JPH02270945A - Production of copper alloy for ic lead frame - Google Patents

Abstract

PURPOSE:To produce a copper alloy for IC lead frame having high flatness characteristic and reduced in internal strain by subjecting a copper alloy having a specific composition to finish temper rolling, to low-temp. annealing or continu ous annealing, and then to tension leveler straightening. CONSTITUTION:A stock for lead frame composed of a copper alloy having a composition consisting of 0-5wt.% of one or more elements selected from Al, Si, P, Ti, Cr, Mn, Fe, Co, Ni, Zn, Zr, Sn, Mg, Ag, Te, and B and the balance Cu is prepared. The above stock is subjected to finish temper rolling, to low- temp. annealing at 150-400 deg.C for 30-400min or continuous annealing at 250-600 deg.C for 5-300sec, and then to tension leveler straightening at 0.15-1.0% elongation percentage, by which the copper alloy can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a copper alloy for IC lead frames that has excellent flatness and eliminates internal strain.

[Conventional technology]

Generally, copper alloys for IC lead frames are subjected to heat finish rolling to obtain the desired thickness, but after this process, the purpose is to correct shape defects during heat finish rolling.

Correction is performed using a tension leveler.

Materials for IC lead frames require highly precise shapes. This includes the steepness of the material, curls, lateral bends, etc., and these poor flatness lead to deterioration of dimensional accuracy during subsequent frame molding, and also significantly reduce productivity.

By the way, since it is difficult to obtain such flatness only by finish skin-pass rolling, the desired flatness is achieved by straightening with a tension leveler after finishing skin-pass rolling.6 [Problems to be Solved by the Invention] ] However, although the conventional tension leveler correction can achieve high flatness, there is a problem in that it is not sufficient to remove the internal strain contained in the material during finish skin-pass rolling. Internal strain in the material is released during frame molding, resulting in uneven lead legs.

If it is mounted on the board as it is, problems such as poor conduction occur. In addition, due to high integration, deformation of the die pad part of the frame on which the IC block is mounted reduces the adhesion reliability of the wire bonding board. This has become more noticeable due to the trend of

The present invention was made to solve the above-mentioned problems, and an object of the present invention is to provide a method for manufacturing a copper alloy for an IC lead frame, which provides high flatness and reduces internal distortion.

(Means for Solving the Problems) A method for manufacturing a copper alloy for an IC tree frame according to the present invention includes six additional elements: AD, Si, P, Ti,
Cp.

Mn, Fe, Co, Ni, Zn, Zr, S
1 selected from n, Mg, Ag, Te and 13
A lead frame material made of a copper alloy containing 0 to 5% by weight of one or more species and the balance being Cu is subjected to low-temperature annealing at 150° C. to 400° C. for 30 minutes to 400 minutes after pass-rolling step 4. or at 250℃~600℃ for 5 seconds~
After continuous annealing for 300 seconds, the elongation rate was 0.15%1
This method performs tension leveler correction at ~1.0%.

[For production]

In this invention, after finish-pass rolling the copper alloy for IC lead frames, the internal strain of the material is released by low-temperature annealing or continuous annealing under the conditions listed in 1, and then tension leveler correction under the above conditions. :J, high flatness obtained.

Here, in the first low-temperature annealing, the temperature was adjusted to 150°C to 4°C.
The reason why the temperature was set at 00°C was that if the temperature was lower than 1.50°C, the desired removal of internal strain would be insufficient, and the upper limit was set at a temperature at which the strength of the ladle would not decrease. Further, the annealing time is set to 30 minutes to 400 minutes because if it is less than 30 minutes, sufficient and uniform internal strain cannot be removed, and the upper limit is the time λ· which can ensure industrial productivity.

Ta.

On the other hand, the limitations on temperature and time for continuous annealing are also based on the same basis as for the above-mentioned low-temperature annealing.

Next, in the annealing tension leveler correction 1]-,
The elongation rate is 0.15% ~ 1.0%, which is 0.1!
If it is less than i%, sufficient shape correction cannot be performed and high flatness cannot be obtained. Also, 1.0% is 1.0%.
If the correction exceeds %, the internal strain will accumulate again due to excessive correction, which will cancel out the effect of the previous annealing.

Regarding the range of each component in lead frame materials,
To ensure appropriate mechanical strength, heat resistance, etc. as a copper-based lead frame material, various elements are added l11, conductivity,
In view of cost, the total weight was set at 5% or more.

[Embodiments of the invention]

An embodiment of the present invention will now be described.

Sn, 2.0% by weight, Nj O, 2% by weight, balance Cu
After melting an alloy consisting of aluminum and unavoidable impurities in the above-mentioned composition ratio, repeating rolling and annealing, the final processing rate was reduced to 7%, and the plate thickness was reduced to 0° by finishing temper rolling. 2m
111 alloy strips were produced. After degreasing this alloy strip, it was annealed and straightened with a tension leveler under the conditions shown in the table, and the various items shown in Table 2 were measured. Table 1 Table 2 Note 1) Steepness of the material The height of the ear wave of the material is divided by the length of the ear wave and expressed as a percentage.

Note 2) Internal strain "1F! As a direct method, material 220mm x 50
Melt the mm by etching every 2 mm, and use the hanging method.
It is shown as the variation in curl (the difference between the maximum R value and the minimum value) for each month.

Various evaluations when processed under the processing conditions shown in Table 1 are shown in the second table.
As shown in the table, &1 to 4 examples are Nα5.7.8.1
It can be seen that the internal distortion can be removed well when compared with the comparative example shown at No. 0 and the conventional example shown at Nα13.14. This is recognized to be the effect of removing internal strain due to low-temperature annealing or continuous annealing.

Here, in the comparative examples, NQ 6 and Na 9 have an effect of removing internal strain, but a decrease in material strength is observed due to excessive annealing, which is inappropriate.

Also, shame 5 and 8 are due to lack of temperature.

Regarding circle 7.10, due to insufficient machining time, no internal strain removal effect was observed. moreover.

As for the rod 11, the flatness is unsatisfactory, and the Nα12
In this case, the internal strain removal effect of annealing is canceled out by excessive tension leveler correction.

In addition, in the above example, the raw material was shown in the middle of the manufacturing process, but after this process, after slitting to the width of the board to be used,
For the purpose of removing distortion at the time of slitting, it is a useful means to perform distortion relief annealing or leveler correction.

Further, in the above example, Sn 2.0% by weight, NiO
, 2% by weight, and the balance is Cu. However, as additive elements A(1, Si, P, Ti, C
r, Mn, Fe, Co, Ni, Zn, Zr,
One or two of Sn, Mg, Ag, Te, B
It is effective for copper alloys containing 0 to 5% by weight of Cu and the remainder being substantially Cu.

〔Effect of the invention〕

As described above, according to the present invention, since tension leveler correction is performed after low-temperature annealing or continuous annealing, it is possible to obtain a copper alloy for an IC lead frame with high flatness and low internal strain.

Claims (1)

[Claims] (1) Additive elements: An, Si, P, Ti, Cr, M
n, Fe, Co, Ni, Zn, Zr, Sn, Mg, Ag
, Te, and B.
A lead frame material made of a copper alloy containing 5% by weight and the remainder being Cu is heated at 150°C to 400°C after finishing temper rolling.
After low-temperature annealing at ℃ for 30 minutes to 400 minutes or continuous annealing at 250℃ to 600℃ for 5 seconds to 300 seconds, tension leveler straightening with an elongation rate of 0.15% to 1.0%. A method for producing a copper alloy for an IC lead frame, the method comprising: