KR102285168B1 - Cu-Ni-Si-based copper alloy bath and manufacturing method thereof - Google Patents

Abstract

An object of this invention is to provide the Cu-Ni-Si type|system|group copper alloy strip excellent in adhesiveness with resin, and its manufacturing method by suppressing generation|occurrence|production of smut moderately while improving intensity|strength. The Cu-Ni-Si-based copper alloy bath of the present invention is a Cu-Ni-Si-based copper alloy bath containing Ni: 1.5-4.5 mass %, Si: 0.4-1.1 mass %, the remainder being Cu and unavoidable impurities, The electrical conductivity is 30% IACS or more, the tensile strength is 800 MPa or more, and after being immersed in a 40 wt% aqueous nitric acid solution at room temperature for 10 seconds, L ^* a ^* b ^* lightness L ^* in the colorimetric system specified in JIS-Z8781:2013 50-75.

Description

Cu-Ni-Si-based copper alloy bath and manufacturing method thereof

TECHNICAL FIELD This invention relates to the Cu-Ni-Si type|system|group copper alloy strip which can be used suitably for manufacture of electronic components, such as an electronic material, and its manufacturing method.

In recent years, along with the miniaturization of IC packages, miniaturization of lead frames, various terminals of electronic devices, connectors, and the like, as well as multiple pins, are required. In particular, a structure has been developed in which electrode pads are disposed on the land of the LSI package, which is called a QFN (Quad Flat Non-leaded package), so that the lead pins do not come out, and more pins and narrower pitches are required. Since microfabrication by etching is required in order to make these lead frames etc. multi-pinned, while improving the intensity|strength of the copper alloy used as a material, it is calculated|required to improve etching property, plating adhesiveness, resin adhesiveness, etc. In this regard, an aging-precipitation type Cu-Ni-Si-based copper alloy has been developed.

However, when a Cu-Ni-Si-based copper alloy is used for electronic components such as lead frames, pickling is performed as a pretreatment, but during pickling, the Ni-Si-based compound is oxidized and remains on the surface of the material as smut in some cases. When the residue of this smot increases, it may interpose between the lead frame and the mold resin in the IC package assembly process to reduce the adhesion of the resin or the adhesion of solder or plating.

Therefore, by regulating the particle size of Ni-Si-based precipitates of Cu-Ni-Si-based copper alloys and limiting the content of Ni and Si, and suppressing the residual smut during pickling, a technique for improving solder adhesion and plating properties has been proposed. There is (Patent Document 1).

Japanese Patent Laid-Open No. 8-319527

However, in the case of the technique described in Patent Document 1, in order to improve solder adhesion and plating property, it is attempted to almost completely remove smut of NiSi particles by pickling. Therefore, there is a problem that the surface of the material exposed after pickling hardly produces irregularities due to the precipitates, the anchor effect due to the irregularities is reduced, and the adhesion to the resin is poor. Accordingly, for example, the adhesion between the lead frame and the mold resin in the above-described IC package assembly process is affected.

That is, the present invention has been made in order to solve the above problems, and at the same time improving strength and appropriately suppressing the occurrence of smot, providing a Cu-Ni-Si-based copper alloy strip excellent in adhesion to resin and a method for producing the same is intended for

As a result of various studies by the present inventors, the state in which smut is excessively generated during pickling of the Cu-Ni-Si-based copper alloy bath until stratified reduces the resin adhesion, but even if the smot is excessively removed, irregularities caused by NiSi precipitates It was lost, and it discovered that the anchor effect by unevenness was reduced and adhesiveness with resin fell. That is, it discovered that the surface unevenness|corrugation remained and adhesiveness with resin improved by making smut remain suitably at the time of pickling. Moreover, as a method of controlling generation|occurrence|production of smut in this way, it discovered adjusting the solution heat treatment conditions at the time of copper alloy bath manufacture.

