JP3911439B2 - Wiring board manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a wiring board, and more particularly, to a method of manufacturing a wiring board in which external connection terminals for surface mounting are integrally provided on a substrate used in a semiconductor device or the like .
[0002]
[Prior art]
Conventionally, a wiring substrate 100 as shown in FIG. 4 is used in a package for a semiconductor device. In the wiring substrate 100, a mounting hole 102 for mounting a semiconductor element is formed at a substantially central portion of the substrate 101, and a large number of externals are provided on the bottom surface (mounting surface side) of the substrate 101 so as to surround the mounting hole 102. Terminal bumps 103, 103,... As connection terminals are mounted. Usually, the terminal bump 103 is formed by melting a solder ball and protruding in a hemispherical shape from a land formed on the mounting surface side of the substrate 101.
[0003]
However, in the conventional method in which the solder balls are melted to form the terminal bumps 103, 103..., The bonding strength between the substrate 101 and the terminal bumps 103 may be insufficient. Further, at the time of mounting, the terminal bump 103 may be crushed and adjacent terminal bumps may be short-circuited.
[0004]
In order to eliminate such a collapse of the terminal bumps, Japanese Patent Application Laid-Open No. 7-226456 proposes a method of manufacturing a package for a semiconductor device in which the external connection terminals shown in FIG. Yes.
According to the manufacturing method shown in FIG. 5, first, the metal layer 132 is formed by plating or the like on both surfaces of the resin substrate 101 and the inner wall surface of the through hole 130 penetrating the substrate 101 to form the through hole via 134. . Further, on the back surface of the substrate 101, a land 136 is formed around the opening edge of the through-hole via 134 by a photolithography method [step of FIG. 5A]. The land 136 is electrically connected to the metal layer 132 on the surface of the substrate 101 through the through-hole via 134.
[0005]
Next, an electrically insulating or conductive resin paste 137 is pushed from the front opening of the through-hole via 134, and a part of the resin paste 137 is extruded from the back-side opening of the through-hole via 134 onto the land 136, and extruded. A hemispherical convex protrusion 138 is formed based on the weight and surface tension of the resin paste 137 [step of FIG. 5B].
[0006]
After the resin paste 137 forming the hemispherical convex protrusion 138 is solidified, a metal layer 139 is formed on the surface of the resin convex protrusion 138 and the surface of the substrate 101 by plating or the like [FIG. Step (5)]. A terminal bump 140 as an external connection terminal formed by forming a metal layer 139 on the surface of the protruding protrusion 138 is electrically connected to and protected from the through-hole via 134 by the metal layer 139. Thereafter, a conductor pattern 105 is formed by photolithography on the surface of the substrate 101 on which the metal layers 132 and 139 are formed [step of FIG. 5 (d)].
Unlike the conventional method of forming the terminal bumps 103, 103... By melting the solder balls, the terminal bumps 140 as the external connection terminals formed by the manufacturing method shown in FIG. Accordingly, the terminal bump 140 from the substrate 101 can be prevented from being missing or electrically short-circuited.
[0007]
[Problems to be solved by the invention]
However, since the manufacturing method shown in FIG. 5 is a method of forming the convex protrusion 138 by extruding the resin paste 137, variations in the physical properties of the resin paste 137, the amount of paste to extrude, the force to extrude, etc. are affected. However, it is very difficult to form the plurality of convex protrusions 138 in a desired shape. Thus, if the height of the plurality of convex protrusions 138 provided on a single substrate is not constant and varies, reliable mounting is difficult.
[0008]
Therefore, the present invention has been made to solve these problems, and the object of the present invention is to arrange a plurality of external connection terminals integrally provided on a substrate into a desired shape, for example, with a uniform height. An object of the present invention is to provide a method of manufacturing a wiring board that can be easily formed on a product.
[0009]
[Means for Solving the Problems]
As a result of repeated studies to solve the above-mentioned problems, the inventor sandwiched a film-like molded body made of an insulating resin between a substrate and a metal plate in which a plurality of through holes are formed. Then, after removing the protruding insulating resin, the metal plate is removed by etching to form insulating protrusions, whereby the surface of the insulating protrusions is covered with a conductor layer. The inventors have found that a plurality of external connection terminals can be easily formed, and have reached the present invention.
