JPH0616522B2 - Copper alloy foil for tape carrier - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a copper alloy foil for a tape carrier suitable for mounting a semiconductor chip on a wiring board.

[Conventional technology]

Since a semiconductor chip is usually a small piece with a size of several millimeters square and a thickness of about 100 microns, it is difficult to mount it on a wiring board as it is. Therefore, it is stored in a kind of container generally called an IC package.

The basic system of this IC package has a structure in which a semiconductor chip is mounted on a heat sink, which is a metal plate for heat dissipation, and the electrode terminals of the chip are bonded to a lead wire for external circuit connection by a bonding wire.

The lead wire projects outside the package like a centipede foot and is also called a pin.

Such IC and LSI packages are currently available in a dual in-line package (DIP) method in which pins project vertically downward from both sides in two rows and in a flat package (FP) method in which pins project in the plane direction of the four sides. However, it is becoming mainstream.

The FP method has the advantage that the number of leads (the number of pins) can be made relatively larger than that of the DIP method, so that the mounting density on the wiring board can be slightly increased.

However, recently, as the integration density of LSIs has advanced and the number of pins has tended to increase rapidly in proportion to this, a new package that can cope with the increase in the number of pins because the above-mentioned FP method and DIP method cannot keep up. A method was required.

Under such circumstances, a packaging system called a tape carrier (also called a film carrier) has been developed.

As shown in FIG. 1, this tape carrier system is a long tape-like 2 with a sprocket wheel 1, and the base material of the tape 2 is polyimide, polyester, polyether sulfone (PES), polyparavanic wire. (PP
A resin such as A) is used, a copper foil is adhered thereon, and this is further photo-etched to form a copper chip bonding finger 3 and a copper external connection finger 4.

Bumps are formed on the electrodes of the semiconductor chip, and the electrodes (bumps) of the chip and the fingers are joined by gang bonding, which simultaneously joins all the terminals. Then, a semiconductor element having copper external connection fingers is exposed from the carrier and mounted on a wiring board.

The tape carrier thus formed can be handled as a tape (long length) and can be positioned using the sprocket holes.

Compared to the wire bonding method, there is almost no crushing of the fingers during bonding, so the terminal pitch can be significantly increased (up to about 80 microns).

Since it is a gang bonding method, the number of bonding steps is one and does not depend on the number of terminals.

The chip burn-in test can be performed with the carrier attached.

Since the carrier is thin and has flexibility, it can be mounted in a thin and flexible type.

 Easy chip replacement after mounting.

It is suitable for high-density mounting type LSIs that require a large number of pins.

By the way, such a tape carrier system also has drawbacks. That is, fine copper finger portions formed by photo-etching a copper foil of about 20-50 μm are softened by heat during the manufacturing process, resist is peeled off during etching, fluctuations in plating solution flow, or film carrier. Deformation is likely to occur due to contact of rolls when moving the. When the hanger portion is deformed in this manner, there is a possibility that a short circuit of the terminal may occur or defective bonding may occur.

The characteristics required for the copper foil as the metal conductor of the tape carrier including the above examples are as follows.

(1) It has high conductivity as a metal conductor.

(2) Thinning is being studied, and it has higher strength than pure copper and does not deform during the manufacturing process.

(3) Since heat of around 200 ° C is applied during the tape carrier manufacturing process, it has heat resistance to withstand this temperature.

(4) Since the fingers are formed in four directions, there is no anisotropy in strength and heat resistance.

(5) Since the IC element is bonded to the back surface of the finger portion, the surface is smooth.

(6) The shape is flat for the same reason.

(7) Etching is easy.

(8) Good adhesion to resin.

[Problems to be solved by the invention]

The present invention has been made in view of such a point, and by using a copper alloy in which a horny element is added to copper, it is intended to improve the above-mentioned drawbacks and provide an optimum copper alloy foil for a tape carrier. To do.

The present invention will be described in detail below.

[Structure of Invention]

The feature of the present invention is to add various additive elements to copper,
It is to improve strength as compared with copper and to have heat resistance of 200 ° C., and at the same time improve anisotropy.

That is, the present invention is Al 0.01 ~ 0.5 wt%, Co 0.01 ~ 0.5
% By weight, In 0.01 to 0.5% by weight, Mn 0.01 to 0.5% by weight,
Ni 0.01-0.5 wt%, Si 0.01-0.5 wt%, Hf 0.0
A copper alloy foil for a tape carrier, which contains 0.01 to 1.5% by weight of one or more components selected from the group (1) of 1 to 1% by weight, and the balance Cu and unavoidable impurities. And Al 0.01 to 0.5% by weight, Co 0.01 to 0.5% by weight, In 0.01 to 0.5% by weight, Mn 0.01 to 0.5% by weight, Ni
0.01-0.5 wt%, Si 0.01-0.5 wt%, Hf 0.01-1
0.01 to 1.5% by weight and P 0.005 to 0.05% by weight, B 0.
005 to 0.05% by weight, Fe 0.01 to 0.5% by weight, Mg 0.01 to 0.5
% By weight, Sn 0.01-0.5% by weight, Te 0.01-0.5% by weight, Ag
0.01-1 wt%, Cr 0.01-1 wt%, Zn 0.01-1 wt%, Zr 0.01-1 wt% 1 selected from the group (b)
A tape carrier, containing one or more components so that the total of the groups (a) and (b) is 0.01 to 1.5% by weight, and the balance Cu and inevitable impurities. Regarding copper alloy foil.

