HK1069792B - Nonleaded solder alloy and electronic parts using it - Google Patents

Description

Lead-free solder alloy and electronic component using the same

Technical Field

The present invention relates to a lead-free solder alloy (lead-free solder alloy) which is a solder alloy containing no lead (Pb), and an electronic component using the same.

Background

Conventionally, as a solder used for electrical connection inside an electronic component or for connecting an electronic component to a circuit board, a tin (Sn) -lead (Pb) solder alloy containing a large amount of lead has been often used.

In recent years, attention has been paid to the problem of the harmfulness of lead, and studies have been made to legally restrict its use. Therefore, a solder alloy containing extremely small amount of lead or a lead-free solder alloy containing no lead component at all has been developed to replace the Sn — Pb solder alloy.

Examples of the lead-free solder alloy include japanese patent No. 3036636 and U.S. patent No. 4758407.

Patent No. 3036636 relates to a lead-free solder alloy for connecting electronic components to a circuit board of an electronic machine, which is an alloy in which a part of the copper component of a tin (Sn) -copper (Cu) alloy is replaced with nickel (Ni) in order to obtain a solder alloy having a composition ratio determined as Cu: 0.05 to 2.0 wt%, Ni: 0.001 to 2.0 wt%, Sn: and the rest part, to improve the mechanical strength of the joint part.

As described above, the solder alloy is used for reflow (リフロ -; reflow) for bonding an electronic component to a conductor portion of a circuit board, and its use temperature (temperature during soldering) is about 230 ℃.

Further, in U.S. Pat. No. 4758407, in order to prevent lead and cadmium from dissolving into drinking water from a lead pipe used in a water supply pipe, copper pipes and brass pipes have been proposed as water supply pipes, and the patent relates to a solder alloy for welding these copper pipes and brass pipes and a joint for connecting them.

The main component of the solder alloy is tin (Sn) or tin (Sn) and antimony (Sb), and neither solder alloy contains lead (Pb) and cadmium (Cd).

Here, the composition of the solder alloy of the tin body is Sn: 92.5 to 96.9 wt%, Cu: 3.0 to 5.0 wt%, Ni: 0.1-2.0 wt%, Ag: 0.0 to 5.0 wt%.

The composition of the solder alloy of tin-antimony main body is Sn: 87.0 to 92.9 wt%, Sb: 4.0 to 6.0 wt%, Cu: 3.0 to 5.0 wt%, Ni: 0.0-2.0 wt%, Ag: 0.0 to 5.0 wt%.

The melting temperature of the solder alloy is about 240 ℃ to 330 ℃, and the solder alloy is used for welding, for example, a copper pipe, a brass pipe, and a joint thereof used as a water supply pipe of a household water heater, and therefore, in consideration of workability at the time of welding, the melting temperature of the solder alloy is preferably low.

Among electronic components, there are high-frequency coils and transformers (hereinafter, referred to as "coil components") formed by winding a linear or thin strip-shaped conductor (hereinafter, referred to as "winding material"). As a winding material of these coil components, an insulated coated wire is used in which an enamel, urethane, or the like is applied to a copper core wire to form an insulating coating.

The coil component is soldered to electrically connect a leading end portion of a winding material wound around a bobbin or the like to an electrode portion provided at a terminal or the like of the bobbin. In order to electrically connect the terminal and the like to the leading end portion of the winding material by soldering, it is necessary to remove the insulating coating material of the leading end portion. Generally, as a method for removing the insulating coating material of the insulating coated wire, there are a mechanical removal method, a method using a chemical solution, and a method of decomposition or melting by heating at a high temperature.

A method of heating at a high temperature has been widely used.

The coil component is produced by winding the leading end portion of the winding material around the terminal, immersing the wound portion in a solder bath heated to a high temperature, and soldering while melting and removing the insulating film material by the heat of the solder liquid.

When a lead-free solder alloy containing no copper component is used for soldering the wound portion of the lead terminal and the terminal, copper which is a base material of the insulated coated wire (winding material) is dissolved in the solder material liquid during the period when the wound portion is in contact with the molten solder (solder liquid), and a phenomenon called "copper corrosion (copper erosion)" occurs, which causes thinning. This "copper etching" phenomenon is a large factor causing a disconnection accident in an electronic component such as the coil component.

