JPS63262448A - Production of copper alloy having excellent peeling resistance of tin or tin alloy plating - Google Patents

Abstract

PURPOSE:To improve the thermal peeling resistance of tin (alloy) plating and to provide good strength, spring characteristics, heat resistance and electroconductivity together to the titled copper alloy by specifying the aging treatmental conditions of the copper alloy contg. specific ratios of Ni and Si. CONSTITUTION:The copper alloy contg. by weight, 0.4-4.0% Ni, 0.1-1.0% Si and the balance consisting of copper with inevitable impurities is subjected to the aging treatment at T deg.C. At this time, aging treatment is executed for longer times than the times at which the hardness H (Hv) expressed by the equation can be obtd. The copper alloy subjected to the above-mentioned aging treatment is preferably cold rolled as well at about >=5% working ratio and is annealed at about 350-800 deg.C if necessary. The total 0.001-3.0% of one or more kinds among Zn, P, Sn, As, Cr, Mg, Mn, Sb, Fe, Co, Al, Ti, Zr, Be, Ag, Pb, B, Hf, In and lanthanoids are furthermore added as the secondary component to said alloy at need.

Description

[Detailed Description of the Invention] [Objective] The present invention provides a copper alloy suitable for lead materials of semiconductor devices such as transistors and integrated circuits (ICs), and conductive spring materials for connectors, terminals, relays, switches, etc. This relates to a manufacturing method. In particular, it relates to a method for producing a copper alloy that has excellent solder heat peeling resistance (here, heat peeling resistance refers to the property of the soldered material having a peeling resistant effect against the effects of heat, etc.). .

[Prior art and problems] Conventionally, lead materials for semiconductor devices include Kovar (Fe-29Ni-16Co) and 42 alloy (F
High nickel alloys such as e-42Ni) have been preferred. However, in recent years, as the degree of integration of semiconductor circuits has improved, the number of ICs with high power consumption has increased, resins have been increasingly used as sealing materials, and improvements have been made to the bonding between elements and lead frames. As a result, copper-based alloys with good heat dissipation properties have come to be used as lead materials.

Generally, lead materials for semiconductor devices are required to have the following properties.

(1) Leads must exhibit excellent thermal and electrical conductivity, as they are required to act as an electrical signal transmission unit and also have the function of discharging heat generated during the packaging process and circuit use to the outside. .

(2) Since the adhesion between the lead and the mold is important from the viewpoint of protecting the semiconductor element, the thermal expansion coefficients of the lead material and the mold material should be similar.

(3.) Good heat resistance as various heating processes are added during packaging.

(4) Most leads are manufactured by punching or bending lead material, so the processability of these is good.

(5) Since the surface of the lead is plated with precious metals, the plating adhesion with these precious metals must be good.

(6) Exposed outside the sealing material after packaging.

Many items are soldered to the so-called outer leads, so good soldering is a sign of good soldering.

(7) Good corrosion resistance from the standpoint of equipment reliability and lifespan.

(8) The price must be low.

Improved alloys containing phosphor bronze and some additional elements have been widely used to meet these various required properties. However, in recent years, reliability requirements for semiconductors have become more stringent, and surface mounting types that support miniaturization have become more common, so solder heat resistance and peelability, which had not been considered an issue in the past, has become an extremely important characteristic item. It has become.

That is, the lead frame and the printed circuit board are soldered together, but during use, the temperature of the lead frame and the soldering area rises up to about 120° C. due to external temperatures and heat generated by energization. If exposed to such temperatures for a long period of time, the solder and lead frame may peel off, which may cause the semiconductor to malfunction. Therefore, when high reliability is required from the perspective of longevity, this solder heat peeling resistance is the best. This is one of the important characteristics. In particular, FPP (FLA
T PLAS'jICPACKAGE) and P L CC
(PLASTICLEADIED CHIP CARR
The surface mounting type represented by IER) is not inserted into the printed circuit board, but is in surface contact, so solder heat resistance and peelability are even more important.

Also, conventionally, 1! Cheap brass, nickel silver, which has excellent spring properties and corrosion resistance, and phosphor bronze, which has excellent spring properties, have been used as spring materials for springs for air equipment, springs for measuring instruments, switches, connectors, etc. However, brass has inferior strength and splash characteristics, and nickel silver has poor conductivity.

Phosphor bronze is the most widely used reliable material. Even in the field of conductive spring materials, Sn or solder plating is applied for reasons such as reducing contact resistance and improving corrosion resistance, and since soldering is often performed, solder heat-resistant peeling as mentioned above is applied. In recent years, reliability has become extremely important due to the demand for improved reliability.

