Soldering method for low-temperature solder and soldering device for low-temperature solder

Abstract

[Purpose] The present invention relates to a soldering method for a low-temperature solder and a soldering device for the low-temperature solder, and an objective of the present invention is the realization of strong low-temperature soldering resulting from enhanced adhesive strength. [Constitution] The present method has a step for supplying heat from a heating body to an object being soldered via a soldering bit and a step for supplying power from a power supply device to the object being soldered via the soldering bit, wherein an oxide or a conductive oxide on the surface of the object being soldered is removed or reduced by the supplied power, causing the adhesive strength of the melted low-temperature solder in relation to the object being soldered to be enhanced.

Description

Low-temperature soldering method and low-temperature soldering device

[0001] The present invention relates to a low-temperature soldering method and apparatus for low-temperature soldering of aluminum substrates, conductive oxide plates, etc.

[0002] Conventionally, when soldering to aluminum plates, aluminum foils, and even conductive oxide plates, ultrasonic waves are applied to remove or reduce the oxide or conductive oxide on the surface, or soldering is performed after removing the oxide with a paste (acid) in order to remove or reduce the thin oxide film or conductive oxide on the surface.

[0003] In particular, there is a demand for forming a solar cell on a flexible resin film such as PET, and for low-temperature soldering of lead wires to the electrodes (aluminum electrodes, copper electrodes, etc.).

[0004] Conventional ultrasonic soldering methods and soldering methods using paste (acid) have problems such as the need for expensive ultrasonic application equipment, and the use of paste can cause adverse effects due to the need to wash it away and the residue it leaves behind.

[0005] Furthermore, when aluminum electrodes of solar cells are formed on a resin film, the soldering temperature is too high.

[0006] The inventors have used low-temperature solder, a type of lead-free solder, consisting of an alloy of Sn and In, or Sn, In and Zn, by supplying heat and power from the soldering tip to melt the low-temperature solder and then supplying it onto the object to be soldered, thereby removing or reducing oxides, increasing adhesion and achieving strong low-temperature soldering.

[0007] Therefore, the present invention provides a low-temperature soldering method for soldering low-temperature solder to an object to be soldered, which includes the steps of supplying heat from a heating element to the object to be soldered via a tip, supplying power from a power supply device to the object to be soldered via the tip, and using the supplied power to remove or reduce oxides or conductive oxides on the surface of the object to be soldered, thereby increasing the adhesion of the molten low-temperature solder to the object to be soldered.

[0008] In this case, the power supply is set to have a current in the range of 1 mA to 3 mA or a voltage in the range of 3V to 7V.

[0009] The low-temperature solder is an alloy made of Sn and In or Sn, In and Zn, and containing unavoidable impurities.

[0010] In addition, low-temperature solder is supplied by supplying wire solder to the tip, melting it, and supplying it to the object to be soldered.

[0011] The object to be soldered is a plate or film made of a metal or conductive oxide whose surface is subject to oxidation.

[0012] FIG. 1 shows a configuration diagram of one embodiment of the present invention.

[0013] In FIG. 1, the power supply device 1 supplies power to an object 2 to be soldered, and in this case supplies current and voltage, and is composed of a power adapter 21, a controller 22, a power supply display device 23, a resistive element 24, and mounting hardware 25.

[0014] The power adapter 21 outputs power (direct current) from the A and B terminals.

[0015] The controller 22 controls the power adapter 21 and controls the output of predetermined voltage, current, and power from terminals A and B. The output control is performed according to instructions from software (not shown) or manually.

[0016] The power supply indicator 23 is a device that lights up an LED or the like when power is supplied from the power adapter 21 to the object 2 to be soldered.

[0017] The resistor element 24 controls the voltage, current, and power from the power adapter 21 to the soldering target 2, and in this case, a resistor element for limiting current is used. The resistor element 24 is not limited to the resistor element 24, and may be a constant current semiconductor element, a constant voltage semiconductor element, or a constant power semiconductor element.

[0018] The mounting metal fitting 25 is a detachable metal fitting that supplies power to the object 2 to be soldered.

[0019] The object to be soldered 2 is a plate, film, wire, etc. that is the object of low-temperature soldering, and may be a metal (such as aluminum or stainless steel) on which an oxide film is formed, or a plate or film of a conductive oxide.

[0020] Next, the operation of the configuration shown in FIG. 1 will be described.

