JPH09199650A - Method for manufacturing lead material for semiconductor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a lead material for semiconductor with small internal residue stress and improved etching processability. SOLUTION: A metal line material after finishing temper rolling is passed between two work roll surfaces 20 where a work roll 10 of a multi roller tension leveler is arranged flatly for calibration. In this case, equations regarding a tilt angle (an inclination angle between two work roll surfaces) θ of the above work roll surface 20, an amount of out-side intermesh (out-side interval between two work roll surfaces) D, and a unit tension T applied to the metal line material can be met, namely 60>=K>=-60, 1.0deg>=θ×L/250>=0.1deg, 60N/mm<2> >=T>=10 N/mm<2> , where K=85.6×D (mm)+470.1×θ(deg)×L/250+3.7×T(N/mm2)-277.2, L: distance (mm) between in-side and out-side work rolls, work roll diameter: 10-20mm, the number of work rolls (both sides): 5-25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor lead material having a small internal residual stress and excellent etching processability.

[0002]

2. Description of the Related Art Lead materials for semiconductors (lead frames, etc.)
In general, copper alloy, 42 alloy, etc. are used.
The lead material for semiconductors is, for example, hot-rolling a copper alloy ingot, chamfering it, then repeating cold rolling and intermediate annealing, and then finishing temper rolling to finish it to a desired plate thickness, and then a tension leveler. Is applied to correct the shape, and then it is manufactured by pressing or etching into a predetermined shape. During the etching process, dimples are formed in the die pad portion (the portion where the semiconductor chips are joined) to enhance the joining property of the semiconductor chips.

By the way, the tension leveler has
For example, as shown in FIG. 1, two roll groups 30 each having a work roll surface 20 in which a plurality of work rolls 10 are arranged in a plane.
A multi-roller tension leveler configured by arranging the work roll surfaces 20 to face each other is used. The space between the work roll surfaces 20 is configured to widen from the entrance side to the exit side. The metal strip to be straightened is repeatedly bent and corrected by the individual work rolls 10 forming the work roll surface 20 when passing between the work roll surfaces 20. Here, the diameter of the work roll 10 is generally 10 to 20 mm, and the number thereof is generally 5 to 25 on both sides. Also, in order to better correct the shape of the strip material, the interval between the work roll surfaces 20 on the side where the metal strip material enters (hereinafter referred to as the entry side intermesh amount E, see FIG. 2) is increased to 3.0 mm or more. Tension per unit area applied to the metal strip (hereinafter,
The unit tension T) is also increased to 100 N / mm ² or more.

[0004]

In recent years, as electronic devices have become smaller and more highly integrated, lead frames for semiconductors have become thinner, and metal strips having a smaller internal residual stress have been required. Came to be. However, with the conventional method, it has not been possible to stably manufacture a semiconductor lead material that satisfies the above requirements. Therefore, the inventors of the present invention conducted extensive research into a method for reducing internal residual stress, and found that the internal residual stress can be reduced by optimizing the setting conditions of the tension leveler, and further researches have made the present invention. Came to complete. It is an object of the present invention to provide a method for producing a semiconductor lead material having a small internal residual stress and excellent etching processability.

[0005]

According to the first aspect of the present invention,
In the method for producing a semiconductor lead material, the metal strip material after finish temper rolling is straightened by passing it between two work roll surfaces on which work rolls of a multi-roller tension leveler are arranged in a plane. Tilt angle of (2
The inclination angle between each work roll surface) θ, the exit side intermesh amount (distance between two work rolls located on the exit side) D, and the unit tension T applied to the metal strip are as follows (1),
A method of manufacturing a lead material for a semiconductor, characterized in that the expressions (2) and (3) are satisfied. 60 ≧ K ≧ −60 ………………………… (1) 1.0deg ≧ θ × L / 250 ≧ 0.1deg ………… (2) 60N / mm ² ≧ T ≧ 10N / mm ² …. ………………… (3) However, K = 85.4 × D (mm) + 470.1 × θ (deg) × L / 250 +
3.7 × T (N / mm ² ) -277.2, L: Distance between work rolls on the input side and output side (mm), work roll diameter: 10 to 20 mm, number of work rolls (both sides): 5 to 25.

