SnZn Solder and Method for Producing the Same

Abstract

PURPOSE: To provide an inexpensive SnZn solder and a production method of an SnZn solder, the solder having resistance to a high temperature / low temperature repetition test and being extremely adamant to an electrode of a solar cell substrate, the solder capable of maintaining an almost equal fusion temperature or lower temperature even being mixed.CONSTITUTION: There is provided an SnZn solder obtained by, mixing to a base material being an alloy of Sn and Zn, a main material including two or more kinds of P, In and Bi so that P, In and Bi are included by 1.0 wt% or less in total, then the mixture is fused and made into an alloy.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to SnZn solder used for solar cell substrates, liquid crystal substrates, etc., and a method for manufacturing the same.

Background Art

[0002] Conventionally, for soldering lead wires to electrodes such as solar cell substrates and liquid crystal substrates, tin-lead solder has been widely used because of its high strength and low price.

[0003] In the case of electrodes such as aluminum, since sufficient soldering strength cannot be obtained, a silver paste is applied and sintered, and a lead wire is soldered thereon with tin-lead solder.

[0004] Recently, there has been an increasing demand for lead-free solder from the perspective of environmental pollution and the like.

Disclosure of the Invention

Problems to be Solved by the Invention

[0005] Conventional lead-free solders have problems in that, compared with tin-lead solder, their strength is slightly insufficient for the required strength, and their price is high and they have not been replaced.

Means for Solving the Problems

[0006] The inventors of the present invention have found that for SnZn solder made of an alloy of Sn and Zn, which is a kind of lead-free solder, by mixing a total of 1 to 1.5 wt% or less of trace amounts of main materials such as P, In, Bi, and Sb and melting and alloying them, and if necessary, mixing trace amounts of auxiliary materials such as Al, Si, Ag, Cu, and Ni and melting and alloying them, the resulting SnZn solder is extremely strong for electrodes of solar cell substrates, etc., and is resistant to high-temperature and low-temperature repeated tests, and even when mixed, the melting temperature of the SnZn solder is almost the same or decreases.

[0007] Therefore, in the SnZn solder composed of an alloy of Sn and Zn, the present inventors mix a main material containing one or more of P, In, Bi, and Sb into the base material, which is an alloy of Sn and Zn, in a total amount of 1 to 1.5 wt% or less, and then melt and alloy them.

[0008] At this time, the melting temperature of the SnZn solder after melting and alloying is made the same as or lower than the melting temperature of the base material.

[0009] Also, the main material is alloyed within the framework of the alloy of Sn and Zn.

[0010] In addition, a secondary material containing one or more of Al, Si, Cu, Ag, and Ni or glass containing one or more of them is mixed into the base material in an amount of 5 wt% or less as needed, and then melted and alloyed.

[0011] Also, as the main material and the secondary material, an alloy of the main material and the secondary material is mixed into the base material and melted and alloyed.

[0012] Also, the alloy of the main material and the secondary material is made to be an alloy of Cu and P.

[0013] Also, the base material, the main material, and the secondary material are mixed together or separately in multiple portions and then melted and alloyed.

[0014] Also, it is used for soldering lead wires to the electrodes of a solar cell substrate and a liquid crystal substrate.

[0015] Also, ammonium chloride hydrate powder or powder containing ammonium chloride hydrate is mixed into the prepared SnZn solder in an amount of 3 wt% or less and 0.05 wt% or more, and it decomposes during soldering heating to improve the soldering adhesion to the object to be soldered.

Advantages of the Invention

[0016] As described above, in the present invention, a main material containing one or more of P, In, Bi, Sb, etc. is mixed in a trace amount of 1 to 1.5 wt% or less in a base material which is an alloy of Sn and Zn, and a sub-material containing a glass containing one or more of Al, Si, Cu, Ag, Ni, etc. or one or more is mixed in a trace amount and melted and alloyed, whereby a solder that is extremely strong for electrodes such as solar cell substrates and resistant to high-temperature and low-temperature repeated tests is obtained, and even if it is mixed, the melting temperature of the SnZn solder is almost the same or decreased, and it can be manufactured at a lower cost.

[0017] In addition, the melting temperature of the SnZn solder after melting and alloying is the same as or lower than the melting temperature of the base material, and an increase in the melting temperature due to mixing can be eliminated.