This phenomenon is caused by the fact that the higher the melting temperature of the solder liquid is, the more copper is dissolved in the solder liquid and the faster the copper is dissolved. Therefore, the wire breakage easily occurs as the wire diameter of the winding material becomes smaller.

On the other hand, in order to prevent the "copper corrosion" phenomenon, a means of adding a small amount of copper to the above-mentioned lead-free solder alloy is generally known, but when the copper content is too large, the viscosity of the molten solder (solder liquid) becomes high, and when soldering is performed, solder of a required amount or more adheres to a portion where soldering is performed, for example, between adjacent terminals, and a bridging phenomenon occurs in which electrical short circuits occur between terminals, or inconveniences occur such as unevenness in plating thickness (amount of adhesion of solder) and poor wettability.

The smaller the electronic component size and the narrower the interval (pitch) between adjacent terminals, the more likely the bridging phenomenon occurs.

However, in order to reduce the "copper corrosion" of the lead-free solder alloy, if the melting temperature of the molten solder is lowered, the insulating film material such as enamel or urethane at the leading end of the winding material cannot be completely melted, and the residue of the coating material adheres to the wound portion, so that the soldering becomes incomplete and the conduction failure becomes a factor. The residue also causes the bridging.

The inventor finds that: in a lead-free solder alloy in which an appropriate amount of copper (Cu) and nickel (Ni) is added to tin (Sn) in advance, "copper corrosion" can be prevented by adding nickel (Ni), and the lead-free solder alloy has increased mechanical strength after soldering.

However, even in the case of this lead-free solder alloy, it is preferable to increase the copper content in order to sufficiently prevent the "copper corrosion" phenomenon, but as the copper content increases, the viscosity of the solder alloy at the time of melting increases, and the wettability of the solder liquid deteriorates. Therefore, when electronic components such as small coil components having a narrow gap (pitch) between adjacent terminals as described above are soldered, a bridging phenomenon is likely to occur.

Therefore, the object of the present invention is: provided is a lead-free solder alloy which can reduce the viscosity of molten solder (solder liquid) while sufficiently maintaining the property of suppressing "copper corrosion" of a tin-copper-nickel lead-free solder alloy.

Disclosure of Invention

The present invention relates to a copper (Cu) -containing: 3.0 to 5.5 wt%, nickel (Ni): 0.1 to 0.5 wt%, and germanium (Ge): 0.001 to 0.1 wt% and the balance tin (Sn).

Further, the present invention relates to an electronic component, characterized in that: in an electronic component using a conductor in which a core portion is made of copper or an alloy containing copper and an insulating coating is applied to the core portion, the conductor or the conductor and other portions of the electronic component are made of a material containing copper (Cu): 3.0 to 5.5 wt%, nickel (Ni): 0.1 to 0.5 wt%, and germanium (Ge): 0.001 to 0.1 wt% and the balance tin (Sn) is soldered.

That is, the present invention relates to a lead-free solder alloy in which copper and nickel are added to tin, wherein the amount of nickel added is set to a certain range, the amount of copper added is set to a certain range, and germanium is added to a certain range, thereby preventing a disconnection accident caused by a "copper corrosion" phenomenon when a coil component is soldered using the lead-free solder alloy, and reducing the occurrence of a bridge phenomenon between terminals of the coil component.

The lead-free solder alloy of the present invention is suitable for soldering between the insulating film leads or between the insulating film leads and other parts in a so-called fine pitch electronic component in which the space between adjacent terminals is small, particularly in an electronic component using an insulating film lead in which a core is made of copper or an alloy containing copper and an insulating film is applied to the surface thereof.

Brief description of the drawings

Fig. 1, 2, and 3 are explanatory views showing an example of the coil component.

Fig. 1 is a rear surface of a coil component, fig. 2 is a partial enlarged view showing an electric wire connection portion of a terminal, and fig. 3 is a partial enlarged view showing a state where solder bridges are formed.

