JPS622639A - Manufacture of lead frame with supporting body - Google Patents

Abstract

PURPOSE:To reduce the number of entire processes, by using a photoresist mask, which is provided on the side of the surface of a metal foil, as a plating mask at first, then using the film as a resist pattern for etching, and using a metal as a corrosion resisting material in etching. CONSTITUTION:On one surface of a metal foil 1, a supporting film 2, in which an inserting hole 3 is provided, is laminated. Then, positive photoresist films 4 and 5 are formed on the upper and lower surfaces. An exposing plate is applied on the photoresist film 4. The film 4 is exposed with light including rich ultraviolet rays. After development, a first resist pattern 6 is formed. Then, alloy is electrodeposited on the surface of the metal foil 1, which is exposed through opening parts 7 to a thickness of 10-30mum. Thus, metal electrodeposited parts 8 are formed. A second resist pattern 9 is formed by the similar way. The unnecessary part of the metal foil 1 is etched away. Finally, the remaining resist film is dissolved and removed, and the device is washed with water.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a lead frame with a support.

[Conventional technology]

The pads of semiconductor chips are used for sending and receiving electrical signals from the outside.
Usually, a chromium layer is formed on the base of the aluminum wiring circuit by vapor deposition to a thickness of 500 to 100 OA, and then a copper layer is formed on the base of the aluminum wiring circuit to a thickness of 500 to 100 OA by vapor deposition. 10-2 gold layers are deposited by electrodeposition or other methods.
It is manufactured by forming it to a thickness of 0 μm. Then, bonding using a gold wire is usually performed on the pads produced in this way.

As mentioned above, conventionally, many layers of heavy metals have to be formed in minute areas of semiconductor chips by vapor deposition or electrodeposition, so it takes a long time to fabricate pads for semiconductor chips. In addition, there was a manufacturing problem in that the large number of steps could easily lead to a decrease in yield.

In addition, the tips of the inner leads of semiconductor lead frames were formed long enough to reach the pads of the semiconductor chip, and were bonded directly to the semiconductor chip by wire bonding, but even in that case, for example, , in the case of solder bonding, a titanium layer and a lead layer of 500 to 100% each are placed on the base of an aluminum wiring circuit by
It was necessary to form the pad to a thickness of 00 OA and raise the pad.

[Problem that the invention seeks to solve]

Therefore, the problem to be solved by the present invention is to provide a method for manufacturing a lead frame with a support that enables bonding between a semiconductor chip and a lead frame without raising the pad portion of the semiconductor chip. The aim is to reduce the number of process steps and improve yield.

[Means for solving problems]

As a result of research to solve the above problems, the inventors of the present invention laminated a support film with holes for semiconductor device insertion on one side of metal foil, and then laminated the support film on the metal foil, but coated both sides with positive photoresist. A master plate for exposure is applied to the surface of the positive photoresist film coated and formed on the support film side, and after exposure, development is performed to form a first resist pattern in which the portion corresponding to the bump formation location at the tip of the inner lead is opened. 5 Then, gold, silver, lead, or an alloy made of gold, silver, tin, lead, chromium, etc. is electrodeposited on the metal foil layer exposed through the opening of the first resist pattern to a thickness of 10 to 30 μm. After the electrodeposition, an original plate for exposure is applied to the surface of the positive type photoresist film coated on the metal foil side, exposed, and then developed to form an inner lead frame of a TEP carrier tape or a lead frame for semiconductors. A second resist pattern is formed in which areas other than the areas to be exposed are open, and then unnecessary metal foil portions are corroded away by etching from the second resist pattern side, and finally the remaining resist film is peeled off. The inventors have discovered that a lead frame with a support having bumps (protrusions) at the tips of inner leads can be easily obtained with a small number of steps, and the present invention has been completed based on this knowledge.