That is, the Cu-Ni-Si-based copper alloy bath of the present invention is a Cu-Ni-Si-based copper alloy bath containing Ni: 1.5 to 4.5% by mass, Si: 0.4 to 1.1% by mass, the remainder being Cu and unavoidable impurities. , having a conductivity of 30% IACS or more, a tensile strength of 800 MPa or more, and after immersion in a 40 wt% aqueous nitric acid solution at room temperature for 10 seconds, L ^* a ^* b ^* lightness L ^{* in the colorimetric system specified in JIS-Z8781:2013} is 50 to 75.

Moreover, it is preferable to contain 0.005-0.8 mass % of 1 or more types chosen from the group of Mg, Fe, P, Mn, Co, and Cr in total.

The manufacturing method of the Cu-Ni-Si type copper alloy bath of this invention contains Ni: 1.5-4.5 mass %, Si: 0.4-1.1 mass %, and Cu-Ni-Si type copper which consists of remainder Cu and an unavoidable impurity. After hot rolling and cold rolling of the ingot of the alloy bath, solution treatment and aging treatment are performed in this order, and cold rolling is performed after aging treatment with a workability of 40% or more, and the material after the solution heat treatment and before the aging treatment After immersion in 40 wt% nitric acid aqueous solution at room temperature for 10 seconds, the solution treatment is adjusted so that it becomes 40 to 70 when the brightness L ^{* in the L *} a ^* b ^{* color system specified in JIS-Z8781:2013 is measured.} do.

ADVANTAGE OF THE INVENTION According to this invention, the Cu-Ni-Si type|system|group copper alloy strip which is high in intensity|strength, and suppresses generation|occurrence|production of smot appropriately, and is excellent in adhesiveness with resin is obtained.

Hereinafter, the Cu-Ni-Si type copper alloy bath which concerns on embodiment of this invention is demonstrated. In the present invention, % refers to mass% unless otherwise specified.

First, the reason for limitation of the composition of a copper alloy bath is demonstrated.

<Ni and Si>

Ni and Si form precipitated particles of an intermetallic compound mainly _{containing fine Ni 2} Si in which Ni and Si are subjected to an aging treatment, thereby remarkably increasing the strength of the alloy. Further, along with the precipitation of the Ni ₂ Si in the aging treatment, thereby improving the conductivity. However, when the Ni concentration is less than 1.5% or when the Si concentration is less than 0.4%, the desired strength cannot be obtained even if the other component is added. Further, when the Ni concentration exceeds 4.5% or when the Si concentration exceeds 1.1%, although sufficient strength is obtained, the conductivity is low, and furthermore, the coarse Ni-Si type does not contribute to the improvement of strength. Particles (crystals and precipitates) are generated in the mother phase, resulting in deterioration of bending workability, etching properties and plating properties. Accordingly, the content of Ni is set to 1.5 to 4.5%, and the content of Si is made to be 0.4 to 1.1%. Preferably, the Ni content is 1.6 to 3.0%, and the Si content is 0.4 to 0.7%.

<Other elements>

In addition, in the alloy, for the purpose of improving the strength, heat resistance, stress relaxation resistance, etc. of the alloy, 0.005 to 0.8 mass in total of at least one selected from the group consisting of Mg, Fe, P, Mn, Co and Cr % may be contained. When the total amount of these elements is less than 0.005 mass %, the said effect does not arise and when it exceeds 0.8 mass %, although desired characteristics are acquired, electroconductivity and bending workability may fall.

<Conductivity and Tensile Strength (TS)>

As for the Cu-Ni-Si-type copper alloy bath which concerns on embodiment of this invention, electrical conductivity is 30 %IACS or more, and tensile strength (TS) is 800 Mpa or more.

Since heat_generation|fever by electricity increases with increase in the operating frequency of a semiconductor element, the electrical conductivity of a copper alloy bath shall be 30 %IACS or more.

Moreover, in order to prevent the deformation|transformation of the lead frame at the time of wire bonding, etc., and to maintain a shape, tensile strength (TS) shall be 800 MPa or more.

