JP2007042805A - Wiring board, its manufacturing method, and semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board capable of securing high connection reliability by restraining corrosion of a projected electrode caused by moisture at an interface between the protruded electrode of a portion formed in a region on an insulating base member on opposite sides of conductive wiring and the insulating base member. <P>SOLUTION: There are provided the insulated base member 1; a plurality of conductive wirings 2 provided in alignment on the insulating base member 1; protruded electrodes 3 each formed on the conductive wiring and formed over a region on the insulating base member 1, on opposite sides of the conductive wiring 2 traversing the conductive wiring 2 longitudinally of the same 2; and a metal plating layer 4 applied on the conductive wiring 2 and the protruded electrode 3, and consisting of a metal more unlikely to be ionized than the metal of the protruded electrode 3. A metal plating layer 4a is formed also on the interface between the protruded electrode 3 of a portion formed in a region on the insulating base member 1 on opposite sides of the conductive wiring 2 and the insulating base member 1. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a wiring board having a configuration in which a conductive wiring is provided on a flexible insulating base material, such as a tape carrier board, and a protruding electrode for connection is formed on the conductive wiring, and in particular, corrosion resistance of the protruding electrode. It relates to the improvement of sex.

  COF (Chip On Film) is known as a type of package module using a tape carrier substrate. The COF has a structure in which a semiconductor element is mounted on a tape carrier substrate and the mounting portion is protected by sealing with a resin. A tape carrier substrate used for COF is composed of an insulating film base material and a large number of conductor wirings formed on the surface thereof. Generally, polyimide is used as the film substrate, and copper is used as the conductor wiring. If necessary, a metal plating film and a solder resist layer which is an insulating resin are formed on the conductor wiring. The conductor wiring on the tape carrier substrate and the electrode pad of the semiconductor element are connected via the protruding electrode. Patent Document 1 discloses a tape carrier substrate in which this protruding electrode is previously formed on a conductor wiring.

  The structure of the tape carrier substrate described in Patent Document 1 will be described with reference to FIG. FIG. 5A is a perspective view showing a part of the tape carrier substrate. A plurality of conductor wirings 2 are provided in alignment on the film substrate 1, and protruding electrodes 3 are formed on the respective conductor wirings 2. The planar shape of the protruding electrode 3 extends across the regions on both sides of the conductor wiring 2 across the conductor wiring 2. FIG. 5B is a plan view of the tape carrier substrate. FIG. 5C is a cross-sectional view taken along the line D-d in FIG. 5B, and is a cross-sectional view in a direction crossing the conductor wiring 2 at the position of the protruding electrode 3. The cross-sectional shape of the protruding electrode 3 in the width direction of the conductor wiring 2 is a medium-high shape bonded to the upper surface and both side surfaces of the conductor wiring 2 and having a central portion higher than both sides. Further, the protruding electrode 3 is formed so as to be in contact with the surface of the film base 1 at both sides of the conductor wiring 2. Although not shown in Patent Document 1, as shown in FIG. 5C, it is described that a metal plating layer 4 such as Au plating or Sn is applied to the surfaces of the conductor wiring 2 and the protruding electrode 3. ing.

  By forming the protruding electrode 3 as described above, the protruding electrode 3 is held on the conductor wiring 2 with a practically sufficient strength. That is, since the protruding electrode 3 is bonded not only to the upper surface of the conductor wiring 2 but also to both side surfaces, sufficient stability against the force applied in the lateral direction can be obtained.

In addition, since the upper surface of the protruding electrode 3 is not flat but medium-high, it is suitable for connection to the electrode pad of the semiconductor element. That is, even if there is a misalignment in the alignment between the protruding electrode 3 and the electrode pad, the protruding electrode 3 is less likely to be connected to the adjacent inappropriate electrode pad as compared with the case where the upper surface is flat. Further, when connecting to the electrode pad, the oxide film formed on the surface of the electrode pad can be easily crushed by the convex upper surface of the protruding electrode 3, and a good electrical connection can be made with the non-oxidized interior. can get.
JP 2004-327936 A

  However, in the protruding electrode 3 having the above structure, the protruding electrode 3 may be corroded due to ion decomposition caused by moisture in a high-temperature and high-humidity environment. That is, since the metal plating layer 4 is provided on the surface of the protruding electrode 3 and the metal plating layer 4 is made of a material that is difficult to ionize, sufficient weather resistance can be maintained even in a high temperature and high humidity environment. . On the other hand, moisture may enter at the interface between the surface of the film substrate 1 and the metal plating layer 4. Since the protruding electrode 3 is usually formed of copper, if a voltage is applied in a state where moisture has penetrated, the ionized electrode 3 is easily decomposed and migrated. As a result, the protruding electrode 3 may be corroded and a defective connection may occur.

