JP2007005678A - Partial flow soldering equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide soldering equipment that makes the extent of temperature deterioration small. <P>SOLUTION: A local-flow soldering equipment comprises a soldering vessel housing a melted solder 2, and an opening 41a in an upper cylinder 41. The equipment prepares a nozzle, connecting to the soldering vessel in a lower cylinder 42, and a pump sending the solder 2 housed in the soldering vessel to the opening 41a of the nozzle in a pressurized manner. In order to join a through-hole 30a of printed circuit board 30 with a terminal 31a of electronic part threaded into the through-hole 30a, the solder 2 pressure fed to the opening 41a of the nozzle is made to be attached with the through-hole 30a and terminal 31a. The nozzle is arranged between the opening 41a and lower cylinder 42, and prepares an intermediate portion 43 having passage cross section smaller than that of the lower cylinder 42, and an outflow 41b making a part of the solder 2 that has passed through the intermediate portion 43, arranged in between the intermediate portion 43 and opening 41a flow out to the exterior of the nozzle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a local flow soldering apparatus that joins a through hole of a printed circuit board and a terminal of an electronic component by molten solder pressure-fed to a nozzle.

A known soldering apparatus is described in Patent Document 1 described later. This device is used to join through-holes of printed circuit boards and terminals of electronic components inserted through the through-holes by soldering, and has a solder bath for containing molten solder and an opening at the top. And a nozzle communicating with the solder bath at the lower portion and a pressure feeding means for pumping the solder contained in the solder bath to the opening of the nozzle. The device joins the through hole and the terminal by attaching the solder fed to the opening of the nozzle to the through hole and the terminal.
JP 2002-368404 A

  In the soldering apparatus as described above, it is necessary to consider the temperature drop of the solder when the solder fed by pressure comes into contact with the printed circuit board (through hole). This temperature drop is caused by the amount of heat that the solder has transferred to the printed circuit board (having a large heat capacity).

  As the solder temperature decreases, the solder viscosity increases. In this case, it is difficult for the solder that has been fed into the through hole of the printed circuit board (so-called deterioration of solderability), and the required soldering quality may not be ensured. The degree of the temperature drop of the solder can be reduced, for example, by preheating the printed circuit board. However, there is a limit to the temperature at which the printed circuit board can be preheated due to the heat resistance problem of electronic components mounted on the printed circuit board. Furthermore, in recent years, the use of Pb-free solder having a melting point higher than that of conventional solder containing Pb has been demanded, and the consideration regarding the temperature drop of the solder has become more severe.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a soldering apparatus in which the degree of temperature drop of the solder is reduced.

  In order to solve the above-mentioned problem, the technical means taken in the present invention, as described in claim 1, has a solder bath for containing molten solder, an opening in the upper part, and the lower part in the lower part. A nozzle connected to the solder tank, and a pressure feeding means for pressure-feeding the solder contained in the solder tank to the opening of the nozzle, and a through hole of the printed circuit board and a terminal of the electronic component inserted through the through hole; In the local flow soldering apparatus for adhering the solder fed to the opening of the nozzle to the through hole and the terminal to join the nozzle, the nozzle is provided between the opening and the lower part. A reduced diameter portion having a flow path cross-sectional area smaller than the flow path cross-sectional area, and a portion of the solder provided between the reduced diameter portion and the opening and having passed through the reduced diameter portion outside the nozzle. And the outflow part It is configured and the comprise.

  Preferably, as described in claim 2, the nozzle includes a first cylinder part having the opening and an internal flow path, and a second cylinder part having an internal flow path connected to the solder bath, The reduced diameter portion may have a through hole that communicates the internal flow path of the first cylindrical portion and the internal flow path of the second cylindrical portion.

  Preferably, as described in claim 3, the through hole of the reduced diameter portion may be installed coaxially with the through hole of the printed circuit board.

  Preferably, as described in claim 4, the solder may be lead-free solder.

  According to the first aspect of the present invention, the nozzle is provided between the opening and the lower portion, and has a reduced diameter portion having a channel cross-sectional area smaller than the lower channel cross-sectional area, and the reduced diameter portion and the opening. And an outflow portion for allowing a part of the solder that has passed through the reduced diameter portion to flow out of the nozzle. In this structure, since the flow path of the solder is narrowed by the reduced diameter portion, the flow rate of the solder flowing through the reduced diameter portion increases, and the counter flow rate (circulation amount) of the solder pumped to the opening portion increases. Thereby, even if the amount of heat is transferred from the solder to the printed circuit board, the amount of heat of the solder itself is ensured, and the degree of the temperature drop of the solder is reduced.

  According to the second aspect of the present invention, the reduced diameter portion for increasing the counter flow rate of the solder fed to the opening is realized by a simple structure.

  According to the third aspect of the present invention, since the through hole of the reduced diameter portion is installed coaxially with the through hole, the solder pressure-fed to the opening of the nozzle easily enters the inside of the through hole, and the soldering quality Will improve.

  According to the invention of claim 4, since the counter flow rate of the solder that is pumped to the opening increases, especially when using lead-free solder that has a higher melting point and lower temperature than conventional lead-containing solder. A remarkable effect is obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of a local flow soldering apparatus 1 according to the present invention. The local flow soldering apparatus 1 includes a solder bath 3 that accommodates molten solder 2, a nozzle 4 that has an opening 41 a in the upper portion and is connected to the solder bath 3 in the lower portion, and a solder that is accommodated in the solder bath 3. And a pump 5 that pumps 2 to the opening 41 a of the nozzle 4.

  The solder bath 3 is formed of a heat resistant material (for example, stainless steel) to which the molten solder 2 does not adhere. The solder bath 3 includes a heater 7 for keeping the solder 2 in a molten state and a flow path 8 for guiding the solder 2 to the nozzle 4. A pump 5 is provided inside the flow path 8. The pump 5 sucks the solder 2 in the solder bath 3 into the flow path 8 through the suction port 9 formed in the flow path 8. A base 10 for attaching the nozzle 4 is integrally provided in the flow path 8. The nozzle 4 is connected to a discharge port 11 formed in the base 10. That is, the nozzle 4 is connected to the flow path 8 (solder tank 3) at the lower part. The nozzle 4, the flow path 8, and the base 10 are also formed using the same stainless steel material as the solder tank 3.

  The pump 5 is composed of, for example, a sirocco fan, and the number of rotations of the fan is controlled by a control means (not shown). When the fan rotates, the solder 2 is sucked into the flow path 8 through the suction port 9 and the amount of the solder 2 in the flow path 8 increases. Thereby, the solder 2 is pumped to the nozzle 4. As the pump 5, a moving magnetic field is generated like an electromagnetic induction pump, and the liquid level is changed by a pump that feeds the solder 2 to the nozzle 4 or a pneumatic pump or the like to apply pressure in the flow path 8. It is also possible to use what feeds the solder 2 to the nozzle 4.

  FIG. 2 is a schematic diagram of the printed circuit board 30 and the electronic component 31 to be soldered using the local flow soldering apparatus 1. The printed circuit board 30 is obtained by attaching a wiring (not shown) with a copper foil to an insulating plate (bakelite, epoxy resin or other material that does not conduct electricity) having a thickness of 1 to 2 mm. The printed board 30 is provided with a through hole 30a. The through hole 30a is for electrically connecting wirings on both sides. The through hole 30a is a through hole that penetrates the printed circuit board 30 in the thickness direction, and is formed by performing copper plating on the hole. The electronic component 31 (resistor, capacitor, transistor, IC, etc.) is provided with a terminal 31a. The terminal 31 a is inserted through the through hole 30 a of the printed board 30. The local flow soldering apparatus 1 electrically joins the through hole 30a of the printed circuit board 30 and the terminal 31a of the electronic component 31 inserted through the through hole 30a by soldering.

  Hereinafter, the structure of the nozzle 4 will be described with reference to FIGS. 3 is a perspective view showing the structure of the nozzle 4, and FIG. 4 is a cross-sectional view taken along line IV-IV in FIG.

  The nozzle 4 has a roughly rectangular tube shape. The nozzle 4 is provided with an upper cylinder part 41, a lower cylinder part 42, and an intermediate part 43. Inside the upper cylinder portion 41 and the lower cylinder portion 42, a flow path for the solder 2 is formed. The upper cylinder part 41 is provided with the opening part 41a and the outflow part 41b. The opening 41a is formed at the upper edge of the upper cylinder portion 41 and opens upward. The outflow part 41b is a through hole formed in the side wall 41c forming the upper cylinder part 41 and penetrating through the side wall 41c. In addition, regarding the shape of the outflow portion 41b, it is also possible to apply a shape (notch) in which the upper portion of the side wall 41c is partially cut off. The lower cylinder portion 42 is attached to the base 10 of the flow path 8. The lower cylinder portion 42 is connected to the flow path 8 (solder tank 3) at the discharge port 11 formed in the base 10. The intermediate portion 43 is provided between the opening 41 a and the lower cylinder portion 42. The outflow part 41 b is provided between the opening 41 a and the intermediate part 43. The intermediate part 43 is provided with a communication hole 43a. The communication hole 43 a communicates the flow path of the upper cylinder portion 41 and the flow path of the lower cylinder portion 42 and extends in the vertical direction of the nozzle 4. Regarding the cross-sectional area of the communication hole 43a, the flow path cross-sectional area of the lower cylinder portion 42 may be set to about 2 to 10 times the flow path cross-sectional area of the communication hole 43a. In other words, the intermediate portion 43 has a channel cross-sectional area that is smaller than the channel cross-sectional area of the lower cylinder portion 42.

  The solder 2 accommodated in the solder bath 3 is sucked into the flow path 8 by the pump 5 and guided to the lower cylinder portion 42 of the nozzle 4 attached to the base 10 of the flow path 8. Then, the solder 2 guided to the lower cylindrical portion 42 of the nozzle 4 is pressure-fed to the opening 41 a of the upper cylindrical portion 41 through the communication hole 43 a. A part of the solder 2 pressure-fed to the upper cylinder portion 41 of the nozzle 4 flows out of the nozzle 4 through the outflow portion 41 b and is returned to the solder tank 3. The amount of solder 2 pumped to the nozzle 4 is controlled by a control unit (not shown) connected to the pump 5.

  FIG. 5 is a diagram schematically showing a soldering mode using the local flow soldering apparatus 1. The solder 2 guided to the lower cylinder part 42 of the nozzle 4 by the pump 5 flows through the communication hole 43 a and is pumped to the opening 41 a of the upper cylinder part 41. Part of the solder 2 that has passed through the communication hole 43a flows out of the nozzle 4 through the outflow portion 41b. In this structure, the flow path cross-sectional area of the solder 2 is abruptly reduced, that is, the flow path through which the solder 2 flows is narrowed, so that the flow velocity of the solder 2 flowing through the communication hole 43a increases. Thereby, in the solder 2 pressure-fed to the upper cylinder part 41, the height of the liquid surface (hereinafter, solder local part 2a) located above the communication hole 43a is partially higher than the other parts. .

  Then, the solder local portion 2a of the solder 2 pressure-fed to the upper cylinder portion 41 is brought into contact with the through hole 30a of the printed circuit board 30 and the terminal 31a of the electronic component 31 inserted through the through hole 30a. 2 is attached. During this time, the through hole 30a of the printed circuit board 30 is arranged coaxially with the communication hole 43a of the nozzle 4, that is, the solder local portion 2a of the solder 2, as shown in FIG. In this structure, as indicated by a two-dot chain line in the figure, the solder 2 pressure-fed to the upper cylindrical portion 41 easily enters the through hole 30a, and has good solderability (the solder 2 into the through hole 30a). Ease of entry). Thereby, the through hole 30a of the printed circuit board 30 and the terminal 31a of the electronic component 31 can be more reliably joined, and the soldering quality is improved.

  Further, the flow rate of the solder 2 flowing through the communication hole 43a of the nozzle 4 increases, so that the counter flow rate (circulation amount) of the solder 2 pressure-fed to the upper tube portion 41 increases. In this structure, even when the amount of heat is transferred from the solder 2 to the printed circuit board 30 when the solder 2 and the printed circuit board 30 (through hole 30a) are in contact with each other, the amount of heat of the solder 2 itself is secured, and the degree of the temperature decrease of the solder 2 Get smaller. As a result, a decrease in the viscosity of the solder 2 is suppressed, and good solderability is ensured.