[0018] In addition, the main material can be alloyed within the skeleton of the Sn-Zn alloy, and the adverse effects of precipitation can be eliminated.

[0019] In addition, by mixing and melting and alloying a glass containing one or more of Al, Si, Cu, Ag, Ni, etc. or one or more to produce a SnZn solder, electrical characteristics such as contact potential with respect to the soldering target can be improved.

[0020] In addition, by mixing and melting and alloying an alloy of the main material and the sub-material to produce a SnZn solder, the main material can be stabilized, and a solder resistant to high-temperature and low-temperature repeated tests can be obtained.

[0021] In addition, ammonium chloride hydrate powder or powder containing ammonium chloride hydrate is mixed in the prepared SnZn solder in an amount of 3 wt% or less and 0.05 wt% or more, and decomposed during soldering heating to improve the soldering adhesion to the object to be soldered.

Example 1

[0022] FIG. 1 shows an explanatory diagram of solder manufacturing according to the present invention.

[0023] (a) of FIG. 1 shows a flowchart, and (b) of FIG. 1 shows a material example.

[0024] In Fig. 1(a), S1 prepares the base material, main materials, and auxiliary materials. This prepares the following materials shown in the material example of Fig. 1(b).

[0025] · Base material: Sn91 Zn9 · Main materials: P, In, Bi, Sb · Auxiliary materials: Al, Si, Cu, Ag, Ni Here, the base material is the material (base material) that forms the basis of the SnZn solder of the present invention. Here, Sn is 91 wt% and Zn is 9 wt% were used in the trial production. The weight ratio of Sn and Zn can be arbitrary within the range where the alloy can be made. For example, if Zn is 1 to 15 wt% and the rest is Sn (the ratio can be appropriately selected by experiments based on the melting temperature, etc.).

[0026] Also, the main materials are materials that affect soldering, such as removing the oxide film on the surface of the object to be soldered, adhesion, wettability, fluidity, and viscosity during soldering. In the present invention, the total amount of the main materials is 1 to 1.5 wt% or less. Here, it is the material to be melted and alloyed by mixing one or more of P (removing the oxide film on the object to be soldered, adhesion), In (wettability, fluidity), Bi (adhesion), and Sb (adhesion). Also, the main materials, combined with a trace amount of 1 to 1.5 wt% or less in total, make the melting temperature of the SnZn solder after melting and alloying the main materials with the base material equal to or slightly lower (for example, about 1 to 5 °C lower) than the melting temperature of the base material. This is presumably because the total amount of the main materials is a trace amount of 1 to 1.5 wt% or less with respect to the base material, and it enters the framework of the base material and is reconfigured.

[0027] In addition, the secondary material is a material further added to the base material and the main material, and is a material for improving the electrical characteristics (contact potential difference, contact resistance, I-V characteristics in the case of solar cells, etc.), adhesion, etc. of the object to be soldered (semiconductor substrates such as solar cell substrates and liquid crystal substrates, fired aluminum films, copper electrodes, etc.). Here, materials such as Al (for fired aluminum films), Si (for silicon substrates), Cu (for copper electrodes), Ag (for all), and Ni (for silicon substrates when microscopically nickel-plated) are used. As the secondary material, not only metals but also glasses containing metals may be added by mixing, melting, and alloying (gas components such as oxygen in the glass are released to the outside during melting and alloying, etc.).

[0028] S2 mixes the main material and the secondary material with respect to the base material. This mixes the main material and the secondary material with the base material prepared in S1.

[0029] In S3, the base material, the main material, and the secondary material are melted and alloyed. This involves heating and melting the base material, the main material, and the secondary material mixed in S2, and thoroughly stirring to alloy them. At this time, when it is difficult to alloy because the main material and the secondary material are oxidized by oxygen in the air, an inert gas (for example, nitrogen gas) is blown into the crucible as necessary, or a melting furnace or a vacuum melting furnace filled with an inert gas is used instead.

[0030] In S4, the solder material (ABS-S) is completed.

[0031] By the above, it becomes possible to manufacture the SnZn solder (ABS-S) according to the present invention by preparing the base material, the main material, and the secondary material, mixing them, and melting and alloying them. This will be described in detail sequentially below.

[0032] Figure 2 shows an explanatory diagram of the material manufacturing apparatus of the present invention.

[0033] In Figure 2, the solder material 1 is the base material, the main material, and the secondary material prepared in S1 of Figure 1 described above, and here, it is fragments (coarsely pulverized) such as metals and glasses.