[0021] (1) The object 2 to be soldered is fixed with one of the mounting brackets 25 constituting the power supply device 1, and another of the mounting brackets 25 is fixed to a soldering device (not shown), and the supply of power and heat (or low-temperature solder melted with heat at a temperature at which low-temperature solder melts) is started from the tip of the mounting bracket to the object 2 to be soldered. Note that there are cases where low-temperature solder melted with heat is supplied, and cases where only heat is supplied to melt low-temperature solder that has been pre-low-temperature soldered to the object 2 to be soldered.

[0022] (2) In (1), the object to be soldered 2 is supplied with molten solder (or heat only) and power. The power source removes or reduces oxides on the surface of the object to be soldered 2, or reduces oxides on the surface of the conductive oxide. The molten low-temperature solder is then tightly adhered to the object to be soldered 2, allowing low-temperature soldering to be performed (see Figure 5 below).

[0023] (3) In the state of (2), low-temperature soldering can be performed at any location by moving the soldering tip (not shown). Low-temperature soldering can be performed on plates, films, and wires made of aluminum, stainless steel, or other materials that form an oxide film, as well as TCO (transparent conductive oxide) films that have a conductive oxide film. Power is supplied from the B (positive) and A (negative) terminals of the power adapter 21.

[0024] Fig. 2 shows a diagram (part 1) of the configuration of the present invention. This diagram explains the relationship between the current supplied to the soldering target 2 by the power adapter 21 of Fig. 1 and the quality of low-temperature soldered products. Here, the horizontal axis represents the current, and the vertical axis represents the quality range of low-temperature soldered products.

[0025] In Fig. 2, the current on the horizontal axis is the current supplied to the soldering object 2 in Fig. 1. In experiments, a range of 1 mA to 3 mA, for example, was found to be within the range of acceptable products for low-temperature soldering.

[0026] The pass-quality range on the vertical axis is the pass-quality range for low-temperature soldering when a current is supplied to the soldered object 2 in Fig. 1. In experiments, low-temperature soldering was in the pass-quality range when the current was in the range of 1 mA to 3 mA, for example (a pass-quality product has strong adhesion (for example, a tensile strength of 5N or more), as shown in Fig. 5 (a-1) described later). Currents below 1 mA are in the defective range, and currents above 3 mA are close to the current range (usually 10 mA) that poses a risk to the human body during low-temperature soldering, so are not suitable for practical use and are in the defective range to allow for some leeway.

[0027] As described above, in the present invention, when low-temperature soldering is performed on the object 2 to be soldered using the configuration shown in Figure 1 described above, supplying low-temperature molten solder and current (1 mA to 3 mA) from the power adapter 21 to the object 2 to be soldered makes it possible to perform soldering within the acceptable range for low-temperature soldering (the range in which the adhesion is strong and low-temperature soldering is possible).

[0028] Fig. 3 shows a second diagram of the configuration of the present invention. This diagram explains the relationship between the voltage supplied to the soldering target 2 by the power adapter 21 of Fig. 1 and the quality of low-temperature soldered products. Here, the horizontal axis represents voltage, and the vertical axis represents the range of quality of low-temperature soldered products.

[0029] In Fig. 3, the voltage on the horizontal axis is the voltage supplied to the soldering object 2 in Fig. 1. In experiments, a range of, for example, 3V to 5V was within the range of acceptable products for low-temperature soldering.

[0030] The pass-quality range on the vertical axis is the pass-quality range for low-temperature soldering when a voltage is supplied to the soldered object 2 in Fig. 1. In experiments, low-temperature soldering was found to be in the pass-quality range when the current was in the range of, for example, 3V to 5V (a pass-quality product has strong adhesion (for example, a tensile strength of 5N or more), as shown in Fig. 5 (a-1) described later). Currents below 3V are in the defective quality range, and currents above 7V are close to the voltage range (usually 10mA) that may be dangerous to the human body during low-temperature soldering, so are not suitable for practical use and are in the defective quality range to allow for some leeway.

[0031] As described above, in the present invention, when low-temperature soldering is performed on the object 2 to be soldered using the configuration shown in Figure 1 described above, by supplying low-temperature molten solder and voltage (3V to 5V) to the object 2 to be soldered from the power adapter 21, soldering can be performed within the acceptable range for low-temperature soldering (the range in which the adhesion is strong and low-temperature soldering is possible).

[0032] 4 shows a flowchart for explaining the operation of the present invention, which is a flowchart for explaining the operation of the low temperature soldering of FIG.

[0033] 4, S1 prepares a power supply device, which is the power supply device 1 of FIG.

[0034] S2 sets the target to be soldered to earth potential by fixing one of the mounting metal fittings 25 (earth potential) constituting the power supply device 1 of FIG.

[0035] In step S3, the tip of the soldering prong is held at, for example, +5V for an initial period of approximately 10-15 seconds. With the object 2 to be soldered held at ground potential in step S2, molten solder is supplied from the tip of a soldering prong (not shown) fixed to another one of the mounting brackets 25 (here, +5V, for example) that constitutes the power supply device 1 in FIG. 1, while supplying, for example, +5V. This initial period is maintained for approximately 10-15 seconds. Note that this example is for a case where an oxide is present on the surface of the aluminum plate. In the case of copper, copper oxide becomes a P-type semiconductor, and the voltage is set to, for example, +7V to +15V, and the initial period is maintained for, for example, 60 seconds (the optimum value is determined experimentally).

[0036] In S4, it is determined whether the LED is lit. After waiting for an initial 10-15 seconds in S3 (or about 60 seconds in the case of copper), the power supply indicator (e.g., LED) 23 constituting the power supply device 1 in FIG. 1 lights up, and it is determined whether current is flowing and low-temperature soldering has begun. If the answer is YES, low-temperature soldering is performed in S5. If the answer is NO, the process returns to S3 and waits.

[0037] As described above, when the power supply device 1 shown in FIG. 1 is prepared and low-temperature solder is melted from the tip of the soldering tip (not shown) and supplied to the object 2 to be soldered, and voltage is also supplied, after a while current will flow and the power supply indicator (e.g., LED) 23 will light up, indicating that low-temperature soldering has begun. It is then possible to move the tip (not shown) to perform the desired low-temperature soldering.

[0038] FIG. 5 shows an explanatory diagram (part 1) of the effects of the present invention.

[0039] 5A shows a photographic example of soldering. The photograph shows an example of soldering performed using a solder dispenser. The solder dispenser is a handy dispenser that supplies molten solder and power, as will be described later with reference to FIGS. 12 to 14.

[0040] 5(a-1) shows a photograph of an example of soldering according to the present invention (with current applied). In the photograph, the tensile strength of the low-temperature solder was 5N or more (multiple identical samples were made, and when other samples not shown in the photograph were pulled, the tensile strength at which the low-temperature soldered portion shown in the photograph did not peel off was 5N or more). For example, a 0.4 mm diameter tin-plated copper wire was low-temperature soldered, and the tensile strength of this was 5N or more.

[0041] Figure 5 (a-2) shows a photograph of a conventional soldering process (no current applied). In the photograph, the tensile strength of the low-temperature solder was about 2N (multiple identical soldering samples were made, and when other samples not shown in the photograph were pulled, the tensile strength at which the low-temperature solder shown in the photograph did not peel off was also about 2N).

[0042] As described above, it was found that the present invention (with current application) of FIG. 5(a-1) had a tensile strength of 5N or more, and had sufficient adhesion force.

[0043] Fig. 6 shows an explanatory diagram (part 2) of the effect of the present invention. This Fig. 6 shows a photographic example of a very small resistor element (1.6 mm x 0.8 mm) with both ends attached to wiring (transfer film) on a substrate by low-temperature soldering according to the present invention.

[0044] FIG. 6(a) shows a schematic side view of low-temperature soldering.

[0045] Figure 6 (a-1) shows the state of the resistor element to be subjected to low-temperature soldering in the present invention, with the pre-soldered portions at both ends placed on the edges of the conductive transfer film from the left side of the substrate and the conductive transfer film from the right side, as shown, before being pressed downward from above with the tip of the iron (a tip heated to a temperature at which the low-temperature solder melts).

[0046] FIG. 6(a-2) shows the state in which, in the state of FIG. 6(a-1), the tip of the iron (small tip) is lightly pressed from top to bottom, melting the pre-soldered low-temperature solder and supplying an electric current or the like, resulting in a neat and strong adhesion (low-temperature soldered state).

[0047] FIG. 6(b) shows an example of soldering a resistor element according to the present invention.

[0048] The upper photograph in FIG. 6(b) shows a top view of a resistor element (1.6 mm×0.8 mm) after low-temperature soldering to a conductive transfer foil as in FIG. 6(a-2).

[0049] The lower photograph in Figure 6(b) shows a top view of the conductive transfer foil after pre-low-temperature soldering as shown in Figure 6(a-2). The spacing between the conductive transfer foils is approximately 1 mm as shown. Figures 6(c) and 6(d) show photographs of the resistor element held with tweezers.

[0050] As described above, by preliminarily low-temperature soldering both ends of a minute resistance element, placing it on a cut portion of the conductive transfer foil of about 1 mm as shown in Figure 6 (a-1), and then performing the low-temperature soldering of the present invention (low-temperature soldering with the supply of heat and current, etc.), it is possible to firmly low-temperature solder the resistance element onto the substrate.

[0051] Fig. 7 is an explanatory diagram of an embodiment of the present invention. Fig. 7 shows an example of the structure of a low-temperature solder used in the low-temperature soldering of the present invention. Here, for example, the following is shown in the figure.

[0052] Solder name Melting point Main components (weight ratio wt%) Low temperature solder-1 119°C Indium 52wt%, Tin 48wt% Low temperature solder-2 165°C Tin 76wt%, Zinc 9%, Indium 15wt% Note that the weight ratios above are not the only options, and the weight ratios of the main components should be determined through experimentation to obtain the desired melting point.

[0053] Figure 8 shows test results (part 1) of the present invention. In Figure 8, samples were created by low-temperature soldering onto a glass slide (oxide film, etc.) using the two types of low-temperature solders 1 and 2 already described in Figure 7. Then, after a predetermined time had passed from the TC test, the samples were subjected to the tensile test already described (see Figure 5 (a-1) and the like), and the graph shows an example of the number of samples that did not peel off. The horizontal axis represents the elapsed time (H) after the TC test (see Figure 9 described later), and the vertical axis represents the remaining number of samples that did not peel off.

[0054] In Figure 8, the curve for low-temperature solder 2 shows an example of the number of remaining pieces that did not peel off when samples were created by low-temperature soldering of the present invention to a slide glass using the low-temperature solder 2 already described in Figure 7, and then conducting a TC test and a tensile strength test after the specified time shown in the figure.

[0055] The curve for low-temperature solder 1 shows an example of the number of remaining pieces that did not peel off when samples were created by low-temperature soldering of the present invention to a slide glass using the low-temperature solder 1 in Figure 7 described above, and then conducting a TC test and a tensile strength test after the specified time shown in the figure.

[0056] Comparing the two curves, the curve for low-temperature solder-1 showed a stronger adhesive strength than the curve for low-temperature solder-2.

[0057] Figure 9 shows the test results (part 2) of the present invention. Figure 9 shows an example of the TC test results, with the horizontal axis representing elapsed time and the vertical axis representing temperature and humidity. Here, a sample of the present invention, which was low-temperature soldered on an aluminum plate using low-temperature solder-2, was prepared, and the TC test was performed at temperatures ranging from approximately -25°C to +80°C in the cycle shown in the figure. The humidity at that time ranged from approximately 5% to 85%.

[0058] The samples prepared as described above were subjected to a TC test. After each predetermined time had elapsed since the TC test, a tensile strength test similar to that shown in FIG. 8 was performed, and favorable results were obtained.

[0059] Fig. 10 shows the configuration of another embodiment of the present invention. This Fig. 10 shows a specific example of the configuration of Fig. 1, and is a specific configuration example of an experimental device in which wire solder 33 is melted by heater section 31 and power (e.g., current) is supplied from power supply device 1 (not shown) via mounting bracket 25 to perform low-temperature soldering of an object to be soldered 2 according to the present invention. Here, the lower part of mounting bracket 25 shown in the photograph is connected to object to be soldered 2, and the upper part of mounting bracket 25 shown is connected to wire solder 33 (or the part electrically connected to wire solder 33).

[0060] In FIG. 10, an object to be soldered 2 is an object to be subjected to low-temperature soldering of the present invention.

[0061] The heater portion 31 is a heater that melts the wire solder 33 .

[0062] The tip 311 discharges the wire solder 33 melted by the heater portion 31 to the outside and also supplies power to the object 2 to be soldered.

[0063] The solder extrusion supply unit 32 is a mechanism that automatically extrudes the illustrated wire solder 33 to the right.

[0064] The LED 34 is an indicator that turns on when the molten low-temperature solder is discharged from the tip 311 onto the object 2 to be soldered and the oxides are removed or reduced by the power source. When the LED 34 lights up, it is clear that low-temperature soldering has started, so the tip 311 can be moved and low-temperature soldering can be performed at any desired location.

[0065] The solder dispenser (FIG. 11) 3 is attached to the location indicated by the arrow on a device (the soldering iron of the present invention) that supplies the rod-shaped wire solder 33 shown in the figure, and has the structure shown in FIG. 11. The solder dispenser 3 has built-in LED 34 shown in FIG. 10 and other components (see FIG. 11 and its description).

[0066] By using the experimental device configured as shown in FIG. 10, it becomes possible to supply molten low-temperature solder to the object 2 to be soldered, supply power, and perform low-temperature soldering.

[0067] FIG. 11 shows a configuration diagram (solder dispenser) according to an embodiment of the present invention.

[0068] FIG. 11(a) shows an external view, and FIG. 11(b) shows a schematic perspective view.

[0069] In FIG. 11(a), the LED corresponds to the LED 34 in FIG. 10 already described, and shows the state where the low-temperature soldering of the present invention has started.

[0070] In FIG. 11B, the power supply side portion on the right side is the portion where the LED 34 in FIG. 10 is fastened (connected) with a clip of the mounting bracket 25 (in this case, the LED 34 is shorted or removed).

[0071] The portion to the clip on the left side is the portion that electrically connects to the wire solder 33 etc. in FIG.

[0072] The IK ohm resistor is a current limiting resistor for passing a constant current.

[0073] By providing the above configuration and fixing it to the solder dispenser 3 in FIG. 10, it is possible to detect that low-temperature soldering has been initiated when the LED in FIG. 11 lights up, and it is then possible to move the tip 311 in FIG. 10 and perform the low-temperature soldering of the present invention.

[0074] 12 is a diagram for explaining the effects of another embodiment of the present invention, showing a photographic example of soldering using the solder dispenser shown in FIGS.

[0075] FIG. 12(a) shows a photographic example (left photo) of soldering using a solder dispenser.

[0076] FIG. 12(a-1) shows a photograph of the board after soldering and then removing the solder.

[0077] In this case, SES is present (the low-temperature soldering method of the present invention is present, in which the molten low-temperature solder of the present invention is supplied and power is supplied), and as a result of the improved adhesion, the solder remains firmly attached even when peeled off, and some of the low-temperature solder remains.

[0078] FIG. 12(a-2) shows a photograph (left side photograph) after soldering to the board and then removing the solder.

[0079] In this case, without SES (the low-temperature soldering method of the present invention in which the molten low-temperature solder of the present invention and power supply are both supplied is not used, and only the molten low-temperature solder is supplied), it was confirmed that although there was adhesion, it was weaker than when SES was used.

[0080] As described above, from the photographs of soldering using a solder dispenser, it was experimentally confirmed that the soldering method of the present invention, which supplies the low-temperature melting solder of the present invention and also supplies power, can judge the adhesion strength to be stronger than the conventional soldering method without power supply.

[0081] Figure 13 shows the configuration of another embodiment of the present invention. In this Figure, pre-low-temperature soldering is performed directly on the component or wire material to be soldered 2 without supplying wire solder 22 or the like. Then, as an example of use when supplying heat and power without supplying wire solder 33 or the like to perform the low-temperature soldering of the present invention, here is shown an example of the configuration of an apparatus for soldering the low-temperature solder of the present invention to tin-plated copper wire in advance using the method of the present invention. This will be described in detail below.

[0082] In FIG. 13, a stainless steel container 41 is used to heat the low-temperature solder of the present invention with a heater (not shown) to form molten solder 42 .

[0083] The molten solder 42 is the low-temperature solder of the present invention melted inside the stainless steel container 41 .

[0084] The unwinder 51 is a reel or the like around which tin-plated copper wire is wound, and in this case, it unwinds the wound tin-plated copper wire with a predetermined tension.

[0085] The tin-plated copper wire 52 is a tin-plated copper wire pulled from the unwinder 51 with a constant tension.

[0086] The slider 53 supplies power to the tinned copper wire 52 .

[0087] The slider 54 slightly rubs the surface of the tin-plated copper wire 52 to remove dust, remove or reduce oxide films, and furthermore, to facilitate the flow of power supplied from the slider 53 to the tin-plated copper wire 52 into the molten solder 42. The slider 54 may be combined with the slider 53 to have both functions.

