Solder processing apparatus

Abstract

To provide a solder processing apparatus capable of preventing damage to a solder tank in which molten solder is stored.SOLUTION: A solder processing apparatus 1 comprises a solder tank 3 that stores molten solder and a nozzle 5 that ejects the molten solder. The solder tank 3 is provided with a plurality of heater units 7 for heating and melting solder, and a molten-state maintaining heater unit 9. After soldering processing is completed, the molten-state maintaining heater unit 9 maintains a state of solder such that a solder solidified portion 31 in which solder is solidified and a solder molten portion 33 in which solder is molten coexist in the solder tank 3, and the solder molten portion 33 is located at a position away from the nozzle 5.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a soldering processing apparatus. [Background technology]

[0002] Soldering is one of the methods for mounting electronic components on printed wiring boards. Soldering is performed by immersing the printed wiring board on which the electronic components are mounted in a jet of solder. Traditionally, one type of solder has been Sn-3Ag-0.5Cu solder. In recent years, Sn-58Bi solder (Sn-Bi based solder) has sometimes been used to comply with carbon neutrality.

[0003] The melting point of Sn-3Ag-0.5Cu solder is 220°C, while that of Sn-58Bi solder is 140°C. Using Sn-Bi solder with a lower melting point is said to contribute to energy savings and, as a result, carbon neutrality. Patent Document 1 proposes a soldering processing device that uses such Sn-Bi solder. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7332971 Summary of the Invention [Problem to be solved by the invention]

[0005] In soldering equipment, electronic components are soldered to printed wiring boards by spraying molten solder stored in a solder bath from a nozzle onto the board. Sn-Bi solder, which has a lower melting point, has the property of expanding in volume when it solidifies from a molten state.

[0006] In a soldering processing device, when a series of soldering processes is completed, the power to the heater unit that heats the solder bath that stores the molten solder is turned off. When the power to the heater unit is turned off, the molten solder solidifies. At this time, the solder may expand, which may damage the solder bath, for example, the nozzle.

[0007] The present disclosure has been made to solve such anticipated problems, and its purpose is to provide a soldering processing device that can prevent damage to the solder bath in which molten solder is stored. [Means for solving the problem]

[0008] The soldering processing apparatus according to the present disclosure is a soldering processing apparatus for mounting electronic components on a printed wiring board by soldering with Sn-Bi solder, and includes a solder bath, a nozzle, and a molten state maintaining unit. The solder bath stores molten solder. The nozzle is provided in the solder bath and ejects the molten solder toward the printed wiring board. The molten state maintaining unit is provided in the solder bath and maintains the state of the solder so that, after the soldering process is completed, one portion of the solder bath contains solidified solder and another portion of the solder is molten, and the other portion of the solder is located away from the nozzle. [Effects of the Invention]

[0009] The soldering processing apparatus according to the present disclosure includes a molten state maintaining unit that maintains the state of the solder so that, after the soldering process is completed, one portion of the solder is solidified and another portion of the solder is molten, and the other portion of the solder is located away from the nozzle. This allows the volume expansion of the one portion of the solder is absorbed by the other portion of the solder is molten, located away from the nozzle. As a result, damage to the solder bath due to solder expansion can be prevented. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view showing a printed wiring board on which electronic components to be soldered by a soldering processing apparatus according to each embodiment are mounted; [Figure 2] 1A to 1C are cross-sectional views showing a typical process for soldering electronic components to a printed circuit board using a soldering processing device. [Figure 3] FIG. 10 is a cross-sectional view showing one state of a soldering processing apparatus according to a comparative example. [Figure 4] 1 is a cross-sectional view showing a first state of the soldering processing apparatus according to the first embodiment. [Figure 5] FIG. 4 is a cross-sectional view showing a second state of the soldering processing apparatus in the embodiment. [Figure 6] FIG. 4 is a top view showing a second state of the soldering processing apparatus in the embodiment. [Figure 7] FIG. 10 is a cross-sectional view showing one state of a soldering processing apparatus according to a modified example of the embodiment. [Figure 8] FIG. 10 is a cross-sectional view showing a first state of the soldering processing apparatus according to the second embodiment. [Figure 9] FIG. 4 is a cross-sectional view showing a second state of the soldering processing apparatus in the embodiment. [Figure 10] FIG. 10 is a cross-sectional view showing a first state of the soldering treatment apparatus according to the third embodiment. [Figure 11] FIG. 4 is a cross-sectional view showing a second state of the soldering processing apparatus in the embodiment. [Figure 12] FIG. 2 is a conceptual diagram showing the configuration of a soldering processing apparatus in each embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Introduction) First, an example of a printed wiring board on which electronic components are mounted, which is to be soldered by a soldering processing device, will be described. As shown in Fig. 1, a printed wiring board 41 (substrate) on which electronic components 45 and the like are mounted is a substrate made of glass cloth impregnated with epoxy resin. A through hole 43 is formed in the printed wiring board 41, penetrating the printed wiring board 41 from one main surface to the other main surface.

