Patent Application
20130143062
This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2011-266721 filed on Dec. 6, 2011, the entire contents of which are incorporated herein by reference.
The embodiments discussed herein are related to a method and a support member for manufacturing a wiring substrate, and a structure member for the wiring substrate.
As one known conventional method for manufacturing a wiring substrate, there is a method of adhering a metal foil to prepreg. With this method, first, a base layer is arranged on a target wiring formation area of the prepreg, then the metal foil is arranged on the prepreg interposed by the base layer, so that the metal foil having a larger area than the base layer contacts an outer peripheral part of the target wiring formation area, and then the prepreg is cured by applying heat and pressure thereto.
However, because a base layer is used in the conventional method for manufacturing the wiring substrate, manufacturing cost of the wiring substrate becomes high. For example, a copper foil is used as the base layer.
According to an aspect of the invention, there is provided a method for manufacturing a wiring substrate, the method including: forming a layered configuration including a first metal layer, a peeling layer, and a second metal layer; removing an edge part of the layered configuration, so that the first metal layer is smaller than the second metal layer from a plan view; forming a support body by adhering the first metal layer to a base member and adhering the base member to a process part, the process part being formed by the removing of the edge part of the layered configuration; forming a wiring substrate on the second metal layer; removing a part of the support body and a part of the wiring substrate that are superposed with respect to the process part from a plan view; separating the second metal layer and the wiring substrate from the support body after the removing of the part of the support body and the part of the wiring substrate.
The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
It is to be understood that both the foregoing generation description and the followed detailed description are exemplary and explanatory and are not restrictive of the invention as claimed.
In the following, embodiments of a method and a support member for manufacturing a wiring substrate, and a structure member for the wiring substrate are described with reference to the accompanying drawings.
With the wiring substrate manufacturing method according to the first embodiment, a layered body 10 having a cross-section illustrated in
The metal foil 11, the peeling layer 12, and the metal foil 13 have rectangular shapes of the same dimensions from a plan view (i.e. same dimensions with respect to the X axis direction and the Y axis direction). The dimensions of the metal foil 11, the peeling layer 12, and the metal foil 13 can be arbitrarily set in correspondence with the dimensions of the below-described wiring substrate.
The cross section illustrated in
The metal foil 11 is an example of a first metal layer. The metal foil 11 may be, for example, a copper foil. The thickness of the metal foil 11 (thickness in the Z axis direction) may be, for example, approximately 3 μm to 5 μm.
The peeling layer 12 is an example of a peeling layer interposed between the metal foil 11 and the metal foil 13. The peeling layer may be a metal layer (e.g., nickel (Ni) layer, chrome (Cr) layer, an inorganic layer (e.g., a layer formed of silicone oil), or a resin layer formed of an organic material (e.g., imidazole, triazole, or a silane coupling agent). The peeling layer 12 is used for adhering the metal foil 11 and the metal foil 13 together to build the layered body 10. In addition, the peeling layer 12 is used for separating the metal foil 11 in a subsequent step. Therefore, the peeling layer 12 is desired to have an adhesive property strong enough for building the layered body 10 but also an adhesive strength weak enough for allowing the metal foil 11 to be peeled therefrom. Accordingly, the adhesive strength between the metal foil 11 and the peeling layer 12 is set to be less than the adhesive strength between the metal foil 13 and the peeling layer 12.
The metal foil 13 is an example of a second metal layer. The metal foil 13 may be, for example, a copper foil. The thickness of the metal foil 13 (thickness in the Z axis direction) may be, for example, approximately 10 μm to 15 μm. In this embodiment, although the thickness of the metal foil 13 is greater than the thickness of the metal foil 11, the thickness of the metal foil 13 may be less than or equal to the thickness of the metal foil 11.
It is to be noted that a process for improving the adhesiveness between the peeling layer 12 and the metal foil 13 may be performed on the surface of the metal foil 13 to which the peeling layer 12 is adhered. The process for improving the adhesiveness may be, for example, a process of roughening a target surface (roughening process), a process of applying a silane coupling agent on a target surface (silane coupling process), or a process of applying a primer to a target surface (priming process). These processes are particularly effective in a case where the peeling layer 12 is a resin layer formed of an organic material.
A commercially available material having the metal foil 11, the peeling layer 12, and the metal foil 13 layered in the above-described manner may be used the layered body 10.