[0010]
That is, the present invention manufactures a wiring board in which each surface of a plurality of insulating protrusions made of an insulating resin formed to protrude on one surface side of a board is formed on an external connection terminal covered with a conductor layer. In this case, insulation is provided between the pattern forming surface on which the first wiring pattern of the substrate forming the wiring substrate is formed and the one surface side of the metal plate in which the through hole is formed in the portion where the external connection terminal is formed. By sandwiching a film-like molded body made of a conductive resin, a part of the softened insulating resin protrudes from each through hole on the other surface side of the metal plate, and an insulating resin made of an insulating resin is formed on the pattern forming surface. A plurality of layers protruding from the insulating layer by laminating layers and then removing each protruding portion made of an insulating resin protruding to the other side of the metal plate, and then removing the metal plate by etching. Insulation bump After that, a second wiring pattern including a via for electrically connecting the first wiring pattern and a conductor layer covering each surface of the insulating protrusion is formed in the insulating layer. It is a manufacturing method of a wiring board.
[0011]
The “film-like molded body made of an insulating resin” means that a thin film can be applied or placed on the pattern forming surface of the substrate, and is sandwiched between the substrate and the metal plate and a predetermined force is applied. When heated (or when a predetermined force is applied by heating), it means that the insulating resin forming the film-like molded body is softened to the extent that it protrudes from the through hole of the metal plate. Accordingly, the form includes a resin film, a liquid resin, a pasty resin, and the like.
[0013]
In the present invention, the through hole of the metal plate has a truncated cone shape, and when the film-shaped molded body made of an insulating resin is sandwiched between the substrate and the metal plate, the diameter of the through hole of the truncated cone shape is increased. The metal plate is disposed so that the side faces the film-like molded body. Thereby, the insulating resin in the softened state can be inserted from the enlarged diameter side of the through hole to the reduced diameter side, and the insulating resin can be easily inserted over every corner of the through hole. The insulating protrusion formed in this way has a truncated cone shape that is reduced in diameter toward the tip thereof, and is not easily deformed with a stable shape, and is also difficult to drop off from the substrate.
[0014]
According to the present invention, the insulating protrusion forming the external connection terminal is formed by causing the insulating resin in a softened state to protrude from the through hole of the metal plate and removing the protruding portion and the metal plate. For this reason, the formed insulating protrusion is formed following the shape of the through hole of the metal plate, and the tip portion is formed on a flat surface. Therefore, by appropriately selecting the thickness of the metal plate and the shape of the through hole, it is possible to easily form an insulating protrusion having a desired protrusion height and shape.
In the present invention, since the external connection terminals are formed on the basis of such insulating protrusions, a plurality of external connection terminals of a desired shape, for example, having a uniform height, can be easily provided. Can be formed.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An example of a method for manufacturing a wiring board according to the present invention will be described with reference to FIGS.
First, as shown in FIG. 1A, through-holes 30a, 30a,. A resin film 17 that is a film-like molded body made of an insulating resin is sandwiched between the formed metal plate 30 and the one surface 30b side.
The substrate 10 shown in FIG. 1A may be a substrate having the first wiring pattern 11 only on one side or a double-sided wiring substrate having a wiring pattern on the other side. Alternatively, it may be a multilayer wiring board in which a plurality of inner layer wiring patterns are formed in multiple layers on one or both sides via an insulating layer. 1, 2, and 3, only the pattern forming surface side is shown, and the other parts are omitted.
[0016]
As the resin film 17 made of an insulating resin, a film made of a thermosetting resin, for example, a film made of a thermosetting polyimide resin can be suitably used.
A copper plate or the like is used as the metal plate 30. In particular, a thin copper plate having a uniform thickness is preferable, and specifically, a thickness of 0.1 mm or less is preferable. Further, the metal plate 30 has a plurality of through holes 30a drilled at predetermined locations in the same truncated cone shape by drilling or etching.
Note that the “predetermined portion” referred to here is a portion where an external connection terminal is formed on the substrate 10 when the substrate 10 is overlaid, as will be described later.
[0017]
In this way, the metal plate 30 is aligned so that the through holes 30a, 30a,... Are located at positions where the external connection terminals 20, 20,. The resin film 17 is sandwiched and overlapped, and the metal plate 30 is further pressed. In this way, as shown in FIG. 1B, a part of the softened insulating resin protrudes from each through hole 30a on the other surface 30c side of the metal plate 30 and is laminated on the pattern forming surface of the substrate 10. An insulating layer 18 made of an insulating resin is formed. At this time, the insulating resin may be heated in order to obtain a better softened state that easily protrudes from the through hole.