<Brightness L ^* >

After the Cu-Ni-Si-based copper alloy bath according to the embodiment of the present invention is immersed in a 40 wt% aqueous nitric acid solution at room temperature for 10 seconds, the brightness L ^{in the L*} a ^* b ^{* color system prescribed in JIS-Z8781:2013 *} is 50 to 75.

When a sample is immersed in a nitric acid aqueous solution, smut is generated and remains on the sample surface, and the color of the sample surface changes to dark. Therefore, by measuring the color tone of the sample surface, it is possible to determine the presence or absence of occurrence of smut.

When the lightness L ^* approaches 0, it becomes black, and when it approaches 100, it becomes white.

^{By setting the brightness L*} after immersion in the aqueous nitric acid solution of the Cu-Ni-Si-based copper alloy bath according to the embodiment of the present invention to 50 to 75, the surface of the concave-convex shape in which NiSi precipitates are appropriately left on the surface of the material after pickling can be obtained. and adhesiveness with resin becomes favorable by the anchor effect.

On the other hand, when lightness L ^* is less than 50, many smut generate|occur|produces after pickling, the material surface is covered in a layered form, and resin adhesiveness falls by peeling of a smut layer and a copper alloy layer. In the case where the brightness L ^* exceeds 75, smut is excessively removed by pickling, the NiSi precipitate on the surface becomes small, and the surface asperity becomes small. As a result, the anchor effect is no longer obtained, or the surface area of the copper alloy (matrix) on the surface of the material increases, so that the Cu oxide film growth is accelerated, and the oxide film peels off and adhesion to the resin decreases.

^{As a method of controlling the brightness L*} of a copper alloy bath to 50-75, adjusting the solution heat treatment conditions mentioned later is mentioned. The solution treatment conditions will be described later.

<Production of Cu-Ni-Si-based copper alloy bath>

The Cu-Ni-Si-based copper alloy bath according to the embodiment of the present invention can be usually manufactured by performing hot rolling, cold rolling, solution heat treatment, aging treatment, cold rolling after aging, and strain relief annealing of an ingot in this order. . Cold rolling before a solution treatment is not essential, and you may implement it as needed. In addition, you may perform cold rolling after a solution heat treatment and before an aging process as needed. Grinding, polishing, shot blasting, pickling, etc. for removing oxidized scale on the surface can be performed suitably between said each process.

The solution treatment is a heat treatment for dissolving a silicide such as a Ni-Si compound into a solid solution in the Cu matrix and recrystallizing the Cu matrix at the same time.

In the method for producing a Cu-Ni-Si-based copper alloy bath according to the embodiment of the present invention, the material after the solution treatment and before the aging treatment is immersed in a 40 wt% aqueous nitric acid solution at room temperature for 10 seconds, then JIS-Z8781:2013 The solution treatment conditions are adjusted so that when the brightness L ^* in the L ^* a ^* b ^* color space specified in is 40 to 70, it is measured.

By adjusting the solution treatment conditions as described above, Ni and Si, which are the causes of smut, are appropriately solution-formed in Cu, and the amount of NiSi precipitates is controlled without excess or deficiency, and as a result, the Cu-Ni-Si-based copper obtained The brightness L ^* in the alloy bath can be controlled to 50 to 75.

^{When the lightness L*} of the material after the solution treatment is less than 40, the amount of NiSi precipitates used as smut due to insufficient solution treatment is excessively large.

^{When the lightness L*} of the material after the solution treatment exceeds 70, the amount of NiSi precipitates which becomes smut due to excessive solution treatment decreases too much.

In addition, in order to change the solution treatment conditions, the temperature and time of the solution treatment may be controlled, but the specific temperature and time of the solution treatment are not prescribed, but the addition amount of Ni, Si, etc. in the copper alloy bath, and the solution treatment It is because the quantity and particle diameter of the Ni-Si type compound before a solution treatment differ depending on the conditions of the pre-processing process.

