JPS62199022A - Mounting means of semiconductor device - Google Patents

Abstract

PURPOSE:To enable the formation of bumps by a minute pad pitch by making the central part of a film thinner than that of an edge part in a film carrier on which bumps are formed via through-holes of the film. CONSTITUTION:A Cu wiring 11 pattern is formed on a polyimide film 12 and a central part of the film 12 is made thinner by etching. A through-hole is formed in the part which is to be in contact with an Al pad 16 and subsequently a bump 13 connected to the wiring 11 is formed. The bump 13 on the film 12 thus formed is positioned to be in accordance with the pad 16 and these are bonded by inner lead bonding. Consequently, the formation of bumps by a minute pitch becomes possible and a film for tape automated bonding having a high stiffness can be fabricated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a bonding method for bonding an electrode on a semiconductor element and an external metal lead.

[Technical background of the invention and its problems]

In recent years, semiconductor elements such as ICs and LSIs have been introduced into various home appliances and industrial equipment. These electronic devices are designed to save power and use effective space.
We are on the path to becoming smaller, thinner, and lighter.

For this purpose, there is a strong demand for smaller and thinner packaging for semiconductor devices, and after semiconductor devices are completed as devices through various processes, they are packaged for handling or mechanical protection. However, due to the necessity of electrical connection, only the electrode leads must be taken out of the package.Normally, the connection between the semiconductor element and the outside of the package is by lead frame and wire bonding, or by metal protrusions (bumps) and board wiring. A tape carrier system is used. Among these, there is a tape carrier method that has a particularly large number of connections and is suitable for the demand for smaller and thinner devices.

In the tape carrier method, a multilayer metal film called a barrier metal is provided on an electrode terminal on a semiconductor element, and a metal protrusion is further provided on the barrier metal by electroplating. Then, a long polyimide tape of a certain width is prepared with metal lead terminals, and the metal lead terminals and the metal protrusions are simultaneously bonded to the electrodes on the same chip regardless of the number of electrode terminals. This method is °1'A,B
(Tap θ Automated Bonding) method is becoming popular in the field of thin multi-terminal devices, but there are problems such as the electrode connection process requires a large number of steps, resulting in high cost, and the addition of processing to the device reduces the device yield.

Therefore, recently, the method of etching the lead to make it into a protruding electrode phase and the transfer bump method (for example, Japanese Patent Laid-Open No. 57
A TAB method using a method in which protruding electrodes (bumps) are formed on the lead side in advance by a method called JP-A-152147 has also appeared. According to these methods, a normal Affi pad (electrode) can be used on the element side, and the range of application is widened.

However, when creating a protrusion shape by etching, the limit of etching ability prevents higher lead density.In the transfer bump method, it is necessary to prepare and optimize a bump formation substrate called a transfer substrate, and also to improve the lead surface. Problems remain, such as the need to control the Sn plating thickness and the time it takes to find stable bonding conditions. Furthermore, as shown in FIG. After forming the metal wiring 21, the metal protrusion electrode 23 is formed on the opposite side of the film carrier and the electrode portion 26 of the semiconductor device are electrically connected through the through hole of the film 22 at the tip of the metal wiring 21. There is a way. However, in this method, it is difficult to deal with fine pitches or minute electrode pads 26 due to the influence of the etching angle.

Therefore, there is a method of making the polyimide film 32 thinner as shown in Fig. 4 in order to accommodate the microelectrode butt, but there is a problem that the rigidity of the entire film is lost and the reliability of the joint is reduced. Purpose] The present invention solves the above-mentioned problems and provides a TA with improved reliability.
The purpose is to provide B technology.

[Summary of the invention]

The present invention is an improved TAB film having the structure shown in FIG. First, prepare a polyimide film thick enough to maintain its overall rigidity, and then conduct metal wiring on the polyimide film. Place the element on the film side and align the wiring pattern and the element electrode pad. A metal protruding electrode (bump) is formed by penetrating the polyimide from the metal wiring at the portion corresponding to the electrode pad on the element. At this time, with the thickness of the polyimide, only an excessively large bump can be formed due to the limit of etching ability, so only the element portion at the center of the film is made thinner by etching. As a result, bumps can be formed at a fine pitch, so that the electrode pads on the element formed at a fine pitch and I L B (Inner Le
ad Bondinlc).

〔Effect of the invention〕

According to the present invention, bumps can be formed with a finer pad pitch than the structure shown in FIG. 3, and the TA has higher rigidity than the structure shown in FIG.
A film for B can be created. Since it has higher rigidity, high reliability can be obtained for bonding metal leads and bumps and pads. Furthermore, since the element fits into the etched area as shown in FIG. 3, it is possible to mount it thinner.

[Embodiments of the invention]

An embodiment of the present invention is shown in FIG. 1, and the configuration according to this embodiment will be explained hereinafter.

In Figure 1, a polyimide film 12 of approximately 125 tm is used.
On top, Cu wiring 11-P layer-in-line cord bud sides 4-7 are formed, and the center of the polyimide film is etched to a length of about 251 m. Then, the part corresponding to the AQ pad 16 is etched to provide a through hole, and then the Cu pad 16 is etched.
A Cu bump 13 connected to the wiring 11 is formed. Then, in order to improve the reliability of the bond, the Cu bumps 13 are plated with Au JflL4.

The Cu bumps 13 on the polyimide film made in this way are aligned with the All pads 16, and rLB(I
nner Lead Bonding).

[Other embodiments of the invention]

(2) Copper was used as the bump material in the above example, but Au or the like may be used to further improve the bonding reliability.

■ In the above example, Au plating M14 is applied on Cu bump 13.
However, in order to make the bump cheaper, even if it is only the Cu bump 13, it may be bonded in an atmosphere that does not oxidize.

■ Etching was used to thin the central part of the polyimide film, but as shown in Figure 4, the peripheral part can be made thicker by attaching a polyimide film that will become the outer frame to an originally thin film using an adhesive or the like.

(a) Instead of varying the thickness of the polyimide film, it is also effective to increase the thickness over part or all of the Cu wiring 41 as shown in FIG.

[Brief explanation of drawings]

and FIG. 4 are cross-sectional views of a joint made by a conventional method. 11.21, 31.41...Metal wiring 12.22, 3
2,42...Polyimide film 13.23,33.
43... Copper bump by plating 14.24,34,4
4... Gold plating layer 15.25, 35, 45... Passivation film 16.26, 36, 46... - Electrode pad 17.27, 37.47... Silicon element agent
Patent Attorney Nori Chika Yudo Kikuo Takehana

Claims (1)

[Claims] A film carrier in which a metal wiring is provided on a film and a metal protruding electrode is formed at the inner end of the metal wiring through a through hole in the film, wherein the thickness of the film is thicker in the center than in the peripheral part. A mounting tool for a semiconductor device, characterized in that a portion of the mounting device is made thinner.