At this time, the substrate 10 has the pattern formation surface facing the resin film 17 side, and the metal plate 30 overlaps the surface 30b on the enlarged diameter side of the through hole 30a drilled in a truncated cone shape toward the resin film 17 side. . As a result, the insulating resin can easily enter from the enlarged diameter side of the through hole 30a to the reduced diameter side, and the insulating resin can be filled into the corners of the through hole 30a.
[0018]
After the insulating resin of the resin film 17 is cured in the state of FIG. 1B, the protruding of the insulating resin that protrudes to the other surface 30c side so that the other surface 30c of the metal plate 30 is formed as a flat surface. Part is polished and removed [step of FIG. 1 (c)].
After polishing, all of the metal plate 30 is removed by etching or the like [step of FIG. 1 (d)]. By removing the metal plate 30 in this manner, an insulating layer 18 made of an insulating resin and flatly laminated on the substrate 10 and a plurality of insulating protrusions 19 protruding from the insulating layer 18 are formed. . The plurality of insulating protrusions 19 are formed in a truncated cone shape having substantially the same shape following the shape of the through hole 30a at a position where the external connection terminal of the substrate 10 is formed.
[0019]
Thereafter, a via hole 14 is formed in the insulating layer 18 to form a via (non-penetrating via hole) 15 that electrically connects the first wiring pattern 11 and a second wiring pattern 12 described later [FIG. Process]. The via hole 14 is formed by drilling the insulating layer 18 so that the first wiring pattern 11 is exposed on the bottom surface of the via hole 14 by laser light irradiation or etching.
[0020]
After forming the electroless copper plating layer on the surface of the substrate including the inner wall surface of the formed via hole 14 and the surface of the insulating protrusion 19 to form an electroless copper plating layer, the electroless copper plating layer is used as a power feeding layer. Electrolytic copper plating is performed [step of FIG. 1 (f)]. At this time, a sputtering method or a vapor deposition method may be employed instead of the electroless copper plating.
Thus, the conductor layer 16 is formed on the surface of the substrate including the inner wall surface of the via hole 14 and the surface of the insulating protrusion 19 by electroless copper plating and electrolytic copper plating. Of the conductor layer 16, the via 15 is formed by the conductor layer 16 b provided on the inner wall surface of the via hole 14.
The external connection terminal 20 is formed by the conductor layer 16 a provided on the surface of the insulating protrusion 19.
[0021]
Next, the second wiring pattern 12 is formed on the insulating layer 18.
In forming the second wiring pattern 12, first, a resist layer 31 is formed on the surface of the conductor layer 16. The resist layer 31 is formed by applying a liquid photosensitive resist using an electrodeposition resist or the like, or by sticking a film coated with the photosensitive resist on a support [step of FIG. ]. According to the electrodeposition resist, the resist layer 31 can be easily and satisfactorily formed along the fine irregularities of the substrate.
[0022]
The resist layer 31 is exposed and developed to form a resist pattern 32 [step of FIG. 2 (b)]. At this time, if a parallel light and a non-contact photomask are used for the exposure, a good resist pattern 32 can be formed over the details of the irregularities such as between the external connection terminals 20.
Then, etching is performed using the resist pattern 32 as a mask to form the second wiring pattern 12 [step of FIG. 2C].
Thereafter, the state where the resist pattern 32 is removed is shown in FIG. In the state shown in FIG. 2D, the conductor layer 16 a of the external connection terminal 20 is electrically connected to the second wiring pattern 12, and the second wiring pattern 12 is connected to the first wiring pattern 11 through the via 15. ing.
[0023]
Further, as shown in FIG. 2E, a solder resist layer 22 is formed on the substrate surface excluding the external connection terminals 20 to protect the conductor layer 16. The solder resist layer 22 is formed by printing a photosensitive solder resist on the surface of the substrate or applying it using a curtain coater or the like, and then exposing and developing. By using a photomask with parallel light and non-contact for exposure, the solder resist layer 22 can be easily and satisfactorily formed over the details of the substrate surface. In forming the solder resist layer 22, the thickness of the solder resist layer 22 does not hinder the contact between the external connection terminals 20 and the solder bumps 41 provided on the mounting substrate during mounting. Is formed thinner than the protruding height of the external connection terminal 20.
