Soldering method and soldering device

Abstract

To prevent a soldering ball from being generated when soldering a land and a pad which have preliminary soldered layers formed on surfaces thereof to an electrode of an electronic component.SOLUTION: A method, which solders a land Ld having a preliminary soldered layer PS formed preliminarily on a surface of a print circuit board CB to a pin electrode P of an electronic component Ep, using a soldering iron tip 5a that has a soldering hole 51 in a nearly cylindrical shape which is penetrated through in a vertical direction and can be heated, includes the steps of: contacting a lower surface of the soldering iron tip 5a with the print circuit board CB; supplying a solder piece Wh into the soldering hole 51; and melting by heating the supplied solder piece Wh in the soldering hole 51 to solder the land Ld to the pin electrode P of the electronic component Ep. A recessed part 52 is provided on a lower surface of the soldering iron tip 5a that is used, where an opening at a lower end of the soldering hole 51 is formed on the bottom surface of the recessed part 52 and an inner peripheral surface of the recessed part 52 is positioned to surround the preliminary soldered layer PS in a planar view.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a soldering method and a soldering apparatus. [Background technology]

[0002] In recent years, most devices are equipped with printed circuit boards on which electronic components are mounted. In the process of manufacturing these printed circuit boards, soldering is performed to join various electronic components to the wiring patterns (lands, pads) of the printed circuit board. In addition, various soldering devices have been proposed to mechanically perform the soldering process, and some are already in use.

[0003] For example, one type of soldering device supplies a solder piece (a cut piece of solder wire with a layer of flux inside the solder layer) into a solder hole that penetrates the axial direction of a cylindrical soldering iron tip, and then heats and melts the solder in the solder hole and supplies it downward to perform soldering (e.g., Patent Document 1, etc.).

[0004] Furthermore, from the standpoint of performing soldering more reliably, a solder paste is often applied to the surfaces of lands and pads of a printed circuit board by screen printing to form a preliminary solder layer (see, for example, Patent Document 2, etc.). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2009-195938 A [Patent Document 2] JP 2010-80945 A Summary of the Invention [Problem to be solved by the invention]

[0006] When a land or pad with a preliminary solder layer formed on its surface is soldered to an electrode of an electronic component using a device that heats and melts a solder piece in a solder hole, the molten solder may splash around the land or pad, creating solder balls that may get between the wires and short out the circuit.

[0007] The present invention has been made in consideration of these conventional problems, and its purpose is to prevent the formation of solder balls when soldering lands or pads having a preliminary solder layer formed on their surface to electrodes of electronic components using a device that heats and melts a solder piece in a solder hole in the tip of a cylindrical soldering iron. [Means for solving the problem]

[0008] One embodiment of a soldering method according to the present invention which achieves the above-mentioned object is a method of soldering a land or pad on the surface of a printed circuit board on which a preliminary solder layer has been previously formed, to an electrode of an electronic component, using a heatable iron tip which is approximately cylindrical and has a solder hole penetrating in the vertical direction, the method comprising the steps of contacting the underside of the iron tip with the printed circuit board, supplying a solder piece into the solder hole, and heating and melting the supplied solder piece within the solder hole to solder the land or pad to the electrode of the electronic component, wherein the iron tip has a recess on its underside, the bottom surface of the recess is formed with a lower end opening of the solder hole, and the inner surface of the recess is positioned so as to surround the preliminary solder layer when viewed in a plane.

[0009] In a soldering method configured as described above, when the underside of the iron tip comes into contact with the printed circuit board, the recess formed on the underside of the iron tip surrounds the spare solder layer on the surface of the land or pad, thereby preventing the molten spare solder layer from being pushed out from the iron tip and splashing around the land or pad.

[0010] In the soldering method configured as described above, it is preferable that the vertical depth of the recess is greater than the vertical thickness of the spare solder layer.

[0011] With this arrangement, the pre-solder layer can be completely surrounded by the printed circuit board and the recess in the iron tip.

[0012] In the soldering method configured as described above, the vertical depth of the recess is preferably 25 μm or more and 500 μm or less.

[0013] In the above-mentioned soldering method, the pin electrodes protruding outward from the body of the electronic component are soldered to the printed circuit board. board When the pin electrode is inserted into a through hole and soldered to a land formed on the outer periphery of the through hole, it is preferable that the solder hole has an enlarged portion at its lower end which expands radially outward, and the sum of the vertical length of the enlarged portion and the vertical depth of the recess is longer than the protruding length of the pin electrode from the surface of the printed circuit board.

[0014] Furthermore, one embodiment of a soldering device according to the present invention which achieves the above-mentioned object is a soldering device which solders lands or pads on the surface of a printed circuit board on which a preliminary solder layer has been formed in advance to electrodes of an electronic component, and which comprises a heatable iron tip having a roughly cylindrical solder hole penetrating in the vertical direction, a solder piece supply means for supplying a solder piece into the solder hole, a heating means for heating the iron tip, and a moving means for relatively moving the iron tip and the printed circuit board in a contact direction and a separation direction, wherein the iron tip has a recess on its underside, a lower end opening of the solder hole is formed on the bottom surface of the recess, and the inner surface of the recess is positioned so as to surround the preliminary solder layer when viewed in a plane.

[0015] In the device having the above-mentioned configuration, the vertical depth of the recess is preferably greater than the vertical thickness of the spare solder layer.

[0016] In the device having the above-mentioned configuration, the vertical depth of the recess is preferably 25 μm or more and 500 μm or less.

[0017] In the device having the above configuration, the pin electrodes protruding outward from the body of the electronic component are connected to the printed circuit board. board When the pin electrode is inserted into a through hole and soldered to a land formed on the outer periphery of the through hole, it is preferable that the solder hole has an enlarged portion at its lower end which expands radially outward, and the sum of the vertical length of the enlarged portion and the vertical depth of the recess is longer than the protruding length of the pin electrode from the surface of the printed circuit board.

