Jet soldering apparatus

Abstract

This jet soldering apparatus includes a storage tank 110 for storing molten solder S, and a supply section 125 having a plurality of nozzles 127 for supplying the molten solder S. The height of the nozzles 127 is between 3 mm and 10 mm, inclusive.

Description

Wave soldering equipment

[0001] The present invention relates to a jet soldering apparatus that supplies molten solder to a substrate.

[0002]

[0003] A jet soldering apparatus for supplying molten solder to a substrate has been known. For example, Japanese Patent Application Laid-Open No. 2019-114718 discloses a jet soldering tank that performs soldering by jetting molten solder to contact the substrate, and discloses that the jet soldering tank includes a first jet nozzle that jets molten solder using a first jet pump, and a second jet nozzle that is disposed downstream of the first jet nozzle in the substrate transport direction and jets molten solder using a second jet pump.

[0003] Conventional jet soldering devices sometimes fail to perform reliable soldering on a circuit board.

[0004] The present invention provides a wave soldering apparatus that can perform soldering on a board more reliably.

[0005] [Concept 1] A jet soldering apparatus according to the present invention comprises: a reservoir tank for storing molten solder; and a supply unit having a plurality of nozzles for supplying the molten solder, wherein the height of the nozzles may be 3 mm or more and 10 mm or less.

[0006] [Concept 2] In the jet soldering apparatus according to Concept 1, the center-to-center spacing between the nozzles in the board transport direction may be longer than the center-to-center spacing between the nozzles in a direction perpendicular to the board transport direction.

[0007] [Concept 3] In the jet soldering apparatus according to Concept 1 or 2, all of the nozzles may have the same height.

[0008] [Concept 4] In the jet soldering apparatus according to any one of Concepts 1 to 3, the plurality of nozzles may be arranged in three rows in the board transport direction.

[0009] [Concept 5] In the jet soldering apparatus according to any one of Concepts 1 to 4, the nozzle may have a height of 5 mm or more.

[0010] [Concept 6] In the jet soldering apparatus according to any one of Concepts 1 to 5, the nozzle may have a height of 7 mm or less.

[0011] [Concept 7] In the jet soldering apparatus according to any one of Concepts 1 to 6, the center-to-center spacing between the plurality of nozzles may be 9 mm or more and less than 20 mm.

[0012] [Concept 8] In the jet soldering apparatus according to any one of Concepts 1 to 7, the plurality of nozzles may be arranged in a plurality of rows in the board transport direction, and the height of the nozzles in the final row in the board transport direction may be lower than the height of the nozzles in the other rows.

[0013] [Concept 9] In the jet soldering apparatus according to any one of Concepts 1 to 8, the molten solder may contain 35 mass % or more of Bi.

[0014] [Concept 10] In the jet soldering apparatus according to any one of Concepts 1 to 9, the height positions of the plurality of nozzles may be adjustable.

[0015] In the present invention, by adopting an embodiment in which the nozzle height is 3 mm or more, soldering to the board can be performed more reliably, and by setting the nozzle height to 10 mm or less, oxidation of the solder can be prevented.

[0016] FIG. 1 is a schematic diagram showing a soldering apparatus according to the present embodiment. FIG. 2 is a side cross-sectional view showing an embodiment in which the nozzles in the first supply section are all the same height in the jet soldering apparatus according to the present embodiment. FIG. 3 is a plan view showing an example of a jet soldering apparatus according to the present embodiment. FIG. 4 is a perspective view showing multiple nozzles in the first supply section according to the present embodiment. FIG. 5 is a side cross-sectional view showing one nozzle according to the present embodiment. FIG. 6 is a bottom view of multiple nozzles in the first supply section according to the present embodiment. FIG. 7 is a side cross-sectional view showing an embodiment in which the nozzles in the final row (third row) of nozzles in the first supply section are lower in height than the nozzles in the first and second rows in the jet soldering apparatus according to the present embodiment.