[0012] Electronic components 45 and connectors 47 are inserted into corresponding through holes 43 from one main surface of printed wiring board 41 and soldered to the other main surface. Soldering portions 49 to which electronic components 45 and connectors 47 are soldered are formed on the other main surface.

[0013] Next, a method for soldering electronic components 45, connectors 47, etc. to printed wiring board 41 using soldering processing apparatus 1 will be described. As shown in FIG. 2, soldering processing apparatus 1 includes solder bath 3 that stores molten solder 21 and nozzle 5 that sprays the molten solder. Nozzle 5 includes primary nozzle 5a and secondary nozzle 5b. Solder bath 3 is provided with a heater unit (not shown) that heats solder bath 3. The heater unit will be described later, including a comparative example.

[0014] First, flux is applied to the other main surface of printed wiring board 41, in which electronic components 45 and the like have been inserted into through-holes 43. The flux is applied by a spray fluxer (not shown). Next, printed wiring board 41 to which the flux has been applied is preheated, for example, by a preheating unit (not shown).

[0015] Next, molten solder 21 is jetted from nozzle 5 toward the other main surface of printed wiring board 41. Molten solder 21 is jetted from primary nozzle 5a as primary solder jet 23a. Molten solder 21 is jetted from secondary nozzle 5b as secondary solder jet 23b.

[0016] By conveying printed wiring board 41 in one direction (see arrow), the other main surface of printed wiring board 41 first comes into contact with primary solder jet 23a and then with secondary solder jet 23b. Thereafter, printed wiring board 41 is cooled, completing a series of processes for mounting electronic components 45 and the like on printed wiring board 41.

[0017] As mentioned above, Sn-58Bi solder (Sn-Bi solder) is used to comply with carbon neutrality. Sn-Bi solder has the property of expanding in volume when it solidifies from a molten state.

[0018] Here, a soldering processing apparatus according to a comparative example will be described. As shown in Fig. 3, a soldering processing apparatus 101 according to the comparative example includes a solder bath 103 that stores molten solder, and a primary nozzle 105a and a secondary nozzle 105b that spray the molten solder. A heater unit 107 that heats the solder bath 103 is disposed in the solder bath 103.

[0019] In the soldering processing apparatus 101 according to the comparative example, when a series of processes for mounting electronic components 45 and the like on a printed wiring board 41 (see FIG. 2) is completed, the power to the heater unit 107 that heats the solder bath 103 is turned off. When the power to the heater unit 107 is turned off, the molten solder solidifies and expands. This may result in damage to the solder bath 103, for example, the primary nozzle 105a or the secondary nozzle 105b.

[0020] Unlike the soldering processing apparatus 101 according to the comparative example, the soldering processing apparatus 1 according to the embodiment can prevent damage to the solder bath 3 due to solidification of the solder. The soldering processing apparatus according to the embodiment will be described below.

[0021] Embodiment 1 An example of a soldering processing apparatus according to the first embodiment will be described. As shown in Fig. 4, the soldering processing apparatus 1 includes a solder bath 3 including a solder bath wall 3a for storing molten solder, and a nozzle 5 for spraying the molten solder. The nozzle 5 includes a primary nozzle 5a and a secondary nozzle 5b. The solder is a Sn-Bi solder, and Sn-58Bi solder is used here as an example. The solder bath wall 3a, the primary nozzle 5a, and the secondary nozzle 5b are formed of, for example, stainless steel.

[0022] A plurality of heater units 7 (space heaters) that heat and melt the solder are arranged on the outer wall surface of the solder bath 3 (solder bath wall 3a). Furthermore, a molten state maintaining heater unit 9 is arranged on the outer wall surface of the solder bath 3 (solder bath wall 3a) as a molten state maintaining unit. Here, the molten state maintaining heater unit 9 is arranged downstream of the secondary nozzle 5b in the conveying direction of the printed wiring board 41. The molten state maintaining heater unit 9 is also arranged so as to maintain the molten area of ​​the molten solder.