[0018] Furthermore, one embodiment of the soldering tip of the present invention which achieves the above-mentioned object is an iron tip for use with any of the soldering devices described above, characterized in that it has a roughly cylindrical solder hole which penetrates in the vertical direction, has a recess on its underside, a lower end opening of the solder hole is formed in the bottom surface of the recess, and the inner surface of the recess is positioned so as to surround the spare solder layer when viewed in a plane. Effect of the Invention

[0019] According to the soldering method and soldering apparatus of the present invention, it is possible to prevent the formation of solder balls when soldering a land or pad having a preliminary solder layer formed on its surface to an electrode of an electronic component. [Brief description of the drawings]

[0020] [Figure 1] 2 is a vertical cross-sectional view of an iron tip 5a and a printed circuit board CB according to the first embodiment. FIG. [Diagram 2] FIG. 2 is an enlarged plan view of a land Ld of the printed circuit board CB. [Diagram 3] 11 is a vertical cross-sectional view showing a state in which the iron tip 5a and the printed circuit board CB are in contact with each other. [Figure 4] 13 is a vertical cross-sectional view showing a state when a solder piece Wh is supplied to a solder hole 51. FIG. [Diagram 5] 1 is a vertical cross-sectional view showing a state in which the spare solder layer PS and the solder piece Wh are melted. [Figure 6] 1 is a vertical cross-sectional view showing a state in which a pin electrode P and a land Ld are soldered together. [Figure 7] 13 is a vertical cross-sectional view showing a state where a trowel tip 5b having a shallow depth dp of a recess 52 is used. FIG. [Figure 8] 13 is a vertical cross-sectional view showing a state where a trowel tip 5b having a shallow depth dp of a recess 52 is used. FIG. [Figure 9] FIG. 11 is a vertical sectional view showing another example of the trowel tip. [Figure 10] 1 is a perspective view of an example of a soldering apparatus AP according to an embodiment of the present invention. [Figure 11] FIG. 2 is a perspective view showing the internal structure of the device main body A1. [Figure 12] 3 is a schematic vertical sectional view of the device main body A1 shown in FIG. 2. [Figure 13] 3 is an exploded perspective view of a part of a drive mechanism provided in the apparatus main body A1 shown in FIG. 2. FIG. [Figure 14] FIG. 1 is an explanatory diagram of the cause (mechanism) of the generation of solder balls. [Figure 15] FIG. 1 is an explanatory diagram of the cause (mechanism) of the generation of solder balls. [Figure 16] FIG. 1 is an explanatory diagram of the cause (mechanism) of the generation of solder balls. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The inventors of the present invention have conducted extensive research into the cause of solder balls being generated around lands and pads when soldering lands or pads with a pre-solder layer formed on the surface to electrodes of electronic components using a device that heats and melts solder pieces in a solder hole. As a result, they have found that the main cause is that the pre-solder layer is heated and melted when the bottom surface of the iron tip comes into contact with the pre-solder layer and pressure is applied by the iron tip. The present invention was made based on this finding.

[0022] First, the cause (mechanism) of the generation of solder balls in a conventional soldering device will be specifically described with reference to Figures 14 to 16. These figures are partial vertical cross-sectional views of the soldering tip 5e and the printed circuit board CB.

[0023] The iron tip 5e is a cylindrical member having a solder hole 51 with a circular cross section that penetrates the center in the axial direction. The solder hole 51 has an enlarged portion 510 at the bottom end that expands radially outwardly in a concentric manner with the center axis C1 of the solder hole 51. The iron tip 5e is heated by a heater (not shown). Solder pieces Wh (shown in FIG. 16) are supplied to the solder hole 51 of the iron tip 5e from a supply means (not shown).

[0024] The printed circuit board CB has a board body Bd, through holes Th penetrating the board body Bd in the vertical direction, lands Ld formed around the through holes Th on both the upper and lower surfaces of the board body Bd, spare solder layers PS formed on the surfaces of the lands Ld, and a solder resist SR covering the surface of the board body Bd other than the lands Ld (spare solder layers PS). The upper surface of the spare solder layers PS protrudes above the upper surface of the solder resist SR.

[0025] The pin electrodes P of the electronic component Ep are inserted through the through holes Th from the bottom to the top, and the tips of the pin electrodes P protrude upward from the top surface of the printed circuit board CB.

[0026] As shown in FIG. 14, when the pin electrode P of the electronic component Ep and the land Ld of the printed circuit board CB are soldered, the tip of the iron 5e first moves relatively to the printed circuit board CB in a direction approaching the printed circuit board CB. Then, the lower surface of the tip of the iron 5e comes into contact with the upper surface of the spare solder layer PS on the surface of the land Ld. Then, as shown in FIG. 15, the spare solder layer PS is heated and melted mainly by heat transfer from the tip of the iron 5e while being pressed by the tip of the iron 5e. The molten spare solder layer PS is spread over the surface of the land Ld by the lower surface of the tip of the iron 5e. Then, as shown in FIG. 16, a part of the molten spare solder layer PS is pushed out from the lower surface of the tip of the iron 5e to the outside of the tip of the iron 5e. The molten solder pushed out from the tip of the iron 5e is spherically shaped by surface tension and cooled to become a solder ball SB.

[0027] In consideration of the mechanism by which such solder balls SB are generated, in the soldering method and device according to the present invention, a recess whose inner circumferential surface surrounds the spare solder layer in plan view is formed on the underside of the iron tip.

[0028] (First embodiment) Fig. 1 shows a vertical cross-sectional view of an iron tip 5a and a printed circuit board CB according to an embodiment of the present invention. Fig. 2 is an enlarged plan view of a land Ld of the printed circuit board CB, in which a spare solder layer PS formed on the upper surface of the land Ld and an inner peripheral surface of a recess 52 of the iron tip 5a are shown by dashed lines.

[0029] The tip 5a is cylindrical and has a solder hole 51 with a circular cross section penetrating the center in the axial direction. The solder hole 51 has an enlarged portion 510 at the lower end, which expands concentrically radially outward around the central axis C1 of the solder hole 51. A recess 52 is formed on the lower surface of the tip 5a, which expands concentrically around the central axis C1 of the solder hole 51 and has a depth dp from the lower surface. In other words, the lower end opening of the enlarged portion 510 of the solder hole 51 is formed on the bottom surface (upper surface) of the recess 52 formed on the lower surface of the tip 5a. The tip 5a also has a release hole 53 above the enlarged portion 510, which communicates with the solder hole 51 and the outer circumferential surface. The release hole 53 plays a role in releasing nitrogen gas supplied from a gas supply unit (not shown) and vaporized flux to the outside of the tip 5a when the lower end opening of the solder hole 51 is blocked by molten solder.