[0017] EMBODIMENT «Configuration» The soldering apparatus shown in FIG. 1 is an apparatus for performing a soldering process on a substrate 200 having electronic components, such as semiconductor elements, resistors, and capacitors, mounted on a circuit. Typically, the electronic components are positioned below the substrate 200. The soldering apparatus includes a main body 1 and a conveying unit 5 for conveying the substrate 200. The main body 1 includes an inlet 2 through which the substrate 200 is conveyed and an outlet 3 through which the substrate 200 is conveyed. The substrate 200 may be conveyed at a predetermined angle, for example, an inclination of approximately 3 to 6 degrees, as viewed from the side (see FIG. 2). In this case, the downstream side of the substrate conveying direction A is positioned higher than the upstream side. However, this is not limited to this, and the substrate 200 may be conveyed horizontally, for example. The conveying unit 5 may include a conveying drive unit (not shown) that applies a driving force for conveying the substrate 200 and a conveying rail 6 that guides the substrate 200.

[0018] As shown in FIG. 1 , the main body 1 may include a fluxer 10 that applies flux to a substrate 200, a preheater 15 that preheats the flux-coated substrate 200, a jet soldering device 100 that jets molten solder to contact the substrate 200, and a cooler 20 that cools the soldered substrate 200. The substrate 200 transported along the transport rails 6 of the transport section 5 passes through the fluxer 10, the preheater 15, the jet soldering device 100, and the cooler 20 in that order. The jet soldering device 100 may include a control unit 50 that issues commands to and controls each component, a memory unit 60 that stores various information, and an operation unit 70 that allows an operator to operate the soldering device by inputting various information. Note that FIG. 1 shows the soldering device in a top plan view, except for the control unit 50, the memory unit 60, and the operation unit 70.

[0019] The fluxer 10 is used to apply flux to the transported substrate 200. The flux may contain a solvent, an activator, etc. The fluxer 10 may be provided with a plurality of application devices. Different types of flux may be used depending on the type of solder and the type of substrate 200.

[0020] The preheater unit 15 heats the substrate 200, thereby raising the temperature of the substrate 200 uniformly to a predetermined level. Heating the substrate 200 in this manner facilitates solder adhesion to predetermined locations on the substrate 200. The preheater unit 15 may be, for example, a far-infrared panel heater. The far-infrared panel heater can rapidly heat the substrate 200 to a set temperature. Alternatively, the substrate 200 may be heated by blowing gas (hot air) heated by the heater onto the substrate 200 using a fan. Alternatively, a halogen heater or the like may be used as the preheater unit 15.

[0021] The cooler 20 has a cooling fan (not shown) and cools the board 200 that has been soldered by the jet soldering apparatus 100. The cooling fan may be controlled simply by turning it on and off, or the air speed may be adjusted. The cooler 20 may also be a chiller or the like that cools the board 200 to a predetermined temperature.

[0022] The control unit 50 shown in FIG. 1 is communicatively connected to the transport unit 5 including the transport rail 6, the fluxer 10, the preheater 15, the jet soldering apparatus 100, the cooler 20, the operation unit 70, and the memory unit 60. The communicative connections include both wired and wireless connections. The operation unit 70 may include a liquid crystal display panel, a numeric keypad, or the like, and is typically a personal computer, smartphone, tablet, or the like. When an operator operates the operation unit 70, the control unit 50 may control the transport speed of the transport unit 5, the timing of transporting the substrate 200, the temperature of the flux in the fluxer 10, the amount of flux applied, the temperature of the preheater 15, the temperature of the molten solder S in the jet soldering apparatus 100, the jet flow rate, the jet speed, and ON / OFF of the cooling fan of the cooler 20. The memory unit 60 may store information input via the operation unit 70, instructions from the control unit 50, the operating time of the jet soldering apparatus 100, and the like.