After preparing the above-described layered body 10, an edge part 11A extending along the four sides of the metal foil 11 of the layered body 10 illustrated in
As a result of removing the edge part 11A, the layered body 10 illustrated in
A part of the peeling layer 12, which is positioned more outward than the metal foil 11B from a plan view, is hereinafter referred to as an outer edge part 12A of the peeling layer 12. As illustrated in
The removing of the edge part 11A may be performed by, for example, forming a cut line between a border between the edge part 11A and the metal foil 11B by using a die, and peeling the edge part 11A from the metal foil 11. Alternatively, the removing of the edge part 11A may be performed by forming a cut line between a border between the edge part 11A and the metal foil 11B by using a laser (half cut), and peeling the edge part 11A from the metal foil 11. Alternatively, the removing of the edge part 11A may be performed by forming a mask on the surface of the metal foil 11 and removing the edge part 11A from the metal foil 11 by wet etching. Other methods besides those described above may also be used for removing the edge part 11A.
Next, the steps for manufacturing a support body 30 for manufacturing a wiring substrate according to an embodiment of the present invention is described with reference to
In the steps illustrated in
As long as the prepreg 20 can maintain a sufficient heat releasing property and strength, a filler may be mixed into the insulating resin of the prepreg 20 or an insulating resin containing no fiber may be used as the prepreg 20. For example, alumina or silica may be used as the filler mixed into the insulating resin of the prepreg 20.
In the first embodiment, the dimensions of the prepreg 20 from a plan view (i.e. dimensions in the X axis direction and the Y axis direction) are the same as the dimensions of the peeling layer 12 and the metal foil 13 of the layered body 10A. Further, the thickness of the prepreg 20 (thickness in the Z axis direction) may be, for example, approximately 200 μm to 1000 μm.
First, as illustrated in
Then, the prepreg 20 is cured by applying heat and pressure to the prepreg 20 in a state where the prepreg 20 is sandwiched between the two layered bodies 10A. Thereby, the two layered bodies 10A are respectively adhered to the upper and lower sides of the prepreg 20. In this embodiment, a vacuum laminator is used to cure the prepreg 20. This step of curing the prepreg 20 is an example of a second step.
In adhering each of the layered bodies 10A to the prepreg 20 as illustrated in
By adhering the two layered bodies 10A to the prepreg 20 together, the manufacturing of the support body 30 is completed as illustrated in
The support body 30 of the first embodiment has the metal foil 11B and the outer edge part 12A of the peeling layer 12 adhered to the prepreg 20. The adhesive strength between metal foil 11B and the prepreg 20 is greater than the adhesive strength between the metal foil 11B and the peeling layer 12.
In this embodiment, the adhesive strength between the metal foil 11B and the peeling layer 12 is set to be significantly weak compared to the adhesive strength between the metal foil 11B and the prepreg 20 because the metal foil 11B is to be peeled from the peeling layer 12 in a subsequent step.
Therefore, in the state illustrated in
Next, the steps of forming a built-up substrate 53 are described with reference to
First, the steps for forming pads 41 of the built-up substrate 53 on a surface of the metal foil 13 are described with reference to
First, as illustrated in
Then, as illustrate in
Then, as illustrated in
Next, the steps for forming, for example, an insulating layer 42 of the built-up substrate 53 are described with reference to
First, as illustrated in
The insulating layer 42 may be formed by forming a film-like epoxy resin or a polyimide resin into a semi-cured resin film, laminating the semi-cured resin film, and curing the semi-cured film by applying heat and pressure with a vacuum laminator.
Then, as illustrated in
Then, as illustrated in
An example of forming the wiring layer 43 with the semi-additive method is described below. First, a seed layer is formed on an inner wall and a bottom surface of the via hole 42A and a surface of the insulating layer 42 by performing an electroless copper plating method or a copper-sputtering method. Then, a plating resist pattern is formed on the seed layer. The plating resist pattern includes an opening part(s) that constitutes a shape of a wiring pattern. Then, a copper plating (which is to become the wiring pattern) is deposited on the seed layer exposed in the opening part and the inner wall of the via hole 42A by performing a copper electroplating method where the seed layer is used as the power feeding layer. Then, the plating resist is removed. Then, the seed layer exposed from the wiring pattern is removed. Thereby, the forming of the wiring layer 43 is completed.
Then, by repeating the steps described with
By performing the above-described steps, a structural body (also referred to as “structure member”) 50 illustrated in
Next, a step for forming a solder resist layer of the built-up substrate and a step for separating the structural body 50 are described.