<Aging treatment>

In the aging treatment, the silicide dissolved in the solution treatment is precipitated as fine particles of an intermetallic compound mainly containing _{Ni 2 Si.} The strength and conductivity are increased by this aging treatment. The aging treatment can be performed under conditions of, for example, 375 to 625° C. and 1 to 50 hours, whereby the strength can be improved.

When the aging time is less than 1 hour, the precipitated amount of the Ni-Si type precipitates is small, and the strength may be insufficient. In addition, when the aging temperature exceeds 625° C. or the aging time exceeds 50 hours, coarsening or re-dissolution of the precipitate occurs, the amount of smot is increased, the strength is insufficient, or the electrical conductivity may be lowered.

<Cold Rolling>

Next, cold rolling (cold rolling after aging treatment) is performed with a workability of 40% or more after an aging process.

When cold rolling is performed with a workability of 40% or more, tensile strength will be 800 MPa or more by work hardening.

When the workability is less than 40%, the strength may be insufficient.

It is more preferable to perform cold rolling after the aging treatment at a workability of 40 to 90% or more. When the workability exceeds 90%, the decrease in conductivity due to work strain becomes significant, and even if strain relief annealing is performed, the conductivity may be low.

The workability of cold rolling after aging treatment is a rate of change in thickness by cold rolling after aging treatment with respect to the material thickness immediately before cold rolling after aging treatment.

Although the thickness of the Cu-Ni-Si-type copper alloy bath of this invention is not specifically limited, For example, it can be set as 0.03-0.6 mm.

<Strain relief annealing>

After the aging treatment, the strain relief annealing can be performed after the cold rolling. What is necessary is just to perform strain relief annealing on general conditions, for example, 300 degreeC - 550 degreeC, and holding time can perform under conditions from 5 second to 300 second. Thereby, the residual stress in the material can be removed.

Example 1

The samples of each Example and each comparative example were produced as follows.

Electric copper was used as a raw material, and copper alloys of the compositions shown in Tables 1 and 2 were melted using an atmospheric melting furnace, and cast into an ingot having a thickness of 20 mm x width of 60 mm. This ingot was hot-rolled at 950 degreeC to 10 mm of plate|board thickness. After hot rolling, grinding was performed and cold rolling was performed in this order.

Next, under the conditions shown in Tables 1 and 2, a solution treatment and an aging treatment were performed in this order. Then, cold rolling was performed after an aging process to 0.150 mm of plate|board thickness by the workability shown in Tables 1 and 2, strain relief annealing for 30 second was performed at 450 degreeC, and the sample was obtained.

<Conductivity (%IACS)>

About the obtained sample, the electrical conductivity (%IACS) at 25 degreeC was measured by the 4-probe method based on JIS H0505.

<Tensile strength (TS)>

About the obtained sample, according to JIS-Z2241, the tensile strength (TS) in the direction parallel to a rolling direction was measured with the tensile tester, respectively. First, from each sample, a JIS 13B test piece was produced using a press machine so that the tensile direction became the rolling direction. The conditions of the tensile test were a test piece width of 12.7 mm, room temperature (15-35°C), a tensile rate of 5 mm/min, and a gauge length of 50 mm.

<Brightness L ^* >

One side of the sample after the solution treatment and before the aging treatment and the sample after the strain relief annealing was immersed in a 40 wt% nitric acid aqueous solution at room temperature for 10 seconds, and then washed with running water. About the sample surface after a process, the brightness L ^* was calculated|required using the color-difference meter.

The color difference meter was measured using Konica Minolta CR-200.

<Adhesiveness with resin>

The sample after strain relief annealing was cut out to a length of 100 mm in a rolling parallel direction and a width of 20 mm, and then one side of the sample was immersed in a 40 wt% aqueous nitric acid solution at room temperature for 10 seconds, and then washed with running water. Next, about this sample, atmospheric heating for 5 minutes was performed at 240 degreeC. After air heating, the acid-resistant tape was stuck in a range of 60 mm in length on one side and then peeled off, and the presence or absence of an adherent on the adhesive surface of the acid-resistant tape was determined by image processing. Specifically, the image of the adhesive surface of the acid-resistant tape was binarized, the ratio of the total area of the black image area used as the adhered to the area of the adhesive surface of the acid-resistant tape was calculated, and the following criteria were evaluated. If evaluation is (circle), it is excellent in adhesiveness with resin.