The present invention can be obtained by limiting the straightening conditions in the multi-roller tension leveler to reduce the elongation due to bending of the metal strip during straightening, and to keep the unit tension applied to the metal strip low. This is to reduce the internal residual stress while maintaining the shape of the obtained semiconductor lead material in a good condition.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the tilt angle θ is an inclination angle formed between both work roll surfaces of a multi-roller tension leveler, and θ = tan ^-1 [(ED) / L].
(However, E is an entrance side distance between two work roll surfaces, D is an exit side distance between two work roll surfaces, and L is a distance between the entrance side and the exit side). In the present invention, [85.4 × D (mm) +
470.1 x θ (deg) x L / 250 + 3.7 x T (N / mm ² ) -277.2
The reason why the K value shown by [] is limited to 60 or less and -60 or more is that when the K value exceeds 60, the elongation of the metal strip increases and the internal residual stress increases. If it is less than -60, the shape and warp are not corrected. The formula showing the K value and its limited range are empirical formulas obtained based on many experiments. In the present invention, the reason why the angle obtained by multiplying the tilt angle θ by L / 250 is limited to 0.1 to 1.0 deg is that the shape and the warp cannot be corrected when the angle is less than 0.1 deg. If it exceeds 1.0 deg, the shape and warp can be corrected, but the internal residual stress increases and the warp of the die pad portion of the lead frame becomes a large value exceeding 10 μm during etching. The reason for limiting the unit tension 10~60N / mm ^2, in less than unit tension 10 N / mm ^2, the shape and warpage of the strip material is not sufficiently corrected, exceed 60N / mm ^2, the shape Ya Although the warp can be corrected, the internal residual stress increases, and the warp of the die pad portion of the lead frame becomes a large value exceeding 10 μm during etching. In the present invention, the multi-roller tension leveler is put in after finish rolling. When annealing is applied after finish rolling, a tension leveler may be added before or after annealing, or either one may be used before or after annealing. Further, the tension leveler may be applied to the wide strip material after finish rolling, or may be applied to the narrow strip material in which the wide strip is slit to the plate width to be used.

[0008]

The present invention will be described below in detail with reference to examples. Example 1 A copper alloy containing 0.25 wt% of Sn and 0.30 wt% of Cr, the balance of which is copper and unavoidable impurities is melt-cast by an ordinary method to form an ingot, and the ingot is subjected to hot-rolling and surface-cutting. Then, after repeatedly performing cold rolling and annealing, finish temper rolling with a working rate of 40% was performed to obtain a copper alloy strip having a thickness of 0.2 mm. Next, the copper alloy strip was annealed and then hung on the multi-roller tension leveler shown in FIG. 1 to be straightened to manufacture a copper-based lead material for semiconductors. Upon correction, the inter-mesh amount E on the incoming side,
The outgoing side intermesh amount D, the tilt angle θ, and the unit tension T were variously changed (see FIGS. 2A and 2B for E and D, and FIG. 1A).

The steepness, the curl, the internal residual stress, and the warp amount of the die pad portion of each of the obtained copper-based semiconductor lead materials for semiconductors were examined. The steepness is represented by the percentage of the height of waviness of the plate divided by its pitch. The curl hangs a material having a length of 1 m on a wall and expresses the distance from the lower end to the wall. The internal residual stress was obtained by removing the surface of the strip to a predetermined thickness by etching, measuring the warpage at that time to determine the internal residual stress distribution, and expressing it as the maximum tensile residual stress of the distribution.
The amount of warp of the die pad part is 20 × 20
The material of mm was etched with a dimple area of 10% of the total area and a dimple depth of 50% of the strip thickness, and expressed as the difference in height between the center and the periphery of the die pad. Table 1 shows the straightening conditions and Table 2 shows the test results.

[0010]

[Table 1] *: Those with a minus sign (-) have the lowermost surface of the upper work roll above the uppermost surface of the lower work roll. ☆: θ = tan ^-1 [(E-D) / L], L = 250 mm.

[0011]

[Table 2] *: Warpage after etching.

As is clear from Table 1, the product of the present invention (N
In o.1 to 6), the strip shape (steepness, curl) and tensile strength are as good as those of the conventional product (No. 13), and the internal residual stress and the amount of warpage of the die pad are Is a conventional product (No.
13) It was significantly better than On the other hand, Comparative Examples Nos. 7 to 9 did not satisfy the formula (1), and the internal residual stress and the warp amount of the die pad part were significantly increased. or
In Nos. 10 and 11, the tilt angle was small, so the shape and warpage were significantly reduced. Therefore, the internal residual stress and the warp amount of the die pad were not measured. No. 12 had a small tilt angle, but had a large tension, resulting in a large internal residual stress and a large warp in the die pad.

[0013]

As described above, according to the present invention,
A lead material for semiconductors having a small internal residual stress and an excellent etching processability can be obtained, and a remarkable effect is industrially achieved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example of a multi-roller tension leveler used in the present invention.

FIG. 2 is an explanatory diagram of an input side intermesh amount and an output side intermesh amount of a multi-roller tension leveler.

[Explanation of symbols]

 10 …… Work roll 20 …… Work roll surface 30 …… Roll group

Claims (1)

[Claims] 1. A method of manufacturing a semiconductor lead material, comprising: a metal strip material after finish temper rolling; and straightening the metal strip material by passing it between two work roll surfaces on which flat work rolls of a multi-roller tension leveler are arranged. , The tilt angle of the work roll surface (the tilt angle between the two work roll surfaces) θ,
Output side intermesh amount (distance between two work rolls located on the output side) D, unit tension T applied to the metal strip
Satisfies the following formulas (1), (2), (3): 60 ≧ K ≧ −60 ………………………… (1) 1.0deg ≧ θ × L / 250 ≧ 0.1deg ………… (2) 60N / mm ² ≧ T ≧ 10N / mm ² …. ………………… (3) However, K = 85.4 × D (mm) + 470.1 × θ (deg) × L / 250 +
3.7 × T (N / mm ² ) -277.2, L: Distance between work rolls on the input side and output side (mm), work roll diameter: 10 to 20 mm, number of work rolls (both sides): 5 to 25.