  Such a problem of corrosion in the protruding electrode 3 has a very large influence on connection reliability when the pitch of the conductor wiring 2 is reduced and the size of the protruding electrode 3 is reduced.

  The present invention suppresses the corrosion of the protruding electrode caused by moisture at the interface between the protruding electrode and the insulating substrate in the region on the insulating substrate on both sides of the conductor wiring and ensures high connection reliability. An object of the present invention is to provide a wiring board that can be used.

  It is another object of the present invention to provide a manufacturing method suitable for manufacturing such a wiring board, and a semiconductor device using such a wiring board.

  The wiring board of the present invention includes an insulating base material, a plurality of conductor wirings arranged in alignment on the insulating base material, and the conductor wirings formed on the conductor wirings, respectively, across the longitudinal direction of the conductor wirings. A protruding electrode formed over a region on the insulating base on both sides of the insulating substrate, and a metal plating layer applied to the conductive wiring and the protruding electrode, the metal plating layer being ionized more than the metal of the protruding electrode The metal plating layer is also formed at the interface between the protruding electrode and the insulating base material in the portion formed on the insulating base material on both sides of the conductor wiring. Features.

  The method for manufacturing a wiring board of the present invention includes a step of arranging a plurality of conductor wirings on an insulating base material, a step of forming a photoresist on the surface of the insulating base material on which the conductor wiring is provided, Forming in the photoresist an opening extending across the conductor wiring across the conductor wiring to expose a part of the conductor wiring in the opening; and one of the exposed conductor wirings Forming a protruding electrode on a portion by plating, removing the photoresist, and forming a metal plating layer on the conductor wiring and the protruding electrode, which is made of a metal that is more difficult to ionize than the metal of the protruding electrode. A process. In the step of forming a metal plating layer on the conductor wiring and the protruding electrode, the surface of the insulating base opposite to the conductor wiring has a curved shape with a convex cross section in a direction crossing the conductor wiring. By applying metal plating in a state along the surface, the metal is also applied to the interface between the protruding electrode and the insulating base of the portion formed in the region on the insulating base on both sides of the conductor wiring. A plating layer is formed.

  According to the present invention, the metal plating layer formed at the interface between the part of the projecting electrode formed in the region on the insulating base on both sides of the conductor wiring and the insulating base allows the projecting electrode due to moisture intrusion to occur. Corrosion is suppressed and high connection reliability can be secured.

  In the wiring board according to the present invention, the interval between the outer edge of the protruding electrode and the edge of the conductor wiring in the portion formed in the region on the insulating base is L, and the region on the insulating base is When the interval between the inner edge of the metal plating layer formed at the interface between the protruding electrode and the insulating base in the formed portion and the outer edge of the protruding electrode is Lp, L / 10 < Lp is preferable. More preferably, L / 2 <Lp.

  Moreover, it is preferable that the thickness of the metal plating layer formed at the interface between the protruding electrode and the insulating substrate is thinner than the thickness of the metal plating layer formed on the exposed surface of the conductor wiring and the protruding electrode. .

  The conductor wiring and the protruding electrode can be formed of copper.

  The metal plating layer can be a gold plating layer.

  A wiring board having any one of the above structures, a semiconductor element mounted on the wiring board, and an insulating resin interposed between the wiring board and the semiconductor element, through the protruding electrode, A semiconductor device in which the electrode pad of the semiconductor element and the conductor wiring are connected can be configured.

  Hereinafter, embodiments of the present invention will be described more specifically with reference to the drawings.

  With reference to FIG. 1, the structure of the tape carrier substrate in the first exemplary embodiment will be described. Fig.1 (a) is a top view which shows a part of tape carrier board | substrate, FIG.1 (b) is sectional drawing along the AA line of Fig.1 (a). FIG.1 (c) is an enlarged view of the part B of FIG.1 (b).

  As shown in FIG. 1A, a plurality of conductor wirings 2 are arranged on an insulating film substrate 1, and a protruding electrode 3 is electrolyzed at the tip of each conductor wiring 2, respectively. It is formed by plating. Similar to the conventional example, the protruding electrode 3 is formed across a region on the film substrate 1 on both sides of the conductor wiring 2 across the longitudinal direction of the conductor wiring 2.

  As shown in FIG. 1B, the cross-sectional shape in the width direction of the conductor wiring 2 of the protruding electrode 3 is higher at the center than at both sides. A metal plating layer 4 is formed on the surface of the protruding electrode 3. Although not shown in FIG. 1B, the metal plating layer 4 is formed on the surface of the conductor wiring 2 other than the portion where the protruding electrode 3 is formed, similarly to the protruding electrode 3. In the present embodiment, a metal plating layer 4a is also formed at the interface between the protruding electrode 3 and the film substrate 1 in the region formed on the film substrate 1 on both sides of the conductor wiring 2. ing.