[0034] The solder material input dish 2 is for placing the solder material 1 and feeding it into the melting furnace 3.

[0035] The melting furnace 3 is for heating with a heater 4 etc., feeding the solder material 1 inside, melting the base material, main material, and sub-material, and stirring to alloy them. The melting furnace 3 usually melts the base material, main material, and sub-material fed inside in the atmosphere, stirs them, and alloys them. At this time, if necessary, an inert gas (such as nitrogen gas) is blown in to reduce oxidation by oxygen in the air, and further, if necessary, it is sealed and filled with an inert gas (or evacuated).

[0036] In the above manner, the base material, main material, and sub-material prepared at S1 in FIG. 1 are mixed, melted in the melting furnace 3, stirred, and alloyed, making it possible to manufacture the SnZn solder of the present invention.

[0037] FIG. 3 shows an explanatory diagram of soldering of the lead connection of the present invention.

[0038] (a) of FIG. 3 shows a flowchart, and (b) of FIG. 3 shows an example of a substrate / lead connection.

[0039] In (a) of FIG. 3, S11 is to perform pre-soldering of the solder (ABS-S) on the substrate pattern with ultrasonic waves. This is, for example, to supply the SnZn solder of the present invention (the SnZn solder manufactured at S4 in FIG. 1) to the tip of the soldering iron of an ultrasonic soldering iron on the part (pattern) to be soldered later on the electrode of a solar cell substrate, melt it, and apply ultrasonic waves to perform pre-soldering (referred to as ultrasonic pre-soldering) on the said pattern part on the substrate in advance.

[0040] S12 is to perform ultrasonic soldering or ultrasonic non-soldering on the lead connection etc. This is to melt the SnZn solder of the present invention along the lead connection and solder the lead connection while applying ultrasonic waves from above or without applying ultrasonic waves on the part (pattern) where ultrasonic pre-soldering was performed on the electrode of a solar cell substrate in S11. Incidentally, when the SnZn solder has been pre-soldered to the lead connection in advance, the supply of solder is not necessary.

[0041] As described above, it is difficult to perform normal soldering on the part to be soldered (for example, the electrode part of a solar cell substrate). Therefore, ultrasonic pre-soldering of the SnZn solder of the present invention is performed on the part to be soldered (pattern) using ultrasonic waves (S11), and lead wires are ultrasonically soldered or ultrasonically solderless soldered using the SnZn solder of the present invention on the part (pattern) where the pre-soldering has been performed (S12). As a result, it is possible to perform ultrasonic-assisted pre-soldering on the electrode parts of a solar cell substrate that could not be soldered conventionally, and then perform ultrasonic soldering or ultrasonic solderless soldering of lead wires thereon.

[0042] Note that ultrasonic soldering is performed at 10 W or less, usually at 2 to 3 W. If the power is too high, it may damage the film (for example, a nitride film) formed on the solar cell substrate or the crystal on the surface of the substrate, so it should not be increased.

[0043] Fig. 3(b) shows an example of a substrate / lead wire connection.

[0044] In Fig. 3(b), the substrate is an Al, Si substrate, a glass substrate, etc., which are examples of substrates that are extremely difficult to solder by normal soldering. For the parts (patterns) that serve as electrodes on these substrates, ultrasonic pre-soldering of the SnZn solder of the present invention is performed. Then, by performing ultrasonic soldering or ultrasonic solderless soldering of lead wires on the pre-soldered part (pattern), it becomes possible to solder the lead wires to the substrate.

[0045] Also, the lead wire is a lead wire that is soldered to the electrode part (pattern) on the substrate using the SnZn solder of the present invention, and is a wire (a wire obtained by electroplating the SnZn solder of the present invention on a circular copper wire, and it is easier to solder if it is slightly flattened into an ellipse), a ribbon (a ribbon obtained by cutting a thin copper plate into a width of about 1 mm and pre-plating the SnZn solder of the present invention thereon), etc.

[0046] Fig. 4 shows an explanatory diagram of soldering according to the present invention.

[0047] (a) of Fig. 4 shows an example of preliminary soldering, and (b) of Fig. 4 shows an example of soldering a ribbon or a wire.

[0048] In Fig. 4(a), the silicon substrate 11 is, here, an example of a solar cell substrate, and an aluminum sintered film 12 is formed on, for example, the entire back surface of the silicon substrate 11.

