JP2000150706A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate contact to a bonding pad of a metallic fine line by forming a projection part for bonding which projects from a second connection wiring in a space formed of a GND bonding pad and the second connection wiring. SOLUTION: Since a wiring does not extend downward from a lower end of bonding pads 70, 77 connected to a first connection wiring 66, a dead space is formed therebelow. Therefore, a projection part 78 is formed in a second connection wiring 80 connected to a bonding pad 4 or 1 at both sides of the bonding pads 70, 77 for using it as a bonding area. According to this constitution, a metallic fine line 71 can be subjected to bonding without access to the bonding pads 70, 77. Electric short circuit between the bonding pads 70, 77 and the first connection wiring 66 caused by the metallic fine line 71 can be restrained.

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 CSP (Chip Size / Scale P) employing a BGA (Ball Grid Array).
Acquisition).

[0002]

2. Description of the Related Art In recent years, the use of IC packages in portable equipment and small-sized / high-density mounting equipment has been advanced, and the concept of mounting IC packages and conventional IC packages is about to change significantly. The details are described in, for example, a special issue of “CSP technology and mounting materials and devices supporting the CSP technology” in Electronic Materials (September 1998, p. 22-).

FIG. 2 shows an example in which a flexible sheet 50 is employed as an interposer substrate. A copper foil pattern 5 is provided on the flexible sheet 50 via an adhesive.
1 is pasted. In this copper foil pattern 51,
An IC chip 52 is fixed, and bonding pads are formed around the IC chip. A solder ball connection pad is formed via wiring formed integrally with the bonding pad, and a solder ball 53 is formed on the solder ball connection pad.

FIG. 3 shows a specific example of this, in which the flexible sheet 50 is the portion indicated by the solid line on the outside, and the dotted line is the IC chip 52. An elongated chip formed around the IC chip 52 is a bonding pad group 54.
... A first solder ball connection pad group 55 is formed inside the bonding pad group 54. A second solder ball connection pad group 5 is further formed inside the first solder ball connection pad group 55.
6 are formed.

A third solder ball connection pad group 57 is formed outside the bonding pad group 54, and a fourth solder ball connection pad group 58 is formed further outside.
Are formed. A first wiring 59 is connected from the bonding pad 54 to the first solder ball connection pad 55, and a second wiring 60 is connected from the bonding pad 54 to the second solder ball connection pad 56. ,
A third wiring 61 is provided from the bonding pad 54 to the third solder ball connection pad 57, and a third wiring 61 is provided from the bonding pad 54 to the fourth solder ball connection pad group 58.
A fourth wiring 62 is formed. Further, a fifth wiring 63 extending from the bonding pad 54 to the periphery of the flexible sheet 50 is provided.

The back side of this solder ball connection pad group is
An opening 11 in which the flexible sheet is opened is provided, and a solder ball 53 is formed through this opening.

The solder ball connection pad 64 is formed by an IC
It is connected to the fixing land 65 of the chip 52, and is connected to the bonding pad via the wiring 66.

[0008]

FIG. 4 is an enlarged view of the bonding pad group and the solder ball connecting pad group in the X-axis direction of FIG. In FIG. 3, the wiring 66 electrically connected to the land 65 is connected to the second and third from the left in FIG.
It passes between the solder ball connection pads and is shown in an enlarged view.

The details will be described in the embodiment, but FIG.
In the above, the thin metal wire is formed for performing a pattern test on the flexible sheet 50. However, if the thin metal wire 71 is formed so as to exceed the bonding pad 70 integrated with the wiring 66, the fine metal wire 71 may come into contact with the bonding pad 70 due to a bonding error.

Further, the bonding is performed by ball bonding from the inside to the outside, the ball bonding is formed on the inside, and the stitch bond is formed on the outside. For example, the thin metal wire 72 in FIG. 4 is a portion to be stitch-bonded at a portion indicated by a black dot, and a X portion at a neck portion of the bonding pad group here.
There was a problem that cracks occurred in the portions indicated by.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problem, and firstly, a method is provided in which a space formed by a GND bonding pad and a second connection wiring projects from the second connection wiring. The problem is solved by having a bonding protruding portion formed in this way.