The manufacturing method of the lead frame with a support of the present invention includes the steps of laminating a support film with holes for semiconductor device insertion on one side of metal foil, and applying positive photoresist on both sides of the support film laminated to the metal foil. After applying an exposure master plate to the surface of the positive photoresist film coated and formed on the support film side and exposing it to light, it is developed to form a first resist pattern in which the portion corresponding to the bump formation location at the tip of the inner lead is opened. In the process of forming gold, silver, and lead on the metal foil surface exposed through the opening of the first resist pattern.

Or υ alloys such as gold, silver, tin, lead, chromium, etc.
A process of electrodeposition to a thickness of ~30 μm, and after the electrodeposition, an exposure master plate is applied to the surface of the positive photoresist film coated on the metal foil side, exposed, and then developed to form the inner lead frame of the chip carrier tape. , or a step of forming a second resist pattern in which a region other than the region corresponding to the semiconductor lead frame is open, and a step of etching from the second resist pattern side to remove unnecessary metal foil portions by corrosion, It consists of a step of peeling off the resist film.

In the present invention, the metal foil is 0.015 to 0.0.
301111 electrically conductive material mainly made of copper, or ←
is mainly copper, with copper and other metal species (zinc.

Alloys of iron (e.g. lead, etc.) or iron, metal, etc.

Metal foils made of metals such as tin, zinc, aluminum, tantalum, or metals of the above-mentioned metal types can be used.

Next, as a material for the support film, a material having a thickness of 50 to 150 .mu.m such as polyimide, polyester, glass fiber-filled Evokin resin, triazine resin, etc. can be applied.

Next, as a positive photoresist, 0FPR-800 (Tokyo Ohka 11ri1nin z-1350 (manufactured by Hoechstshahan) was used.
Quinone diazide photoresists such as quinone diazide photoresists can be applied.

Next, in the present invention, gold, silver, and lead are deposited on the metal foil surface exposed through the opening of the first resist pattern.

Or an alloy consisting of gold, silver, tin, lead, chromium, etc.
The reason why it is electrodeposited to a thickness of ~30 Pll is that this electrodeposited part forms the bump of the inner lead.
This is because if the protruding height of the bump is less than 10 μm, the bonding with the pad portion of the semiconductor chip will not be successful.On the other hand, it is not economical to make the bump protrude more than 30 μm. Also, if the protruding parts (bumps) are too high, semiconductor chips may occur.

This is because when bonding the pad portion of the bump to the inner lead portion with the bump, the wire bent in the lateral direction may be excessively melted and protrude, which may adversely affect other wiring.

Next, in the present invention, after electrodepositing a metal such as gold or silver and then forming a second resist pattern, corrosion removal of unnecessary metal foil parts is performed by electrodepositing a metal such as gold or silver, which corrodes the metal foil. It is necessary to use an etchant and plating conditions that do not corrode or only slightly corrode the electrodeposited portion.

[For production]

In the present invention, the positive photoresist film coated on the metal foil side functions as a plating mask when plating metals such as gold and silver, and also serves as a plating mask when exposed to light and developed.
After forming the resist pattern, it functions as a mask for etching and etching.

〔Example〕

Hereinafter, an embodiment of the present invention will be described in detail with reference to one drawing.

First, as shown in the first diagram, a good electrical conductor with a thickness of 0.015 to 0.30 and mainly composed of copper, copper mainly composed of copper and other metals (zinc, iron, tin, lead), etc. etc.),
Or iron, two, kel, tin, zinc.

Polyimide with a thickness of 50 to 150 μm with a hole (3) for inserting a semiconductor device into which a semiconductor tip or the like is inserted on one side of the metal foil (1) made of metal such as aluminum or tantalum, or a crack or dowel between the above metals. , polyester, glass fiber filled epoxy resin. A supporting film (2) made of triazine resin or the like is adhered via an adhesive or laminated by thermocompression bonding.

Next, as shown in the second figure, a positive photoresist such as a quinone diazide photoresist (AZ-13) is applied to the front and back sides of the metal foil (1) laminated with a support film.
50, manufactured by Hoechst Javan) and dried to form a positive photoresist film +41. (Form 51.

Next, an exposure original plate is applied to the surface of the positive photoresist film (4) coated on the support film (2) side, exposed to light rich in ultraviolet rays, and developed to form the inner lead tips as shown in the third figure. A first resist pattern (6) is formed in which portions corresponding to bump formation locations are open.