[0049] The aluminum sintered film 12 is an electrode (aluminum sintered film) formed by applying an aluminum paste (or screen printing in a predetermined pattern) on the entire back surface of the illustrated silicon substrate 11 which is a solar cell substrate and sintering it.

[0050] The tip 13 of the ultrasonic soldering iron is a soldering iron tip that is heated while applying ultrasonic waves from an ultrasonic generator (not shown).

[0051] The solder (ABS-S) 14 is the SnZn solder of the present invention (the SnZn solder manufactured at S4 in Fig. 1).

[0052] Next, the soldering operation will be described.

[0053] (1) The silicon substrate 11 is transported onto the preliminary heating stage, vacuum-sucked and fixed, and preliminarily heated (for example, preliminarily heated to about 180°C).

[0054] (2) Starting from the starting point to the ending point of the electrode pattern (strip-shaped pattern) formed on the aluminum sintered film 12, the solder 14 is automatically supplied to the illustrated ultrasonic soldering iron tip 13, ultrasonic waves are applied while melting, and it is moved at a constant speed in a state close enough not to rub on the aluminum sintered film 12, thereby forming a strip-shaped preliminary solder pattern on the aluminum sintered film 12.

[0055] As described above, it becomes possible to solder the SnZn solder 14 of the present invention onto the aluminum sintered film 12 to form a preliminary solder pattern with a predetermined pattern.

[0056] Fig. 4(b) shows an example of soldering a ribbon or a wire.

[0057] In FIG. 4(b), the tip 13-1 of the ultrasonic soldering iron is the tip of the soldering iron that is being heated while applying ultrasonic waves from an ultrasonic generator (not shown) or without applying ultrasonic waves.

[0058] The ribbon or wire 15 with solder is one in which the SnZn solder of the present invention is pre-soldered to the ribbon or wire. Incidentally, it is better for the wire 15 to be slightly deformed into an elliptical shape for better solderability.

[0059] Next, the soldering operation on the pre-solder pattern portion of the ribbon or wire will be described.

[0060] (1) Similar to FIG. 4(a), the silicon substrate 11 is pre-heated.

[0061] (2) With respect to the ribbon or wire 15 with solder arranged along the pre-solder pattern portion formed on the portion of the aluminum sintered film 12 on the upper (back) surface of the silicon substrate 11, while gently pressing from above with the ultrasonic or non-ultrasonic soldering iron tip 13-1, it is moved at a constant speed in the right direction shown in the figure to melt the solder of the ribbon or wire 15 with solder and solder it to the pre-solder pattern portion.

[0062] As described above, it becomes possible to solder the ribbon or wire 15 pre-soldered with the SnZn solder 14 of the present invention to the portion of the pre-solder pattern on the aluminum sintered film 12.

[0063] Incidentally, whether the soldering with ultrasonic waves or without ultrasonic waves of the present invention is good or not is determined as good when, after performing soldering with ultrasonic waves or without ultrasonic waves on the ribbon or wire to the soldering target portion, the ribbon or wire is pulled with a force slightly weaker than the force that would cause the substrate or the like to crack and it does not peel off from the substrate or the like, and as bad when it peels off.

[0064] FIG. 5 shows an example of the composition of the solder (ABS-S) of the present invention.

[0065] In FIG. 5, the base material, main material, and auxiliary material are the distinctions of the base material, main material, and auxiliary material described in FIG. 1.

[0066] The composition example is an example of the composition of the base material, main material, and auxiliary material.

[0067] The wt% example is an example of the wt% of the composition of the base material, main material, and auxiliary material.

[0068] The wt% range is an example of the wt% range of the composition of the base material, main material, and auxiliary material.

[0069] As shown below in FIG. 5, the composition, wt% example, and wt% range are obtained.

[0070] Base material Main material Auxiliary material Composition example SnZn alloy P In Bi Al Si Cu Ag wt% example Sn Zn CuP8 In Bi Al Si Cu Ag 91 9 0.3 0.3 0.3 0.3 0.3 0.3 0.3 wt% range 99 - 85 1 - 15 Trace - 0.1(P) 0.1 - 1.0 Trace - 0.5 Each 5Wwt or less Here, as a composition example, in the trial production, Sn91wt% and Zn9wt% shown in the figure were used as the base material. Also, the composition range may be stable within the range where the SnZn alloy can be produced. For example, it may be Zn1 to 15wt% with the remainder being Sn, and it may be determined by actual measurement of the melting temperature of the produced SnZn base material and experiments.

