JPH0770567B2 - Carrier tape and method for manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a carrier tape used, for example, in tape transfer bonding (TAB).

(Prior Art) Wire bonding technology, which is a bonding technology for semiconductor devices, and wireless bonding technology, are roughly classified. The former is to connect the electrode of the semiconductor chip and the lead terminal of the lead frame with a wire. This technology
Although it is possible to sufficiently deal with the case where the number of connections is small, as the size of the electrode becomes 100 μm or less and the density becomes higher with the high integration of the element, there are many problems particularly in reliability. On the other hand, in the latter method, the electrodes of the semiconductor chip and the lead terminals of the lead frame (carrier tape, which will be described later) or the electrodes on the glass or ceramic substrate are bonded together, which results in high integration of the device. It has been put to practical use in order to ensure reliability in response to this.

As this wireless bonding technology, for example, tape automated bonding method (TAB method),
Flip chip method or CCB method is known.

Among them, the TAB method includes a tape-shaped conductive medium having an inner lead that is connected to a protrusion (bump) formed on an electrode on a chip surface, which is called a carrier tape as shown in FIG.

Generally, the inner lead of the carrier tape is made of copper alloy, which has sufficient ductility and excellent bending workability.
Good etching properties and excellent mechanical strength at 250 ° C or higher are required items.

(Problems to be Solved by the Invention) However, in recent years, the miniaturization of the electrodes on the chip or the reduction of the pitch between the electrodes has been progressing, so that the carrier tape is required to be finely etched with high precision. However, conventional copper-based carrier tapes have not been able to sufficiently meet such requirements.

An object of the present invention is to enable the highly accurate etching property required for a carrier tape.

[Structure of Invention]

(Means and Actions for Solving Problems) The inventors of the present invention made a study on the improvement of the above characteristics, especially the etching property, in the course of earnestly researching to achieve the above object. First, the fact that the etching property is poor is judged by the fact that irregularities of large and small size are formed on the inner wall formed during etching, resulting in a so-called irregular “rough wall”. Therefore, fine etching finish required by the design standard cannot be applied to a material having poor etching property.

This means that the type and homogeneity of the metallographic structure of the material,
It is considered that the problems are caused by the size of the crystal grain size, the aggregation of the crystal orientations, and the like. Therefore, the present inventors have made various studies on the influence of each of the above factors on the properties required of the carrier tape. As a result, we have developed this carrier tape.

That is, the carrier tape of the present invention, as shown in FIG.
The grain size number specified by S-GO551 is 7 or more,
And the crystal orientation is aggregated at (100) in the etching direction.

In the tape of the present invention, when the crystal grain size number is less than 7, the grain size is too coarse, so that the etching removal during etching does not proceed sufficiently, and eventually a portion that does not open occurs. However, if the particle size number is too large, curling may occur, so it is desirable to use 8 to 13
Is good.

In the material of the present invention, the crystal orientation is (100)
It is desirable to be gathered in. This is because when the material is etched, the inner wall surface of the formed lead becomes very smooth and smooth as in the conventional case, which is suitable for fine etching.

It is desirable that the degree of aggregation to normal (100) is 40% or more. Etching properties are particularly related to the (100) and (110) orientations. If they are gathered in the (110) orientation, the gaps between the leads formed by etching will be uneven, resulting in high accuracy and high density. It becomes impossible to form the inner leads, and this has an adverse effect. On the other hand, if they are gathered in the (100) orientation, such a phenomenon does not occur, and accurate lead formation can be performed. There is also a (111) orientation, which is also convenient for etching.

A usual X-ray diffraction method is good for measuring this tendency. In this analysis method, if the ratio of the (200) peak intensity corresponding to the (100) direction and the (220) peak intensity corresponding to the (110) direction is taken and (200) / (220) is 3 or more, the etching property is I found it good.

In addition, such a carrier tape tends to have a (100) orientation when it is made of rolled copper. As the type of carrier tape, as shown in FIG. 3, the whole may be made of rolled copper. (A) Glass epotin, polyimide or other inorganic or organic tape may be provided with rolled copper inner leads ( bc). It can also be applied to lead frames used for plastic and ceramic packages. As a manufacturing step, a step of melting an alloy ingot in which a predetermined amount of copper and an addition source and the like are added and then making an alloy ingot (first step); % Or more final cold rolling treatment step (second step); cold rolling treatment material annealing treatment at a temperature of 150 to 1000 ° C (third step); annealing treatment material rolling rate 30% or less And the step of performing the adjusted rolling process (the fourth step);

The first step is a step of melting a predetermined amount of each of the above-mentioned components and preparing an alloy ingot having a predetermined composition from the melt. This may be carried out by applying a conventional atmospheric melting method or an electroslag melting method.

The second step is a step of rolling the obtained alloy ingot. What is important in this step is that the final rolling is cold rolling, and the rolling rate during cold rolling is 40% or more. In this step, the degree of aggregation of crystal orientations on the (100) plane is basically adjusted. When the rolling ratio is less than 40%, it is difficult to orient the crystal orientation in the ingot to the (100) plane because the processing energy input is small, and further, the annealing treatment of the next stage (3rd In the process), the recrystallized grains growing do not have a desired size, and the crystal grain size becomes small. However, when working at an extremely high rolling rate, a phenomenon such as a crack occurs in the working process due to the accumulation of added working strain. It is preferably 80% or more.

In the third step, the cold-rolled material obtained in the second step is subjected to an annealing treatment so that the crystallographic orientation and the predetermined grain size are obtained.

