JP2000068402A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable semiconductor device having bumps with prolonged service life, which are connection terminal parts to external circuits. SOLUTION: In this semiconductor device, a wiring layer 8 such as signal lines, etc., inner leads 9 and connection pads 10, which are external connection terminals, are disposed on one surface of an insulating resin film 7. Excluding the upper surface of the connection pads 10, a solder resist layer 11 is formed by coating. A semiconductor element 12 is placed in a device hole 7a and bonded with inner leads, then a connection part such as this is resin-sealed. Furthermore, cylindrical bumps 18 are disposed on the connection pads 10. These bumps 18 have a structure where an intermediate solder coated layer and heat-resistant insulating resin layer are provided successively on a copper core material. The height of a bump is set greater than the diameter of the bump.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly, to a method for reducing the pitch of external connection terminals.
The present invention relates to a semiconductor device capable of high-density mounting.

[0002]

2. Description of the Related Art Conventionally, semiconductor elements have been mounted and mounted on a film carrier tape in which a wiring pattern such as a copper foil is provided on one surface of an insulating resin film for the purpose of reducing costs and simplifying the configuration. A semiconductor device called TCP (tape carrier package) is known. In such a TCP, bumps such as solder balls are arranged on connection pads, which are external connection terminals, from the viewpoints of increasing the number of input / output terminals, miniaturizing the outer shape, and facilitating mounting.
A structure called a ball grid array (hereinafter, referred to as BGA), in which these balls are arranged in a grid, is employed.

FIG. 4 shows a structure of a solder ball joint of a conventional T (tape) -BGA type semiconductor package.

In FIG. 1, reference numeral 1 denotes an insulating resin film such as a polyimide resin film, and reference numeral 2 denotes a wiring layer such as a signal line disposed on one surface (the lower surface in the figure) of the insulating resin film 1; Denotes a connection pad which is an external connection terminal; reference numeral 4 denotes a solder resist layer which is formed by covering the surface on which the wiring layer 2 is formed with the arrangement of the connection pad 3 as an opening;
Reference numeral 5 indicates a solder ball disposed on the connection pad 3. The structure of the insulating resin film 1 on the semiconductor element mounting surface side is not shown.

As shown in FIG. 5, such a semiconductor package is mounted on a motherboard 6 such as a glass epoxy wiring board, and connected to connection pads 3 of the semiconductor package and the motherboard 6 via solder balls 5 reflowed by heating. Connection pads (not shown)
Connected mechanically.

[0006]

However, such a semiconductor package has the following problems. That is, since the solder balls 5 are provided as bumps on the connection pads 3, as the pitch of the connection pads 3 becomes smaller, the solder resist layers 4 are formed so that the solder balls 5 after reflow do not contact each other. It is necessary to reduce the diameter of the opening and the diameter of the solder ball 5. Therefore, not only the area of the joint between the wiring film and the mother board 6 and the solder ball 5 is reduced, but also the height of the solder ball 5 is reduced. Therefore, the effect of relieving the thermal stress (stress caused by thermal load or the like) concentrated on the solder ball 5 is not sufficient, and the solder ball and its joint are fatigued and destroyed in a relatively short period of time. there were.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a highly reliable semiconductor device in which the life of a bump serving as a connection terminal portion with an external circuit is extended. And

[0008]

According to the present invention, there is provided a semiconductor device comprising:
A wiring base on which at least one main surface of a plate-like or film-like insulating base is provided with a wiring layer and a connection pad serving as an external connection terminal; and a wiring base mounted on the wiring base and electrically connected to the wiring layer. And a columnar bump having a coating layer made of solder and disposed on the connection pad.

In the present invention, as the plate-like or film-like insulating base material, for example, an insulating resin film such as a polyimide resin film or a prepreg obtained by impregnating a glass cloth with a thermosetting resin such as an epoxy resin is laminated. And a resin-impregnated glass cloth substrate.

