JP2013153001A - Soldering apparatus and soldering method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soldering apparatus and a soldering method which stabilize the solder adhesion amount.SOLUTION: A soldering apparatus is used for transferring a printed circuit board 1 to jetted molten solder 2 and immersing the printed circuit board 1 in the molten solder 2 and includes: a jet nozzle 11 having an upper end part defined by a plate member 15 vertically extending and jetting the molten solder 2 so that the molten solder 2 contacts with one surface 15a of the plate member 15; a duct 12 disposed in a transfer direction TD of the printed circuit board 1 relative to the jet nozzle 11, the duct 12 in which the molten solder 2 flows down while contacting with the other surface 15b of the plate member 15; and an inactive gas supply nozzle 13 that is disposed in the transfer direction TD of the printed circuit board 1 relative to the duct 12 and may supply an inactive gas G to the printed circuit board 1.

Description

  The present invention relates to a soldering apparatus and a soldering method, and more particularly to a soldering apparatus and a soldering method in jet soldering.

  As a method for soldering an electronic component to a printed circuit board, there is a jet soldering method in which an object to be soldered is immersed in molten solder. In the jet soldering method, flux is applied in advance to the solder joint. The soldered joint is immersed in the molten solder in a state where the flux is activated and the oxide film on the electrode surface is removed. The soldering device used for the jet soldering method is a primary jet nozzle that sucks molten solder contained in a solder bath from below and jets molten solder in a rough state and a secondary jet that jets molten solder in a gentle state. A jet nozzle is provided.

  In the jet soldering method, it is important to suppress short-circuit defects caused by the formation of bridges in adjacent electrodes having a narrow electrode pitch such as QFP (Quad Flat Package). Since the primary jet solder is disturbed, molten solder may be supplied excessively. When the molten solder is excessively supplied and solidified, a bridge may be formed on the adjacent electrode to cause poor soldering.

  The bridge is then corrected by gentle molten solder jetting from the secondary jet nozzle. However, when there is too much secondary jet solder and when the solder fluidity deteriorates due to the formation of oxide in a state where the oxygen concentration in the atmosphere where the molten solder solidifies is high, a bridge may be formed in the adjacent electrode. is there. This bridge causes a short circuit failure. Note that the amount of solder attached at the secondary jet nozzle is mainly determined by the angle and speed at which the printed circuit board is detached from the molten solder.

  A jet soldering method capable of suppressing the occurrence of poor soldering has been proposed in, for example, Japanese Patent Laid-Open No. 9-181437 (Patent Document 1). In the jet soldering method of this publication, a nozzle for supplying an inert gas is provided around a peelback point where the printed circuit board and the molten solder are separated. Since the low oxygen atmosphere is formed by supplying the inert gas, the formation of the bridge due to the deterioration of the solder fluidity due to the formation of the oxide is suppressed.

JP-A-9-181437

  However, the jet soldering method of the above publication has a problem that the amount of solder adhesion is not stable because excess molten solder flows in the direction in which the printed circuit board is conveyed.

  This invention is made | formed in view of the said subject, The objective is to provide the soldering apparatus and the soldering method which can stabilize the amount of solder adhesion.

  The soldering apparatus of the present invention is a soldering apparatus for transporting and immersing a printed circuit board in jetted molten solder, the upper end portion being defined by a plate member extending vertically, and on one surface of the plate member A jet nozzle in which molten solder jets in contact, a duct arranged in the printed board conveyance direction with respect to the jet nozzle, and the molten solder flowing in contact with the other surface of the plate member, and a printed board conveyance direction in relation to the duct And an inert gas supply nozzle capable of supplying an inert gas toward the printed circuit board.

  According to the soldering apparatus of the present invention, the molten solder jets while contacting the one surface of the plate member extending vertically, and flows down while contacting the other surface arranged in the transport direction of the printed circuit board. The amount of excess molten solder that flows can be reduced. For this reason, it can suppress that a molten solder flows into the conveyance direction of a printed circuit board. Moreover, since inert gas is supplied toward the printed circuit board from the inert gas supply nozzle arranged in the printed circuit board transport direction with respect to the duct, the molten solder flowing in the printed circuit board transport direction is blocked by the inert gas. can do. For this reason, it can suppress that a molten solder flows into the conveyance direction of a printed circuit board. Therefore, the amount of solder adhesion can be stabilized.

