JP2662209B2 - Copper alloy for electronic equipment with excellent plating adhesion and solder bondability and its manufacturing method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has high strength, excellent electrical conductivity and heat resistance, good workability and good plating adhesion, and a long-term evaluation of interface strength with solder. The present invention relates to a copper alloy for electronic equipment which does not cause deterioration and a method for producing the same. 2. Description of the Related Art Generally, semiconductor devices, for example, lead frames for semiconductor devices are required to have the following characteristics. (1) High strength and good heat resistance, (2) Heat dissipation, that is, high thermal and electrical conductivity, (3) Good bending formability after frame formation, (4) Plating adhesion (5) There is no deterioration with time of the joint with the solder, and a 42 alloy (Fe-42 wt% Ni) is mainly used for such a lead frame. This alloy has excellent properties such as tensile strength of 63 kg / mm ² and heat resistance of 670 ° C (temperature at which it becomes 70% of the initial strength by heating for 30 minutes), but conductivity is inferior to about 3% IACS. It is. In recent years, semiconductor devices have been required to have high reliability at the same time as the degree of integration and miniaturization, and the form of semiconductor devices has been changing from conventional DIP type ICs to chip carrier type or PGA type. For this reason, lead frames for semiconductor devices have become thinner and smaller, and at the same time, characteristics exceeding 42 alloys have been required. In other words, to improve the strength to prevent a decrease in the strength of the component parts due to thinning, to improve the heat conductivity due to the increase in the degree of integration, to improve the conductivity, which is the same property as the heat conductivity, to further improve the heat resistance, Improve plating and adhesion to lead frame surface, moldability with encapsulation resin, and reliability as a pre-bonding process for fixing semiconductor on the frame and bonding the semiconductor to the wiring of the foot of the lead frame. As a problem, it is desired that the solder bonding strength in the bonding between the frame and the substrate does not deteriorate with time. [0004] The above-mentioned 42 alloy has a low conductivity of 3% IACS, and has a drawback that heat dissipation is inferior. If a copper alloy is used instead, the conductivity becomes 50-30% IACS. It can be dramatically improved, but also about other characteristics
It was extremely difficult to obtain the same performance as the alloy. [0005] In view of the foregoing, the present invention has been subjected to various studies, and as a result, has shown a conductivity far superior to that of 42 alloy.
With regard to other properties, a copper alloy for semiconductor devices that exhibits properties substantially equivalent to those of the 42 alloy and a method for producing the same have been developed. That is, the alloy of the present invention has a Ni content of not less than 0.1 wt%
Ni and Ti in a range of less than 4 wt% and less than 0.1 wt% and 1.0 wt% of Ti, and Ni / Ti of less than 4;
6.0 wt% and Mn, Mg, misch metal (MM), B,
Any one or more of Sb, Te, and Zr are added in total 0.0
05 to 3.0 wt% (hereinafter wt% is abbreviated as%).
containing one or two of n and Al in total of 3.0% or less;
Further, it is characterized in that the O ₂ content is 20 ppm or less, the precipitate size is 5 μm or less, and the balance is Cu and unavoidable impurities. Further, the production method of the present invention is characterized in that Ni is 0.1% or more and 3.0% or more.
% And Ti within the range of 0.1 to 1.0%.
/ Ti included so as to be less than 4, and Sn 0.1 to 6.0
% And Mn, Mg, misch metal (MM), B, Sb,
One or more of Te and Zr in total 0.005 to
An alloy ingot containing 3.0% and further containing one or two of Zn and Al in a total amount of 3.0% or less and the balance of Cu and inevitable impurities was homogenized at 750 to 960 ° C for 0.5 to 15 hours. Thereafter, hot rolling is performed at a temperature of 700 to 920 ° C., and cooling is performed immediately thereafter. In the present invention, the alloy composition is limited as described above for the following reasons. The addition of Ni and Ti is intended to improve the strength and the electrical conductivity by a synergistic effect, and the content is limited to 0.1% or more to less than 3.0% of Ni and 0.1 to 1.0% of Ti. If the amount is less than the lower limit, no improvement in properties is observed. If the amount exceeds the upper limit, castability, workability, and bendability are remarkably reduced, and it becomes difficult to produce an alloy. Also, the reason why Ni and Ti are limited so that Ni / Ti is less than 4 is as follows.
Ni / Ti is 4 to obtain excellent strength and high conductivity.