[0071] As main materials, there are P, In, Bi, Sb, etc. In the trial production, P (red phosphorus) and CuP8 alloy (an alloy with 8 wt% P and the remainder being Cu, and the wt% of P is 8% of CuP8, i.e., copper phosphide) were used. When adding about 0.1 wt% of P (red phosphorus) (P-saturated state), and when adding P in CuP8 as the main material, it was necessary to add a larger amount, about 0.16 wt% (P-saturated state). In the case of P, it saturates at about 0.1 wt% (or about P = 0.16 wt% in the case of CuP8). If more is added, it becomes supersaturated, and the viscosity of the SnZn solder increases significantly. Therefore, for normal use to ensure fluidity, wettability, etc., it is desirable to add below the saturation of P. In the case of P, a very small amount (about 0.001 wt% or so) may be sufficient. Also, even in the case of P saturation or supersaturation, it can be used appropriately depending on the application. Similarly, since other main materials also have this tendency, the optimal addition amount can be determined through experiments as needed.

[0072] Also, the total amount of the main materials was preferably 1 to 1.5 wt% or less. The SnZn solder of the present invention obtained by mixing, melting, and alloying this total amount of 1 to 1.5 wt% or less of the main materials with the base material (Sn 91 wt%, Zn 9 wt%) was measured to have a melting temperature equal to or 1 to 5 °C lower than the melting temperature of the base material (for example, around 195 °C). It is presumed that this is because the total amount of 1 to 1.5 wt% or less of the main materials is incorporated into the interior of the skeleton of the base material (SnZn alloy) and the skeleton is reconfigured, resulting in the melting temperature being equal to or decreased. Also, it can be presumed from the fact that a net-like skeleton appears during mixing, melting, and alloying in the crucible, and when this is stirred and the whole is dissolved and melted, a uniform alloy is obtained.

[0073] Also, as for the auxiliary materials, since solar cell substrates, liquid crystal substrates, etc. have silicon, and an aluminum sintered film, etc. exists on the silicon, Si, Al, further Cu (copper wire, copper pattern, etc.), Ag (sintered electrode), Ni (nickel plating on the surface of silicon), etc. were added considering them, which can improve electrical properties (contact potential difference, contact resistance, I-V characteristics in the case of solar cells, etc.) and further joint strength, etc.

[0074] Figure 6 shows a solder prototype example of the present invention. The illustration shows an example of those that can be used for soldering in Figure 4 among the many prototypes made. Those that cannot be used are omitted.

[0075] In Figure 6, for the base material of the SnZn solder (SnZn solder manufactured at S4 in Figure 1) of the present invention, Sn 91 wt% and Zn 9 wt% were used.

[0076] For the auxiliary materials, Al and Si (others are omitted) were used.

[0077] For the main materials, In, Bi, and P (red phosphorus) were used as metallic materials. For CuP8, copper phosphide with 8 wt% P and the remainder being Cu was used. As described above, when using CuP8, the addition amount of P among them had to be made equivalent to 0.16 wt% to achieve saturation (saturation occurred at 0.1 wt% for P (red phosphorus)).

[0078] Sample No is the number of the prototype samples.

[0079] Regarding the above prototype sample Nos, ultrasonic soldering and non-ultrasonic soldering as shown in Figure 5 were performed, and only the good ones are described. Those that could not be soldered are omitted.

[0080] Figure 7 shows an explanatory diagram of the TC test of the solder of the present invention. Here, the one used for the TC test was Sample No "A-14" in Figure 6 described above.

[0081] Figure 7(a) schematically shows an example of the TC test of ABS-S solder (A-14). At present, the TC test has exceeded 1000 hours (and is still continuing).

[0082] Figure 7(b) shows an example of a sample photo. As shown in the illustration, copper wires were soldered (ultrasonic soldering or soldering with scratches) to the aluminum plate, silicon surface, and aluminum surface using A-14.

[0083] Figure 7(c) shows an example of the temperature conditions of the TC test. Here, as shown in the illustration, · The maximum temperature is 87.5 °C · The minimum temperature is -24.4 °C · The maximum humidity is 98.3% · The minimum humidity is 1.6% The TC test was carried out under the above conditions.