It is a schematic side view of the soldering apparatus in one embodiment of the present invention. It is a schematic perspective view which shows the jet nozzle, duct, and inert gas supply nozzle periphery of the soldering apparatus in one embodiment of this invention. It is a schematic sectional drawing which shows the state by which the printed circuit board is soldered with the soldering apparatus in one embodiment of this invention. It is a schematic sectional drawing which shows a mode that molten solder jets from the jet nozzle of a comparative example. It is a schematic sectional drawing which shows the state by which the printed circuit board is soldered with the soldering apparatus of a comparative example.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Initially, the structure of the soldering apparatus of this Embodiment is demonstrated.

  Referring to FIGS. 1 and 2, the soldering apparatus according to the present embodiment is an apparatus for immersing and soldering in molten solder 2 that is conveyed and jetted from printed circuit board 1. The soldering apparatus according to the present embodiment includes a fluxer 3, a solder bath 4, a primary nozzle 5, a preheater 6, a conveyor 7, a jet nozzle 11, a duct 12, an inert gas supply nozzle 13, and a guide member. 14, a plate member 15, and an inclined member 16. For convenience of explanation, FIG. 1 also shows a printed circuit board 1, a molten solder 2, and an electronic component 10. Further, in FIG. 2, the molten solder 2 is shown by a broken line for easy viewing.

  The fluxer 3 is configured to be able to apply the flux 8 to the solder joint portion of the printed circuit board 1. The solder tank 4 is constituted by a hollow casing having at least a part of the upper surface opened. The solder bath 4 is formed so that the molten solder 2 can be stored inside the casing. The solder tank 4 includes solder supply means (not shown) for supplying the molten solder 2 stored in the solder tank 4 to the primary nozzle 5 and the jet nozzle 11. The solder supply means has, for example, a propeller and a drive means.

  The propeller is disposed inside the housing of the solder bath 4. For example, the propeller is rotatably disposed below the primary nozzle 5 and the jet nozzle 11. In addition to the propeller, a pump can be applied to the solder supply means. The propeller is connected to the driving means. The drive means has, for example, a motor and a motor shaft. The driving means is configured to rotate the propeller when the driving force of the motor is transmitted to the propeller via the motor shaft.

  The primary nozzle 5 is installed inside the solder bath 4 so as to protrude upward from the opened upper surface of the solder bath 4. The primary nozzle 5 is configured to jet the molten solder 2. The primary nozzle 5 is a nozzle for use in primary jet soldering. The primary nozzle 5 is disposed on the front side in the transport direction TD of the printed circuit board 1 with respect to the jet nozzle 11.

  The preheater 6 is configured to be able to preheat the printed circuit board 1. The conveyor 7 is configured to be able to transport the printed circuit board 1 in the transport direction TD. The conveyor 7 may be a belt conveyor, for example.

  Referring to FIGS. 2 and 3, jet nozzle 11 is configured such that molten solder 2 jets while contacting one surface 15 a of plate member 15. The jet nozzle 11 has an upper end portion 11a defined by a plate member 15 extending vertically. In this embodiment, the jet nozzle 11 is a nozzle for use in secondary jet soldering.

  The plate member 15 is provided so as to extend in the vertical direction. The plate member 15 forms a boundary between the jet nozzle 11 and the duct 12. Since the plate member 15 has a small area extending along the transport direction TD of the printed circuit board 1, the distance between the jet nozzle 11 and the duct 12 is short.

  The duct 12 is configured such that the molten solder 2 flows down while being in contact with the other surface 15 b of the plate member 15. The duct 12 is arranged with respect to the jet nozzle 11 in the transport direction TD of the printed board. The duct 12 is configured such that excess molten solder 2 flows in the transport direction TD of the printed circuit board 1. The duct 12 is disposed immediately below the peel back point PP where the printed circuit board 1 and the molten solder 2 are separated after immersion. The peel back point PP is positioned so as to overlap the duct 12 in the vertical direction.

  The material of the duct 12 may be Cu (copper) that easily wets the solder. The material of the duct 12 is at least one selected from the group consisting of Au (gold), Ag (silver), Cu (copper), Pd (lead), Ni (nickel), Pt (platinum), and Fe (iron). It only needs to contain an element.

The inert gas supply nozzle 13 is configured to be able to supply the inert gas G toward the printed circuit board 1. The inert gas supply nozzle 13 is disposed in the transport direction TD of the printed circuit board 1 with respect to the duct 12. The inert gas supply nozzle 13 is configured to be able to eject the inert gas G. As the inert gas G, N ₂ (nitrogen) gas can be used. The inert gas G is not limited to this, and Ar (argon) gas may also be used. The inert gas G only needs to contain at least one of Ar (argon) and N ₂ (nitrogen).