Above this is because the strength is improved, but the conductivity is significantly reduced, and it is preferable to set Ni / Ti to about 2. [0010] The addition of Sn further increases the strength and the bending formability, and further suppresses variations in characteristics due to hot rolling conditions (start temperature, end temperature, cooling rate, etc.). The reason why the content is limited to ~ 6.0% is that if the content is less than the lower limit, the effect is poor, and if the content exceeds the upper limit, not only the conductivity is remarkably reduced, but also the workability is reduced, and it becomes difficult to produce an alloy. Mn, Mg, MM, B, Sb, Te, Zr
The addition of any one or two or more of the above all improves the castability by the deoxidizing effect and also reduces the hot rolling property, especially the reheat cracking during homogenization treatment before hot rolling and the cracking during rolling. This is to prevent the deterioration of the solder bonding strength with time by strengthening the bonding interface with the solder. Therefore, the total content is limited to 0.005 to 3.0% because the effect is poor below the lower limit and not only deteriorates castability but also deteriorates plating adhesion and bending moldability above the upper limit. Any one or two of Zn and Al are used to further improve the strength and prevent the deterioration of the solder bonding strength with time, and the total content is limited to 3.0% or less, which exceeds the upper limit. This is for reducing the adhesion to the plating and the electrical conductivity. Next, reduce the O ₂ content to 20 ppm or less (preferably,
10 ppm or less) because the O ₂ content in the molten metal during casting is 2
If the content exceeds 0 ppm, Ti becomes slag as an oxide from the molten metal, which makes it difficult to control the Ti component and deteriorates castability, as well as deteriorates plating adhesion and solderability of the alloy. When the size of the precipitate is 5
The reason why the thickness is set to be not more than μm is that the size of the precipitate greatly affects the surface condition of the plating, adhesion and solder wettability, and if the precipitate exceeds 5 μm, these properties are greatly reduced. In the production method of the present invention, an alloy having the above composition range is formed into an ingot by semi-continuous or continuous casting, and the ingot is formed at 750 to 960 ° C.
The alloy is homogenized for 0.5 to 15 hours, then hot-rolled from 700 to 920 ° C., and then immediately cooled.Ti used in the alloy of the present invention is rich in activity, easily oxidized, and In this case, the oxide tends to become an oxide, and slag is generated to cause a component failure. However, by performing melting casting in a non-oxidizing atmosphere such as Ar or N _{2, the} above-mentioned disadvantage can be covered, and a great improvement in productivity can be achieved. Furthermore, the cooling rate in semi-continuous or continuous casting is 100
C./sec or more is desirable, and if it is less than that, precipitates due to the constituent elements are generated, and coarsening occurs during the homogenization treatment before hot rolling, which adversely affects properties and manufacturing methods thereafter. Further, the homogenization treatment before hot rolling is carried out at 750 to 960.
When the temperature is set at 0.5 ° C. for 0.5 to 15 hours, the effect of homogenization is not seen below the lower limit, and the reheat cracking and the production cost are deteriorated above the upper limit. 830 ~ 950 ℃ for homogenization
For 1 to 8 hours. The reason for setting the hot rolling start temperature after the homogenization treatment to 700 to 920 ° C is that a hot rolling crack easily occurs outside this range. Hot rolling start temperature is 8
It is desirable that the temperature be 20 to 900 ° C. The cooling after the hot rolling may be performed at any cooling rate due to the effect of Sn addition, but it is preferable that the cooling rate is 1000 ° C./min or more. Further, as the production method of the present invention, cold working and annealing at 400 to 800 ° C. for 10 seconds to 360 minutes are repeated after hot working, and finally heat treatment annealing at 200 to 500 ° C. and a tension leveler are combined. More excellent characteristics can be obtained. EXAMPLE A copper alloy having the composition shown in Table 1 was melted and cast in an Ar gas using an atmosphere melting furnace to obtain an ingot having a thickness of 50 mm and a width of 120 mm. This was chamfered, homogenized at 850 ° C for 3 hours, hot-rolled at 830 ° C, and water-cooled to a thickness of 10mm.
