JP2902830B2 - Lead frame material and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame molding material for an integrated circuit device, and more particularly to a lead frame material having reduced shrinkage during heating and improved processing accuracy during processing.

[0002]

2. Description of the Related Art The lead frame of an integrated circuit device is Fe-
Fe-Ni alloy represented by 42% Ni alloy or Fe-29%
It is manufactured by slitting a strip of Fe-Co-Ni alloy represented by Ni-17Co% (Kovar) into a predetermined width and then punching. In this punching process, the positional accuracy of the lead frame, particularly the inner lead, has a very important effect on the automatic positioning in the wire bonding operation in the assembly process of the integrated circuit element. In recent years, leads have become very multi-pin (pins are also referred to as leads) and complicated due to the high integration of integrated circuit elements. The standard for the position of the inner lead is becoming very strict, and it is extremely difficult to satisfy the standard for the position of the inner lead only by the conventional punching technique alone. Therefore, FIG.
As shown in (a), the inner lead b is subjected to strain relief annealing (stress relief) in an intermediate lead frame state connected to the tab a, and after releasing the processing strain added by the punching process, the punching process is performed again. Then, a method of separating the inner lead b from the tab a and processing the inner lead b into a final lead frame shown in FIG. 1B has been adopted. However, if the heat shrinkage of the lead frame material subjected to this punching process is large, the pitch of the feed holes c shrinks during the strain relief annealing performed on the frame in the intermediate state, making the next final punching process difficult or Since problems such as inferior processing accuracy occur, a lead frame material with small heat shrinkage is required.

[0003]

Since the conventional lead frame material has been given special emphasis on punching workability, it has been manufactured in the direction of increasing the internal strain of the material from the viewpoint of workability. That is, a general hardness standard for lead frames
A method of applying a relatively large tension (tension) to aim at the upper limit hardness by rolling strain for HV = 200 ± 20 and to improve flatness even in strain relief annealing after slitting of material (tension annealing ) Has been taken. However, such a lead frame material has a large heat shrinkage in the strain relief annealing in the frame in the above-described intermediate state of the punching process, a large amount of change in the pitch of the feed hole of the frame, and the final punching process is impossible. However, there are problems such as lack of processing accuracy. In view of the above, an object of the present invention is to provide a lead frame material with small heat shrinkage and a method for manufacturing the same.

[0004]

The present inventor has studied to reduce the heat shrinkage of the lead frame material, and as a result,
We found the following: That is, after cold rolling to a product thickness, slit processing to a predetermined width, and then in the manufacturing process of performing the strain relief annealing, no tension is applied at all during strain relief annealing, or the tension is 5.0 kg / mm ² or less. It has been found that, by suppressing the temperature of the lead frame material, a novel material having significantly smaller heat shrinkage than the conventional lead frame material can be obtained. In addition, this new material has a shrinkage rate of 0.03% or less of the original length of the material when heated at 650 ° C for 10 minutes assuming conditions for strain relief annealing in an intermediate state during frame manufacturing, and In the case of, it was found that good frame processing accuracy was obtained. Here the defined tension during stress relief annealing of the material to 5.0 kg / mm ² or less, more in the tension is added newly tensile stress during stress relief annealing, since the heat shrinkage is more than 0.03% It is. Preferably, the tension during the strain relief annealing is desirably suppressed to 2.0 kg / mm ² or less. The Fe-Ni-based alloy referred to in the present invention is, as a main component,
An alloy containing 20% or more Ni by weight and Fe.
-Ni-Co alloys are Ni, Co and F as main components.
These alloys contain a small amount of other elements (eg, Si, Mn, Cr, V, Nb, Mo, W, etc.).
May be contained.

[0005]

The present invention will be described below with reference to examples. Fe-
42% Ni alloy, Fe-50% Ni alloy and Fe-29% Ni-17% C
o By manufacturing a strip of alloy and performing a predetermined slitting process after the cold rolling process, a thickness of 0.25 mm and a width of 70 mm
mm lead frame material was obtained. 600-700 ℃ for this material
Under the condition of heating at a temperature of 1 to 3 minutes, the amount of tension applied to the material was changed in the range of 0 to 7.0 kg / mm ² , and strain relief annealing was performed to obtain a lead frame material. As shown in FIG. 2, the heat shrinkage of the lead frame material obtained under each condition
After cutting to a length of 200 mm, make an indentation d of 160 mm in length, which is the original length, and then measure the distance between the indentations after heating at 650 ° C. for 10 minutes to measure the amount of shrinkage. It was determined by the formula. Heat shrinkage = {(160 mm−L ₁ ) / 160 mm} × 100 (%) L ₁ : Length at room temperature after heating at 650 ° C. for 10 minutes Table 1 shows the results. As is clear from the table, in the lead frame material of the present invention, the heat shrinkage is significantly reduced as compared with the conventional material. The lead frame material is punched into a shape that does not separate the tab a and the inner lead b shown in FIG. 1A, and then heated at 600 ° C. for 3 minutes to dissolve the processing strain, and then the tab a and the inner lead b are finished. The shape shown in FIG. 1 (b) was obtained by cutting by punching. At the time of this finish punching, the pitch of the feed hole c shrinks, and the one that cannot be fed is defective (x), and the one that can feed smoothly without any problem is good (○), but the feed is possible. ,
Unsmoothness was evaluated as slightly good (△), and the finish punching workability was evaluated. Table 1 shows the results. Table 1
It can be seen from the above that the lead frame material of the present invention does not cause feeding failure in finish punching. In addition, it was confirmed that a lead frame material having a tension of 2.0 kg / mm ² enables smooth feeding and is more preferable.

[0006]

[Table 1]

[0007]

According to the method of the present invention, a novel lead frame having a small amount of material shrinkage during heating can be obtained by a relatively simple method of performing strain relief annealing during production of a lead frame material while minimizing tension. The material is obtained. This lead frame material has a property that has not been realized until now, that the shrinkage after heating at 650 ° C. for 10 minutes is 0.03% or less of the original length. The lead frame material of the present invention has a small amount of pitch change of the perforation hole in the strain relief annealing in the intermediate lead frame state of the manufacturing process in which the inner lead is connected to the tab as described above. Is very effective in improving the workability and the processing accuracy in

[Brief description of the drawings]

FIG. 1A is a diagram showing an intermediate state of a lead frame in which inner leads are connected to tabs, and FIG.
FIG. 3 is a view showing a lead frame in a state where finish punching has been performed after strain relief annealing.

FIG. 2 is a diagram showing a method of measuring a heat shrinkage amount.

[Explanation of symbols]

 a tab b inner lead c sprocket hole d indentation

Claims (2)

(57) [Claims] 1. A material made of a Fe-Ni-based alloy or a Fe-Ni-Co-based alloy, which is heated at 650 ° C. for 10 minutes and has a contraction rate of 0.03% or less with respect to an original length of the material at room temperature. Characteristic lead frame material. 2. In a manufacturing process in which a product is cold-rolled to a product thickness, slitted to a predetermined width, and then subjected to strain relief annealing, the strain relief annealing is performed without applying tension, or the tension is reduced.
A method for manufacturing a lead frame material, wherein the material is heated at 650 ° C. for 10 minutes and the shrinkage of the material at room temperature is reduced to 0.03% or less by performing strain relief annealing at 5.0 kg / mm ² or less. .