[0084] Figure 7(d) shows an example of the test environment and results. Here, as shown in the figure, (1) The test period was from May 1, 2019 to June 12 (1000 hours) (2) The copper wire was joined to the aluminum plate, silicon plate, and aluminum surface with solder A-14 (3) The high-temperature condition was to put it in a high-temperature furnace at 80 °C. After putting the sample in, the temperature was raised.

[0085] (4) The low-temperature condition was to put it in a freezer at -20 °C.

[0086] (5) For replacement, the sample was replaced immediately without leaving it at room temperature.

[0087] The test results show that there is no problem with the solder coming off.

[0088] As a result of conducting a 1000-hour TC test under the above test conditions, for sample No. "A-14", a passing test result was obtained.

[0089] Figure 8 shows an example of the TC test of the solder (A-14) of the present invention.

[0090] In Figure 8, the horizontal axis represents the elapsed time (h). The vertical axis represents temperature (°C) / humidity (%), the upper graph in the graph shows humidity, and the lower graph shows temperature.

[0091] In Figure 8, the lower temperature graph in the graph is · The high temperature (maximum temperature) is 87.6 °C as described in Figure 7(c) · The low temperature (minimum temperature) is -24.4 °C as described in Figure 7(c) and shows the record up to 1000 hours elapsed.

[0092] In FIG. 8, the upper humidity graph in the graph shows that · The maximum humidity is 98.3% as described in FIG. 7(c) · The minimum humidity is 1.6% as described in FIG. 7(c) and shows the record up to 1000 hours elapsed.

[0093] FIG. 9 shows an ultrasonic (rubbing) / paste example of the present invention. Here, in FIG. 9 · "Paste / ultrasonic (rubbing)" is the distinction between "soldering with ultrasonic", "rubbing the soldering object with a soldering iron tip without ultrasonic", "using ammonium chloride (NH4Cl)·hydrate (3 wt% or less, 0.05 wt% or more) of the paste", "using ammonium chloride·anhydride (3 wt% or less, 0.05 wt% or more) of the paste", and "using resin (rosin) (3 wt% or less, 0.05 wt% or more) of the paste" when soldering an object to be soldered using the SnZn solder of the present invention.

[0094] · The object to be soldered is the material to be soldered using the SnZn solder of the present invention, and is the distinction between Si (wafer, about 0.2 mm thick), Al sintered film sintered on the wafer, Cu (0.1 mm thick plate), Al (0.1 mm thick plate), and stainless steel (0.1 mm thick plate).

[0095] · ◎ represents excellent adhesion of the SnZn solder of the present invention to the object to be soldered (judged as excellent adhesion when the silicon wafer breaks when a 0.4 mmφ tin-plated wire is soldered and pulled (tensile strength)).

[0096] · 〇 represents good adhesion of the SnZn solder of the present invention to the object to be soldered (judged as good adhesion when the silicon wafer breaks or has a slightly weak force (tensile strength) when a 0.4 mmφ tin-plated wire is soldered and pulled).

[0097] · △ represents weak adhesion of the SnZn solder of the present invention to the object to be soldered (a state where it peels off immediately when a 0.4 mmφ tin-plated wire is soldered and pulled).

[0098] ·× represents poor adhesion of the SnZn solder of the present invention to the object to be soldered.

[0099] From the experiments in FIG. 9 above, it was found that sufficient soldering strength can be obtained for Si wafers, Al sintered films, Cu, Al, and stainless steel when "with ultrasonic waves" or "rubbing the object to be soldered with the tip of a soldering iron without ultrasonic waves".

[0100] Furthermore, it was found that sufficient soldering strength can be obtained for Cu and Al when ammonium chloride hydrate (3 wt% or less, 0.05 wt% or more) is used.

[0101] Furthermore, it was found that sufficient soldering strength can be obtained for Cu when resin (rosin) (3 wt% or less, 0.05 wt% or more) is used.