Plate. Cold rolling and intermediate annealing of these sheets (Nos. 1 to 10 in Table 1 at 570 ° C for 1 hour, No. 11 at 700 ° C
Is repeated for 1 hour) with a final processing rate of 40% and a thickness of 0.25.
mm, heat-anneal at 300 ° C for 0.5 hours, cut out test specimens, tensile strength and bend formability (R /
t), plating adhesion, moldability (oxide film peelability), and solder joint strength were examined. Table 2 shows the results. The tensile strength is based on JIS-Z2241, and the conductivity is
It was measured based on JIS-H0505. The bending formability (R / t)
The test was performed based on the block method of JIS-Z2248, and the value was obtained by dividing the minimum bending radius (R) at which a crack occurred on the surface of the test piece by the thickness (t) of the test piece. The plating adhesion of a test piece of 30 × 30 mm was subjected to Ag plating after the surface was cleaned, and this was heated in the air. Thereafter, the swelling of the plating surface was observed, and the coating was heated at 550 ° C. for 5 minutes. Those with no swelling are indicated by a circle, and those with swelling are indicated by a cross. The oxide film peeling property of a test piece of 10 × 50 mm was subjected to a surface cleaning treatment, heated at 420 ° C. for 1 minute in the air, and then subjected to a peeling test using a cellophane tape. A mark and a mark where peeling was observed on the entire surface were indicated by a cross. Regarding the solder joint strength, a test piece of 5 × 50 mm was joined to an oxygen-free plate of the same shape by a 60/40 eutectic solder, subjected to a heating acceleration test at 150 ° C. for 500 hours, and then subjected to a tensile test. Perform the test. If the strength is 80% or more before the accelerated test, mark ○, if the strength is 50 to 80%, mark △,
Indicated by a mark. [Table 1] [Table 2] As is clear from Tables 1 and 2, the alloys Nos. 1 to 3 of the present invention are all 42 alloys (No. 1) which are conventional alloys.
Compared to 1), it can be seen that it has the same strength and much better conductivity. On the other hand, the comparative alloy No. 4 having a small Ti content was inferior in the improvement in strength and conductivity, and the comparative alloy No. 5 having a large Ti content was difficult to hot work.
In Comparative Alloy No. 6 having a large Ni content, not only no improvement in conductivity was observed, but also poor plating adhesion and moldability. In the case of Comparative Alloy No. 7 having a large Sn content, hot rolling was difficult as in Comparative Alloy No. 5. Further, the comparative alloy No. 8 having a large content of other elements not only has poor conductivity, but also has poor plating adhesion and bendability. The comparative alloy No. 9 having a large O ₂ content and the comparative alloy N having a large precipitation grain size
In the case of o.10, the plating adhesion and the solder bonding are inferior. As described above, according to the present invention, it is possible to provide a copper alloy excellent in conductivity, strength, bending formability, and solder bonding property, and is used as a semiconductor device material such as a lead frame. However, the present invention has a remarkable industrial effect, such as making it thinner and smaller.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Shoji Shiga               500 Furukawa Electric, Kiyotaki-cho, Nikko-shi, Tochigi               Industrial Co., Ltd. Nikko Electric Copper Works                (56) References JP-A-60-184655 (JP, A)                 JP-A-62-278243 (JP, A)                 Showa 60-262933 (JP, U)

Claims (1)

(57) [Claims] Ni 0.1wt% or more and less than 3.0wt%, Ti 0.1 ~ 1.0wt
%, Ni and Ti are contained so that Ni / Ti is less than 4, and 0.1 to 6.0 wt% of Sn and one of Mn, Mg, misch metal (MM), B, Sb, Te, and Zr
Contains at least 0.005 to 3.0 wt% of one or more species, further contains at most 3.0 wt% of one or two of Zn and Al, further has an O ₂ content of 20 ppm or less, and a precipitate size of 5 μm.
m or less, and a copper alloy for electronic equipment which is excellent in plating adhesion and solder bonding, comprising a balance of Cu and unavoidable impurities. 2. Ni 0.1wt% or more and less than 3.0wt%, Ti 0.1 ~ 1.0wt
%, Ni and Ti are contained so that Ni / Ti is less than 4, and 0.1 to 6.0 wt% of Sn and one of Mn, Mg, misch metal (MM), B, Sb, Te, and Zr
An alloy ingot containing a total of 0.005 to 3.0% by weight of at least one kind or two or more and a total of at most 3.0% by weight of at least one of Zn and Al and a balance of Cu and unavoidable impurities is 75%.
After homogenizing at 0 to 960 ° C for 0.5 to 15 hours, 700 to 9
A method for producing a copper alloy for electronic equipment having excellent plating adhesion and solder bonding, characterized by hot rolling at a temperature of 20 ° C and cooling immediately thereafter.