More specifically, in a space formed by the third wiring (or the fourth wiring) extending from the GND bonding pad and the bonding pad adjacent to the GND bonding pad. This problem can be solved by having a bonding protruding portion formed by protruding from the third wiring (or the fourth wiring).

The formation of the protruding portions allows the fine metal wires 71 to be formed.
In the test, contact with the bonding pad 70 is suppressed, and a highly accurate test can be performed.

In addition, the first wiring can be solved by providing a detour in a space above the bonding pad formed integrally with the third wiring (or the fourth wiring).

Since the first wiring on the stitch bond side has a long wiring length, cracks due to ultrasonic vibration can be prevented.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.
This will be described in detail with reference to FIG. In addition, the part which corresponds to the conventional structure is shown with the same reference numeral.

FIG. 3 shows the left corner of the flexible sheet 50 and its vicinity. The number of pins is 256 pins in this case.

First, as is clear from FIGS. 2 and 3, this structure has an IC chip 52 on a flexible sheet 50.
Is mounted, and the IC chip 52 and the pattern on the flexible sheet 50 are electrically connected via the thin metal wires 10.
It is molded.

First, the flexible sheet 50 will be described. The sheet 50 is made of a polyimide resin, and has a metal pattern attached to the surface thereof via an epoxy or acrylic adhesive.

More specifically, a 75 μm polyimide sheet has a circular opening 11 indicated by a dotted line.

The sheet 50 is made of an epoxy-based adhesive of about 1
It is applied in a thickness of 2 μm and supplied in a state where a laminate sheet is stuck on the surface. In this state, an opening indicated by a dotted line is opened, and a copper foil is bonded thereon. The thickness of the copper foil is 18 μm. That is, the entire surface has a copper foil, and the opening on the back surface has Cu exposed. Thereafter, the Cu pattern is etched, and a Ni plating layer of 1 μm is formed on the exposed portion of Cu, and an Au layer of 0.3 μm is further formed thereon.
m are stacked. Therefore, the conductive pattern on the surface is Au /
With a three-layer structure of Ni / Cu, Au / Ni is laminated on the exposed surface of Cu at the opening on the back surface of the flexible sheet.

The pattern has a three-layer structure made of the above-mentioned material. Cu is used as a wiring having a small resistance, Ni is used to wet solder, and Au is used to prevent surface oxidation of Ni.
Improves solderability.

The various pattern wirings described later are C
u, or a laminate of Cu / Ni, or only the solder ball connection pad may have a laminate structure of Cu / Ni / Au.

In FIG. 3, the flexible sheet 50 is indicated by an outer solid line, and the dotted line is the IC chip 52. This IC
What is formed elongated around the chip 57 is the bonding pad group 54. The bonding pad groups 54 are formed in a rectangular shape along four sides of the chip.
At least 64 sides are formed. A first solder ball connection pad group 55 is formed inside the bonding pad group 54, and a second solder ball connection pad group 56 is formed inside this. A third solder ball connection pad group 57 is formed outside the bonding pad group 54, and a fourth solder ball connection pad group 58 is formed further outside. That is, since there are at least 256 bonding pad groups 54, the first to fourth solder ball connection pad groups 55 ..., 56 ..., 57 ..., 58 ... are also formed at least 256 in total. In addition, the solder ball connection pad group includes an opening 1 on the back surface of the flexible sheet 50.
1, the solder ball 53 is formed.

From the bonding pad 54, the first
The first wiring 59 is provided on the solder ball connection pad 55.
However, a second wiring 60 is connected from the bonding pad 54 to the second solder ball connection pad 56, and a third wiring 61 is connected from the bonding pad 54 to the third solder ball connection pad 57. , Bonding pad 5
The fourth to fourth solder ball connection pad groups 58 include the fourth
Wiring 62 is formed. Further, a fifth wiring 63 extending from the bonding pad 54 to the periphery of the flexible sheet 50 is provided.

