JP2614005B2 - Film carrier tape and lead bonding method therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a film carrier tape used in a semiconductor device according to the present invention and a bonding method for electrically connecting a semiconductor chip or a mounting board using the film carrier tape.

[0002]

2. Description of the Related Art Generally, a film carrier tape is shown in FIG.
As shown in a plan view and a cross-sectional view taken along line CC of FIGS. 1A and 1B, a sprocket hole 2 for conveyance and positioning is formed on an insulating tape 1 made of polyimide or the like. In addition, a device hole 3 is formed as an opening into which the semiconductor chip 10 enters. And tape 1
A metal foil such as copper is adhered to the surface of the lead 6 and formed into a required pattern by photolithography to form a lead 6.
Then, pads 7 and the like for electric sorting are formed. The lead 6 includes an inner lead 6A protruding into the device hole 3 and an outer lead 6B connected to the inner lead 6A and extending outside the device hole.
Metal plating 9 such as tin or solder is applied. The tip of the outer lead 6B faces the outer lead hole 4 opened in the tape 1, and the space between the outer lead hole 4 and the device hole 3 serves as a suspender 5 for holding the lead 6.

[0003] When bonding the leads 6 of the film carrier tape to the semiconductor chip 10, bumps 11, which are metal projections, are provided on the electrodes of the semiconductor chip 10 in advance. The inner lead 6A is bonded to the bump 11 by the thermocompression bonding method or the eutectic method by placing the lead 6A and heating or scrubbing while pressing the inner lead 6A with a bonding tool from behind. , ILB). After the bonding of the inner leads is completed, a contact needle (not shown) is brought into contact with the pad 7, and the semiconductor chip 10 is energized through the contact needle and the pad to perform an electrical property test, perform an electrical selection, and the like. In order to improve the reliability and mechanical protection of the semiconductor device, the semiconductor chip and the inner lead are sealed by potting or the like. When mounting the semiconductor device configured as described above, as shown in FIG.
The outer lead 6B is cut to a required length, and the semiconductor chip 1 is attached to a required portion of the printed circuit board 20 with an adhesive 23 or the like.
0 is fixed, and then the outer leads 6B are bonded to the circuit pattern 21 of the printed board formed as a conductive pattern (this is abbreviated as OLB).
For bonding, brazing such as solder is used. 24 is a potting material.

[0004]

In such a conventional film carrier tape, unless the metal plating 8 is formed on the leads 6, the surface of copper as the main material is oxidized by heat applied to the leads during ILB. However, there is a problem that good connection with the electrode (bump) 11 of the semiconductor chip cannot be performed, mechanical connection strength is reduced, and electrical resistance of the connection portion is increased. For this reason, metal plating of gold, tin, solder, or the like is performed. However, if gold plating that provides high reliability particularly when connecting to electrodes is applied, there is a problem that the cost of the semiconductor device is increased.

A conventional film carrier tape is
Since the metal plating of the lead is exposed, FIG.
When the lead is deformed after or after performing the ILB or OLB as shown in FIG. 2, a part of the lead 6 comes into contact with the semiconductor chip 10 or the printed circuit board 20, and the two are electrically short-circuited. There is a problem that a device failure occurs. An object of the present invention is to provide a film carrier tape that enhances the reliability of the connection between a semiconductor chip and a lead and prevents an electrical short circuit to prevent a semiconductor device failure. Another object of the present invention is to provide a bonding method which enables good connection of leads of a film carrier tape.

[0006]

SUMMARY OF THE INVENTION The present invention relates to an entirety of a tape including leads formed of metal foil on the surface of an insulating tape.
The same resin film is formed thin on the surface. Also,
The present invention is formed of metal foil on the surface of an insulating tape,
At the time of bonding for electrically connecting the lead having a resin film formed on its surface to the electrode of the semiconductor chip or the circuit pattern of the mounting board, the lead is pressed against the electrode or the circuit pattern by a bonding tool, and the bonding tool is used.
By applying ultrasonic waves to the connection via the
Destroy only the resin film on the contact surface with the electrode, etc.
And heat-press the lead and electrode or circuit pattern or
A brazing method is employed.