[0088] The support rod 55 is a support rod provided in the molten solder 42 so that the tin-plated copper wire 52 is securely placed in the molten solder 42 .

[0089] The solder-coated wire 56 is a wire in which molten solder 42 is uniformly and firmly soldered to the outer circumference of a tin-plated copper wire 52 at low temperature using the power supply of the present invention. The thickness of the solder coating on the wire is determined to be optimal through experiments by changing the temperature of the molten solder 42, the wire running speed, etc. Note that although the winder 57 is shown as being close to the molten solder 42, its speed and forced cooling (not shown) are experimentally determined and positioned so that the solder-coated wires 57 are sufficiently cooled and solidified to prevent them from soldering together.

[0090] 1, the USB power adapter 21, the resistor element 24, the LED 23, etc. are the same as those in Fig. 1, and therefore description thereof will be omitted. The USB power adapter 21 here has 0V and -5V terminals as shown in the figure.

[0091] Next, the operation of the configuration of FIG. 13 will be described in detail with reference to the flowchart of FIG.

[0092] FIG. 14 is a flowchart illustrating the operation of another embodiment of the present invention.

[0093] 14, S11 prepares an applied voltage system, which includes the above-mentioned components 21 to 23 and 53 in FIG.

[0094] In step S12, the metal having an opening through which the wire passes is set to 5 V. This supplies power (for example, −5 V as shown in FIG. 13) to the slider 53 in FIG. 13 prepared in step S11.

[0095] In step S13, the solder melting furnace in which the wire is immersed is set to earth potential. For example, this is done by connecting the stainless steel container 41 in FIG. 13 to earth potential (0 V) and the USB power adapter 21 to earth potential (0 V).

[0096] In step S14, the process waits as it is, that is, the preparations and connections from step S11 to step S13 are performed, and the process waits until, for example, the LED 23 in FIG. 13 lights up, a current flows between the tinned copper wire 52 and the molten solder 42, and the LED 23 lights up.

[0097] In step S15, it is determined whether the LED is lit. If the answer is YES, the process proceeds to step S16. If the answer is NO, step S15 is repeated.

[0098] In step S16, the wire continues to be wound up and unwound.

[0099] In step S17, it is determined whether the wire is present. If the answer is YES, step S16 is repeated. If the answer is NO, it is determined that the wire has run out, and the process ends. If the answer is NO in steps S16 and S17, the wire (tin-plated copper wire 52) is wound up by the winder 57 shown in FIG. 13, the unwinder 51 is braked, and the wire (tin-plated copper wire 52) is continuously wound up in the molten solder 42 at a predetermined tension and a predetermined speed using the power supply of the present invention until the wire runs out (until the wire is detected by a wire detection device not shown).

[0100] As described above, with the configuration of Figure 13, it is possible to continuously pass a tin-plated copper wire through molten solder 42 while supplying power, and produce a solder-coated wire 56 with the low-temperature solder of the present invention soldered to the surface at low temperature.

[0101] Fig. 15 is an explanatory diagram of a test method for verifying the effectiveness of the present invention. In Fig. 15, a soldering target material 61 is a material to be soldered in the present invention, such as Cu, Al, glass, conductive oxide, etc.

[0102] The solder 62 is the solder of the present invention, and may be the low-temperature solder made of the alloy of Sn and In or Sn, In and Zn as described above, or may be a normal solder (for example, SnBi, SnZn, or the like).

[0103] The lead wire 63 is a lead wire such as a tin-plated copper wire (for example, about 0.4 mm diameter) for conducting a soldering strength test on the soldering target material 61. Furthermore, it is not limited to a wire, and may be a thin, strip-shaped rectangular wire.

[0104] The mounting fixture (grip) 64 is a mounting fixture that fixes the lead wire 63. The force gauge (FGJN-2) 65 is a gauge that measures a tensile force (for example, 4 N).

[0105] With the above configuration, the lead wire 63 is soldered to the soldering target material 61 using the method of the present invention described above, and after bending the lead wire 63 as shown, it is fixed with a mounting bracket 64. The lead wire 63 is pulled upward using a force gauge 65, and the tensile force (N) when the lead wire 63 peels off is measured. This makes it possible to measure the tensile strength of the soldered lead wire 63 to the soldering target material 61 using the method of the present invention.