  The inert gas supply nozzle 13 has a guide member 14. The guide member 14 is provided so that the inert gas G supplied from the inert gas supply nozzle 13 can be guided toward the printed circuit board 1. The guide member 14 is provided so as to extend upward on the opposite side of the duct 12 of the inert gas supply nozzle 13. The guide member 14 is provided so as to be inclined toward the duct 12 side.

  The inclined member 16 is provided so as to extend downward on the front side of the jet nozzle 11 in the transport direction TD of the printed circuit board 1. The inclined member 16 is provided to be inclined to the opposite side to the duct 12.

  For the printed board 1, for example, a base material in which an epoxy resin is contained in glass cloth may be used. The printed circuit board 1 is not limited to this, and an insulating material, for example, a base material in which a polyimide resin, a phenol resin, or the like is contained in a glass nonwoven fabric or a paper base material may be used.

  Moreover, as a material of the molten solder 2, for example, a solder alloy (Sn-3Ag-0.0) containing 3% by mass Ag (silver) and 0.5% by mass Cu (copper) and the balance being Sn (tin) and inevitable impurities. 5Cu) can be used. The material of the molten solder 2 is not limited to this, but Sn—Cu solder, Sn—Bi (bismuth) solder, Sn—In (indium) solder, Sn—Sb (antimony) solder, or Sn— Any of Pb (lead) solder may be used.

Next, the operation and soldering method of the soldering apparatus according to the present embodiment will be described.
Referring to FIG. 1 again, a printed circuit board 1 on which an electronic component 10 is fixed with an adhesive is prepared. This printed circuit board 1 is conveyed by the conveyor 7 in the conveyance direction TD. First, flux 8 is applied to the soldering target surface of the printed circuit board 1 by the fluxer 3. The fluxer 3 has a spray nozzle, for example, and the flux 8 is injected from this spray nozzle. Thereby, the flux 8 adheres to the electrode pad 1a of the printed circuit board 1 which is a part to be soldered.

  Subsequently, the printed circuit board 1 coated with the flux 8 is preheated by the preheater 6. Then, the electrode pad 1a of the printed circuit board 1 is immersed in the molten solder 2 jetted from the primary nozzle 5, and immersion soldering is performed. In the present embodiment, primary jet soldering is performed by the primary nozzle 5, and secondary jet soldering is performed by the jet nozzle 11.

  Referring again to FIG. 3, molten solder 2 is jetted as shown by arrow A in the figure while coming into contact with one surface 15 a of plate member 15 from jet nozzle 11. Most of the jetted molten solder 2 flows down along the inclined member 16 to the side opposite to the transport direction TD of the printed circuit board 1. Also, the molten solder 2 that has contacted the printed circuit board 1 is attracted in the transport direction TD of the printed circuit board 1.

  A part of the molten solder 2 jetted from the jet nozzle 11 flows down the duct 12 while being in contact with the other surface 15 b of the plate member 15. Since the duct 12 is disposed immediately below the peel back point PP, the molten solder 2 separated from the printed circuit board 1 flows down to the duct 12. Therefore, the molten solder 2 is suppressed from flowing in the transport direction TD of the printed circuit board 1.

  Further, the inert gas G is injected from the inert gas supply nozzle 13 toward the peel back point PP of the printed circuit board 1. The inert gas G has an air curtain effect, and the flow of the molten solder 2 attracted in the transport direction TD of the printed circuit board 1 by the inert gas G is blocked. Thereby, a substantially constant peelback point is obtained. For this reason, the separation angle between the printed circuit board 1 and the molten solder 2 is controlled. Therefore, the solder adhesion amount is stabilized. Also, solder breakage is improved. Therefore, the highly reliable printed circuit board 1 in which defective solder is suppressed can be obtained.

Next, the effects of the present embodiment will be described in comparison with a comparative example.
4 and 5, the jet nozzle 11 of the comparative example does not have the duct 12 and the inert gas supply nozzle 13 of the present embodiment. Therefore, since the excess molten solder 2 jetted from the jet nozzle 11 also flows in the transport direction TD of the printed circuit board 1, the molten solder 2 acts in a direction in which the molten solder 2 is pressed against the electrode pad 1 a of the electronic component 10. For this reason, the molten solder 2 is attracted in the transport direction TD of the printed circuit board 1. Therefore, the peel back point PP is not stable. In addition, solder breakage becomes worse. As a result, a bridging failure may occur.