Thereafter, by forming a metal layer 21 of nickel, gold or the like on the surface of the conductor layer 16a of the insulating protrusion by electroless plating or the like, the wettability with the solder bumps of the mounting substrate can be improved during mounting.
[0024]
As another method, after the conductor layer 16 is formed, the surface of the conductor layer 16 is sequentially subjected to nickel plating and gold plating and laminated, and this is etched to form the metal layer 21 and at the same time, the second wiring pattern 12 is formed. There is also a method of forming.
In this way, finally, the wiring board 50 shown in FIG.
[0025]
The wiring substrate 50 shown in FIG. 2 (e) is integrated with the substrate 10 in a state in which a plurality of external connection terminals 20, 20,... Protrude beyond the solder resist layer 22 applied to the surrounding substrate surface. Provided. Specifically, the protruding height is about 0.04 to 0.10 mm from the surface of the solder resist layer 22.
[0026]
The external connection terminal 20 is formed by providing a conductor layer 16a on the insulating protrusion 19 protruding from the insulating layer 18 so as to cover the surface, and further providing a metal layer 21 so as to cover the conductor layer 16a. ing. According to the external connection terminal 20 having such a configuration, the shape thereof depends on the shape of the insulating protrusion 19. In this regard, in the wiring board 50 shown in FIG. 2 (e), the insulating protrusion 19 is made of an insulating resin filled in the through hole 30a of the metal plate 30, and thus has the shape of the through hole 30a. It will be a thing. Therefore, as in the manufacturing method shown in FIGS. 1 to 2, the thickness of the metal plate 30 is made uniform, and the plurality of through holes 30a have substantially the same shape. Can be obtained simultaneously. As a result, the external connection terminal 20 having no variation in shape can be obtained.
[0027]
The external connection terminals 20, 20... Having such a configuration are electrically connected to the second wiring pattern 12 formed on the insulating layer 18 by the conductor layer 16 a. Further, the second wiring pattern 12 is electrically connected to the first wiring pattern provided on the substrate 10 through the via 15 provided through the insulating layer 18.
For this reason, each of the plurality of external connection terminals 20 is electrically connected to the first wiring pattern through the second wiring pattern 12 including the via 15.
[0028]
FIG. 3 shows a state when the wiring board 50 is mounted on the mounting board 40. In the mounting substrate 40 shown in FIG. 3, solder bumps 41 are mounted on the exposed surfaces of the pad portions 42 exposed from the insulating layer (solder resist) 43.
The wiring board 50 abuts the external connection terminals 20, 20,... On the corresponding solder bumps 41, 41... Of the mounting board 40, and the solder bumps 41, 41,. Bonded to the mounting substrate 40.
At this time, if the metal layer 21 is provided on the surface of the external connection terminal 20, adhesion to the solder bump 41 is improved, and the solder bump 41 can be reliably bonded. In addition, when the solder of the solder bump 41 has good adhesion to the conductor layer 16a of the external connection terminal 20 and is well bonded, the metal layer 21 may not be provided.
[0029]
Since the external connection terminals 20, 20,... Of the wiring board 50 shown in FIG. 2 (e) are integrally provided on the board 10 by the insulating protrusions 19, the conventional wiring board 100 shown in FIG. As described above, it is possible to solve the problem that the solder ball mounted as the external connection terminal falls off or is crushed during mounting. In addition, the external connection terminal 20 has a truncated cone shape with a reduced diameter at the tip, has a stable shape, is more difficult to deform, and is less likely to fall off the substrate 10. For this reason, the electrical connection between the mounting board 40 and the wiring board 50 does not become unstable, and the adjacent external connection terminals 20 are not short-circuited.
Further, the plurality of external connection terminals 20, 20... Provided on the substrate 10 are formed in substantially the same shape, and particularly the protrusion height is substantially the same, so that the solder bumps 41, 41. At the same time, and can be reliably joined. For this reason, the electrical connection between the mounting board 40 and the wiring board 50 can be easily and reliably performed.