[0023] When the above-described soldering apparatus 1 is used to solder electronic components 45 and the like to a printed wiring board 41, the Sn-58Bi solder is heated by turning on the heater elements 7 and the molten state maintaining heater element 9, thereby melting the Sn-58Bi solder. As shown in Fig. 4, molten solder 21 is stored in the solder bath 3.

[0024] 2, printed wiring board 41 is conveyed in one direction (see arrow) so that the other main surface of printed wiring board 41 first comes into contact with primary solder jet 23a and then with secondary solder jet 23b. Thereafter, printed wiring board 41 is cooled, completing the process of mounting electronic components 45 and the like on printed wiring board 41.

[0025] In the above-described soldering processing apparatus 1, when a series of processes for mounting electronic components 45 and the like on printed wiring board 41 is completed, the power supplies to the heater units 7 are simultaneously turned off. Meanwhile, the molten state maintaining heater unit 9 is maintained on. As a result, the molten solder 21 in the solder bath 3 begins to solidify.

[0026] On the other hand, the state of molten solder 21 is maintained near heater section 9 for maintaining a molten state. Therefore, as shown in Figures 5 and 6, in solder bath 3, there exists solidified solder section 31, which is one portion where molten solder 21 has solidified, and molten solder section 33, which is another portion where the state of molten solder 21 is maintained. Melted solder section 33 is located in solder bath 3 at a position away from nozzle 5.

[0027] Here, when the Sn-Bi based molten solder 21 solidifies, its volume expands. The volume in the solidified state expands (volume expansion) by 5% from the volume in the molten state. For this reason, in the case of a solder bath 3 that stores, for example, 400 kg of molten solder 21, the molten state maintaining heater unit 9 is designed so that the volume of the solder melting portion 33 can maintain 20 kg or more of molten solder 21 (solder melting portion 33).

[0028] In this way, after the series of processes is completed, the presence of the molten solder portion 33 in the solder bath 3 at a position away from the nozzle 5 can absorb the volume expansion of the solidified solder portion 31. As a result, damage to the solder bath 3, such as the primary nozzle 5a, the secondary nozzle 5b, or the solder bath wall 3a, can be prevented.

[0029] The solder used in the above-described soldering processing apparatus 1 has been described using Sn-58Bi solder as an example. The solder is not limited to Sn-58Bi solder, and any Sn-Bi based solder that expands in volume upon solidification can be used. For example, Sn-Bi-Ag based solder or Sn-Bi-X based solder (X: any element) such as Sn-Bi-Cu based solder can be used.

[0030] Furthermore, although a space heater has been used as an example of the heater section 7, the heater section 7 is not limited to a space heater, and similar effects can be obtained by using a ceramic heater or a sheathed heater, for example.

[0031] Also, the case where the molten state maintaining heater unit 9 is arranged downstream of the secondary nozzle 5b in the transport direction of the printed wiring board 41 has been described as an example. The molten state maintaining heater unit 9 may be arranged at any position away from the primary nozzle 5a and the secondary nozzle 5b, and as shown in Fig. 7, the molten state maintaining heater unit 9 may be arranged upstream of the primary nozzle 5a in the transport direction of the printed wiring board 41.

[0032] Embodiment 2 An example of a soldering processing apparatus according to embodiment 2 will be described. As shown in Fig. 8, in the soldering processing apparatus 1, a lower heater section 11a, a middle heater section 11b, and an upper heater section 11c (space heater) are arranged from the bottom to the top of the outer wall surface of the solder bath 3 (solder bath wall 3a). The lower heater section 11a, the middle heater section 11b, and the upper heater section 11c are individually turned on and off.

[0033] Furthermore, a molten state maintaining heater section 13 is disposed on the outer wall surface of the solder bath 3 (solder bath wall 3a) as a molten state maintaining section. The molten state maintaining heater section 13 is disposed downstream of the secondary nozzle 5b in the conveying direction of the printed wiring board 41. The molten state maintaining heater section 13 is also disposed so as to maintain the molten area of ​​the molten solder. The rest of the configuration is the same as that of the soldering processing device 1 shown in FIG. 4, so the same components are designated by the same reference numerals, and their description will not be repeated unless necessary.

[0034] When the above-described soldering apparatus 1 is used to solder electronic components 45 and the like to printed wiring board 41, lower heater unit 11a, middle heater unit 11b, upper heater unit 11c, and molten state maintaining heater unit 9 are turned on to heat the Sn-58Bi solder, thereby melting the Sn-58Bi solder. As shown in Fig. 8, molten solder 21 is stored in solder bath 3.