Best mode for carrying out the invention

Fig. 1, 2 and 3 show an example of a coil component using an insulated wire in which an enamel (enamel) or urethane (urethane) is applied to a copper core wire as a winding material to form an insulating film.

In fig. 1, 2, and 3, reference numeral 1 denotes a bobbin (bobbin) of a high-frequency transformer, and terminal blocks 2 are provided at opposite ends thereof. Reference numeral 3 denotes terminals arranged in parallel at a predetermined interval on the terminal block 2, 4 denotes an insulating coated wire (winding material) wound around the bobbin 1, and 5 denotes a lead-out end of the insulating coated wire 4, and the lead-out ends are wound around the root of each terminal 3 arranged on the terminal block 2. The lead terminal 5 and the terminal 3 are electrically connected by a solder 6.

In fig. 3, Brd indicates a bridge state in which an excessive solder adheres between adjacent terminals 3. In addition, the HCP wire in which copper is plated on the surface of the steel core wire or the CP wire in which copper is plated on the surface of the iron core wire is often used as the terminal 3.

Here, in order to electrically connect the terminal 3 and the lead-out end 5 of the winding material, it is necessary to remove the insulating film material at the lead-out end. As described above, the method of removing the insulating coating material includes a mechanical removal method, a method of dissolving the insulating coating material with a chemical, and a method of decomposing or melting the insulating coating material by heating at a high temperature. In the present invention, a method of melting and removing by heating at a high temperature is employed.

That is, the lead-out end 5 of the winding material 4 is wound around the terminal 3, and then the wound portion is immersed in a solder bath, whereby the insulation film of the winding material is melted and removed and soldering is performed.

Examples

Table 1 shows the relationship between the ratio of bridging between terminals and the composition content of the solder alloy when samples comprising enamel-coated copper wire having a diameter of 0.35mm as the winding material 4, and CP wire in the form of a ribbon plated with copper on the core of iron as the material of the terminal 3, and the bobbin of a high-frequency transformer having a terminal 3 width of 0.5mm and a gap (pitch) between adjacent terminals of 1.0mm were immersed in a solder liquid melted at a high temperature (430 ℃ C.).

Further, in Table 1, "there is a possibility of correction by solder again", which indicates whether or not the sample in which the bridge was generated when the sample was first immersed in the molten solder liquid is immersed in the molten solder liquid again, can eliminate the bridge.

When germanium (Ge) is added to a tin (Sn) -copper (Cu) -nickel (Ni) based lead-free solder alloy, the melting temperature of the solder alloy becomes about 350 ℃.

However, in an insulated coated wire used for a winding material of a coil component, for example, in order to remove an enamel coating of an enamel coated copper wire, it is necessary to set the melting solder temperature (soldering temperature) of a lead-free solder alloy to 350 ℃ or higher, and therefore, when an electronic component using an insulated coated copper wire is soldered, it is preferable to set the melting solder temperature (soldering temperature) of the lead-free solder alloy to about 400 ℃ in order to reliably melt the insulating coating material of the insulated coated copper wire. In the present example, the molten solder temperature (soldering temperature) of the above-described lead-free solder alloy was set to 430 ℃.

TABLE 1

(molten solder temperature: 430 ℃ C.)