Current phosphor bronze alloys cannot meet these strict requirements for heat-soldering peeling resistance, and the emergence of a high-strength, high-conductivity copper alloy with improved heat-soldering peeling resistance has been awaited.

[Structure of the invention]

The present invention has been made in view of the above, and aims to provide a method for producing a copper alloy that improves the drawbacks of conventional copper-based alloys and has various properties suitable for use as lead materials and conductive spring materials for semiconductor devices. That is.

The present invention uses 0.4 to 4.0 wt% Ni and Sin.

When aging a copper alloy containing 1 to 1.0 wt% and the remainder Cu and unavoidable impurities at T°C, the aging treatment is performed for a longer time than the time required to obtain hardness H (IIv) defined by the following formula 0. A method for producing a copper alloy with excellent heat peeling resistance of tin or tin alloy plating, the method comprising:

H= H□ -(II 1-H.)Xo, 25 ・
・・・ ・・・ ・・・ ・・・ ［1］Ho;
Hardness of the above copper alloy before aging treatment 1lv) H work;
The highest hardness l1 v) obtained by aging the same copper alloy at 1'°C, and 350-800 depending on need
A method for producing a copper alloy with excellent heat peeling resistance of the tin or tin alloy plating, characterized in that annealing is performed at a temperature of °C.

And Ni0.4-4.0wt%, SiO, 1-1.
0 wt%, and Z0. P, Sn,
As, Cr% Mg% M0.
S'b, r+”e % Go, Al,
Ti, Zr, Be, Ag, Pb, 13°Hf, I0. The total amount of one or more lanthanoid elements is 0.
001-3. When aging a copper alloy consisting of Ow t% and the balance Cu and unavoidable impurities at T°C, the following 0
A method for producing a copper alloy with excellent heat-resistant peelability of tin or tin alloy plating, characterized by performing aging treatment for a longer time than the time required to obtain hardness H (llv) defined by the formula.

H=H, - (H knee ■ (.) Xo, 25...
・・・・・・・・・[2] H,; Hardness of the above copper alloy before aging treatment It v ) [I work; T”
The highest hardness obtained by aging treatment with C (
Hv) and the copper alloy subjected to the above aging treatment is cold rolled at a working degree of 5% or more, and then rolled at 350 to 800°C as necessary.
A method for producing a copper alloy with excellent heat peeling resistance of the tin or tin alloy plating, characterized in that annealing is performed at a temperature of .

And, the O concentration of the copper alloy is O,0020 wt% or less,
The present invention relates to a method for producing a copper alloy with excellent heat peeling resistance of the tin or tin alloy plating, characterized in that the S concentration is 0.0015 wt% or less.

[Detailed description of the invention]

Next, the reason for limiting the alloy components constituting the method for producing the alloy of the present invention will be explained.

The reason for setting the Ni content to 0.4 to 4.0 wt% is that N
i is an element that is co-added with Si in Cu and when subjected to aging treatment forms intermetallic compounds such as Ni and Si to improve strength, but when the Ni content is less than 0.4 wt%, Si Even if Ni is co-added, sufficient strength cannot be obtained, and if the Ni content exceeds 4.0 wt%, sufficient strength can be obtained, but
This is because the conductivity decreases, the workability deteriorates, and the price also increases.

The reason why the Si content is set to 0.1 to 1.0 wt% is to form an intermetallic compound and improve strength, similar to Ni, but if the Si content is less than O, 1 wt%, sufficient strength is not achieved. However, if the Si content exceeds 1.0 wt%, sufficient strength can be obtained, but the conductivity decreases and the soldering properties become poor. Further, the conductivity is improved when the composition ratio of Ni and Si is closer to the composition of the intermetallic compound (Ni3Si).

It is desirable that Ni/5L=4/1.

Furthermore, Z0. P, Sn%As, Cr, Mg
, M0. Sb, Fe, Go, Al, Ti.

Zr, Be, Ag, Pb, , B, Hf, I0. One or more lanthanoid elements in a total amount of 0.0O1
This is to improve the strength of the rings containing ~3.0 wt%, but no improvement in strength is observed when the total amount is less than 0.001 wt%, and the strength improves when the total amount exceeds 3.0 wt%. This is because the conductivity decreases and half-EH properties deteriorate.

Among these subcomponents, Zn is an additive element that improves the thermal peeling resistance of Cu-Ni-8i-based alloys or tin plating, and by adding 1 wt% or more of O, Zn has a great effect. Therefore, 1- transistors and integrated circuits (ICs)
), it is recommended to add 0.1 wt% or more of Zn when used in copper alloys suitable for conductive bulk materials such as lead materials for semiconductor devices, connectors, terminals, relays, switches, etc.