[0102] In addition, the SnZn solder of the present invention with powder mixed used in the experiment was processed as follows: a hole (about 1 - 3 mm in diameter) was drilled or a notch was made in the center of the thick rod-shaped solder, and a predetermined amount of powder (for example, powder of ammonium chloride hydrate or resin) was put into the inside of this hole or notch, and it was repeatedly stretched into a thin rod shape a plurality of times with a grooved rolling roller, and finally processed (rolled) into a filamentous solder of about 1 mm in diameter or 1 mm square. The powder put in (mixed) can be observed near the center of the cross-section of this filamentous solder. Then, while heating by applying the tip of the soldering iron to the object to be soldered (for example, a Cu plate, placed on a preheating stage (for example, 180 °C) as required), the filamentous solder was melted, and the powder (for example, powder of ammonium chloride hydrate) mixed in the filamentous solder was decomposed to attempt to significantly improve the adhesion to the part of the object to be soldered (for example, in the case of a Cu plate, the adhesion was significantly improved. See FIG. 9).

Brief Description of the Drawings

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Figure 1

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Figure 9

Explanation of reference numerals

[0104] 1: Solder material 2: Solder material input tray 3: Melting furnace 4: Heater 11: Silicon substrate 12: Aluminum sintered film 13: Tip of ultrasonic solder iron 13-1: Tip of solder iron with or without ultrasonic 14: Solder 15: Ribbon or wire with solder

Claims

1. A SnZn solder obtained by melting and alloying a base material which is an alloy of Sn and Zn, a main material composed of an alloy of Cu and P and two or more of In, Bi and Sb, with the total amount being 1.0 wt% or less and P being 0.1 wt% or less based on 100 wt% of the Sn-Zn alloy which is the base material, wherein the removal of the oxide film, adhesion, fluidity and viscosity are improved as compared with the base material, and the melting temperature of the SnZn solder after the melting and alloying is the same as or lower than the melting temperature of the base material and is prevented from becoming higher than the melting temperature of the base material.

2. The SnZn solder according to claim 1, characterized in that a subsidiary material composed of one or more of Al, Si, Ag and Ni is mixed into the base material, which is the SnZn alloy, in an amount of 5 wt% or less based on 100 wt% of the base material and melted and alloyed.

3. Characterized in that it is used for soldering a lead wire to an electrode of a solar cell substrate or a liquid crystal substrate The SnZn solder according to any one of claims 1 to 2.

4. The SnZn solder according to any one of claims 1 to 3, wherein ammonium chloride hydrate powder or ammonium chloride hydrate contained in the powder containing ammonium chloride hydrate is mixed in an amount of 3 wt% or less to 0.05 wt% or more based on 100 wt% of the SnZn solder, and when the SnZn solder is heated for soldering, the ammonium chloride hydrate decomposes, and the soldering adhesion to the object to be soldered is improved as compared with the SnZn solder without ammonium chloride hydrate.

5. A method for manufacturing SnZn solder, which comprises melting and alloying a base material which is an alloy of Sn and Zn, a main material composed of an alloy of Cu and P and two or more of In, Bi and Sb, with the total amount being 1.0 wt% or less and P being 0.1 wt% or less based on 100 wt% of the Sn-Zn alloy which is the base material, wherein the removal of the oxide film, adhesion, fluidity and viscosity are improved as compared with the base material, and the melting temperature of the SnZn solder after the melting and alloying is the same as or lower than the melting temperature of the base material and is prevented from becoming higher than the melting temperature of the base material.

6. A method for manufacturing SnZn solder according to claim 5, characterized in that a secondary material made of glass containing one or more of Al, Si, Ag, and Ni, or one or more thereof, is melted and alloyed by mixing it into the base material in an amount of 5 wt% or less, which is the total content ratio of each element of Al, Si, Ag, and Ni contained in the secondary material, with respect to 100 wt% of the Sn and Zn alloy as the base material.

7. The method for manufacturing SnZn solder according to claim 6, characterized in that an alloy of the main material and the secondary material is mixed into the base material and melted and alloyed as the main material and the secondary material.

8. The method for manufacturing SnZn solder according to any one of claims 6 to 7, characterized in that the base material, the main material, and the secondary material are mixed together or separately in plurality and melted and alloyed.

9. A method for manufacturing SnZn solder, wherein ammonium chloride hydrate powder or, in the case of powder containing ammonium chloride hydrate, the ammonium chloride hydrate contained therein is mixed in an amount of 0.05 wt% or more to 3 wt% or less with respect to 100 wt% of the SnZn solder according to any one of claims 5 to 8. When the SnZn solder is heated for soldering, the ammonium chloride hydrate decomposes, and the soldering adhesion to the object to be soldered is improved as compared with the SnZn solder without the ammonium chloride hydrate being mixed therein.

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