Composition of soft soldering alloy	Proportion of occurrence of bridging (number of samples: 5)	Possibility of correction by solder again (O.X:)
			Sn-2Cu-0.2Ni	All without bridge connection	○
Sn-3Cu-0.2Ni	1	○
			Sn-5Cu-0.2Ni	All having a bridge connection	×
Sn-6Cu-0.2Ni	All having a bridge connection	×
			Sn-2Cu-0.05Ge	3	○
Sn-3Cu-0.05Ge	4	○
			Sn-6Cu-0.05Ge	All having a bridge connection	×
Sn-2Cu-0.2Ni-0.001Ge	All without bridge connection	○
			Sn-2Cu-0.2Ni-0.05Ge	All without bridge connection	○
Sn-3Cu-0.2Ni-0.001Ge	2	○
			Sn-3Cu-0.2Ni-0.002Ge	1	○
Sn-3Cu-0.2Ni-0.005Ge	1	○
			Sn-3Cu-0.2Ni-0.01Ge	All without bridge connection	○
Sn-3Cu-0.2Ni-0.02Ge	All without bridge connection	○
			Sn-3Cu-0.1Ni-0.02Ge	All without bridge connection	○
Sn-3Cu-0.2Ni-0.05Ge	All without bridge connection	○
			Sn-3Cu-0.2Ni-0.1Ge	All without bridge connection	○
Sn-3Cu-0.5Ni-0.02Ge	All-purposeWithout bridge connection	○
			Sn-5Cu-0.2Ni-0.001Ge	All without bridge connection	○
Sn-5Cu-0.2Ni-0.002Ge	1	○
			Sn-5Cu-0.2Ni-0.01Ge	1	○
Sn-5Cu-0.2Ni-0.02Ge	1	○
			Sn-5.5Cu-0.2Ni-0.02Ge	All without bridge connection	○
Sn-5Cu-0.2Ni-0.03Ge	All without bridge connection	○
			Sn-5Cu-0.2Ni-0.05Ge	All without bridge connection	○
Sn-5Cu-0.2Ni-0.1Ge	All without bridge connection	○
			Sn-6Cu-0.2Ni-0.05Ge	All having a bridge connection	×
Sn-6Cu-0.2Ni-0.1Ge	All having a bridge connection	×

Table 2 shows the results of measurements of the relationship between the number of times of immersion until iron as the base (core) of the CP wire is exposed and discolored and the composition and component content of the solder alloy when the CP wire used for the terminal 3 is immersed in a high-temperature (430 ℃) molten solder liquid.

That is, table 2 shows the relationship between the component content of the solder alloy composition and the magnitude of "copper corrosion", and shows that the more the above-mentioned dipping times, the less "copper corrosion". In Table 2, the number of dipping times is preferably 10 or more.

TABLE 2

(molten solder temperature: 430 ℃ C.)

Composition of soft soldering alloy	The number of times until the surface of the terminal discolors when soldering is repeated
		Sn-2Cu-0.2Ni	1
Sn-3Cu-0.2Ni	10
		Sn-5Cu-0.2Ni	More than 20
Sn-6Cu-0.2Ni	More than 20
		Sn-2Cu-0.05Ge	1
Sn-3Cu-0.05Ge	4
		Sn-6Cu-0.05Ge	7
Sn-2Cu-0.2Ni-0.001Ge	2
		Sn-2Cu-0.2Ni-0.05Ge	2
Sn-3Cu-0.2Ni-0.001Ge	10
		Sn-3Cu-0.2N-0.002Ge	10
Sn-3Cu-0.2Ni-0.005Ge	10
		Sn-3Cu-0.2Ni-0.01Ge	11
Sn-3Cu-0.2Ni-0.02Ge	10
		Sn-3Cu-0.1Ni-0.02Ge	10
Sn-3Cu-0.2Ni-0.05Ge	10
		Sn-3Cu-0.2Ni-0.1Ge	10
Sn-3Cu-0.5Ni-0.02Ge	20
		Sn-5Cu-0.2Ni-0.001Ge	More than 20
Sn-5Cu-0.2Ni-0.002Ge	More than 20
		Sn-5Cu-0.2Ni-0.01Ge	More than 20
Sn-5Cu-0.2Ni-0.02Ge	More than 20
		Sn-5.5Cu-0.2Ni-0.02Ge	More than 20
Sn-5Cu-0.2Ni-0.03Ge	More than 20
		Sn-5Cu-0.2Ni-0.05Ge	More than 20
Sn-5Cu-0.2Ni-0.1Ge	More than 20
		Sn-6Cu-0.2Ni-0.05Ge	More than 20
Sn-6Cu-0.2Ni-0.1Ge	More than 20

As is clear from table 1 above, in the case of a lead-free solder alloy of tin (Sn) -copper (Cu) -nickel (Ni) type, when the content of nickel is made constant and the content of copper is changed, the viscosity of the solder liquid increases when the content of copper is increased, the generation ratio of the bridges between the adjacent terminals increases, and the bridges generated at the initial stage cannot be eliminated even by re-soldering.