[0030]
The shape of the insulating protrusion 19 can be easily changed by changing the thickness of the metal plate 30 or the shape of the through hole 30a. For this reason, for example, the insulating protrusion 19 can be easily formed in various shapes such as a high protrusion height, a low protrusion height, a hemispherical shape, and a cylindrical shape. Accordingly, the external connection terminal 20 having a more suitable shape can be formed in accordance with the shape of the solder bump 41 on the mounting substrate 40 side in order to ensure the bonding with the mounting substrate 40.
In the past, the metal plate 30 having a uniform thickness was used. However, by using a metal plate having a different thickness depending on the location, the insulating protrusions 19 having different heights were formed, and one wiring board was formed. The external connection terminals 20 having different heights can also be formed on 50. As a result, for example, variations due to warpage of the mounting substrate 40 can be compensated for on the external connection terminal side, and the mounting substrate 40 and the wiring substrate 50 can be reliably electrically connected.
[0031]
Further, when the wiring board 50 shown in FIG. 2 (e) is compared with the wiring board provided with the terminal bumps 140 shown in FIG. 5, the wiring board 50 shown in FIG. 2 (e) has the following points. It is advantageous for high integration.
First, the convex protrusions 138 that form the terminal bumps 140 in FIG. 5 are shaped so that the resin paste 137 is filled into the through holes and covers the openings of the through holes. Therefore, the bump diameter of the terminal bump 140 depends on the opening diameter of the through-hole via. On the other hand, the insulating protrusions 19 that form the external connection terminals 20 of the wiring board 50 have a shape that simply protrudes from the board 10. Therefore, in the wiring board 50 shown in FIG. 2E, the opening of the through-hole via need not be covered, and the external connection terminal 20 can be formed smaller than the terminal bump 140.
[0032]
In the above description, the resin film 17 is used as a film-like molded body made of an insulating resin, but an insulating resin such as liquid or paste may be used. In the case of liquid or paste, the insulating resin is applied to the pattern forming surface of the substrate 10 to a uniform thickness by printing or the like, and the insulating resin is applied by pressing the metal plate 30 against it. The metal plate 30 is projected from the through hole 30a.
[0033]
【The invention's effect】
According to the present invention, the shape of a plurality of external connection terminals provided integrally on a substrate can be formed in a desired shape, and for example, a wiring substrate having uniform external connection terminals without variations in height can be easily obtained. Can do. Therefore, if the present invention is used for a semiconductor device, the wiring board can be reliably mounted on the mounting board.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram for explaining a method of manufacturing a wiring board according to the present invention.
FIG. 2 is an explanatory diagram for explaining a method of manufacturing a wiring board according to the present invention.
FIG. 3 is a cross-sectional view when the wiring board according to the present invention is mounted.
FIG. 4 is a top view of a conventional wiring board.
FIG. 5 is an explanatory diagram for explaining a conventional method of manufacturing an external connection terminal.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Board | substrate 11 1st wiring pattern 12 2nd wiring pattern 15 Via 16 Conductor layer 17 Resin film 18 Insulating layer 19 Insulating protrusion 20 External connection terminal 21 Metal layer 30 Metal plate 31 Resist layer 40 Mounting board 41 Solder bump 50 Wiring board

Claims (2)

When manufacturing a wiring board in which each surface of a plurality of insulating protrusions made of an insulating resin formed to protrude on one surface side of the substrate is formed on an external connection terminal covered with a conductor layer,
An insulating resin is used between the pattern forming surface on which the first wiring pattern of the substrate forming the wiring substrate is formed and the one surface side of the metal plate in which a through hole is formed in the portion where the external connection terminal is formed. By sandwiching the film-shaped molded body, a part of the softened insulating resin protrudes from each through hole on the other side of the metal plate, and an insulating layer made of an insulating resin is laminated on the pattern forming surface. And
Next, after removing each protrusion made of an insulating resin protruding to the other surface side of the metal plate, the metal plate is removed by etching to form a plurality of insulating protrusions protruding from the insulating layer. And
Thereafter, a second wiring pattern including a via for electrically connecting the first wiring pattern and a conductor layer covering each surface of the insulating protrusion is formed in the insulating layer. Method. The through-hole of the metal plate has a truncated cone shape, and when the film-shaped molded body made of an insulating resin is sandwiched between the substrate and the metal plate, the enlarged side of the through-hole of the truncated cone shape is the film shape. The method for manufacturing a wiring board according to claim 1, wherein the metal plate is disposed so as to face the molded body .

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