First, as illustrated in
Thereby, a structural body 51 illustrated in
Then, the structural body 51 is cut along the dash-dot line illustrated in
The broken line illustrated in
The structural body 51 may be cut by using, for example, a laser or a cutter. Alternatively, the structural body 51 may be cut by forming holes with, for example, a drill or a router. The step of cutting of the structural body 51 along the dash-dot line is an example of a fourth step.
Although it is preferable to cut the structural body 51 along the dash-dot line that is positioned more inward relative to the outer periphery of the metal foil 11B (illustrated with the broken line in
In the case where the structural body 51 is cut along the broken line, a part of the structural body 51, which superposes the outer edge part (process part) 12A from a plan view (i.e. a part positioned more outward relative to the broken line in
In the case of cutting the structural body 51 along the dash-dot line, a part of the structural body 51 positioned a predetermined length (L1) inward than the outer edge part (process part) 12A from a plan view is removed.
Then, after the structural body 51 is cut in the steps illustrated in
The structural body 52 includes, for example, the peeling layer 12, the metal foil 13, the pads 41, the insulating layers 42, the wiring layers 43, the insulating layer 44, the wiring layer 45, and the solder resist layer 46. The peeling layer 12 and the metal foil 13 act as a carrier of the structural body 52. Thus, the structural body 52 is configured having the built-up substrate 53 layered on the carrier including the peeling layer 12 and the metal foil 13. The built-up substrate 53 includes, for example, the pads 41, the insulating layers 42, the wiring layers 43, the insulating layers 44, the wiring layers 45, and the solder resist layer 46.
By performing the separating step illustrated in
The prepreg 20 and the peeling layer 12 of the structural body 51 illustrated in
Accordingly, by cutting the structural body 51 along the dash-dot line illustrated in
Therefore, in a case where a small amount of stress is applied to the structural body 51 after the structural body 51 is cut along the dash-dot line illustrated in
Next, the steps for removing the peeling layer 12 and the metal foil 13 from the structural body 52 is described with reference to
The built-up substrate 53 illustrated in
The built-up substrate 53 is manufactured by removing the peeling layers 12 and the metal foils 13 from the structural bodies 52 illustrated in
Hence, with the above-described wiring substrate manufacturing method according to the first embodiment, in a state where the outer edge part 12A of the peeling layer 12 and the prepreg 20 is adhered to each other after the edge part 11A of the metal foil 11 has been removed, the wiring layer 43 and the like are formed to form the built-up substrate 53. Then, the adhering part between the outer edge part 12A and the prepreg 20 is cut off (see, for example,
Then, the structural bodies 52 are separated from the prepreg 20 and the metal foils 11B. Then, by removing the peeling layers 12 and the metal foils 13 from the structural bodies 52, the built-up substrate is manufactured.
Hence, compared to a conventional wiring substrate manufacturing method, the built-up substrate 53 can be manufactured at a low cost because the wiring substrate manufacturing method can manufacture the built-up substrate 53 without using a base layer.
In a case where the conventional wiring substrate manufacturing method uses a base layer, foreign material may be interposed between the base layer and the metal foil when, for example, foreign material is adhered to the base layer. Accordingly, dents may be formed on the metal foil during a middle of a manufacturing process. The dents may cause deformation of a layered structure. As a result, the built-up substrate 53 (which is to be the final product) may also become deformed.
In contrast, the wiring substrate manufacturing method according to the first embodiment manufactures the built-up substrate 53 without using the base layer. Since the base layer is not used, the possibility of foreign material entering a layered structure of the built-up substrate 53 during a process of manufacturing a wiring substrate can be reduced.
Accordingly, reliability during a manufacturing process can be improved compared to the conventional wiring substrate manufacturing method using a base layer.
If the edge part 11A of the metal foil 11 (see, for example,
As described above, the adhesive strength between the metal foil 11 and the peeling layer 12 is set to a relatively small amount, so that the metal foil 11B can be peeled from the peeling layer 12. However, if the adhesive strength between the metal foil 11 and the peeling layer 12 is too weak, the metal foil 11 and the peeling layer 12 may unexpectedly peel from each other during a step of manufacturing the built-up substrate 53 and result to difficulty of forming, for example, the wiring layer 53 in a subsequent process.
If the adhesive strength between the metal foil 11 and the peeling layer 12 is too large (strong), it would become difficult to separate the metal foil 11 and the peeling layer 12 in the step illustrated in
Therefore, the setting of the adhering force of the peeling layer 12 is not easy, and various factors are to be considered when setting the adhering force of the peeling layer 12.