When germanium (Ge) is added to a tin (Sn) -copper (Cu) -nickel (Ni) lead-free solder alloy having a constant nickel (Ni) content and the copper content and the germanium content are changed, bridging hardly occurs when the germanium content is not less than a constant value (0.001 wt%) and the copper content is not more than 5.5 wt%.

As described above, by containing germanium (Ge) in an amount of at least 0.001 wt% in a tin (Sn) -copper (Cu) -nickel (Ni) based lead-free solder alloy containing nickel (Ni) in a specific range, the viscosity of the molten solder liquid can be adjusted, the molten solder liquid becomes extremely fluid, the liquid breaking property of the solder liquid becomes good, and the occurrence ratio of bridging between terminals can be reduced.

In this case, when the copper content is in a predetermined range and the germanium (Ge) content is at least 0.001 wt%, the occurrence rate of bridging can be extremely reduced, and the first bridging can be eliminated by re-soldering. However, in the region where the copper content exceeds the predetermined upper limit, even if the content of germanium (Ge) is increased, the generation ratio of the bridges cannot be reduced, and the bridges that were generated at first cannot be eliminated even if the re-soldering is performed.

When the copper content was constant, the occurrence ratio of the bridge formation did not change even when the content of germanium (Ge) was more than 0.1 wt%.

Depending on the content of germanium (Ge), the amount of suspended matter (copper/nickel precipitates) present in the molten solder bath changes, and when germanium (Ge) is not present, the amount of suspended matter in the molten solder bath increases. The suspended matter adheres to the surface of the soldered portion, the surface of the soldered portion becomes rough, and the solder thickness is hardly uniform. Also, the bridging phenomenon is likely to occur.

Further, as is clear from table 2, the ratio of "copper etching" can be adjusted according to the nickel content of the lead-free solder alloy. That is, in the case of a tin (Sn) -copper (Cu) based lead-free solder alloy, "copper corrosion" tends to be large in size depending on the copper content in a region where the copper content is small and small in size in a region where the copper content is large, but can be reduced in size when the nickel content is large in a region where the copper content is small. In addition, in the region with a high copper content, the "copper corrosion" can be suppressed by using a small nickel content. The content of germanium (Ge) has no correlation with the size of the above-mentioned "copper etch".

Industrial applicability of the invention

As described above, the lead-free solder alloy of the present invention is less likely to cause "copper corrosion" even in a high temperature region during soldering, and therefore can prevent a wire breakage accident during soldering of an electronic component using an insulating film conductor having copper or an alloy containing copper as a core wire, and is low in viscosity and excellent in solder liquid-breaking property, and can prevent the occurrence of a bridging phenomenon in which a short circuit occurs between terminals due to solder in the case of an electronic component in which the gap between the terminals is narrow.

Claims (2)

1. A lead-free solder alloy, which is an Sn-based lead-free solder alloy containing Sn-Cu-Ni components and obtained by bonding conductors to each other or the conductors and other parts of an electronic component by a dipping method, in the electronic component using the conductors composed of copper or a copper alloy having an insulating film formed on the surface thereof, characterized in that the solder alloy contains Sn-Cu-Ni-Ge as a component, and the solder alloy contains Cu: 3.0-5.5 wt% and Ni: 0.1 to 0.5 wt% of an Sn-based lead-free solder alloy containing Ge: 0.001 to 0.1 wt%.

2. An electronic component characterized by: in an electronic component using a conductor in which a core portion is made of copper or an alloy containing copper and an insulating coating is applied to the core portion, the conductor and the conductor or other portions of the conductor and the electronic component are made of a material containing Cu: 3.0 to 5.5 wt%, Ni: 0.1 to 0.5 wt%, and Ge: 0.001 to 0.1 wt% of Sn-Cu-Ni-Ge lead-free solder alloy.