[0010] The connection pad which is a wiring layer for signal lines and the like and an external connection terminal provided on at least one main surface (one or both surfaces) of such an insulating base material is, for example, Cu, C or the like.
u-based alloys, Ni-based alloys such as 42 alloy, etc., and vapor deposition patterning of these metals on an insulating base material, or photolithography of Cu foil or the alloy foil attached to one or both surfaces of the insulating base material It is formed by etching. Further, in the present invention, a device hole corresponding to the size and planar shape of the semiconductor element to be mounted is formed in the semiconductor element mounting region of such an insulating base, and the insulating base is formed on the side of the insulating base on which the wiring layer is formed. In addition, an inner lead whose tip projects into the device hole can be provided.
The formation of such inner leads can be performed in the same manner as the wiring layers and connection pads described above.

In the wiring base having such a device hole and an inner lead, the semiconductor element is mounted by placing the semiconductor element in the device hole and connecting its electrode terminal to the corresponding inner lead via a gold bump or the like. Bonding (inner lead bonding).

In the present invention, the columnar bumps provided on the connection pads, which are external connection terminals, are made of a solder made of a metal having a melting point higher than that of the solder and having a good thermal conductivity. A bump having a three-layer structure in which an intermediate coating layer is provided and a heat-resistant insulating coating layer is provided thereon can be used. Here, examples of the metal constituting the core material include copper, aluminum, iron, and alloys thereof, and examples of the material constituting the outermost insulating coating layer include, for example, an aromatic polyimide resin and a fluorine resin. And an insulating resin having a high melting point and excellent heat resistance.

In such a columnar bump, the diameter of a circle having a cross section perpendicular to the central axis, which is the diameter of the bump, is:
It can be set according to the pitch of the connection pads, and the distance between adjacent bumps can be reduced compared to conventional bumps (solder balls). it can. Furthermore, the bump height, which is the length in the central axis direction, can be set arbitrarily,
In order to obtain a longer-life bump joint, it is desirable that the bump height be larger than the diameter of the bump.

In the semiconductor device of the present invention, a columnar bump having a solder coating layer is provided on a connection pad as an external connection terminal instead of a conventional solder ball as a bump, and the bump is provided via the bump. As a result, electrical and mechanical connection with the motherboard is made, so that the bump height can be made sufficiently higher than the bump diameter, to reduce the stress at the bump joint, It is possible to prevent fatigue and destruction of the bump joint due to heat load and the like. In addition, the bumps are less likely to be crushed and the occurrence of short circuits between the bumps is reduced, so that the distance between adjacent bumps can be reduced, and the cross-sectional area ( Solder joint area)
Can be secured sufficiently large.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a semiconductor device according to the present invention, and FIG. 2 is an enlarged view of a portion A thereof.

In these figures, reference numeral 7 denotes an insulating resin film such as a polyimide resin film having a device hole 7a, and one main surface (lower surface in the figure) of the insulating resin film 7 is provided with a signal line or the like. Wiring layer 8 and inner lead 9 whose tip protrudes into device hole 7a
, Respectively. A connection pad 10 as an external connection terminal is provided at an end of the wiring layer 8 such as a signal line.
The wiring layer is formed in a lattice pattern, and a solder resist layer 11 is coated and formed on the wiring layer forming surface except for the connection pads 10 in order to prevent and protect a short circuit between the wirings. .

Further, a semiconductor element 12 is disposed face down in the device hole 7a of such a wiring film, and an electrode terminal (not shown) of the semiconductor element 12 is connected to the tip of the inner lead 9. Are electrically connected to the corresponding parts via gold bumps 13 and the like.

A resin sealing layer 14 made of epoxy resin or the like is provided outside the connection portion of the semiconductor element 12 for protection and reinforcement of the semiconductor element. A shape holding plate (stiffener) made of a metal such as stainless steel is provided in a region surrounding the device hole 7a on a surface (upper surface in the figure) of the wiring film opposite to the wiring layer forming surface.
15 is adhered via an adhesive layer 16, and a cover plate 17 made of a metal such as copper, aluminum, or stainless steel is provided on the upper surface of the stiffener 15 and the upper surface of the semiconductor element 12. It is adhered via a layer (not shown).