The solder ball connection pad 64 is formed of an IC.
It is connected to the fixing land 65 of the chip 52 and is connected to the bonding pad via the first connection wiring 66.

Here, the outer diameter of the solder ball connection pad is 0.5 mm, and the opening of the flexible sheet is 0.35 mm.
μm. The pitch is 0.8 mm, and the space between the solder ball connection pad and the adjacent solder ball connection pad is 0.7 mm. The width of the wiring is 42
μm, the size of the bonding pad is vertical 200μ
m, 125 μm in width.

On the other hand, the IC chip 52 is fixed to the land 65 of the flexible sheet 50 via solder, silver paste or an insulating adhesive, and the bonding pad of the IC chip 52 and the bonding pad of the flexible sheet 50 are connected. They are connected by thin metal wires 10 as shown in FIG. In the bonding pad on the IC chip 52 side,
Ball bonding, on the flexible sheet side,
Stitch bonded.

Next, a method of testing the characteristics of the flexible sheet will be described. FIG. 5 is substantially the same drawing as FIG.
The different parts are the first thick line shown in the bonding pad group and the second thick line shown in the solder ball connecting pad group. This is called Daisy chain, and shows a connection pattern schematically formed on the flexible sheet 50 of FIG. 6 and a connection pattern of a printed board on which the flexible sheet is mounted for testing. These are connected at the circles, connected in series like a flower of Daisy as shown in FIG. 8, apply a voltage to both ends in a high-temperature and high-humidity atmosphere, and inspect for a leak current or the like.

In FIG. 5, if only the pattern of the flexible sheet 50 and the first thick line are focused on and followed, a connection pattern as shown in FIG. 6 is schematically drawn. Here, FIG.
, A circle 73 indicates a solder ball connection pad group, and a thick solid line 74 schematically indicates to which solder ball connection pad it is connected. On the other hand, in FIG. 5, the second thick line indicates the connection state of FIG. Pads 75 to which the solder balls of FIG. 5 are connected are indicated by circles on the printed circuit board of FIG. The pads 75 are electrically connected by solid lines 76.

That is, in FIG. 5, a flexible sheet connected by a thin metal wire (first thick line) is mounted on the printed circuit board of FIG. 7, and the solder balls of the flexible sheet are electrically connected to the pads 75 of the printed circuit board. Then, the connection shape as shown in FIG. 8 is realized. Since FIGS. 6 and 7 are illustrated with the same dimensions, it is easy to understand if they are viewed by overlapping.

Therefore, in the circuit shown in FIG. 8 realized by laminating the flexible sheet and the printed circuit board, if a current is applied to the terminals A and B or a voltage is applied, the flexible sheet is satisfactory in a high temperature and high humidity situation. You can test if you get the characteristics you want.

However, when the bonding pads 70 and 77 integrated with the first connection wiring 66 in FIG. 4 are short-circuited with the fine metal wires 71 extending thereon, the lands 65 shown in FIG.
Since the wiring 78 electrically connected to and extends to the four corners, there arises a problem that the characteristics of DaisyChain cannot be measured accurately.

A feature of the present invention is to provide a projection 78 as shown in FIG. Since the bonding pads 70 and 78 connected to the first connection wiring 66 do not extend downward from their lower ends, a dead space is formed below them. Accordingly, a protrusion can be formed on the second connection wiring 80 connected to the fourth or first bonding pad on both sides of the fifth bonding pad,
This can be used as a bonding area.

Therefore, bonding can be performed avoiding the fifth bonding pad as in the case of the thin metal wire 71.
This has an advantage that an electrical short circuit between the bonding pads 70 and 77 and the first connection wiring 66 can be suppressed.