[0023] As shown in FIG. 2 , the jet soldering apparatus 100 includes a reservoir 110 for storing molten solder S and a supply unit for supplying the molten solder S to a substrate 200. In this embodiment, the supply unit includes a first supply unit 120 and a second supply unit 130. The first supply unit 120 may include a first pump 141, which is a first drive unit. Similarly, the second supply unit 130 may include a second pump 146, which is a second drive unit. The molten solder S ejected from the first supply unit 120 and the second supply unit 130 is ejected from below upward. The molten solder S, which receives the driving force from the first pump 141, is pressure-fed through a duct and ejected toward the substrate 200, where the solder adheres to a predetermined location on the substrate 200. Similarly, the molten solder S, which receives the driving force from the second pump 146, is pressure-fed through a duct and ejected toward the substrate 200, where the solder adheres to a predetermined location on the substrate 200. The molten solder S is heated to a temperature of, for example, about 180°C to 250°C by a heater (not shown). The molten solder S supplied from the first supply unit 120 and the second supply unit 130 may be circulated for use. In this case, the molten solder S may be circulated by passing through a filter (not shown). The first pump 141 and the second pump 146 are typically each composed of a single pump, but the first pump 141 and the second pump 146 may each be composed of a plurality of pumps.

[0024] The first supply unit 120 of the jet soldering apparatus 100 shown in FIG. 2 has a plurality of first openings 126 (see FIG. 3 , etc.). The plurality of first openings 126 are used to forcefully supply a large amount of molten solder S to the substrate 200. The second openings 136 of the second supply unit 130 are used to supply the molten solder S to the substrate 200 with less force than the first supply unit 120. The jet solder supplied from the first supply unit 120 is a dynamic supply that causes the molten solder S to collide with the substrate 200 with force, and is intended to spread the molten solder S to every corner of the substrate 200. On the other hand, the jet solder supplied from the second supply unit 130 is a static supply that passes through the molten solder S, which is a gentle flow, to neatly apply the solder to the electrodes, etc., of the substrate 200.

[0025] As shown in FIG. 2 , the first supply unit 120 includes a first housing 121 and one or more first openings 126 provided on the upper surface of the first housing 121 for supplying the molten solder S. In this embodiment, the first openings 126 are nozzle-shaped and protrude upward from the upper surface of the first housing 121. The second supply unit 130 includes a second housing 131 and one or more second openings 136 provided on the upper surface of the second housing 131 for supplying the molten solder S. The first housing 121 and the second housing 131 may be spaced apart from each other, or may be integrally formed. In this embodiment, as an example, the first opening 126 is described using a plurality of nozzles 127 and one slit-shaped second opening 136 (see FIG. 3 , etc.). However, this is not limited to this embodiment. For example, multiple slit-shaped second openings 136 may be provided. In this case, the multiple slit-shaped second openings 136 may be arranged in parallel. The second opening 136 may also be formed from multiple nozzles. In this embodiment, the following description will be given using an embodiment in which the first opening 126 is made up of a plurality of nozzles, but when the second opening 136 is made up of a plurality of nozzles, any of the embodiments described for the nozzle 127, which is the first opening 126, can be adopted for the nozzle. Note that the shape of the nozzle does not need to be cylindrical, and may be, for example, a polygonal prism such as a triangular prism or a square prism, or may be another shape (for example, the cross section of the opening may be elliptical, cross-shaped, or star-shaped). The cross-sectional area of ​​the nozzle is 9π to 25π mm ２ (approx. 28.26-78.5mm ２ ) can also be used.

[0026] While the molten solder S is being supplied, the molten solder S supplied from the first supply unit 120 and the molten solder S supplied from the second supply unit 130 may be mixed. The molten solder S mixed in this manner may be configured not to be separated from the substrate 200 transported by the transport unit 5 between the first supply unit 120 and the second supply unit 130. The substrate 200 is transported while being supported by the transport rail 6, and the upper surface of the mixed molten solder S may not be positioned lower than the lower end of the transport rail 6 transporting the substrate 200 when viewed from the side, over the entire length region along the substrate transport direction A between the first supply unit 120 and the second supply unit 130. In this case, the molten solder S is configured not to be separated from the substrate 200 transported by the transport unit 5 between the first supply unit 120 and the second supply unit 130.

[0027] The molten solder S supplied from the first supply unit 120 and the molten solder S supplied from the second supply unit 130 may be integrated and sprayed to a position higher than the transport position of the substrate 200, but this is not limited to such an embodiment.A location where the molten solder S does not come into contact with the substrate 200 may be provided between the molten solder S supplied from the first supply unit 120 and the molten solder S supplied from the second supply unit 130, and the molten solder S may be sprayed in two clearly separated stages.