[0030] Meanwhile, a land Ld having a circular shape in a plan view is formed on the board body Bd of the printed circuit board CB, and a through-hole Th is formed in the center of the land Ld. A spare solder layer PS having a thickness of t is formed on the upper surface of the land Ld. The surface of the board body Bd other than the land Ld (spare solder layer PS) is covered with a solder resist SR. A pin electrode P of an electronic component Ep is inserted from the bottom to the top into the through-hole Th, and the tip of the pin electrode P protrudes upward from the top surface of the printed circuit board CB.

[0031] 1 and 2, the inner diameter D of the recess 52 formed on the lower surface of the iron tip 5a is larger than the outer diameter d of the preliminary solder layer PS applied to the land Ld, and the depth dp of the recess 52 is set deeper than the thickness t of the preliminary solder layer PS. There is no particular limitation on the depth dp of the recess 52, but a range of 25 μm to 500 μm is usually sufficient.

[0032] As will be described later with reference to Fig. 10, the control means Cont of the soldering device AP controls the rotational movement of the articulated arm Am of the manipulator ML to move the iron tip 5a of the device body A1 to a position (separate position) where the central axis C1 of the iron tip 5a is aligned with and spaced upward from the central axis C2 of the pin electrode P protruding from the printed circuit board CB, as shown in Fig. 1. Next, as shown in Fig. 3, the control means Cont controls the manipulator ML to move the iron tip 5a downward.

[0033] As shown in Fig. 3, when the soldering tip 5a moves in a direction approaching the printed circuit board CB, unlike the conventional soldering device shown in Figs. 14 to 16, the bottom surface of the soldering tip 5a abuts against the solder resist SR without contacting the spare solder layer PS due to the recess 52 formed on the bottom surface of the soldering tip 5a. The inner diameter D of the recess 52 formed on the bottom surface of the soldering tip 5a is larger than the outer diameter d of the spare solder layer PS, and the inner peripheral surface of the recess 52 is positioned so as to surround the spare solder layer PS in a plan view. The vertical depth dp of the recess 52 is deeper than the thickness t of the spare solder layer PS, and the top surface of the spare solder layer PS does not contact the bottom surface (top surface) of the recess 52. In other words, the spare solder layer PS is surrounded by the recess 52 with a predetermined gap.

[0034] This effectively prevents the conventional problem of a portion of the pre-solder layer being heated and melted by the iron tip being pushed out from the underside of the iron tip to the outside of the iron tip, thereby forming a solder ball.

[0035] Next, as shown in FIG. 4, a solder piece Wh is supplied to the solder hole 51 of the iron tip 5a. The spare solder layer PS is surrounded by the recess 52, in other words, the spare solder layer PS is not in contact with the iron tip 5a, so it cannot directly receive heat from the iron tip 5a, and when the solder piece Wh is supplied to the solder hole 51, the heating and melting of the spare solder layer PS does not progress significantly. On the other hand, the solder piece Wh supplied into the solder hole 51 usually has a part in contact with the inner peripheral wall of the solder hole 51 (except when the solder piece Wh stands on the pin electrode P without contacting the inner peripheral wall of the solder hole 51), so the solder piece Wh is directly heated by heat transfer from the iron tip 5a. The amount of heat transferred from the iron tip 5a is large, and the solder piece Wh is heated to the melting temperature in a short time. In the heating and melting process of the solder piece Wh, the flux, which has a melting temperature lower than that of the solder, melts first and flows onto the surface of the solder piece Wh. Since the flux has a higher thermal conductivity than solder, heat transfer from the iron tip 5a to the solder piece Wh is accelerated via the flux. Also, some of the flux that flows down from the solder piece Wh reaches the gap between the surface of the spare solder layer PS and the iron tip 5a (recess 52), and heat transfer from the iron tip 5a to the spare solder layer PS is also accelerated via the flux.

[0036] Then, as shown in Fig. 5, when the temperatures of the solder piece Wh and the spare solder layer PS reach the melting temperature, the solder piece Wh and the spare solder layer PS melt and become one body (molten solder MS). Then, as shown in Fig. 6, part of the molten solder MS flows down inside the through hole Th, and as the iron tip 5a moves upward away from the printed circuit board CB, the molten solder MS is cooled and solidified by the outside air, and a cone-shaped fillet of solder is formed between the land Ld and the pin electrode P, and the land Ld and the pin electrode P are soldered together.

[0037] Second embodiment 7 and 8 are vertical cross-sectional views showing the main parts of the soldering apparatus and method according to the second embodiment. The apparatus and method according to the second embodiment shown in these figures differ from the first embodiment in that the depth dp of the recess 52 formed on the lower surface of the soldering tip 5b is shallower than the thickness t of the spare solder layer PS.

[0038] 7, in the device and method configured as above, when the iron tip 5b moves relatively in a direction approaching the printed circuit board CB, the bottom surface (upper surface) of the recess 52 of the iron tip 5b comes into contact with the upper surface of the spare solder layer PS, and a gap G is formed between the lower surface of the iron tip 5b and the surface of the printed circuit board CB. However, similar to the first embodiment, the inner diameter D of the recess 52 formed in the lower surface of the iron tip 5b is larger than the outer diameter d of the spare solder layer PS, and the inner peripheral surface of the recess 52 is positioned so as to surround the spare solder layer PS in a plan view.

[0039] Since the bottom surface of the recess 52 contacts the upper surface of the preparatory solder layer PS, heat is directly transferred from the iron tip 5b to the preparatory solder layer PS, unlike the first embodiment. Also, a downward force is constantly applied to the preparatory solder layer PS by the iron tip 5b. Therefore, the preparatory solder layer PS is heated and melted faster than in the first embodiment. Then, as with the conventional device and method shown in Figs. 14 to 16, the iron tip 5b moves downward as the preparatory solder layer PS melts, and the bottom surface of the iron tip 5b comes into contact with the printed circuit board CB (solder resist SR).

[0040] 14 to 16, the inner peripheral surface of the recess 52 is positioned so as to surround the spare solder layer PS in a plan view, so that the molten spare solder layer PS remains within the recess 52 and the enlarged portion 510 of the iron tip 5b and is not pushed out of the iron tip 5b, as shown in FIG. S.B. (shown in FIG. 16) is effectively prevented.

[0041] (Another example of a trowel tip) FIG. 9 is a vertical cross-sectional view showing another example of the iron tip that can be used in the present invention. Due to deformation of the printed circuit board CB or an error in the installation accuracy of the iron tip, the iron tip may not be in contact with the printed circuit board CB perpendicularly, resulting in a small gap between the printed circuit board CB and the bottom surface of the iron tip. At this time, although it is rare, the molten solder in the solder hole 51 may enter the gap and adhere to the outer periphery of the lower end of the iron tip in the form of a ball (solder ball). The solder ball adhered to the outer periphery of the lower end of the iron tip may fall from the iron tip onto the printed circuit board CB due to the impact when the iron tip moves. If the solder ball falls between the wiring, it will short the circuit. Therefore, in the iron tip 5c shown in FIG. 9(a), a chamfered portion 511 is formed on the outer periphery of the lower end of the iron tip 5c. By forming such a chamfered portion 511 on the outer periphery of the lower end of the iron tip 5c, the adhesion of the solder ball to the outer periphery of the lower end of the iron tip is prevented. This has been confirmed by experiments conducted by the present inventors.

[0042] The iron tip 5d shown in FIG. 9(b) is the same as the iron tip 5a of the first embodiment in that it has a cylindrical shape, a solder hole 51 with a circular cross section penetrating in the axial direction in the center, and a release hole 53 in the upper part that communicates with the solder hole 51 and the outer circumferential surface, but differs from the iron tip 5a of the first embodiment in that no enlarged portion 510 is formed below the solder hole 51. The enlarged portion 510 is for providing a margin when inserting the pin electrode P into the solder hole 51 of the iron tip 5a, so when the relative movement accuracy of the iron tip 5a with respect to the printed circuit board CB is high, the enlarged portion 510 is not required, and it is also possible to use the iron tip 5d without the enlarged portion 510 shown in FIG. 9(b). In addition, when soldering a pad on the surface of the printed circuit board CB to an electrode of an electronic component placed on the pad (when there is no through hole Th), it is also possible to use the iron tip 5d of this type.

[0043] (Overall configuration of soldering device) 10 is a perspective view of a soldering apparatus AP that performs soldering using the soldering iron tip 5a described above. In this case, the soldering apparatus AP solders an electronic component Ep to a printed circuit board CB. Four through holes Th are formed in the printed circuit board CB fixed to a jig Gj, and lands Ld are formed on the inner circumferential surface and periphery of each through hole Th. Four pin electrodes P extending from the electronic component Ep arranged on the back surface side of the printed circuit board CB are inserted from below to above into each of the four through holes Th, with the tips of the pin electrodes P protruding from the top surface of the printed circuit board CB.

[0044] On the other hand, the soldering device AP according to the present invention includes a manipulator ML as a moving means having a multi-joint arm Am, a device body A1 attached to the tip of the manipulator ML, and a control device Cont for controlling the operation of the manipulator ML and the device body A1. The manipulator ML is installed on a base Bs, and the multi-joint arm Am is rotatable at each of a plurality of joints. The control device Cont controls the rotational operation of the multi-joint arm Am of the manipulator ML to move the device body A1 to a desired position in the X direction, Y direction, and Z direction. The control device Cont also controls the operation of a cutter unit 2, a drive mechanism 3, a solder feed mechanism 6, and a heater unit (heating means) 4 of the device body A1, which will be described later. In this embodiment, the cutter unit 2, the drive mechanism 3, and the solder feed mechanism 6 constitute a solder piece supplying means.

[0045] When soldering is performed by the soldering device AP, the device body A1 is moved in the X and Y directions by the manipulator ML to position the device body A1 relative to the land Ld of the printed circuit board CB. Then, the device body A1 is moved in the Z direction, so that the tip of the iron tip 5a comes into contact with the land Ld. In the embodiment described below, the soldering device AP is used to position the pin electrode P protruding from the upper surface of the printed circuit board CB in the solder hole 51 (shown in FIG. 12) of the iron tip 5a of the device body A1, and the solder piece Wh supplied to the solder hole 51 of the iron tip 5a is melted to solder the pin electrode P and the land Ld. In this embodiment, the device body A1 is moved, but the device body A1 may be fixed and the printed circuit board CB may be moved, or both the device body A1 and the printed circuit board CB may be moved.

[0046] Such movement control of the trowel tip 5a by the control means Cont may be performed based on a preset input value, or based on a detection signal from a detection means (not shown) such as a contact sensor.

[0047] (Device body A1) Fig. 11 shows a perspective view of the device main body A1, Fig. 12 shows a vertical cross-sectional view of the soldering device shown in Fig. 11, and Fig. 13 is an exploded perspective view of a part of a drive mechanism provided in the soldering device shown in Fig. 11. In Fig. 11, a part of the housing is cut away to show the inside of the device main body A1.

[0048] As shown in FIG. 11, the device main body A1 has an equipment unit U, a support member SP that supports the equipment unit U movably within a predetermined distance range in the Z direction, and a cover C (dashed line in FIG. 11) that covers the equipment unit U and the support member SP.

[0049] The support member SP comprises a plate-shaped base Mf having a rectangular YZ plane and a predetermined thickness in the X direction, a guide rail Mg having a predetermined width in the Y direction at the center of the Y direction on one side of the base Mf in the X direction, protruding in the X direction and continuing in the Z direction, and a block Mb attached to the guide rail Mg so as to be movably attached in the Z direction.

[0050] The upper end of the base Mf in the Z direction is attached to the tip of the articulated arm Am of the manipulator ML. A wall 11 of the equipment unit U is attached to the block Mb over almost the entire area in the Z direction. In other words, the equipment unit U is fixed to the block Mb and can move in the Z direction together with the block Mb. In addition, a movement restriction pin 91 is provided at the lower end of one side surface of the block Mb in the Y direction so as to protrude vertically outward from the side surface.

[0051] Meanwhile, rectangular parallelepiped upper and lower stopper portions 93 and 94 are provided at the Y-direction end position of the lower Z-direction of one side surface in the X-direction of the base portion Mf so as to face each other and be spaced a predetermined distance apart in the Z direction.

[0052] The movement restricting pin 91 provided on one side of the block Mb is located in an area between an upper stopper portion 93 and a lower stopper portion 94 of the base portion Mf, and in the initial state, i.e., when the iron tip 5a is not in contact with the wiring board Bd, the movement restricting pin 91 is in contact with the lower stopper portion 94 due to the weight of the equipment unit U and the block Mb. In other words, the movement of the equipment unit U downward in the Z direction is restricted by the movement restricting pin 91 abutting against the lower stopper portion 94. On the other hand, when the iron tip 5a abuts against the wiring board Bd and the equipment unit U moves upward in the Z direction, the movement restricting pin 91 abuts against the upper stopper portion 93, and the movement of the equipment unit U upward in the Z direction is restricted.

[0053] (Equipment unit U) The equipment unit U includes a support portion 1, a cutter unit 2, a drive mechanism 3, a heater unit 4, a solder tip 5a, and a solder feed mechanism 6.

[0054] The support portion 1 includes a vertically disposed flat wall 11. In the following description, for convenience, the horizontal direction along the wall 11 is defined as the X direction, the horizontal direction perpendicular to the wall 11 is defined as the Y direction, and the vertical direction along the wall 11 is defined as the Z direction, as shown in Fig. 11. For example, as shown in Fig. 11, the wall 11 has a ZX plane.

[0055] The support portion 1 includes a wall body 11, a holding portion 12, a sliding guide 13, and a heater unit fixing portion 14. The wall body 11 is a flat wall body erected in the vertical direction. The wall body 11 serves as a support member for the device main body A1. The holding portion 12 is fixed at a position shifted upward from the lower end portion of the wall body 11 in the Z direction. The holding portion 12 holds an air cylinder 31 of the drive mechanism 3, which will be described later. The heater unit fixing portion 14 is a member that fixes the heater unit 4, and is provided at the end portion (lower end portion) of the wall body 11 in the Z direction.

[0056] The sliding guide 13 is fixed near the lower end of the wall 11 in the Z direction. The sliding guide 13 is fixed to the wall 11 together with a lower cutter blade 22 (described later) of the cutter unit 2, and guides an upper cutter blade 21 (described later) of the cutter unit 2 so that the upper cutter blade 21 can slide in the X direction.

[0057] The sliding guides 13 are a pair of members facing each other in the Y direction. The sliding guides 13 have a pair of wall portions 131 and a retaining portion 132. The wall portions 131 are flat plate-shaped members extending in the X direction. One wall portion 131 is disposed in contact with the wall body 11, and the surface opposite the wall body 11 is in contact with the cutter lower end 22. The other wall portion 131 is in contact with a side surface of the cutter lower blade 22. That is, the pair of walls 131 sandwich the cutter lower blade 22 from both sides in the Y direction. The pair of walls 131 and the cutter lower blade 22 are fastened together to the wall body 11 by fasteners such as screws and fixed.

[0058] The retaining portions 132 are provided on each of the pair of wall portions 131. The pair of wall portions 131 extend in the Z direction further than the Z direction upper surface of the cutter lower blade 22, and each extends from the upper end portion of the pair of wall portions 131 in the Z direction toward the other. That is, the sliding guide 13 has a pair of retaining portions 132. The Y direction tips of the pair of retaining portions 132 do not contact each other, in other words, the sliding guide 13 has an opening at the top. At least a portion of the cutter upper blade 21 is disposed between the upper surface of the cutter lower blade 22 and the retaining portions 132. As a result, the cutter upper blade 21 is guided in the X direction and prevented from coming off in the Z direction.

[0059] The cutter unit 2 is a cutting tool that cuts the wire solder W fed by the solder feed mechanism 6 into solder pieces Wh of a predetermined length. The cutter unit 2 includes an upper cutter blade 21, a lower cutter blade 22, and a pusher pin .

[0060] As described above, the lower cutter blade 22 is fixed to the wall body 11 together with the sliding guide 13. As shown in FIG. 12, the lower cutter blade 22 includes a lower blade hole 221 and a gas inlet hole 222. The lower blade hole 221 is a through hole penetrating the lower cutter blade 22 in the Z direction, and the solder wire W penetrating the upper blade hole 211 (described later) of the upper cutter blade 21 is inserted into the lower blade hole 221. The upper edge of the lower blade hole 221 is formed in a cutting blade shape. The upper blade hole 211 and the lower blade hole 221 are used to cut the solder wire W into solder pieces Wh of a predetermined length. The cut solder pieces Wh fall downward inside the lower blade hole 221 by their own weight or by being pushed by the pusher pin 23. The lower blade hole 221 communicates with a solder hole 51 (described later) of the iron tip 5a through a solder supply hole 422 (described later) of the heater unit 4. The solder piece Wh that has fallen inside the lower blade hole 221 reaches the solder supply hole 422 and then falls into the solder hole 51.

[0061] The gas inlet hole 222 is a hole that communicates the outer surface of the cutter lower blade 22 with the lower blade hole 221. Gas supplied from a gas supply source (not shown) flows into the gas inlet hole 222. The gas passes through the lower blade hole 221 and the solder supply hole 422 and reaches the solder hole 51. The gas is used to suppress oxidation of the solder when the solder is heated and melted. In other words, the gas is used to suppress contact between the molten solder and oxygen. Examples of the gas include nitrogen gas, argon gas, helium gas, and carbon dioxide. In the soldering device AP of this embodiment, nitrogen gas is supplied.

[0062] As described above, the upper cutter blade 21 is disposed on the Z-direction upper surface of the lower cutter blade 22. The upper cutter blade 21 is guided by the sliding guide 13 so that the sliding direction is the X-direction when sliding, and is prevented from coming off in the Z-direction. That is, the upper cutter blade 21 slides in the X-direction on the Z-direction upper surface of the lower cutter blade 22. The upper cutter blade 21 is slid by the drive mechanism 3.