Next, according to the present invention, the detour 1
3 is provided. First, experimental results will be shown with reference to FIG. This is the result of an experiment and analysis of the situation of cutting the pattern of the flexible sheet when ball bonding is performed on the IC chip side and stitch bonding is performed on the flexible sheet side in the conventional pattern of FIG. The vertical axis of the graph indicates the number of pattern cuts in the flexible sheet, and the horizontal axis indicates power. This power is obtained when the maximum output of the bonder is 1 W, and this is 25
Divided into 5 stages, 30, 40, 50, 75, 100, 12
It was checked every 0, 150, and 200. That is, 25
0 is 1 W hour and 30 is (30/250) × 1 W hour. The bond load was unified at 90 gf, the ultrasonic output time was 15 milliseconds, and the direction of vibration was applied in the vertical direction (Y-axis direction) in FIG.

The Y crack is a crack in a wiring that is oriented vertically with respect to the paper surface of FIG. 3, that is, a wiring provided in parallel with the Y axis (for example, a wiring indicated by the lead lines 59 and 60). Indicate the number and X Crack is
The figure shows the number of cracks of wiring arranged in parallel with the X-axis on which the lead line 57 is arranged.

As a result of the analysis, FIG.
Cracks occur in the wiring parallel to the Y-axis direction of the first wiring 59, and also occur in the first wiring 59 as shown in FIG.
It turned out that it did not occur at 0. Further, it has been found that, among the first wirings 59, cracks are less likely to occur in the line L, and occur in the short first wirings. Here, the short first wiring has a distance indicated by an arrow d of about 1.2 μm or shorter. However, it goes without saying that the length becomes longer depending on the power condition.

In FIG. 4, the direction of the first wiring 59 is
The direction of the ultrasonic vibration (65 KHz) is substantially the same, and cracks have occurred in those having a short length. The inventor has
When the ultrasonic vibration generated from the bonding pad 54 is transmitted to the first solder ball connection pad 55 via the first wiring 59, the vibration passes from the thick part to the narrow part, so that the vibration is transmitted to the neck part. Vibration is concentrated. ・ Because the wires are subject to vertical vibrations in a state where the wires are tight, disconnection may occur at the neck part with no strength. For example, since the wires are short, the wires concentrate directly on the neck part indicated by the symbol X. In consideration of this, a detour was provided in the first wiring 59 as shown by reference numeral 13, and the distance was increased by about 1.2 to 1.5 times.
As a result, the crack became zero.

It is considered that the vertical vibration of the wiring is reduced due to the detour.

The same can be said for the Daisy Chain test because bonding is performed. In FIG. 4, the place where a black dot is shown at the end of the thin metal wire is the stitch bond side, and the third and fifth from the left are liable to crack. Therefore, by providing a detour, Daisy Dh can be used during product assembly bonding.
Cracks can be prevented both at the time of bonding of ain.

Although the numbers are shown in the bonding pad group of FIG. 1, the wirings are arranged substantially regularly except for the fifth. That is, 1 is provided with the second wiring 62 provided above, 2 is provided with the first wiring 59 provided above, 3 is provided with the third wiring 61 provided below, and 4 is provided with the fourth wiring 62 provided below. It is provided in. Particularly, since the third and fourth bonding pads are provided below the second bonding pad, a dead space is formed above the third and fourth bonding pads. Therefore, there is also a feature that the first wiring 59 can be formed long by effectively utilizing the dead space as a detour.

[0043]

As described above, according to the present invention,
First, in the space formed by the GND bonding pad and the second connection wiring, a bonding projection formed by protruding from the second connection wiring is provided. More specifically, the GND bonding pad is provided. Pad and G
Projecting from the third wiring (or the fourth wiring) into a space formed by the third wiring (or the fourth wiring) extending from the bonding pad adjacent to the ND bonding pad By having the bonding protruding portion formed in this way, when forming the Daisy chain, the thin metal wire and the bonding pad of the first connection wiring can be formed without being short-circuited or located close to each other. Therefore, a highly accurate test can be performed. Also the first
In the above wiring, the space above the bonding pad formed integrally with the third wiring (or the fourth wiring) is a dead space, and can be arranged without providing a space for a flexible sheet separately.