Further, on the connection pad 10 at the opening of the solder resist layer 11, an intermediate coating layer 18b made of solder is provided on a round bar-shaped copper core material 18a, and a heat-resistant insulating layer is further provided thereon. The columnar bumps 18 covered with the resin layer 18c are respectively provided. And
In such a columnar bump 18, the bump height, which is the length in the central axis direction, is set to be larger than the bump diameter corresponding to the diameter of a circle having a cross section perpendicular to the central axis.

Here, the formation of the columnar bump 18 has a three-layer structure in which a solder intermediate layer and a heat-resistant insulating resin layer are sequentially coated on a copper core material as shown in FIG. Using the bump forming wire 19 and the bump mounting jig 20 can be performed efficiently. That is,
In the jig 20 for mounting bumps, two mounting plates 21a and 21b are vertically arranged opposite to each other with an appropriate interval, and each of the mounting plates 21a and 21b has a wire insertion hole penetrating the front and back. 22a and 22b are provided at the same pitch as the connection pads of the semiconductor device.
The lower mounting plate 21b has a thickness corresponding to the height of the bump to be formed. Then, such a bump mounting jig 20 is connected to two mounting plates 21.
a, 21b into the wiring film 2
After the wires 19 are aligned with the third connection pads, the wires 19 are inserted one by one from the insertion holes 22a of the upper attachment plate 21a to the insertion holes 22b of the lower attachment plate 21b. Note that a small amount of solder may be applied in advance on the connection pads of the wiring film 23 in order to further ensure the joining by the solder. After the wires 19 are inserted through all the insertion holes, the wires 19 are heated to a temperature equal to or higher than the melting point of the solder and the solder intermediate layer of the wires 19 is reflowed so that the lower ends of the wires 19 are joined to the connection pads.
Next, all the wires 19 inserted through the insertion holes are made to have a predetermined length (equivalent to the thickness of the lower mounting plate 21b) by, for example, inserting a cutting blade into a gap between the two mounting plates 21a and 21b. ) And cut them all at once.

In the semiconductor device of the embodiment configured as described above, the copper core material 18a is provided on the connection pad 10, which is an external connection terminal, and serves as a bump for making electrical and mechanical connection with the motherboard. Solder intermediate coating layer 18b on top
Is provided thereon, and a heat-resistant insulating resin layer 18c is further formed thereon.
Is provided, and the bump height in such a columnar bump 18 is set sufficiently larger than the bump diameter, so that the stress at the bump bonding portion is good. This prevents fatigue and destruction of the bump joint due to periodic thermal load and the like. Therefore, the life of the bump joint portion for a heat cycle test or the like is greatly extended.

Further, in the bump 18 of the embodiment, the copper core material 18a is disposed at the center, so that the heat radiation from the bump joint portion is good and the bump is hardly crushed.
Furthermore, the outermost layer is coated with a heat-resistant insulating resin layer 18c, which suppresses swelling of the solder intermediate coating layer due to melting and maintains a cylindrical shape, thereby preventing short-circuiting between bumps. Therefore, the distance between the adjacent bumps can be reduced, and the diameter of the opening of the solder resist layer 11 can be increased to increase the cross-sectional area (solder joint area) of the bump joint. . Furthermore, a sufficiently large solder joint area can be ensured even in the tendency of the connection pads to be narrower in pitch.

Specific examples of the structure and arrangement of the columnar bumps and the effects of the examples will be described below.

That is, in a conventional semiconductor device in which solder balls having a diameter of 0.5 mm are used as bumps and the solder balls are arranged on connection pads arranged at a pitch of 0.8 mm, an opening of a solder resist layer is formed. Is 0.4mm in diameter
Therefore, the distance between adjacent solder balls is 0.3 mm. On the other hand, as in the conventional semiconductor device, the diameter of the opening of the solder resist layer is 0.4 mm, and connection bumps arranged at a pitch of 0.8 mm are connected to columnar bumps (copper In the semiconductor device of the embodiment in which the core material diameter is 0.1 mm, the thickness of the solder intermediate coating layer is 0.1 mm, and the thickness of the insulating resin layer is 0.05 mm, the distance between adjacent bumps is 0.4 mm. It is enlarged compared with. In addition, the height of the bump can be set to be equal to or larger than the height of the conventional solder ball (0.5 mm), and the concentration of stress due to periodic thermal load or the like can be favorably reduced.