[0007]

Next, the present invention will be described with reference to the drawings. 1A and 1B show an embodiment of the film carrier tape of the present invention, wherein FIG. 1A is a plan view, and FIG. 1B is an enlarged cross-sectional view along the line AA. FIG. 1A has substantially the same plane configuration as that of a conventional film carrier tape. A sprocket hole 2, a device hole 3, an outer lead hole 4, and a suspender 5 are formed on an insulating tape 1. Further, a metal foil such as copper is adhered to the surface of the tape 1 and formed into a required pattern by a photolithography technique to form the leads 6 and the pads 7 for electrical selection. Lead 6
Is the inner lead 6A protruding into the device hole 3.
And an outer lead 6 </ b> B extending over the outer lead hole 4.

As shown in FIG. 1B, a resin film 8 is formed on the surface of the lead 6. The resin film 8 is made of, for example, a resin such as a fluorine-based, polyimide-based, or polyester-based resin. In this case, it is preferable that the resin film 8 is formed as thin as possible in order to perform the bonding described below satisfactorily. Alternatively, the resin film may be formed by a dipping method in which the entire tape is immersed in a resin solution. In this case, the resin film 8 is formed on the entire surface of the tape 1 including the leads 6.

FIG. 2 shows a state in which the leads 6 of the film carrier tape are bonded to the electrodes 11 of the semiconductor chip 10 and mounted on the printed circuit board 20. In bonding (IBL) the inner leads 6, no bumps are provided on the electrodes 11 of the semiconductor chip 10, and the inner leads 6A are mounted on the surfaces of the electrodes 11.
Then, the bonding tool BT1 shown in FIG. 3A is pressed with a required load from the upper surface of the inner lead 6A,
The ultrasonic wave is applied to the bonding tool BT1 while heating. Thereby, the inner lead 6A and the electrode 11
In the contact portion, the resin film 8 on the surface of the inner lead 6A is broken, and the copper foil surface of the main material is exposed. At the same time, the electrode 11
The oxide film 12 on the surface is destroyed, and the electrode metal surface is exposed. Then, the exposed surfaces of the inner lead 6A and the electrode 11 are thermocompression-bonded, so that the two are joined, and suitable bonding is realized. The ultrasonic output applied to the above-mentioned bonding tool is set to a minimum output capable of stably destroying the resin film and the oxide film.
Further, the pressing load of the bonding tool is set to a minimum load that can sufficiently and stably adhere the bonding surface between the inner lead and the electrode.

Therefore, in a semiconductor device in which the semiconductor chip 10 is bonded to the inner lead 6A using the film carrier tape 1 having the lead 6 on which the resin film 8 is formed, the lead 6 is deformed and an intermediate part thereof is Even if such a situation occurs, the resin film 8 prevents the leads 6 and the semiconductor chip 10 from being electrically short-circuited, thereby improving the reliability of the semiconductor device. Further, by forming this resin film 8, the surface oxidation of the copper foil, which is the main material of the lead, can be prevented, and good bonding with the electrode of the semiconductor chip can be ensured. Therefore, it is effective for cost reduction.

On the other hand, when bonding the semiconductor chip electrode 11 to the inner lead 6A on which the resin film 8 is formed, it is not necessary to provide a bump on the electrode 11 as in the prior art. One of the reasons for providing this bump is to prevent a short circuit with the semiconductor chip due to deformation of the lead, and to increase the surface height of the semiconductor chip.
As described above, one of the reasons is eliminated because the short circuit prevention can be expected by the resin film 8. Also, in the soldering connection with the inner lead, which is another reason for providing the bump, by adopting a thermocompression bonding method using ultrasonic waves as in the bonding described above, even if there is no brazing material such as solder. The inner lead and the electrode can be joined. Therefore, no electrode bumps are required at all, which is effective in reducing the cost on the semiconductor chip side. In addition, as shown in FIG. 3B, a bonding tool BT2 having a shape protruding in a thin rod shape can be used as the bonding tool.