[0063] The cutter upper blade 21 has an upper blade hole 211 and a pin hole 212. The upper blade hole 211 is a through hole that passes through the cutter upper blade 21 in the Z direction, and the thread solder W sent from the solder feed mechanism 6 is inserted into the upper blade hole 211. The edge portion of the lower end of the upper blade hole 211 is formed into a cutting blade shape. The pin hole 212 is a through hole that passes through the cutter upper blade 21 in the Z direction. A rod portion 231 of the pusher pin 23, which will be described later, is slidably inserted into the pin hole 212.

[0064] The pusher pin 23 has a rod portion 231, a head portion 232, and a spring 233. The rod portion 231 is a columnar member, and is slidably inserted into the pin hole 212. When the pusher pin 23 moves downward in the Z direction, the tip of the rod portion 23 protrudes from the pin hole 212. The head portion 232 is connected to the upper end of the rod portion 231 in the axial direction. The head portion 232 is a disk shape having an outer diameter larger than the inner diameter of the pin hole 212. The head portion 232 is not inserted into the pin hole 212. That is, the head portion 232 serves as a so-called stopper that limits the movement of the rod portion 231 into the pin hole 212.

[0065] The spring 233 is a compression coil spring surrounding the radial outside of the rod portion 231. The Z-direction lower end of the spring 233 contacts the upper surface of the cutter upper blade 21, and the Z-direction upper end of the spring 233 contacts the lower surface of the head portion 232. That is, the spring 233 receives a reaction force from the upper surface of the cutter upper blade 21 and pushes the head portion 232 upward in the Z direction. As a result, the rod portion 231 connected to the head portion 232 is lifted upward in the Z direction, and the lower end of the rod portion 231 is maintained so as not to protrude from the lower end of the pin hole 212. The Z-direction lower end of the rod portion 231 is provided with a stopper (not shown) that prevents the rod portion 231 from coming out of the pin hole 212.

[0066] The pusher pin 23 pushes downward the solder pieces Wh that have been cut by the upper cutter blade 21 and the lower cutter blade 22 and remain in the lower blade hole 221. The pusher pin 23 is always pushed upward, i.e., toward the opposite side to the lower cutter blade 22, by the elastic force of the spring 233. In other words, when the head portion 232 is pushed, the rod portion 231 protrudes downward from the lower end portion of the pin hole 212 in the Z direction. The head portion 232 is pushed by a cam member 33 of the drive mechanism 3, which will be described later.

[0067] In the upper cutter blade 21, the upper blade hole 211 and the pin hole 212 are arranged side by side in the X direction. The upper cutter blade 21 slides in the X direction to move to a position where the upper blade hole 211 and the lower blade hole 221 overlap vertically, or to a position where the pin hole 212 and the lower blade hole 221 overlap vertically. The upper cutter blade 21 may slide such that the upper blade hole 211 and the lower blade hole 221 overlap when it slides to one sliding end, and the pin hole 212 and the lower blade hole 221 overlap when it slides to the other sliding end.

[0068] When the solder thread W is fed from the solder feed mechanism 6 with the upper blade hole 211 and the lower blade hole 221 overlapping in the Z direction, the solder thread W that has passed through the upper blade hole 211 is inserted into the lower blade hole 221. As described above, the edge of the lower end of the upper blade hole 211 is formed into a cutting edge, and the edge of the upper end of the lower blade hole 221 is also formed into a cutting edge. The lower surface of the upper cutter blade 21 is in contact with the upper surface of the lower cutter blade 22. Therefore, when the upper cutter blade 21 slides in the X direction with the solder thread W inserted into the lower blade hole 221, the solder thread W is cut by the cutting edges of the upper blade hole 211 and the lower blade hole 221.

[0069] The upper cutter blade 21 is slid in the X direction by the cam member 33. Therefore, the upper cutter blade 21 and the pusher pin 23 are synchronized with the cam member 33. The cam member 33 pushes the head portion 232 when the pin hole 212 overlaps with the lower blade hole 221 in the Z direction. Therefore, when the upper cutter blade 21 slides in the X direction, the tip of the rod portion 231 of the pusher pin 23 is housed in the pin hole 212. Therefore, when the upper cutter blade 21 slides in the X direction, the tip of the rod portion 231 is prevented from coming into contact with the upper surface of the lower cutter blade 22, and deformation, damage, etc. of the tip of the rod portion 231 and / or the lower cutter blade 22 are prevented.

[0070] As the cutter upper blade 21 slides in the X direction, the lower blade hole 211 and the pin hole 212 overlap in the Z direction. With the pin hole 212 overlapping the lower blade hole 211, the head portion 232 is pushed by the cam member 33. This causes the pusher pin 23 to move downward in the Z direction. When the pusher pin 23 protrudes downward in the Z direction from the pin hole 212, a part of the pusher pin 23 is inserted into the lower blade hole 211. If a piece of solder remains at the entrance of the lower blade hole 211 after the solder wire is cut, the tip of the pusher pin 23 pushes the piece of solder, causing it to fall.

[0071] As shown in FIG. 11 and FIG. 12, the driving mechanism 3 has an air cylinder 31, a piston rod 32, a cam member 33, a slider portion 34, and a guide shaft 35. The air cylinder 31 is held by the holding portion 12. The air cylinder 31 is cylindrical with a bottom. The piston rod 32 is housed inside the air cylinder 31, and the piston rod 32 is slidably driven (extends and contracts) by the pressure of air supplied from the outside. The air cylinder 31 and the piston rod 32 constitute an actuator of the driving mechanism 3. The piston rod 32 is disposed inside the air cylinder 31, and a part of the piston rod 32 always protrudes from one end of the air cylinder 31 in the axial direction (here, the lower end in the Z direction). The air cylinder 31 is held by the holding portion 12 so that the surface from which the piston rod 32 protrudes faces the cutter unit 2, that is, faces downward in the Z direction.

