, wherein the removal of the transfer sheet includes a step of separating and removing the metal base material from the metal layer to be melted, and a step of melting and removing the metal layer to be melted. Plate manufacturing method. The method for manufacturing a printed wiring board according to claim 17, wherein the pattern forming step is performed by an electroplating method. 18. The method according to claim 17, wherein in the pattern transfer step, an adhesive is applied to an upper surface of the insulating layer in advance. The dissolving metal layer and the conductor pattern are made of different metal materials, and the step of dissolving and removing the dissolving metal layer uses an etching solution that dissolves the dissolving metal layer but does not dissolve the conductor pattern. The method for manufacturing a printed wiring board according to claim 18, wherein the method is performed. In a printed wiring board having a conductor pattern formed on an upper surface of an insulating layer,
The printed wiring board, wherein the conductor pattern is formed of an electroplating layer adhered to an upper surface of the insulating layer. 23. The printed wiring board according to claim 22, wherein the conductor pattern is a transfer film of a pattern plating film deposited on a metal transfer sheet.

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