[Means for solving problems]

Next, the reason for adding the alloy components constituting the alloy of the present invention and the reason for limiting the composition range will be described. Al, Co, In, Mn, Ni, Si,
Hf (group a) or these, and further P, B, Fe, Mg, Sn,
Te, Ag, Cr, Zn, and Zr (group B) are added to copper to improve strength and heat resistance and prevent the development of the (100) orientation, which is a recrystallized texture of copper. It also improves the anisotropy. However, for P and B, less than 0.005% by weight, Al, Co, In, Mn, Ni, Si, Hf and
0.01% by weight for Fe, Mg, Sn, Te, Ag, Cr, Zn, Zr
If it is less than the above, the expected effect cannot be obtained, and conversely, 0.05% by weight for P and B, Al, Co, Fe, In, Mg, Mn, Ni, Si, S
This is because if the content of n or Te exceeds 0.5% by weight and if the content of Ag, Cr, Hf, Zn or Zr exceeds 1% by weight, the conductivity is remarkably lowered. The reason for setting the range of one or more components selected from these groups to 0.01 to 1.5% by weight is that the lower limit is 0.01% by weight as the lower limit of addition of one component and the upper limit is 2%. This is because even if the amount exceeds 1% by weight due to the addition of one or more species, the conductivity is not necessarily significantly reduced due to the formation of an intermetallic compound, etc., but if it exceeds 1.5% by weight, the conductivity is significantly reduced.

When further adding the additional element of the group (b) in addition to the additional element of the above group (a), the total of these should be 0.01% by weight as the lower limit and not more than 1.5% by weight as the upper limit.

The material of the present invention will be described below with reference to examples.

〔Example〕

The ingots of various composition according to the alloy of the present invention shown in Table 1 were melt-cast in a high frequency melting furnace. Next 90
It was hot-rolled at 0 ° C to obtain a plate having a thickness of 8 mm, and then cold-rolled to a thickness of 1 mm. This was annealed at 500 ° C for 1 hour and then cold rolled to a thickness of 0.2 mm, and further annealed at 500 ° C for 1 hour and then cold rolled to a thickness of 0.025 mm.

As an evaluation of the sample thus prepared, the strength was measured by a tensile test in the direction parallel to the rolling parallel to the direction perpendicular to the rolling direction, and the heat resistance was shown by the softening temperature at a heating time of 5 minutes, and the conductivity was shown by the conductivity (% IACS). It was Also, we actually made a three-layer tape carrier using a polyimide film,
The presence or absence of deformation of the finger portion was investigated.

As shown in Table 1, the alloy of the present invention has excellent strength, heat resistance,
It is clear that it has conductivity, has little anisotropy, and does not deform when formed into a tape carrier, and it can be said that it is a material suitable for an alloy foil for a tape carrier.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view showing an example of a tape carrier system. 1: Sprocket wheel 2: Resin film 3: Finger for chip bonding 4: Finger for external connection 5: Test pad

Claims (2)

[Claims] 1. Al 0.01 to 0.5 wt%, Co 0.01 to 0.5 wt%, In 0.01 to 0.5 wt%, Mn 0.01 to 0.5 wt%, Ni 0.01 to 0.5 wt%, Si 0.01 to 0.5 wt%, Hf 0.01 to A copper alloy foil for a tape carrier, which contains 0.01 to 1.5% by weight of one or more components selected from the group (a) of 1% by weight, and the balance Cu and unavoidable impurities. 2. Al 0.01-0.5 wt%, Co 0.01-0.5 wt%, In 0.01-0.5 wt%, Mn 0.01-0.5 wt%, Ni 0.01-0.5 wt%, Si 0.01-0.5 wt%, Hf 0.01- 0.01 to 1.5% by weight and 0.005 to 0.05% by weight of P, 0.005 to 0.05% by weight of B, 0.01 to 0.5% by weight of Fe, M of 1% or more selected from the group (a)
g 0.01 to 0.5% by weight, Sn 0.01 to 0.5% by weight, Te 0.01 to
0.5 wt%, Ag 0.01-1 wt%, Cr 0.01-1 wt%,
0.01 to 1% by weight of Zn and 0.01 to 1% by weight of Zr, the total of 0.01 to 1.5% by weight of one or more components selected from the group (b) of the above group (a) and group (b) A copper alloy foil for a tape carrier, characterized in that it is contained so that the balance is Cu and unavoidable impurities.