[0072] The piston rod 32 passes through a through hole (not shown) provided in the holding portion 12. The piston rod 32 is provided parallel to a guide shaft 35, and linearly reciprocates along the guide shaft 35. The tip of the piston rod 32 is fixed to a cam member 33, and the extension and contraction of the piston rod 32 causes the cam member 33 to slide in the Z direction. The sliding of the cam member 33 is guided by the guide shaft 35.

[0073] 12, the lower end of the guide shaft 35 is fitted into a recessed hole provided in the lower cutter blade 22, and is fixed to the lower cutter blade 22 with a screw 351. The upper part of the guide shaft 35 passes through a hole provided in the holder 12, and its movement is restricted by a pin 352. In other words, the guide shaft 35 is fixed to the lower cutter blade 22 by the screw 351, and to the holder 12 by the pin 352.

[0074] In this embodiment, the guide shaft 35 is fixed by the screw 351 and the pin 352, but this is not limited thereto, and it may be fixed by a fixing method such as press fitting, welding, etc. Also, in this embodiment, the guide shaft 35 is a cylindrical member, but this is not limited thereto, and it may be a polygonal or elliptical cross-sectional shape, etc.

[0075] 12 and 13, the cam member 33 is a rectangular member and includes a recess 330 formed by cutting out a portion of a long side in a rectangular shape, and a cylindrical support portion 331 connected to the cam member 33 and having a through hole through which the guide shaft 35 passes. The slider portion 34 is disposed in the recess 330 so as to be slidable (in the X and Z directions). The support portion 331 has a shape extending parallel to the guide shaft 35, and is provided to suppress rattling of the cam member 33. In other words, in the case where the cam member 33 has a certain thickness and is configured so as not to rattle, the cylindrical portion may be omitted and the support portion 331 may be configured only with a through hole.

[0076] The cam member 33 includes a cylindrical pin 332 provided in the middle of the recess 330 and having a central axis perpendicular to the guide shaft 35, a pin pushing portion 333 adjacent to the recess 330 for pushing the pusher pin 23, and a bearing 334 disposed inside the support portion 331. The pin 332 is inserted into a cam groove 340 (described later) provided in the slider portion 34. The bearing 334 is a member that fits around the guide shaft 35 and allows the cam member 33 to slide smoothly without rattling.

[0077] As shown in Figs. 12 and 13, the slider portion 34 is a rectangular plate-like member and is formed integrally with the cutter upper blade 21. The slider portion 34 has a cam groove 340 that penetrates in the plate thickness direction and extends in the longitudinal direction. The cam groove 340 has a first groove portion 341 extending parallel to the guide shaft 35 on the upper side and a second groove portion 342 extending parallel to the guide shaft 35 on the lower side. The first groove portion 341 and the second groove portion 342 are offset in the X direction, and the cam groove 340 has a connecting groove portion 343 that connects the first groove portion 341 and the second groove portion 342.

[0078] A pin 332 of the cam member 33 is inserted into the cam groove 340, and as the cam member 33 moves along the guide shaft 35, the pin 332 slides on the inner surface of the cam groove 340. When the pin 332 is positioned in a connection groove portion 343 of the cam groove 340, it presses the inner surface of the connection groove portion 343. This causes the slider portion 34 and the cutter upper blade 21 formed integrally with the slider portion 34 to move (slide relative to the cutter lower blade 22) in a direction (X direction) intersecting the sliding direction of the cam member 33 (Z direction).

[0079] In this embodiment, a configuration is described in which the cam member 33 has the pin 332 and the slide portion 34 has the cam groove 340. However, in reality, the cam member may have the cam groove and the slide portion may have the pin.

[0080] In this embodiment, air pressure is used as the actuator of the drive mechanism 3, but this is not limited to this and it may be one that uses a fluid other than air (for example, hydraulic oil) (hydraulics). Also, this is not limited to using a fluid and it may be one that uses electricity such as a motor or a solenoid. In this embodiment, the sliding of the cutter upper blade 21 and the pressing down of the pusher pin 23 are performed using one actuator, a cam, and a cam groove, but this is not limited to this. For example, multiple actuators (two actuators) may be provided to perform the sliding of the cutter upper blade 21 and the pressing down of the pusher pin 23.

[0081] As shown in Figures 11 and 12, the solder feed mechanism 6 supplies the solder wire W. The solder feed mechanism 6 includes a pair of feed rollers 61 and a guide tube 62. The pair of feed rollers 61 are rotatably attached to the support wall 11. The pair of feed rollers 61 rotate while sandwiching the sides of the solder wire W, thereby feeding the solder wire downward. The pair of feed rollers 61 are biased toward each other, and the biasing force sandwiches the solder wire W. The length of the fed solder wire W is measured (determined) based on the rotation angle (number of rotations) of the feed rollers 61.

[0082] The guide tube 62 is an elastically deformable tube, and its upper end is disposed close to the portion of the feed roller 61 from which the solder thread W is fed. The lower end of the guide tube 62 is provided so as to communicate with the upper blade hole 211 of the upper cutter blade 21. The lower end of the guide tube 62 moves following the sliding of the upper cutter blade 21, and the guide tube 62 has a length and shape that prevent it from being excessively pulled or stretched within the range in which the upper cutter blade 21 slides.

[0083] The heater unit 4 is a heating device for heating and melting the solder pieces Wh, and is fixed to a heater unit fixing part 14 provided at the lower end of the wall body 22, as shown in Fig. 12. The heater unit 4 includes a heater 41 and a heater block 42. The heater 41 generates heat when electricity is applied. Here, the heater 41 has an electric heating wire wound around the outer circumferential surface of the cylindrical heater block 42.

[0084] The heater block 42 has a cylindrical shape and is provided with a recess 421 having a circular cross section for attaching the iron tip 5a at its axial end, and a solder supply hole 422 penetrating from the center of the bottom of the recess 421 to the opposite side. The heater block 42 is provided in contact with the cutter lower blade 22 so that the solder supply hole 422 and the lower blade hole 221 communicate with each other. By providing the heater block 42 in this manner, the solder piece Wh moves from the lower blade hole 221 to the solder supply hole 422.