[0035] 2, printed wiring board 41 is conveyed in one direction (see arrow) so that the other main surface of printed wiring board 41 first comes into contact with primary solder jet 23a and then with secondary solder jet 23b. Thereafter, printed wiring board 41 is cooled, completing the process of mounting electronic components 45 and the like on printed wiring board 41.

[0036] In the above-described soldering apparatus 1, when a series of processes for mounting electronic components 45 and the like on printed wiring board 41 is completed, lower heater unit 11a, middle heater unit 11b, and upper heater unit 11c are successively turned off, while molten state maintaining heater unit 9 is maintained on.

[0037] First, the power to the lower heater unit 11a is turned off, solidifying the molten solder 21 located in the lower level (lower portion) of the solder bath 3. Next, the power to the middle heater unit 11b is turned off, solidifying the molten solder 21 located in the middle level (middle portion) of the solder bath 3. Finally, the power to the upper heater unit 11c is turned off, solidifying the molten solder 21 located in the upper level (upper portion) of the solder bath 3.

[0038] As shown in Figure 9, by this operation, the molten state maintaining heater section 9 maintains the state of molten solder 21 (molten solder section 33) in the solder tank 3, while the molten solder 21 solidifies in stages from the bottom of the solder tank 3 toward the top where the molten solder section 33 is located, forming a solidified solder section 31.

[0039] This allows the volume expansion that occurs as the molten solder 21 solidifies to be reliably absorbed by the melted solder portion 33. As a result, damage to the solder bath 3, such as the primary nozzle 5a, the secondary nozzle 5b, or the solder bath wall 3a, can be prevented.

[0040] As mentioned above, the solder used in the soldering apparatus 1 is not limited to Sn-58Bi solder, but may be any Sn-Bi based solder. The lower heater section 11a is not limited to a space heater, but may be a ceramic heater or a sheathed heater.

[0041] Embodiment 3 A description will be given of an example of a soldering processing apparatus according to embodiment 3. As shown in Fig. 10, in the soldering processing apparatus 1, a plurality of heater units 7 (space heaters) are arranged on the outer wall surface of the solder bath 3 (solder bath wall 3a).

[0042] Furthermore, a cast structure 15 is disposed in the solder bath 3 (solder bath wall 3a) as a molten state maintaining section. The cast structure 15 is disposed so as to be a part of the solder bath 3 (solder bath wall 3a). That is, the cast structure 15 is disposed so as to come into contact with the molten solder when the solder melts.

[0043] The cast structure 15 is disposed downstream of the secondary nozzle 5b in the conveying direction of the printed wiring board 41. The cast structure 15 is disposed so as to come into contact with the melted area of ​​the molten solder. The rest of the configuration is the same as that of the soldering processing apparatus 1 shown in Fig. 4, so the same members are designated by the same reference numerals, and the description thereof will not be repeated unless necessary.

[0044] When the above-described soldering apparatus 1 is used to solder electronic components 45 and the like to a printed wiring board 41, the heater unit 7 is turned on to heat the Sn-58Bi solder, thereby melting the Sn-58Bi solder. As shown in Fig. 10, molten solder 21 is stored in the solder bath 3. Heat from the molten solder 21 is conducted to the cast structure 15 in contact with the molten solder 21, thereby heating the cast structure 15.

[0045] 2, printed wiring board 41 is conveyed in one direction (see arrow) so that the other main surface of printed wiring board 41 first comes into contact with primary solder jet 23a and then with secondary solder jet 23b. Thereafter, printed wiring board 41 is cooled, completing the process of mounting electronic components 45 and the like on printed wiring board 41.

[0046] In the above-described soldering processing apparatus 1, when a series of processes for mounting electronic components 45 and the like on printed wiring board 41 is completed, the power supplies to the heater units 7 are simultaneously turned off. As a result, the molten solder 21 in the solder bath 3 begins to solidify.

[0047] On the other hand, since the cast structure 15 heated by the molten solder 21 has a large heat capacity, the temperature of the cast structure 15 decreases slowly. Therefore, the solder in contact with the cast structure 15 remains molten for a while. As a result, as shown in Fig. 11, in the solder bath 3, a solidified solder portion 31 where the molten solder 21 has solidified and a molten solder portion 33 where the state of the molten solder 21 is maintained exist for a while.

[0048] As time passes, the volume expansion that accompanies the solidification of the molten solder 21 is absorbed by the molten solder portion 33, and the molten solder portion 33 gradually solidifies. Eventually, the entire molten solder portion 33 solidifies, and a final solidified solder portion 35 is formed so as to contact the cast structure 15.