  As described above, according to the local flow soldering apparatus 1 of the present invention, the nozzle 4 is provided between the opening 41a and the lower cylinder part 42, and the flow is smaller than the flow path cross-sectional area of the lower cylinder part 42. An intermediate portion 43 having a road cross-sectional area, and an outflow portion 41b provided between the intermediate portion 43 and the opening 41a and allowing a part of the solder 2 that has passed through the intermediate portion 43 to flow out of the nozzle 4 are provided. . In this structure, since the flow path of the solder 2 is throttled by the intermediate portion 43, the flow velocity of the solder 2 flowing through the intermediate portion 43 increases, and the counter flow rate (circulation amount) of the solder 2 pumped to the opening 41a is increased. To increase. Thereby, even if the amount of heat is transferred from the solder 2 to the printed circuit board 30, the amount of heat of the solder 2 itself is ensured, and the degree of temperature drop of the solder 2 is reduced.

  Further, according to the present invention, the intermediate portion 43 for increasing the counter flow rate of the solder 2 pumped to the opening 41a is realized by a simple structure called the communication hole 43a.

  Further, according to the present invention, since the communication hole 43a of the intermediate portion 43 is installed coaxially with the through hole 30a of the printed circuit board 30, the solder 2 that has been pressure fed to the opening 41a of the nozzle 4 is placed inside the through hole 30a. Easy to penetrate, improving the soldering quality.

  Further, according to the present invention, since the counter flow rate of the solder 2 that is pumped to the opening 41a of the nozzle 4 is increased, the use of lead-free solder that has a higher melting point and lower temperature than conventional lead-containing solder. Particularly remarkable effects can be obtained.

  Furthermore, according to the present invention, good solderability is ensured, so that the time during which the solder 2 is brought into contact with the through hole 30a of the printed board 30 and the terminal 31a of the electronic component 31 can be shortened. Thereby, productivity in the soldering operation is improved and the thermal influence on the electronic component 31 on the printed circuit board 30 is reduced.

1 is a schematic view of a local flow soldering apparatus 1 according to the present invention. Schematic of the printed circuit board 30 and the electronic component 31 soldered using the local flow soldering apparatus 1. FIG. The perspective view which shows the structure of the nozzle 4. FIG. Sectional drawing which follows the IV-IV line in FIG. The figure which shows typically the aspect of soldering using the local flow soldering apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Local flow soldering apparatus 2 Solder 3 Solder tank 4 Nozzle 5 Pump (pressure feeding means)
30 Printed circuit board 30a Through hole 31 Electronic component 31a Terminal 41 Upper cylinder part (upper part, 1st cylinder part)
41a Opening part 41b Outflow part 42 Lower cylinder part (lower part, 2nd cylinder part)
43 Middle part (reduced diameter part)
43a Communication hole (through hole)

Claims (4)

A solder bath for containing molten solder;
A nozzle having an opening at the top and connecting to the solder bath at the bottom;
A pumping means for pumping the solder contained in the solder tank to the opening of the nozzle;
With
In the local flow soldering apparatus for adhering the solder fed to the opening of the nozzle to join the through hole of the printed circuit board and the terminal of the electronic component inserted into the through hole to the through hole and the terminal.
The nozzle is provided between the opening and the lower portion, and has a reduced diameter portion having a channel cross-sectional area smaller than a flow passage cross-sectional area of the lower portion, and is provided between the reduced diameter portion and the opening. A local flow soldering device comprising: an outflow portion for allowing a part of the solder that has passed through the reduced diameter portion to flow out of the nozzle.   The nozzle includes a first cylinder part having the opening and an internal flow path, and a second cylinder part having an internal flow path connected to the solder tank, and the reduced diameter part is formed on the first cylinder part. The local flow soldering apparatus according to claim 1, further comprising a through hole that communicates the internal flow path with the internal flow path of the second cylindrical portion.   The local flow soldering apparatus according to claim 2, wherein the through hole of the reduced diameter portion is installed coaxially with the through hole of the printed circuit board.   The local flow soldering apparatus according to claim 1, wherein the solder is lead-free solder.

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