[0028] The temperature of the molten solder S is generally about 50°C above the melting temperature of the solder. In recent years, there has been a growing need to lower the operating temperature to reduce component damage and machine power consumption. Furthermore, as the market prices of Sn and Ag have risen sharply, the use of solders that do not contain these metals has been considered. Typically, Sn-58Bi (melting point 139°C) has been considered as a replacement for Sn-3Ag-0.5Cu (melting point 217°C). Sn-58Bi is a low-temperature eutectic solder. The use of Sn-58Bi allows soldering to be performed at temperatures below 200°C. On the other hand, due to the low surface tension of Sn-58Bi, the solder supplied from the nozzle 127 of the first supply unit 120 tends to be less likely to form a bead shape. Sn-58Bi also has the property of being easily oxidized. These trends are observed in solders containing Bi, and are particularly noticeable in solders containing 35 mass % or more of Bi.

[0029] In this embodiment, the height of the nozzle 127 in the first supply unit 120 is 3 mm or more and 10 mm or less (see FIG. 4 ). The inventors of the present application confirmed that by setting the height of the nozzle 127 to 3 mm or more, the molten solder S ejected from the nozzle 127 can be formed into a bead shape, and the molten solder S can be firmly applied to the substrate 200. Furthermore, if the height of the nozzle 127 is too high, oxidation tends to occur when the molten solder S falls, so it is preferable to set the height of the nozzle 127 to 10 mm or less. In FIG. 5 , H1 is the height of the nozzle 127, and H2 is a value including the thickness of the top surface of the first supply unit 120.

[0030] In order to enhance the effect of forming the ejected molten solder S into a bead shape, the height of the nozzle 127 is preferably 4 mm or more, and more preferably 5 mm or more. In order to prevent the molten solder S from being oxidized as it falls, the height of the nozzle 127 is preferably 8 mm or less, and more preferably 7 mm or less.

[0031] The nozzles 127 may all be the same height. As an example, the top surface of the first housing 121 may extend parallel to a horizontal plane without being inclined, and the nozzles 127 extending upward from the top surface may all be the same height. As shown in Figure 2, when the transport rail 6 is configured such that the downstream side (right side in Figure 2) in the board transport direction A is elevated (the height position on the downstream side is higher than that on the upstream side), adopting such a configuration is advantageous in that a large amount of molten solder S can be applied to the board initially, and smaller amounts of molten solder S can be applied toward the downstream side.

[0032] The nozzle 127 may be formed integrally with the upper surface of the first housing 121 and may not be removable or have its height adjusted. If the nozzle 127 is removable or has its height adjustable, the height position of the nozzle 127 may be unintentionally changed. On the other hand, adopting this embodiment is advantageous in that it can prevent the height position of the nozzle 127 from being unintentionally changed in advance.

[0033] The nozzle 127 may be of a screw type or a slide type, and its height position may be adjustable. When such an embodiment is adopted, the height position of the nozzle 127 can be adjusted depending on, for example, the type of substrate 200. The adjustment range in this case may be approximately 0.1 mm to 3 mm.

[0034] As mentioned above, solder containing Bi tends to have weaker surface tension, so an embodiment in which the height of the nozzle 127 is 3 mm or more is particularly beneficial when using solder containing Bi. Furthermore, solder containing Bi has a higher tendency to oxidize, so an embodiment in which the height of the nozzle 127 is 10 mm or less is particularly beneficial when using solder containing Bi. Furthermore, this tendency is stronger with solder containing 35% or more by mass of Bi, so using this embodiment is extremely beneficial for solders such as Sn-58Bi that contain 35% or more by mass of Bi.

[0035] 3, 4, and 6, the multiple nozzles 127 may be arranged in three rows in the substrate transport direction A. When arranged in four or more rows, if the nozzles 127 are spaced apart to a certain extent, the length (length in the short direction) of the first supply unit 120 in the substrate transport direction A becomes long. However, when arranged in three rows, the nozzles 127 can be spaced apart to a certain extent while preventing the length of the first supply unit 120 in the substrate transport direction A from becoming too long.

[0036] The center-to-center spacing between the multiple nozzles 127 is preferably 9 mm or more and less than 20 mm. If the center-to-center spacing is less than 9 mm, the distance of the molten solder S ejected from the nozzle 127 becomes shorter, which may cause the bead shape of the molten solder S to become distorted. If the bead shape of the molten solder S becomes distorted in this manner, the effectiveness of the molten solder S adhering to the substrate 200 will be reduced. On the other hand, if the center-to-center spacing is 20 mm or more, the amount of molten solder S supplied per unit area will be reduced, which may result in the molten solder S not being efficiently supplied to the substrate 200. The center-to-center spacing is preferably 19 mm or less. The center-to-center spacing may be 18 mm or less, 17 mm or less, 16 mm or less, or 15 mm or less.

[0037] The center-to-center spacing D2 between the nozzles 127 in the substrate transport direction A (the lateral direction of the first supply unit 120) may be different from the center-to-center spacing D1 between the nozzles 127 in the direction perpendicular to the substrate transport direction A (the longitudinal direction of the first supply unit 120), and the center-to-center spacing D2 between the nozzles 127 in the lateral direction may be longer than the center-to-center spacing D1 between the nozzles 127 in the longitudinal direction. The center-to-center spacing D2 between the nozzles 127 in the lateral direction may be 1.1 times or more, or may be 1.2 times or more, the center-to-center spacing D1 between the nozzles 127 in the longitudinal direction. This configuration is expected to maintain the amount of solder supplied by the multiple nozzles 127 arranged in the longitudinal direction (the direction perpendicular to the substrate transport direction A), while minimizing the risk of the bead shape of the solder supplied from a nozzle 127 being distorted by solder from adjacent nozzles 127 in the lateral direction.

[0038] It is also possible to employ a configuration in which the height of the nozzle 127 in the final row in the substrate transport direction A (the nozzle 127 at the right end in FIG. 7 ) is lower than the height of the nozzles 127 in the other rows. The inventors of the present application have confirmed that if bead-shaped solder can be supplied to the substrate 200 upstream in the substrate transport direction A, solder can be efficiently applied to the substrate 200. On the other hand, even if the height of the nozzle 127 in the final row in the substrate transport direction A is increased, the molten solder S supplied from the second supply unit may not be able to supply the bead-shaped solder. Therefore, it may be beneficial to reduce the height of the nozzle 127 in the final row in the substrate transport direction A to avoid problems caused by oxidation of the molten solder S.

[0039] In addition, in order to promote the separation of dross generated by the oxidation of solder, sugars such as rice bran, wheat bran, beans, sesame, sunflower, palm, rapeseed, vegetable oil, and wood flour, as well as pine resin, ammonium chloride, and amine halides may be provided to the molten solder S as an oxidation separating agent.

[0040] Next, an example of a method for processing the substrate 200 will be described mainly with reference to FIG.

[0041] When an operator places the substrate 200 on the transport rail 6, the transport unit 5 transports the substrate 200, and the substrate 200 is carried into the main body 1 through the carry-in entrance 2. When the substrate 200 reaches the top of the fluxer 10, the fluxer 10 applies flux to a predetermined location on the substrate 200.

[0042] The transport unit 5 transports the substrate 200, on which the flux has been applied by the fluxer 10, to the preheater unit 15. The preheater unit 15 heats the substrate 200 to a predetermined temperature.

[0043] Next, the transport unit 5 transports the substrate 200, which has been heated to a predetermined temperature by the preheater unit 15, to the jet soldering device 100. The jet soldering device 100 solders predetermined locations on the substrate 200. While the jet soldering device 100 supplies the molten solder S, the molten solder S supplied from the first supply unit 120 and the molten solder S supplied from the second supply unit 130 are mixed together, and the molten solder S is supplied up to a position above the transport rail 6. At this time, since the height of the nozzle 127 in the first supply unit 120 is 3 mm or more, the molten solder S sprayed from the nozzle 127 can form a bead shape, allowing the molten solder S to be firmly applied to the substrate 200. Furthermore, by setting the height of the nozzle 127 to 10 mm or less, oxidation of the molten solder S can be prevented. As mentioned above, solder containing Bi (especially solder containing 35% or more by mass of Bi, such as Sn-58Bi) has a low surface tension, so the solder supplied from the first supply unit 120 is unlikely to form a bead shape and is prone to oxidation, making it extremely beneficial to adopt the aspect of this embodiment.