○: The total area of the adhesive is 10% or less of the area of the adhesive surface of the tape

x: the total area of the adhesion exceeds 10% of the area of the adhesive surface of the tape

The obtained results are shown in Table 1.

As is clear from Table 1, ^{in the case of each Example whose brightness L*} is 50-75, while intensity|strength was high, it was excellent in adhesiveness with resin.

On the other hand, in the case of the comparative example 1 in which ^{brightness L* exceeded 75, adhesiveness with resin was inferior.} This is considered to be because there are too few NiSi precipitates on the surface of a material, Cu oxidation on the surface is remarkable, and the surface oxide film peels off, and adhesiveness with resin is reduced.

In the case of the comparative example 2 whose brightness L ^* is less than 50, the amount of smut generation increased, and adhesiveness with resin was inferior.

In the case of the comparative example 3 in which the workability of cold rolling after an aging process exceeded 90 %, electrical conductivity became less than 30 %IACS.

In the case of Comparative Example 4 in which the workability of cold rolling after the aging treatment was less than 40%, the tensile strength was less than 800 MPa.

In the case of the comparative example 5 in which content of Ni and Si exceeded the regulation range, electrical conductivity became less than 30 %IACS.

In the case of the comparative example 7 which contained more than 0.8 mass % in total of 1 or more types chosen from the group of Mg, Fe, P, Mn, Co, and Cr, electrical conductivity became less than 30 %IACS.

In the case of Comparative Example 8 having an aging temperature of less than 625° C. and Comparative Example 10 having an aging time of less than 1 hour, aging occurred and the tensile strength was less than 800 MPa.

In the case of Comparative Example 9 in which the aging temperature exceeded 625°C and Comparative Example 11 in which the aging time exceeded 50 hours, overaging occurred and the tensile strength was less than 800 MPa. Moreover, the Ni-Si type|system|group precipitate was remarkably precipitated by ^{over-aging, the brightness L*} became less than 50, the amount of smut generation increased, and adhesiveness with resin was inferior.

Claims (3)

Ni: 1.5-4.5 mass %, Si: 0.4-1.1 mass %, It is a Cu-Ni-Si type copper alloy bath which consists of remainder Cu and an unavoidable impurity,
Electrical conductivity is 30% IACS or more, tensile strength is 800 MPa or more,
After being immersed in 40 wt% nitric acid aqueous solution at room temperature for 10 seconds, the brightness L ^{* in L*} a ^* b ^* colorimetric system prescribed|regulated to JIS-Z8781:2013 is 50-75, Cu-Ni-Si-type copper alloy bath. According to claim 1,
Moreover, the Cu-Ni-Si type copper alloy tank which contains 0.005-0.8 mass % of 1 or more types chosen from the group of Mg, Fe, P, Mn, Co, and Cr in total. Ni: 1.5-4.5 mass %, Si: 0.4-1.1 mass %, The ingot of the Cu-Ni-Si type|system|group copper alloy bath which consists of remainder Cu and unavoidable impurity hot-rolling and cold-rolling, after cold-rolling, a solution heat treatment, 375 Aging treatment at ∼625° C. for 1 to 50 hours is performed in this order, and cold rolling is performed after aging treatment at a workability of 40% or more,
The material after the solution heat treatment and before the aging treatment was immersed in a 40wt% aqueous nitric acid solution at room temperature for 10 seconds, and then the brightness L ^{* in the L*} a ^* b ^* color system specified in JIS-Z8781:2013 was measured. The manufacturing method of the Cu-Ni-Si type copper alloy bath of Claim 1 or 2 which adjusts the said solution treatment so that it may become 40-70 at the time.