However, with the wiring substrate manufacturing method according to the first embodiment of the present invention, the edge part 11A of the metal foil 11 is removed, and the outer edge part 12A of the peeling layer 12 is adhered to the prepreg 20. Because the prepreg 20 and the outer edge part 12A are adhered to each other by applying heat and pressure to the prepreg 20, the outer edge part 12A of the peeling layer 12 and the prepreg 20 can be adhered to each other with a substantial amount of strength regardless of the adhesive strength of the peeling layer 12.
Then, after the structural body 51 is manufactured (see, for example,
Accordingly, because the peeling layer 12 can attain an adhesive strength sufficient to adhere the peeling layer 12 and the metal foil 11B together, the adhesive strength of the peeling layer 12 can be set significantly easily compared to a case of not removing the edge part 11A of the metal foil 11.
Hence, with the wiring substrate manufacturing method according to the first embodiment of the present invention, the built-up substrate 53 can be manufactured significantly easily.
Although built-up substrates 53 are formed one on each side of the prepreg 20 (upper and lower sides of the prepreg 20) according to the above-described embodiment, a single built-up substrate 53 may be formed on either the upper side or the lower side of the prepreg 20.
Further, multiple built-up substrates 53 may be formed on each side of the prepreg 20 (upper and lower sides of the prepreg 20) as illustrated in
Thus, the structural body 51A illustrated in
After the structural body 51A is manufactured, the structural body 51A is cut off along the dash-dot line illustrated in
By the step illustrated in
As illustrated in
By manufacturing a support body 30A by using the two prepregs 20A, 20B, rigidity of the support body 30A can be increased because the total thickness of the prepregs 20A, 20B increases compared to a case where the support body 30 is manufactured by using a single prepreg 20.
Therefore, the number of prepregs 20 can be adjusted in accordance with, for example, the weight of the built-up substrate 53 (weight of the final product) or the load applied to the support body 30 during the processes of manufacturing the built-up substrate 53. It is to be noted that 3 or more prepregs 20 may be used in manufacturing the support body 30.
The built-up substrate 53 manufactured by the wiring substrate manufacturing method according to the first embodiment of the present invention is a coreless type built-up substrate that can be manufactured without a so-called core material. One typical example of a core material is formed by impregnating a glass fabric material in an epoxy resin and adhering copper foil onto both sides of impregnated glass fabric material.
In a case where the core material is used in manufacturing a built-up substrate, the thickness of the built-up substrate increases in correspondence with the thickness of the glass fabric material. In addition, it becomes difficult to form, for example, via holes with a fine pitch in the case where the core material is used.
However, with the wiring substrate manufacturing method according to the first embodiment of the present invention, a coreless type built-up substrate 53 can be manufactured. Accordingly, the thickness of the built-up substrate 53 can be reduced, and via holes or the like can be formed with a fine pitch. Moreover, the built-up substrate 53 can be manufactured at a low cost owing to the built-up substrate 53 manufactured without a core material.
Next, an example of a semiconductor package including the built-up substrate 53 manufactured by the wiring substrate manufacturing method according to the first embodiment of the present invention is described with reference to
The bump 61 may be, for example, solder or a bump formed of gold (Au). The underfill resin 62 may be, for example, an epoxy resin. The semiconductor chip 63 may be, for example, a CPU (Central Processing Unit) chip constituted by a so-called LSI (Large Scale Integrated Circuit).
The mounting of the semiconductor chip 63 may be performed before the removing of the peeling layer 12 and the metal foil 13.
As illustrated in
Then, as illustrated in
As illustrated in
Then, as illustrated in
Although the pads 41 are formed directly on the metal foil 13 in the above-described embodiment (see, for example,
The sacrificial layer may be formed before the pads 41 are formed by using an electroplating method where the metal foil 13 is used as a power feeding layer. For example, in a case where the pads 41 are formed of copper (Cu), the sacrificial layer may be made of nickel (Ni) and formed on the metal foil 13. The sacrificial layer may be made of copper (Cu) and formed on the metal foil 13 in a case where the pad 41 has a four layer structure having a gold (Ag) layer, a palladium (Pd) layer, a nickel (Ni) layer, and a copper (Cu) layer layered in this order from the side toward the metal foil 13. The sacrificial layer may be formed by using an electroplating layer where the metal foil 13 is used as a power feeding layer.
The sacrificial layer may be removed by using, for example, a wet etching method after the peeling layer 12 and the metal foil 13 are removed.