  The conductor wiring 2 is usually formed using copper in a thickness range of 3 to 20 μm. The thickness of the protruding electrode 3 is usually in the range of 5 to 10 μm. As a material of the protruding electrode 3, for example, copper can be used. The thickness of the metal plating layer 4 is in the range of 0.5 to 1 μm. As the metal plating layers 4 and 4a, Au plating, Sn plating, or the like is used.

  Thus, by forming the metal plating layer 4a, even if moisture enters the interface with the surface of the film substrate 1 on both sides of the conductor wiring 2 in a high-temperature and high-humidity environment, the protruding electrode caused by the moisture 3 corrosion can be suppressed. That is, since the metal plating layer 4 a is formed on the lower surface of the protruding electrode 3, even if moisture enters, the metal plating layer 4 a is blocked and moisture contact with the protruding electrode 3 is suppressed. In order to obtain such an effect, the metal plating layer 4a must be formed of a material that is less likely to be ionized than the metal forming the protruding electrode 3. As described above, the effect of the present embodiment can be obtained by Au plating or Sn plating.

  If the metal plating layer 4a is formed over the entire interface between the bump electrode 3 and the film substrate 1, it is most effective for improving the corrosion resistance, but a part extending from the peripheral part to the inside to some extent. If it is formed in this region, a practically sufficient effect can be obtained. Here, the interval between the outer edge of the protruding electrode 3 and the edge measurement of the conductor wiring 2 in the part formed in the region on the film substrate 1 is L. Further, a distance between the inner edge of the metal plating layer 4 a formed at the interface between the protruding electrode 3 and the film substrate 1 in the region formed on the film substrate 1 and the outer edge of the protruding electrode 3. Is Lp. If the ratio of the distance Lp to the distance L is L / 10 <Lp, a practically sufficient effect for suppressing corrosion of the protruding electrode 3 can be obtained. More preferably, L / 2 <Lp.

  In addition, the thickness of the metal plating layer 4 a is preferably thinner than the thickness of the metal plating layer 4 formed on the exposed surfaces of the conductor wiring 2 and the protruding electrode 3.

  As the film substrate 1, polyimide which is a general material can be used. Depending on other conditions, an insulating film material such as PET or PEI may be used. If necessary, an epoxy-based adhesive may be interposed between the film base 1 and the conductor wiring 2.

  FIG. 2 is a cross-sectional view showing an example of the structure of a semiconductor device configured by mounting a semiconductor element on the above-described wiring board. The semiconductor element 5 is mounted by bonding the protruding electrode 3 formed on the conductor wiring 2 of the wiring board and the electrode pad 6 of the semiconductor element 5. An insulating resin layer 7 is provided so as to be interposed between the semiconductor element 5 mounted on the wiring board and the wiring board.

  Next, a method for manufacturing the wiring board having the above configuration will be described below with reference to FIGS. FIG. 3 is a plan view showing a portion where the protruding electrode is formed on the conductor wiring in each step of manufacturing the wiring board.

  First, as shown to Fig.3 (a), the film base material 1 in which the several conductor wiring 2 was formed in alignment with the surface is prepared. A photoresist 10 is formed on the entire surface of the film substrate 1 as shown in FIG. Next, as shown in FIG. 3C, an exposure mask 11 for forming projecting electrodes is opposed to the upper part of the photoresist 10 formed on the film substrate 1. The light transmission region 12 of the exposure mask 11 has a long hole shape that is continuous across the plurality of conductor wirings 2 in the alignment direction of the plurality of conductor wirings 2.

  By exposing and developing through the light transmission region 12 of the exposure mask 11, a long hole-like pattern 13 across the conductor wiring 2 is opened in the photoresist 10 as shown in FIG. Thereby, a part of the conductor wiring 2 is exposed in the long hole pattern 13. Next, the exposed portion of the conductor wiring 2 is subjected to metal plating through the long hole pattern 13 of the photoresist 10 to form the protruding electrode 3 as shown in FIG. Next, if the photoresist 10 is removed, a structure in which the protruding electrode 3 is formed on the conductor wiring 2 is obtained as shown in FIG.