[0049] The relatively high rigidity of the cast structure 15 prevents the solder bath 3 (solder bath wall 3a) from being damaged by the finally solidified solder portion 35 that expands as it solidifies. Furthermore, the volume expansion that accompanies the solidification of the molten solder 21 is absorbed by the molten solder portion 33 until the finally solidified solder portion 35 is formed, thereby preventing damage to the solder bath 3, such as the primary nozzle 5a, the secondary nozzle 5b, or the solder bath wall 3a.

[0050] As mentioned above, the solder used in the soldering apparatus 1 is not limited to Sn-58Bi solder, but may be any Sn-Bi solder. The heater section 7 is not limited to a space heater, but may be a ceramic heater or a sheathed heater. The structure with a large heat capacity may be, for example, a copper structure 17 or an iron structure 19, in addition to the cast structure 15.

[0051] As shown in FIG. 12, the soldering processing apparatus 1 described in each embodiment preferably includes a spray fluxer unit 51 that applies flux to the printed wiring board 41, a preheating unit 53 that preheats the printed wiring board 41, and a cooling unit 55 that cools the printed wiring board 41, as described at the beginning.

[0052] The soldering processing apparatuses described in the respective embodiments can be combined in various ways as required.

[0053] The embodiments disclosed herein are examples and are not intended to be limiting. The scope of the present disclosure is defined by the claims, not the scope described above, and is intended to include all modifications within the meaning and scope equivalent to the claims. [Industrial Applicability]

[0054] The present disclosure is effectively utilized in a soldering processing apparatus that solders printed wiring boards using Sn—Bi solder. [Explanation of symbols]

[0055] 1 soldering processing device, 3 solder bath, 3a solder bath wall, 5 nozzle, 5a primary nozzle, 5b secondary nozzle, 7 heater section, 9 heating maintenance heater section, 11a lower heater section, 11b middle heater section, 11c upper heater section, 13 heating maintenance heater section, 15 cast structure, 17 copper structure, 19 iron structure, 21 molten solder, 23a primary solder jet, 23b secondary solder jet, 31 solder solidification section, 33 solder melting section, 35 final solder solidification section, 41 printed wiring board, 43 through hole, 45 electronic component, 47 connector, 49 soldering section, 51 fluxer section, 53 preheating section, 55 cooling section.

Claims

1. A soldering processing apparatus for mounting electronic components on a printed wiring board by soldering using Sn—Bi solder, a solder bath for storing molten solder; a nozzle provided in the solder bath for spraying the molten solder toward the printed wiring board; a molten state maintaining unit that is provided in the solder bath and maintains the state of the solder so that, after the soldering process is completed, one portion where the solder is solidified and another portion where the solder is molten are present in the solder bath, and the other portion where the solder is molten is present in a position away from the nozzle; A soldering processing device comprising:

2. 2. The soldering processing apparatus according to claim 1, wherein the molten state maintaining section is disposed at least either downstream or upstream of the nozzle in a conveying direction of the printed wiring board that is being conveyed while undergoing the soldering process.

3. The soldering processing apparatus according to claim 1 , wherein the molten state maintaining unit is arranged to maintain a molten region of the molten solder.

4. a heating unit for melting the solder; 4. The soldering processing apparatus according to claim 1, wherein the molten state maintaining unit includes a heating maintaining unit that maintains heating and is arranged in an upper portion of the solder bath.

5. The heating unit is a first heating unit disposed at a first height in the solder bath; a second heating unit disposed at a second height higher than the first height in the solder bath; Including, The soldering processing apparatus according to claim 4 , wherein the heat maintaining unit is disposed at a third height in the solder bath that is higher than the second height.

6. 6. The soldering processing apparatus according to claim 5, wherein the first heating section and the second heating section are turned on and off individually.

7. 2. The soldering processing apparatus according to claim 1, wherein the molten state maintaining section includes a cast structure disposed in contact with the molten solder.

8. The nozzle is A first nozzle; A second nozzle The soldering processing apparatus of claim 1 , comprising:

9. The soldering processing apparatus of claim 1 , wherein the solder bath and the nozzle are formed from stainless steel.

10. a fluxer unit that applies flux to the printed wiring board before the soldering process is performed; a preheating unit that preheats the printed wiring board to which the flux has been applied; The soldering processing apparatus according to claim 1 , comprising:

11. 11. The soldering apparatus according to claim 10, further comprising a cooling section for cooling the printed wiring board after the soldering process.

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