By forming and removing the sacrificial layer as described above, the surface of the pad 41 can be offset from the surface of the insulating layer 42 of the pad 41.
As illustrated in
In this case, only both edges in the X direction of the structural body 51 or both edges in the Y direction of the structural body 51 are cut off in the step illustrated in
The wiring substrate manufacturing method according to the second embodiment of the present invention is different from the wiring substrate manufacturing method according to the first embodiment of the present invention in that an edge part 12B of the peeling layer 12 is removed in addition to the removal of the edge part 11A of the metal foil 11A, and that the prepreg 20 is adhered to the metal foil 13.
In the second embodiment, like components are denoted by like reference numerals as those of the first embodiment and are not further explained.
With the wiring substrate manufacturing method according to the second embodiment, a layered body 10 having a cross-section illustrated in FIG. 12A is prepared. The layered body 10 has a layered structure including a metal foil 11, a peeling layer 12, and a metal foil 13 that are layered in this order.
After preparing the layered body 10 illustrated in
As a result of removing the edge parts 11A, 12B, the layered body 10 illustrated in
A part of the metal foil 13, which is positioned more outward than the metal foil 11B and the peeling layer 12C from a plan view, is hereinafter referred to as an outer edge part 13A of the metal foil 13. As illustrated in
The removing of the edge parts 11A, 12B may be performed by, for example, forming a cut line between a border between the edge part 11A and the metal foil 11B and a border between the edge part 12B and the peeling layer 12C by using a die, and peeling the edge parts 11R, 12B from the metal foil 11 and the peeling layer 12, respectively. Alternatively, the removing of the edge parts 11A, 12B may be performed by forming a cut line between a border between the edge part 11A and the metal foil 11B and a border between the edge part 12B and the peeling layer 12C by using a laser (half cut), and peeling the edge parts 11A, 12B from the metal foil 11 and the peeling layer 12, respectively. Alternatively, the removing of the edge parts 11A, 12B may be performed by forming a mask on the surface of the metal foil 11B and removing the edge parts 11A, 12B from the metal foil 11 and the peeling layer 12 by wet etching. Other methods besides those described above may also be used for removing the edge parts 11A, 12B.
Next, the steps for manufacturing a support body 30B for manufacturing a wiring substrate according to an embodiment of the present invention is described with reference to
First, as illustrated in
Then, the prepreg 20 is cured by applying heat and pressure to the prepreg 20 in a state where the prepreg 20 is sandwiched between the two layered bodies 10B. Thereby, the two layered bodies 102 are respectively adhered to the upper and lower sides of the prepreg 20. In this embodiment, a vacuum laminator is used to cure the prepreg 20. This step of curing the prepreg 20 is an example of a second step.
In adhering each of the layered bodies 10B to the prepreg 20 as illustrated in
By adhering the two layered bodies 10B to the prepreg 20 together, the manufacturing of the support body 302 is completed as illustrated in
The support body 30B of the second embodiment has the metal foil 11B and the outer edge part 13A of the metal foil 13 adhered to the prepreg 20. The adhesive strength between metal foil 11B and the prepreg 20 is greater than the adhesive strength between the metal foil 11B and the peeling layer 12C.
In this embodiment, the adhesive strength between the metal foil 11B and the peeling layer 12C is set to be significantly weak compared to the adhesive strength between the metal foil 11B and the prepreg 20 because the metal foil 11B is to be peeled from the peeling layer 12C in a subsequent step.
Therefore, in the state illustrated in
After the manufacturing of the support body 30B is completed, the built-up substrate 53 of
Similar to the first embodiment, the wiring substrate manufacturing method according to the second embodiment can manufacture the built-up substrate 53 at a lower cost and with manufacturing steps having higher reliability compared to those of the conventional wiring substrate manufacturing method. Further, compared to a conventional wiring substrate manufacturing method, the built-up substrate 53 can be manufactured more easily because there are less factors pertaining to the setting of the adhesive strength of the peeling layer 12 (12C).
Although the adhesive strength between the metal foil 11 and the peeling layer 12 is less than the adhesive strength between the metal foil 13 and the peeling layer 12 in the above-described embodiment, the adhesive strength between the metal foil 13 and the peeling layer 12 may be set to be less than the adhesive strength between the metal foil 11 and the peeling layer 12.
In this case, after the built-up substrate 53 is formed, the metal foil 13 and the peeling layer 12 may be separated from each other in the step illustrated in
All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2011-266721 | Dec 2011 | JP | national |