  On the other hand, according to the soldering apparatus of the present embodiment, the molten solder 2 jets while contacting the one surface 15a of the plate member 15 extending vertically, and contacts the other surface 15b arranged in the transport direction TD of the printed board 1. However, the amount of excess molten solder 2 flowing in the transport direction TD of the printed circuit board 1 can be reduced. For this reason, it can suppress that the molten solder 2 flows into the conveyance direction TD of the printed circuit board 1.

  Further, since the inert gas G is supplied toward the printed circuit board 1 from the inert gas supply nozzle 13 disposed in the transport direction TD of the printed circuit board 1 with respect to the duct 12, printing is performed by the air curtain of the inert gas G. The molten solder 2 flowing in the transport direction TD of the substrate 1 can be blocked. For this reason, it can suppress that the molten solder 2 flows into the conveyance direction TD of the printed circuit board 1.

  Therefore, the amount of solder adhesion can be stabilized. Therefore, bridging failure can be suppressed. Moreover, the formation of a bridge can be suppressed by forming a low oxygen atmosphere by supplying the inert gas G.

  In addition, according to the soldering apparatus of the present embodiment, the duct 12 is disposed immediately below the peel-back point PP where the printed circuit board 1 and the molten solder 2 are separated from each other after immersion, so that the molten material separated from the printed circuit board 1 is used. The solder 2 flows down into the duct 12. Therefore, it is possible to suppress the molten solder 2 from flowing in the transport direction TD of the printed circuit board 1.

Further, according to the soldering apparatus of this embodiment, the inert gas G because it contains at least one of Ar and N _2, it is possible to prevent oxidation of the molten solder 2. For this reason, deterioration of solder fluidity can be prevented. Thereby, the amount of solder adhesion can be stabilized.

  Further, according to the soldering apparatus of the present embodiment, the material of the duct 12 includes one or more elements selected from the group consisting of Au, Ag, Cu, Pd, Ni, Pt, and Fe. By making the material of the duct 12 a metal that easily wets the solder, the excess molten solder 12 attracted by the printed circuit board 1 in the transport direction TD can be pulled away by the wetting force of the duct 12.

  The soldering method of the present embodiment is a soldering method for transporting and immersing the printed circuit board 1 in the molten solder 2 jetted. According to the soldering method of the present embodiment, the method includes the steps of preparing a printed circuit board and transporting and immersing the printed circuit board 1 in the molten solder 2 jetted from the jet nozzle 11 of the soldering apparatus. Yes. For this reason, it can suppress that the molten solder 2 flows into the conveyance direction TD of the printed circuit board 1. Therefore, the amount of solder adhesion can be stabilized.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Printed circuit board, 1a Electrode pad, 2 Molten solder, 3 Fluxer, 4 Solder tank, 5 Primary nozzle, 6 Preheater, 7 Conveyor, 8 Flux, 10 Electronic components, 11 Jet nozzle, 11a Upper end part, 12 Duct, 13 Inactive Gas supply nozzle, 14 guide member, 15 plate member, 15a one surface, 15b other surface, 16 inclined member, G inert gas, PP peelback point, TD transport direction.

Claims (5)

A soldering device for transporting and immersing a printed circuit board in a jetted molten solder,
A jet nozzle in which an upper end portion is defined by a plate member extending vertically and the molten solder jets while contacting one surface of the plate member;
A duct that is disposed in the transport direction of the printed circuit board with respect to the jet nozzle, and the molten solder flows down while contacting the other surface of the plate member;
A soldering apparatus, comprising: an inert gas supply nozzle that is arranged in the transport direction of the printed circuit board with respect to the duct and that can supply an inert gas toward the printed circuit board.   The soldering apparatus according to claim 1, wherein the duct is disposed immediately below a peel-back point where the printed circuit board and the molten solder are separated after immersion. The soldering apparatus according to claim 1, wherein the inert gas includes at least one of Ar and N ₂ .   The soldering apparatus according to any one of claims 1 to 3, wherein the material of the duct includes one or more elements selected from the group consisting of Au, Ag, Cu, Pd, Ni, Pt, and Fe. A soldering method for transporting and immersing a printed circuit board in a jetted molten solder,
Preparing the printed circuit board;
A soldering method comprising: transporting and immersing the printed circuit board in the molten solder jetted from the jet nozzle of the soldering apparatus according to claim 1.

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