In FIG. 3, (7) indicates the opening of the first resist pattern.

Next, as shown in the fourth figure, gold, silver, lead, or gold, silver, tin, lead.

An alloy made of chromium or the like is electrodeposited to a thickness of 10 to 30 μm to form an electrodeposited portion (8) of metal such as gold or silver. For electrodeposition, for example, when electrodepositing gold on copper foil, use a gold plating liquid (Tempere Regis) 7T (manufactured by Nippon Kojundo Kagaku) as a plating liquid, at 80°C ± 1°C, current density of 5 people ± 0. .5 people/d-.

Next, an exposure original plate is applied to the +4 (5) side of the positive photoresist coated on the metal foil (1) side, exposed to light rich in ultraviolet rays, and developed to form a carrier tape as shown in Figure 5. A second resist pattern (9) is formed in which a region other than the region corresponding to the inner lead frame or semiconductor lead frame is open.

Then, etching is performed to remove unnecessary parts of the metal foil (11) by corrosion as shown in Figure 6. When a copper foil with a thickness of 35 μm is used as the metal foil (1), the etching conditions and pressure are: 1.θ to 1.
5%, corrosion time: 2.5 to 3 minutes.

Finally, as shown in Figure 7, the remaining resist film is dissolved and peeled off using an alkaline film removal solution, and washed with water to form a carrier tape as shown in Figure 8 or a semiconductor lead frame as shown in Figure 9. You can get it. Furthermore, the 8th
In Fig. 9, the inner lead, (Iυ
indicates a bump made of gold.

FIG. 10 shows a semiconductor chip using a lead frame with a support obtained by the manufacturing method of the present invention.

This shows the state in which the module is implemented.

As shown in FIG. 10, the pad portion o1 and the inner leads can be easily bonded without raising the pad portion α of the semiconductor chip a3.

〔Effect of the invention〕

As detailed above, according to the present invention, the photoresist film provided on the metal foil side is first used as a plating mask when plating metals such as gold and silver, and then the photoresist film is patterned. By using it for two purposes: as a resist pattern for machining and ching, and by using metals such as gold and silver attached to the metal foil surface together with the resist pattern as a corrosion-resistant material during machining and ching. A lead frame with a support having a bump at the tip of the inner lead can be easily obtained by reducing the total number of steps and without requiring a long time.

[Brief explanation of drawings]

1 to 7 are cross-sectional views of the manufacturing process of the manufacturing method of the present invention, FIGS. 8 and 9 are plan views of a lead frame with a support manufactured by the manufacturing method of the present invention, and FIG. The figure is a cross-sectional view of a semiconductor chip mounted on a lead frame. 1...Metal foil 2...Support film 3...Semiconductor device insertion hole 4.5.
...Positive photoresist film 6...
・First resist pattern 7...Opening part

Claims (1)

[Claims] A process of laminating a support film with a hole for semiconductor device insertion on one side of the metal foil, a process of applying a positive photoresist to both sides of the laminated support film on the metal foil, and a process of applying a positive photoresist coated on the side of the support film. A step of applying an exposure master plate to the surface of the mold photoresist film, exposing it to light, and then developing it to form a first resist pattern in which a portion corresponding to the bump formation location at the tip of the inner lead is opened; and an opening in the first resist pattern. A step of electrodepositing gold, silver, lead, or an alloy consisting of gold, silver, tin, lead, chromium, etc. to a thickness of 10 to 30 μm on the more exposed surface of the metal foil, and after the electrodeposition, the metal foil side After applying the exposure master plate to the surface of the positive photoresist film coated on the surface and exposing it,
A process of developing to form a second resist pattern with openings in areas other than the area corresponding to the inner lead frame of the chip carrier tape or the semiconductor lead frame, and etching from the second resist pattern side to remove unnecessary metal foil. 1. A method for manufacturing a lead frame with a support, comprising a step of corroding a portion and a step of peeling off a remaining resist film.