[0044] Next, the transport unit 5 transports the soldered board 200 to the cooler 20. For example, a cooling fan of the cooler 20 cools the soldered board 200 for a predetermined time. After the board 200 has been cooled, the transport unit 5 ejects the board 200 from the discharge port 3, and the soldering process on the board 200 is completed.

[0045] The results of an experiment (evaluation of performance in preventing unsoldered areas) conducted by the inventors of the present application to confirm the effects of this embodiment will be described below.

[0046] Fifteen evaluation boards (glass epoxy boards (FR-4, size 215.4 x 140.3 mm, thickness 1 mm, Cu-OSP), number of soldering points: 498) were attached to a pallet mask with openings where soldering was to be performed. Then, the evaluation boards attached to the pallet mask were soldered using the nozzle 127 shown in Tables 1 and 2 under the following soldering conditions. (Soldering conditions) Soldering equipment: "BITHUS-Wave MTF-300" made by Senju Metal Flux application equipment: spray fluxer ("SSF-400" made by Senju Metal) Amount of flux applied: 70 mL / m ２ Conveyor speed (transport speed of transport section 5): 1.2 m / min. Board temperature (average temperature): 120°C. Solder bath temperature: 199°C. Solder alloy composition: Sn-58Bi

[0047] The evaluation boards after soldering were visually inspected and the solderability was evaluated according to the following criteria. In each of the examples and comparative examples, the cross section was circular and the diameter was 6 mm (cross-sectional area was 9π mm ２ ) nozzle was used. The evaluation results are shown in Tables 1 and 2. [Unsoldered area evaluation] ○: No unsoldered areas (1 or less) ×: Unsoldered areas (2 or more) [Dross increase] ○: Dross increase within the normally acceptable range ×: Dross increase significantly

[0048]

[0049] As shown in Comparative Example 1, when the height of the nozzle 127 was 2 mm, there were 45 locations out of 498 locations where solder was not attached. In Comparative Example 2, the amount of dross generated in the molten solder S was significantly increased.

[0050] The above-mentioned description of each embodiment and the disclosure of the drawings are merely examples for explaining the inventions described in the claims, and the inventions described in the claims are not limited by the above-mentioned description of each embodiment or the disclosure of the drawings. Furthermore, the description of the claims as originally filed is merely an example, and the description of the claims may be changed as appropriate based on the description in the specification, drawings, etc.

[0051] 110 Reservoir 120 First supply unit (supply unit) 127 Nozzle 130 Second supply unit (supply unit) S Molten solder

Claims

1. A jet soldering apparatus comprising a storage tank for storing molten solder and a supply unit having a plurality of nozzles for supplying the molten solder, wherein the height of the nozzles is 3 mm or more and 10 mm or less.

2. The jet soldering apparatus according to claim 1, wherein the plurality of nozzles are arranged in three rows in the substrate conveyance direction.

3. The jet soldering apparatus according to claim 1 or 2, wherein the heights of all of the plurality of nozzles are the same.

4. The jet soldering apparatus according to claim 1 or 2, wherein the height of the nozzles is 5 mm or more.

5. The jet soldering apparatus according to claim 1 or 2, wherein the height of the nozzles is 7 mm or less.

6. The jet soldering apparatus according to claim 1 or 2, wherein the center-to-center spacing between the plurality of nozzles is 9 mm or more and less than 20 mm.

7. The jet soldering apparatus according to claim 1 or 2, wherein the plurality of nozzles are arranged in a plurality of rows in the substrate conveyance direction, and the height of the nozzles in the last row in the substrate conveyance direction is lower than the height of the nozzles in the other rows.

8. The jet soldering apparatus according to claim 1 or 2, wherein the molten solder contains 35 mass% or more of Bi.

9. The jet soldering apparatus according to claim 1 or 2, wherein the height positions of the plurality of nozzles are adjustable.

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