  Next, as shown in FIG. 3G, a metal plating layer 4 made of Au, Sn, or the like is formed on the surfaces of the conductor wiring 2 and the protruding electrode 3. At that time, as shown in FIG. 4, the film base 1 is subjected to metal plating in a state where it is along the surface of the support base 14. The surface of the support base 14 forms a convex curved surface having a curvature of 15 in a cross section in a direction crossing the conductor wiring 2. For this reason, in the protruding electrodes 3 formed on the film base 1 at portions located on both sides of the conductor wiring 2, a force acts so that the interface between the film base 1 and the protruding electrodes 3 is peeled off. As a result, the plating solution enters between the film substrate 1 and the protruding electrode 3, and the metal plating 4 a is also formed on the lower surface of the protruding electrode 3. In this way, the thickness of the metal plating 4a, the size of the distance Lp shown in FIG. It is possible to adjust.

Below, an example of each part dimension is shown about the area | region in which the protruding electrode 3 of the said wiring board was formed.
(Substrate 1)
Width: 35-70 mm, thickness: 30-60 μm, elastic modulus: 4-10 GPa
(Conductor wiring 2)
Number: 300-900 / pcs, Pitch: 30-100 μm
Width: 15-50 μm, thickness: 6-12 μm, length: 5-15 mm
Elastic modulus: 130-140 GPa
(Projection electrode 3)
Width: 20-50 μm, Height: 10-30 μm, Length: 20-50 μm

  According to the wiring board of the present invention, corrosion of the protruding electrode due to moisture intrusion is suppressed, and high connection reliability can be secured, which is suitable for the configuration of the package module.

(A) is a top view of the wiring board in embodiment of this invention, (b) is AA sectional drawing in (a), (c) is an enlarged view of the B section in (b). The top view of the semiconductor device in an embodiment of the invention Sectional drawing which shows the manufacturing process of the wiring board in embodiment of this invention Sectional drawing which expands and shows the principal part of CC cross section in FIG. (A) is a plan view of a conventional wiring board, (b) is a plan view of the wiring board, and (c) is an enlarged cross-sectional view along the line DD in (b).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base material 2 Conductor wiring 3 Protruding electrode 4, 4a Metal plating layer 5 Semiconductor element 6 Electrode pad 7 Insulating resin layer 10 Photoresist 11 Exposure mask 12 Light transmission area 13 Elongated pattern 14 Support stand 15 Curvature

Claims (8)

An insulating substrate;
A plurality of conductor wirings arranged in alignment on the insulating substrate;
Protruding electrodes formed on the insulating base material on both sides of the conductor wiring across the longitudinal direction of the conductor wiring, each formed on the conductor wiring,
A metal plating layer applied to the conductor wiring and the protruding electrode;
In the wiring board made of a metal that is harder to ionize than the metal of the protruding electrode, the metal plating layer,
The wiring board, wherein the metal plating layer is also formed at an interface between the protruding electrode and the insulating base material in a portion formed in a region on the insulating base material on both sides of the conductor wiring.   The distance between the outer edge of the protruding electrode of the portion formed in the region on the insulating base and the edge of the conductor wiring is L, and the protrusion in the portion formed in the region on the insulating base 2. L / 10 <Lp, where Lp is an interval between the inner edge of the metal plating layer formed at the interface between the electrode and the insulating substrate and the outer edge of the protruding electrode. The wiring board described.   The wiring board according to claim 2, wherein L / 2 <Lp.   The thickness of the said metal plating layer formed in the interface of the said protruding electrode and the said insulating base material is thinner than the metal plating layer thickness formed in the said conductor wiring and the exposed surface of the said protruding electrode. The wiring board according to any one of the above.   The wiring board according to claim 1, wherein the conductor wiring and the protruding electrode are made of copper.   The wiring board according to claim 1, wherein the metal plating layer is a gold plating layer. A step of providing a plurality of conductor wirings in alignment on an insulating substrate;
Forming a photoresist on the surface of the insulating substrate provided with the conductor wiring;
Forming an opening extending on both sides of the conductor wiring across the conductor wiring in the photoresist, and exposing a part of the conductor wiring in the opening;
Forming a protruding electrode on a part of the exposed conductor wiring by a plating method;
Removing the photoresist;
In the method of manufacturing a wiring board, comprising the step of forming a metal plating layer made of a metal that is harder to ionize than the metal of the protruding electrode on the conductor wiring and the protruding electrode.
In the step of forming a metal plating layer on the conductor wiring and the protruding electrode, the surface of the insulating base opposite to the conductor wiring has a curved shape with a convex cross section in a direction crossing the conductor wiring. By applying metal plating in a state along the surface, the metal is also applied to the interface between the protruding electrode and the insulating base of the portion of the conductive wiring that is formed in the region on the insulating base on both sides of the conductor wiring. A method of manufacturing a wiring board, comprising forming a plating layer.   The wiring board according to claim 1, a semiconductor element mounted on the wiring board, and an insulating resin interposed between the wiring board and the semiconductor element, An electrode pad of the semiconductor element and the conductor wiring are connected via the protruding electrode.

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