In addition, when the aging treatment is performed at T''C, the reason why the aging treatment is performed for a longer time than the time required to obtain the hardness HOIv) defined by the following formula is as follows: H=H4-(Hnee H,)xo, 25! ■.; Hardness of the above copper alloy before aging treatment HV)Ho
The highest hardness obtained by aging the same copper alloy at T''C. Tin alloy plating (semi-[[1, etc.]) improves heat peeling resistance, but if the hardness of H (llv) is shorter than the specified aging time, the plated tin or tin alloy (solder, etc.) will be damaged by heating. This is because it can be peeled off in a short time.

The copper alloy strip that has been aged in this way is then cold-rolled to a working degree of 5% or more, and then, if necessary,
The reason for annealing at a temperature of 00°C is that by performing cold rolling, the internal strain that occurs during the aging process is forced, tempered to the specified dimensions and strength, and annealed to remove the strain. This is to recover elongation and improve bendability.

Also, the reason for keeping the 0ilji degree below 0.0020wt%
1. If 0 exists, it will combine with Si and become an oxide,
They become so-called inclusions that exist in steel,
This is because if the content exceeds 0.0020 wt%, a large number of inclusions will be generated, and the bending properties, soldering properties, plating properties, and etching properties will be significantly reduced.

The reason why the S concentration is set to 0,0015 wt% or less is that when S is present, Si is very easy to combine with S, easily becoming a sulfide and existing in steel, but the S content is O
This is because if the amount exceeds .0015 wt%, a large amount of sulfide is produced, and bending properties, soldering properties, plating properties, and etching properties are significantly reduced.

The reason why the working degree of cold rolling is set to 5% or more is that if it is less than 5%, internal strain cannot be completely forced. In addition, Kayama where the subsequent annealing temperature is 350 to 800°C is 350°C.
This is because annealing at a lower temperature takes time and is not economical, and at a temperature exceeding 800° C., the material becomes a solution and its strength and conductivity deteriorate.

〔effect〕

As described above, the manufacturing method of the present invention can significantly improve the heat peeling resistance of tin or tin alloy plating by regulating the aging treatment time of the Cu-Ni-8i alloy, thereby increasing the reliability of electrical and electronic components. It has strength, spring characteristics, heat resistance, and conductivity, and is free from impurities. By limiting the amount of S, it is possible to provide a copper alloy which has significantly improved bendability, semi-EFI properties, plating properties, and etching properties, which have been disadvantages of this alloy so far.

In addition, its coefficient of thermal expansion is close to that of plastic, making it suitable for plastic packages as a lead material for semiconductor devices. Therefore, the alloy of the present invention is suitable as a lead material for semiconductor devices and a conductive spring material, and no prior art alloy has such comprehensive properties.

The material of the present invention will be explained below with reference to Examples.

[Example] Ingots having various alloy compositions according to the present invention shown in Table 1 were melted and cast in a high frequency melting furnace in air, inert or reducing atmosphere, using electrolytic copper or oxygen-free copper as a raw material. . Next, this was hot-rolled at 800°C to obtain a
After forming a plate of I11, it was face-milled and cold-rolled to a H1.
It was set as 5■. This was annealed at 800°C for 30 minutes, cooled with water, removed scale by pickling, cold rolled to a thickness of 0.4 mm, aged at 450°C for a predetermined period of time, and further removed by pickling. removed, 0.25nm
After degreasing, it was annealed at 550° C. for a predetermined time in a 10102-2 atmosphere, and evaluated as a lead material. For evaluation, strength and elongation were measured by tensile tests.
The heat resistance was shown by the softening temperature at a heating time of 60 minutes, and the electrical conductivity (heat dissipation) was shown by the electrical conductivity (%IAC5). Soldering was performed by dipping in a solder bath (60% tin, 40% lead) at 230 ± 5°C for 5 seconds using the vertical dipping method.
The state of wetting was evaluated by visual observation.

Plating adhesion was determined by applying Δg plating with a thickness of 3μ to the sample44.
Heat at 50°C for 5 minutes.

The presence or absence of blisters occurring on the surface was evaluated by visual observation. These results are shown in Table 1 along with comparative alloys.