The annealing temperature is 150-1000 ° C. If the temperature is lower than 150 ° C, the above-described annealing effect is not sufficiently exhibited, and if the temperature exceeds 100 ° C, the crystal grain size becomes large and the etching property deteriorates. The temperature is preferably 300 to 800 ° C.

In the fourth step, since the annealed material obtained in the third step is usually thermally deformed, it is a rolling step of correcting this thermal deformation and adjusting it into a flat plate. The rolling rate at this time is controlled to 30% or less.

This is because when the rolling rate is higher than 30%, the already formed aggregate state of the crystal orientation on the (100) plane is destroyed. It is preferably 20% or less.

Further, in this process, processing strain during rolling is accumulated on the plate material, and this strain may cause problems such as dimensional deformation in various steps of the subsequent carrier tape manufacturing. It is effective to perform the annealing treatment at the following temperature, preferably 100 to 400 ° C.

Example 1. Zr 0.3% by weight, Cr 0.6% by weight, Si 0.01% by weight, PS 0.001% by weight each as an ancillary component, the balance Cu, and prepared in a melting furnace filled with Ar. I prepared an ingot.

This ingot was repeatedly hot-rolled, then pickled and the primary and secondary
Next cold rolled. The rolling ratio in this cold rolling was 80%.

Then, the rolled material was placed in an annealing furnace, annealed at 1 × 10 ⁻⁴ Torr and 400 ° C., and then adjusted and rolled at a rolling rate of 10%. Finally 200
It was annealed at ℃ to correct the thermal deformation. The thickness of the tape is 0.15mm
Is.

This plate material has a crystal grain size of 9 according to the method specified in JIS-GO551, a degree of aggregation of crystal orientation on the (100) plane of 50%, and a (200) / (220) peak intensity ratio of 4.0 according to the X-ray diffraction method. It was

Photoresist was applied to both surfaces of the obtained plate material, dried, and then a film having a reference pattern formed thereon was brought into close contact therewith to expose and develop the photoresist to dissolve and remove the photoresist in the unexposed portion. . Then, the residual photoresist is burned and hardened, then etched with a 20% ferric chloride solution, and then the residual resist is removed with hot alkali to have a cross section as shown in FIG. 3 (a). I made a carrier tape. The width of each lead was 0.5 mm, and the distance between each lead was 0.5 mm. When the side surface of each lead was observed under a microscope, there was no rubbing wall.

After that, about 2 μm of Sn plating was applied to the surface, the Au bumps were aligned with the chips previously formed on the electrodes, and inner lead bonding was performed to complete the semiconductor device.

Example 2. An ingot containing 0.2% by weight of Ni, 0.2% by weight of Sn, 0.04% by weight of Zn, 0.001% by weight of PS as an unavoidable component, and the balance of Cu was melted in the same manner as in Example 1 and finally rolled. 90% rate,
An annealing temperature of 500 ° C. and a controlled rolling rate of 5% were used, and rolled copper having a thickness of 0.075 mm was prepared in the same manner as in Example 1. The grain size number is 8, the aggregation rate in the (100) direction is 60%, and the (200) / (220) peak intensity ratio by the X-ray diffraction method is
It was 6.8. This rolled copper is adhered to a polyimide tape, and then the same procedure as in Example 1 is performed, as shown in FIG.
A carrier tape having a cross section as shown in Figure 3 was made. The width of each lead was 0.2 mm, and the spacing between each lead was 0.4 mm.
When the side surface of each lead was observed under a microscope, there was no rubbing wall.

Then, the solder bumps were aligned with the chips formed on the electrodes in advance, and inner lead bonding was performed to complete the semiconductor device.

Example 3.4 Phosphorus deoxidized copper was melted in the same manner as in Example 1, final rolling ratios were 70% and 95%, annealing temperatures were 600 ° C. and 300 ° C., and adjusted rolling was 20.
% And 3% were selected, and two kinds of rolled copper having 0.1 mm and 0.05 mm were manufactured. The grain size number, the (100) orientation aggregation rate, and the (200) / (220) peak intensity ratio by the X-ray diffraction method were 7, 40%, and 3.0 for the final rolling rate of 70%, and the final rolling rate of 95 %, 13, 70%, 8.0 respectively
Became. As a result of etching the rolled copper in the same manner as in Example 1, a carrier tape having no rough wall was formed.

After that, inner lead bonding was performed on a chip in which Au bumps were previously formed on the electrodes, to fabricate a semiconductor device.

〔The invention's effect〕

According to the present invention, it is possible to obtain a carrier tape having an etching surface with high precision and high quality, and its industrial value is extremely large.

[Brief description of drawings]

1 is a schematic perspective view of the present invention, FIG. 2 is a perspective view showing the appearance of a carrier tape, and FIG. 3 is a sectional view of an inner lead portion of the carrier tape. 1 ... Inner lead, 2 ... Etching inner wall, 3 ...
Glass epoxy, 4 ... polyimide.

Claims (4)

[Claims] 1. A carrier tape comprising a metal base having copper as a main component, the metal base having a crystal grain size of 7 or more as shown in JIS-GO551, and a tape surface having a crystal orientation of (100). Carrier tape characterized by being assembled in. 2. The carrier tape according to claim 1, wherein the metal substrate is rolled copper. 3. X-ray diffraction intensity (200) diffraction intensity (220)
Claim 1 where the diffraction intensity is three times or more.
The carrier tape according to item. 4. A step of melting a copper alloy and then making it into an ingot, a step of subjecting this ingot to multiple rolling-annealing, and then a final cold rolling treatment at a rolling ratio of 40% or more,
A method of manufacturing a carrier tape, comprising: a step of annealing at 0 to 1000 ° C .; a step of adjusting and rolling at 30% or less; and a step of etching the rolled material.