Also, the detour can be arranged by utilizing the dead space, the length of the first wiring on the stitch bond side can be formed long, and cracks due to ultrasonic vibration can be prevented.
Therefore, when forming Daisy Chain, cracks during stitch bonding can be suppressed, and a highly accurate test can be performed.

Further, this detour is effective also at the time of stitch bonding at the time of actual assembling, and has the effect of improving the product yield.

[Brief description of the drawings]

FIG. 1 is a plan view of a flexible sheet employed in a semiconductor device according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a semiconductor device of the present invention.

FIG. 3 is a diagram illustrating a relationship between a flexible sheet and an IC chip used in a semiconductor device.

FIG. 4 is a diagram illustrating a pattern of a flexible sheet used in a conventional semiconductor device.

FIG. 5 is a diagram illustrating a connection mode of Daisy Chain.

FIG. 6 shows Daisy Chai on the flexible sheet side.
It is a figure explaining an n pattern.

FIG. 7 is a diagram illustrating a Daisy Chain pattern on the printed circuit board side.

8 is a diagram showing a Daisy pattern obtained by connecting the patterns of FIG. 6 and FIG.
It is a figure explaining a Chain pattern.

FIG. 9 is a diagram illustrating an experimental result of investigating a cause of crack generation.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Mitsuo Umemoto 2-5-5 Keihanhondori, Moriguchi-shi, Osaka F-term (reference) in Sanyo Electric Co., Ltd. 5F044 KK03 KK09 KK12 RR08 RR18

Claims (3)

[Claims] 1. A bonding pad group adhered in a rectangular shape around a semiconductor chip mounted on an upper surface thereof, and a plurality of bonding pads formed outside and / or inside the bonding pad group in a rectangular shape. A row of solder ball connection pads, a GND solder ball connection pad formed inside the innermost row of solder ball connection pads, and a GND bonding pad in the bonding pad group are connected. A first connection wire, a second connection wire extending from the bonding pad adjacent to the GND bonding pad in a direction opposite to the first connection wire, the GND bonding pad and the second connection wire. A flexible projection having a bonding projection formed in the space formed by the second connection wiring and projecting from the second connection wiring. A semiconductor chip fixed to the mounting area; a thin metal wire connecting a bonding pad group of the semiconductor chip and a bonding pad group of the flexible sheet; and the flexible sheet, the semiconductor chip, and the metal. And a sealing resin for sealing the fine wire. 2. A bonding pad group adhered in a rectangular shape around a semiconductor chip mounted on an upper surface thereof, and a first solder ball formed in a rectangular shape inside the bonding pad group. A connection pad group, a second solder ball connection pad group formed in a rectangular shape inside the first solder ball connection pad group, and a rectangular shape outside the bonding pad group. A third solder ball connection pad group formed in a rectangular shape on the outside of the third solder ball connection pad group; and a fourth solder ball connection pad group formed in a rectangular shape outside the third solder ball connection pad group. A first wiring for connecting the solder ball connection pad and the bonding pad, a second wiring for connecting the second solder ball connection pad and the bonding pad,
A third wire connecting the third solder ball connection pad and the bonding pad, a fourth wire connecting the fourth solder ball connection pad and the bonding pad, and a second wire connecting the fourth solder ball connection pad and the bonding pad. A first connection wiring for connecting a GND solder ball connection pad formed inside the solder ball connection pad group and a GND bonding pad in the bonding pad group;
The third wiring (or the fourth wiring) is formed in a space formed by the bonding wiring and the third wiring (or the fourth wiring) extending from the bonding pad adjacent to the GND bonding pad. A flexible sheet having a bonding protruding portion formed by protruding from the wiring), a semiconductor chip fixed to the mounting area, a bonding pad group of the semiconductor chip, and a bonding pad group of the flexible sheet. And a sealing resin that seals the flexible sheet, the semiconductor chip, and the thin metal wire. 3. The semiconductor device according to claim 2, wherein the first wiring is provided with a detour in a space above a bonding pad formed integrally with the third wiring (or the fourth wiring). .