Also, the arrangement pitch of the connection pads is the same.
Even with 0.8 mm, the diameter of the opening of the solder resist layer is 0.6 mm
The outer diameter of the columnar bump is 0.6 mm (
For example, the diameter of the copper core material is 0.2 mm, and the thickness of the solder intermediate coating layer is
(0.15mm, thickness of insulating resin layer 0.05mm). In this way, even if the outer diameter of the bump is increased and the solder joint area is sufficiently ensured, a sufficient distance (0.2 mm) between adjacent bumps so as not to cause a short circuit can be maintained.

Further, the diameter of the opening of the solder resist layer and the outer diameter of the bump are the same as those of the first structure.
In the case of 0.4 mm, even if the arrangement pitch of the connection pads is further narrowed to 0.6 mm, a sufficient distance between adjacent bumps (
0.2 mm), and a good bump connection portion can be obtained in response to the narrowing of the pitch of the connection pad.

In the above embodiment, a semiconductor device having a structure in which a stiffener is provided on a wiring film on which a semiconductor element is mounted has been described, but the stiffener can be omitted. In addition, a structure in which a wiring element or a wiring board having wiring layers on both sides is used, and a semiconductor element is mounted on such a wiring base material and flip-chip connected can be obtained. In such a structure, a simple sealing structure in which a metal cover or a cap is not provided but only a mold resin sealing layer is provided outside a connection portion of a semiconductor element can be adopted.

[0029]

As is apparent from the above description, according to the semiconductor device of the present invention, the stress at the bump junction with the external circuit is reduced, and the fatigue of the bump junction caused by a periodic thermal load or the like is reduced. And destruction can be prevented, and reliability is improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of an embodiment of a semiconductor device of the present invention.

FIG. 2 is an enlarged sectional view showing a portion A in FIG. 1;

FIG. 3 is a perspective view showing a method of forming a columnar bump in the semiconductor device of the embodiment.

FIG. 4 is a sectional view showing the structure of a solder ball joint of a conventional T-BGA type semiconductor package.

FIG. 5 is a sectional view showing a state in which a conventional T-BGA type semiconductor package is mounted on a motherboard.

[Explanation of symbols]

 7 Insulating resin film 8 Wiring layer 9 Inner lead 10 Connection pad 11 Solder resist layer 12 Semiconductor element 13 Gold bump 14 Resin sealing Stopping layer 18 Cylindrical bump 18a Copper core material 18b Solder intermediate coating layer 18c Heat resistant insulating resin layer 19 Bump forming wire 20 Bump mounting Jig 21a, 21b Mounting plate 22a, 22b Wire insertion hole

Claims (5)

[Claims] A wiring board on which at least one main surface of a plate-shaped or film-shaped insulating base is provided with a wiring layer and a connection pad serving as an external connection terminal; A semiconductor device comprising: a semiconductor element electrically connected to a wiring layer; and a columnar bump having a coating layer made of solder and disposed on the connection pad. 2. The cylindrical bump, wherein the height, which is the length in the axial direction, is larger than the diameter of a cross-sectional circle in a direction perpendicular to the axis. Semiconductor device. 3. A core material made of a metal having a melting point higher than that of solder and having good thermal conductivity, an intermediate layer made of solder provided on the core material, and the solder intermediate layer. The semiconductor device according to claim 1, further comprising a heat-resistant insulating cover layer provided on the semiconductor device. 4. The semiconductor device according to claim 1, wherein the wiring base is a wiring film having a copper wiring layer on at least one main surface of a polyimide resin film. 5. The semiconductor according to claim 1, wherein a solder resist layer having the connection pad portion as an opening is coated on the wiring layer of the wiring base material. apparatus.