[0085] (Soldering device operation) Next, the operation of the soldering apparatus AP will be described. As shown in Fig. 1 and Fig. 10, the control means Cont controls the rotational operation of the articulated arm Am of the manipulator ML to move the iron tip 5a of the apparatus main body A1 to a position (apart position) where the central axis C1 of the iron tip 5a is aligned with the central axis C2 of the pin terminal P protruding from the printed circuit board Bd and is spaced upward. Next, as shown in Fig. 3, the control means Cont controls the manipulator ML to move the iron tip 5a downward, so that the lower surface of the iron tip 5a abuts against the solder resist SR of the printed circuit board Bd, and the pin terminal P of the electronic component Ep is positioned within the solder hole 51 of the iron tip 5a. Heat is transferred to the iron tip 5a from the heater 41 (shown in FIG. 12), and when the iron tip 5a comes into contact with the land Ld, the land Ld is heated by heat transfer through the solder resist SR of the printed circuit board Bd (preheating), and the pin terminal P of the electronic component Ep is also heated by heat transfer via the solder resist SR, the land Ld, and the board body Bd, radiant heat from the iron tip 5a, and convection within the solder hole 51.

[0086] Next, as shown in Fig. 4, a solder piece Wh is supplied to the solder hole 51 of the iron tip 5a. As shown in Fig. 5, when the temperatures of the solder piece Wh and the spare solder layer PS reach the melting temperature, the solder piece Wh and the spare solder layer PS melt and become one body (molten solder MS). Then, as shown in Fig. 6, part of the molten solder MS flows down inside the through hole Th, and as the iron tip 5a moves upward away from the printed circuit board CB, the molten solder MS is cooled and solidified by the outside air, forming a cone-shaped fillet of solder between the land Ld and the pin electrode P, and the land Ld and the pin electrode P are soldered together. The soldering device AP repeats this series of operations to sequentially solder the pin electrode P of the electronic component Ep to the land Ld of the printed circuit board CB.

[0087] The embodiment described above shows one example of the soldering apparatus and the soldering method according to the present invention, and various modifications are possible within the scope that does not impair the effects of the present invention. [Industrial Applicability]

[0088] The soldering method and soldering apparatus according to the present invention can prevent the formation of solder balls when soldering a land or pad having a pre-solder layer formed on its surface to an electrode of an electronic component. [Explanation of symbols]

[0089] AP Soldering Equipment A1 Device body 4 Heater Unit 41 Heater 42 Heater block 5a, 5b, 5c, 5d, 5e Trowel Tip 51 Solder hole 52 Recess 510 Enlarged section 511 Chamfered part 6 Solder feed mechanism Bd Board body CB Printed Circuit Board C1 Central axis of the trowel tip C2 Central axis of pin electrode d Outside diameter of spare solder layer dp Depth of the recess D Inner diameter of recess Ep electronic components MS molten solder Ld Land P pin electrode PS spare solder layer SR solder resist t Pre-solder layer thickness Th through hole W soldering Wh Solder piece

Claims

1. A method for soldering an electrode of an electronic component to a land or pad on which a preliminary solder layer has been formed on a surface of a printed circuit board, using a heatable soldering tip having a substantially cylindrical shape and a solder hole penetrating in the vertical direction, comprising the steps of: contacting a bottom surface of the iron tip with the printed circuit board; providing a solder piece into the solder hole; a step of heating and melting the supplied solder piece in the solder hole to solder the land or the pad to an electrode of the electronic component; having A soldering method characterized in that the tip of the soldering iron has a recess on its underside, the lower end opening of the solder hole is formed on the bottom surface of the recess, and the inner surface of the recess is positioned so as to surround the spare solder layer when viewed in a plane.

2. 2. The soldering method according to claim 1, wherein the vertical depth of the recess is greater than the vertical thickness of the pre-solder layer.

3. 3. The soldering method according to claim 1, wherein the vertical depth of the recess is 25 [mu]m or more and 500 [mu]m or less.

4. 1. A soldering method for inserting a pin electrode protruding outward from a component body of an electronic component into a through hole of a printed circuit board and soldering the pin electrode to a land formed on an outer periphery of the through hole, comprising: The solder hole has an enlarged portion at a lower end thereof, the enlarged portion enlarging radially outwardly; 4. The soldering method according to claim 1, wherein the sum of the vertical length of said enlarged portion and the vertical depth of said recess is longer than the protruding length of said pin electrode from the surface of said printed circuit board.

5. A soldering apparatus for soldering lands or pads on a surface of a printed circuit board, on which a preliminary solder layer has been formed in advance, to electrodes of an electronic component, comprising: A soldering iron tip having a generally cylindrical shape, a solder hole penetrating in the vertical direction, and capable of being heated; a solder piece supplying means for supplying a solder piece into the solder hole; A heating means for heating the tip of the iron; a moving means for relatively moving the tip of the soldering iron and the printed circuit board in a contact direction and a separation direction; A soldering device characterized in that the tip of the soldering iron has a recess on its underside, a lower end opening of the solder hole is formed on the bottom surface of the recess, and the inner surface of the recess is positioned so as to surround the spare solder layer when viewed in a plane.

6. 6. The soldering apparatus according to claim 5, wherein the vertical depth of said recess is greater than the vertical thickness of said pre-solder layer.

7. 7. The soldering apparatus according to claim 5, wherein the vertical depth of the recess is 25 [mu]m or more and 500 [mu]m or less.

8. 1. A soldering device for inserting pin electrodes protruding outward from a body of an electronic component into through holes in a printed circuit board and soldering the pin electrodes to lands formed on an outer periphery of the through holes, comprising: The solder hole has an enlarged portion at a lower end thereof, the enlarged portion enlarging radially outwardly; 8. The soldering device according to claim 5, wherein the sum of the vertical length of said enlarged portion and the vertical depth of said recess is longer than the protruding length of said pin electrodes from the surface of said printed circuit board.

9. A soldering tip for use in the soldering apparatus according to any one of claims 5, 6 and 8, The solder joint is generally cylindrical in shape and has a solder hole penetrating in the vertical direction. A recess having a vertical depth of 25 μm or more and 500 μm or less on the lower surface, a lower end opening of the solder hole is formed on a bottom surface of the recess; The tip of the soldering iron is characterized in that, in a plan view, an inner peripheral surface of the recess is positioned so as to surround the preliminary solder layer.

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