[0106] Fig. 16 shows an example of solder to which the present invention is applicable. This Fig. 16 shows examples of soldering that can be applied to the SnIn and SnInZn alloy solders used in the present invention as described above, as well as soldering using other solders shown in the figures.

[0107] In Figure 16, solder type (wt%) Melting temperature (°C) Medium-high temperature solder 1 Sn / Ag 96.3 / 3.7 220 2 Sn / Ag / Cu 95.8 / 3.5 / 0.79 217 Medium temperature solder 3 Sn / Ag / Bi / Cu 96 / 2.5 / 1 / 0.5 217 4 Sn / In / Ag / Bi 92 / 4 / 3.5 / 0 / 5 207 Medium-low temperature solder 5 Sn / Zn 91 / 9 198 6 Sn / Zn / Bi 89 / 8 / 3 190 Low temperature solder 7 Sn / Bi 42 / 58 139 8 Sn / In 48 / 52 119

[0108] FIG. 1 is a configuration diagram of one embodiment of the present invention. FIG. 2 is a configuration explanatory diagram (part 1) of the present invention. FIG. 3 is a configuration explanatory diagram (part 2) of the present invention. FIG. 4 is a flowchart explaining the operation of the present invention. FIG. 5 is a diagram explaining the effect of the present invention (part 1). FIG. 6 is a diagram explaining the effect of the present invention (part 2). FIG. 7 is an explanatory diagram of an embodiment of the present invention. FIG. 8 is a test result (part 1) of the present invention. FIG. 9 is a test result (part 2) of the present invention. FIG. 9 is a configuration diagram of another embodiment of the present invention. FIG. 10 is a configuration diagram (solder dispenser) of another embodiment of the present invention. FIG. 11 is a diagram explaining the effect of another embodiment of the present invention. FIG. 12 is a configuration diagram of another embodiment of the present invention. FIG. 13 is a flowchart explaining the operation of another embodiment of the present invention. FIG. 14 is an explanatory diagram of a test method for verifying the effect of the present invention. An example of solder to which the present invention is applied.

[0109] 1: Power supply unit 2: Soldered object 21: Power adapter 22: Controller 23, 25: Mounting bracket 23: Power supply display device 24: Resistance element 3: Solder dispenser 31: Heater unit 311: Iron tip 32: Solder extrusion supply unit 33: Wire solder 34: LED 41: Stainless steel container 42: Molten solder 51: Unwinder 52: Tin-plated wire 53, 54: Slider 55: Support rod 56: Solder-coated wire 57: Winder 61: Soldered object 62: Solder 63: Lead wire 64: Mounting bracket 65: Force gauge

Claims

1. A low-temperature soldering method for soldering low-temperature solder to an object to be soldered, comprising the steps of: supplying heat from a heating element to the object to be soldered via a tip; supplying power from a power supply device to the object to be soldered via the tip; and removing or reducing oxides or conductive oxides on the surface of the object to be soldered using the supplied power, thereby increasing the adhesion of the molten low-temperature solder to the object to be soldered.

2. A low-temperature soldering method according to claim 1, characterized in that the power supply has a current in the range of 1 mA to 3 mA or a voltage in the range of 3 V to 7 V.

3. A low-temperature soldering method according to any one of claims 1 to 2, characterized in that the low-temperature solder is an alloy consisting of one of Sn and In, Sn, In and Zn, Sn and Bi, Sn and Zn, or Sn, Zn and Bi, and containing unavoidable impurities.

4. A low-temperature soldering method according to any one of claims 1 to 3, characterized in that the low-temperature solder is supplied to the object to be soldered by supplying wire solder to the tip, melting it, and supplying it to the object to be soldered.

5. A low-temperature soldering method according to any one of claims 1 to 4, characterized in that the object to be soldered is a plate or film made of a metal or conductive oxide whose surface oxidizes.

6. A low-temperature soldering method according to any one of claims 1 to 5, characterized in that the low-temperature solder is lead-free solder.

7. A low-temperature soldering device for soldering low-temperature solder to an object to be soldered, comprising: a tip that supplies heat from a heating body to the object to be soldered; and a power supply device that supplies power to the object to be soldered via the tip, wherein the supplied power is used to remove or reduce oxides or conductive oxides on the surface of the object to be soldered, thereby increasing the adhesion of the molten low-temperature solder to the object to be soldered.

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