In addition, in order to evaluate it as a spring material, a cold-rolled material of the same alloy with a knob size of 1.5 mm was annealed at 800°C for 30 minutes, water-cooled, pickled, and then cold-rolled to a thickness of 0.4 mm. death,
10%Hz -Ni '1 after degreasing! (2) The strength and elongation of the alloy strips subjected to aging treatment at 450° C. for a predetermined period of time in air were evaluated by a tensile test, and the springiness was evaluated by the Kb value. In addition to this, the results of electrical conductivity are shown in Table 2 along with comparative alloys. Regarding the solder heat resistance and peelability, which is the key point of this patent.

The material was plated with 5μ solder (60mS0.40%Pb) and kept in a constant temperature oven at 150°C in the atmosphere for up to 500hr.

The samples were taken out every 100 hours and subjected to 90" bending and reciprocating once to check for peeling of the solder. These results are shown in Tables 1 and 2.

In addition, examples (1) to (18) of the present invention and comparative examples (19) to
Hardness H before aging of (25) i & high hardness achieved by aging H .

Comparative alloys (21) and (22) are alloys (1) according to the present invention with shorter aging times.゛Figure 1 shows alloys with the following components: -(1), (21), (22)
0"C4,:1" Hardness and electrical conductivity when subjected to aging treatment for a predetermined period of time.

The one on the left side of the arrow in the figure has a short aging time, so
The solder plating (60%S0.40%Pb) peeled off within 500 hours when heated at 50℃, but the one on the right side of the arrow did not peel off even after heating for 5ooVfwJ at 150℃ (60%
S0. 40% pb) The solder did not peel off. In addition, there is a similar tendency in the heat-resistant peeling property of tin plating, and as mentioned above, tin plating can be aged for a longer time than the time required to obtain the predetermined hardness defined by the formula 4 of the present invention. Heat-resistant peelability is improved.

From these Tables 1 and 2 and Figure 1, it can be seen that the alloy produced by the method of the present invention has significantly improved heat peeling resistance of solder or tin plating, and can meet the requirements for increasing the reliability of electrical and electronic components. 1. It has strength, spring characteristics, heat resistance, and conductivity, and by limiting O and S as impurities, it improves bendability, solderability, and plating properties, which were the drawbacks of this alloy until now.

It can be seen that the etching properties are significantly improved.

Below margin

[Brief explanation of the drawing]

Figure 1 shows (1), (21), (22) of the present invention example and comparative example.
) shows the changes in hardness and electrical conductivity when an alloy of the following components was aged at 440° C. for a predetermined period of time.

Claims (5)

[Claims] (1) Ni0.4-4.0wt%, Si0.1-1.0
When aging a copper alloy consisting of wt% and the balance Cu and unavoidable impurities at T°C, the aging treatment is performed for a longer time than the time at which the hardness H (Hv) defined by the following formula [1] is obtained. A method for producing a copper alloy with excellent heat peeling resistance of tin or tin alloy plating, characterized by: H=H_1-(H_1-H_0)×0.25...
・・・・・・・・・・・・ [1] H_0: Hardness (Hv) of the above copper alloy before aging treatment H_1: The highest hardness obtained by aging the same copper alloy at T°C (Hv) (2) The aged copper alloy is cold rolled to a working degree of 5% or more, and then annealed at a temperature of 350 to 800°C as required. A method for producing a copper alloy with excellent heat peeling resistance for tin or tin alloy plating. (3) Ni0.4-4.0wt%, Si0.1-1.0
wt%, Zn, P, Sn, As, as subcomponents.
Cr, Mg, Mn, Sb, Fe, Co, Al, Ti, Z
One or more of r, Be, Ag, Pb, B, Hf, In, and lanthanide elements in a total amount of 0.001 to 3
．． When aging a copper alloy containing 0 wt% and the remainder Cu and unavoidable impurities at T°C, the aging treatment should be performed for a longer time than the time at which hardness H (Hv) defined by the following formula [2] is obtained. A method for producing a copper alloy with excellent heat peeling resistance of tin or tin alloy plating, characterized by: H=H_1-(H_1-H_0)×0.25...
・・・・・・・・・・・・ [2] H_0: Hardness (Hv) of the above copper alloy before aging treatment H_1: The highest hardness obtained by aging the same copper alloy at T°C (Hv) (4) Claim 3, characterized in that the aged copper alloy is cold rolled to a working degree of 5% or more, and then annealed at a temperature of 350 to 800°C as required. A method for producing a copper alloy with excellent heat peeling resistance for tin or tin alloy plating. (5) The tin or tin alloy described in each of claims 1 to 4, wherein the copper alloy has an O concentration of 0.0020 wt% or less and an S concentration of 0.0015 wt% or less. A method for producing a copper alloy with excellent heat-resistant plating peelability.