Also, as shown in FIG. 2, when bonding the outer leads 6B to the circuit pattern 21 of the printed circuit board 20 (OBL), the ultrasonic waves are transmitted using a bonding tool in the same manner as the bonding of the inner leads. If the connection by the brazing material 22 is performed while adding, the resin film 8 is broken by the ultrasonic wave, and the copper foil surface is exposed, so that the connection by the brazing material 22 becomes possible. Also in this case, even if a part of the lead 6 is deformed and comes into contact with the circuit pattern 21 of the printed circuit board 20, the resin film 8 provided on the surface of the lead causes the lead and the circuit pattern to be in contact. An electrical short circuit can be prevented, and reliability can be improved. In the above embodiment, the metal plating is not formed on the lead surface in order to reduce the cost. However, when the cost is not a problem, the metal plating such as gold or tin is applied to the lead and the resin film is formed. May be formed. With this configuration, the metal plating of the lead is brought into contact with the electrode of the semiconductor chip to perform the bonding, so that the reliability of the bonding can be further improved depending on the type of the metal material of the electrode.

Here, when a resin film is formed on the entire surface of the film carrier tape including the leads, after the inner leads are connected to the semiconductor chip, when the electrical characteristics are to be tested using the pads, first, By pressing the sharp contact needle against the pad, it is possible to pierce the resin film and make an electrical connection between the contact needle and the pad. If ultrasonic bonding cannot be used to connect the leads to the semiconductor chip or mounting board, a mask tape must be attached to the required location before dipping the film carrier tape into the resin solution, If the mask tape is peeled off immediately before, it is possible to expose the lead surface while keeping it clean and to make a suitable connection without using ultrasonic waves.

[0014]

As described above, according to the present invention, since the resin film is formed on the surface of the lead and the tape formed of the metal foil on the film carrier tape, the surface metal of the lead metal is prevented from being oxidized, and the semiconductor chip or the like is prevented. Enables suitable connection with the mounting board, eliminating the need for metal plating on the lead surface,
Cost reduction can be realized. Further, even when the lead is deformed and comes into contact with the semiconductor chip or the mounting substrate, an electrical short circuit can be prevented by the resin film, and the reliability can be improved. In addition, resin film is easily formed by dipping method
And the resin film is integrated with the tape
To increase the adhesive strength of the lead to the tape
It is possible to increase the reliability of the mechanical strength.
Will be up. Also, by using ultrasonic bonding together when connecting the lead to the electrode of the semiconductor chip or the circuit pattern of the mounting board, the resin film is broken and the lead surface is brought into contact with the electrode or the circuit pattern, and a suitable connection is performed. be able to. In this case, the resin film is bonded
The lead until it is completely covered
During contacting, only the contact surface between the lead and the electrode etc. is broken
The metal surface of the lead after bonding
It is possible to improve moisture resistance etc.
You.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a film carrier tape according to the present invention, wherein (a) is a plan view and (b) is an enlarged sectional view taken along line AA.

FIG. 2 is a cross-sectional view showing a state where a semiconductor chip is mounted on a printed circuit board using the film carrier tape of FIG.

FIG. 3 is an external view of a bonding tool used in the bonding method of the present invention.

4A and 4B show a conventional general film carrier tape, wherein FIG. 4A is a plan view and FIG. 4B is a cross-sectional view.

FIG. 5 is a cross-sectional view showing a state where a semiconductor chip is mounted on a printed board using a conventional film carrier tape.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Tape 6 Lead, 6A inner lead, 6B outer lead 8 Resin film 10 Semiconductor chip 11 Electrode 20 Printed circuit board 21 Circuit pattern

Claims (2)

(57) [Claims] 1. A lead is formed on a surface of an insulating tape with a metal foil, an inner lead of the lead is connected to an electrode of a semiconductor chip, and an outer lead is mounted. A film carrier tape connected to a circuit of a substrate, wherein a thin resin film of the same material is formed on the entire surface of the lead and the tape. 2. A lead formed of a metal foil on a surface of an insulating tape and having a resin film formed on the surface thereof, and an electrode of a semiconductor chip and a circuit pattern of a mounting board are electrically connected to each other. In the bonding method for making the connection, the lead is pressed against the electrode or the circuit pattern side by a bonding tool, and ultrasonic waves are applied to the connection portion through the bonding tool to form the lead. The lead is characterized in that only the resin film on the contact surface with the electrode or the circuit pattern is destroyed, and the connection is heated to thermocompress or braze the lead and the electrode or the circuit pattern. Bonding method.