JP2002100858A - Flux-applying method, flow soldering method, device for the same and electronic circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the occurrence of process defects caused by the residue of flux applied to a substrate adhering to a transportation member as foreign matters in the post process of a flow soldering process, in flux-applying method of the flow soldering process. SOLUTION: The flux-applying method is used for the flow soldering process for sure mounting of electronic components on the substrate by using a solder material. A flux supply means supplies flux from below the substrate and is applied to the lower face of the substrate. When the substrate (1) is positioned above the flux supply means (6), while the substrate (1) is transported, flux (3) is supplied to a lower face (11) of the substrate (1) from the flux supply means (6), in a state where respective edge parts are covered by a pair of covers (8a and 8b) positioned directly below a pair of edge parts of the lower face (11) of the substrate, which follow the transport direction (9) of the substrate. Then, flux is applied to the lower face of the substrate, except for a pair of edge parts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for applying a flux in a flow soldering process for mounting an electronic component or the like on a substrate using a solder material, and a flow solder using the flux applying method and the apparatus. The present invention relates to a mounting method and apparatus, and an electronic circuit board manufactured by a flow soldering method.

[0002]

2. Description of the Related Art Conventionally, in the production of electronic circuit boards, a flow soldering process using a solder jet has been known as one method of joining electronic components or the like to a substrate. This flow soldering process generally involves a flux application step of applying a flux to the substrate, a preheating step of pre-heating the substrate, and a solder material that supplies the solder material to the substrate by contacting the substrate with a jet of solder material. Including a supplying step. This flux application step removes an oxide film (natural oxide film) unavoidably formed on a land formed on the substrate (ie, a portion to which the solder material is to be supplied), and removes the solder material on the land surface. The flux is performed for the purpose of improving the wetting spread, and the flux usually contains an active ingredient such as rosin (resin component) and a solvent such as isopropyl alcohol. As a flux applying method for performing such a flux applying step, there are known a foaming method in which a foam-like flux is brought into contact with a substrate, and a spray-type method in which a mist-like flux is sprayed on the substrate.

[0003] A conventional flow soldering process using a foam type flux application method will be described below with reference to the drawings. FIG. 7 is a schematic cross-sectional view of a conventional flow soldering apparatus using a foam type flux application method. FIG. 8A is a partial cross-sectional view taken along line XX of FIG. 7, and FIG. 8B is a partial top view of FIG. 8A.

First, a board 71 such as a printed board on which electronic components such as through-hole insertion components are appropriately arranged at predetermined positions by a known method is supplied to the flow soldering apparatus 50 shown in FIG. . The substrate 71 is mechanically transported inside the apparatus 50 (along a transport line shown by a dotted line in FIG. 7) at a constant speed in the direction of the arrow 52. More specifically, as shown in FIGS. 8A and 8B, the transfer of the substrate 71 is performed by mechanically moving the transfer claws 72a and 72b that hold the substrate 71 at both ends in the transfer direction indicated by the arrow 52. This is done by letting Here, the transport claw 7
2a and 72b are the chains 74a shown in FIG.
And 74b respectively connected to the conveyor frames 75a and 75b extending from the entrance 51 to the exit 53.
5b is rotated in a plane parallel to the main surface of the substrate 71. When the substrate 71 conveyed in this manner reaches above the foaming fluxer 54, the foaming device 55 foams and rises inside the guide 56, and the flux 73 overflowing outside the guide 56 becomes It is applied to the lower surface in contact with the lower surface. The flux 73 overflowing from the guide 56 is typically a bubble having a diameter of about 1-2 mm. As shown in FIGS. 8A and 8B, the guide 56 has an opening having a width w longer than the width W of the substrate 71 and an appropriate length l. By overflowing, the flux 73 is applied to a region of the lower surface of the substrate 71 other than a region held and covered by the transport claws 72a and 72b.

The substrate 71 coated with the flux as described above is thereafter heated by a preheater 57 such as a far infrared heater while being conveyed. The preheating step by heating is used to vaporize unnecessary solvent components of the flux 73 applied to the substrate 71 by the above-described flux application step, and to cause only the activator component to remain on the substrate 71, and to the substrate 71. Prior to the supply of the solder material, the substrate 71 is heated in advance,
This is performed to reduce the thermal shock that occurs when the molten solder material contacts the substrate 71.

Subsequently, the substrate 71 is provided with a primary jet 58 and a secondary jet 5 made of a solder material previously melted by heating.
9 contacts the lower surface of the substrate 71, and the solder material is supplied to the substrate. At this time, the solder material fills the annular space between the inner wall of the through-hole formed in the substrate and the lead of the through-hole insertion component inserted into the through-hole from the upper surface of the substrate, and the capillary from the lower surface of the substrate. Wet by phenomenon. Thereafter, the solder material supplied to and adhered to the substrate 71 solidifies due to a decrease in temperature, and forms a joint made of the solder material, a so-called “fillet”. In this solder material supply step (or flow soldering step), the primary jet is used to sufficiently wet the surface of the land (and the lead of the electronic component) formed over the wall surface of the through hole with the solder material. Yes, the secondary jet does not allow the solder material to remain and solidify between the lands to form a bridge (this bridge is undesirable because it leads to a short circuit in the electronic circuit) and does not form horn-like protrusions. Then, the solder material attached to the area covered with the solder resist is removed to adjust the shape of the fillet. The substrate 71 thus obtained is
Thereafter, it is taken out from the outlet 53.

As another example, a conventional flow soldering process using a spray type flux application method will be described with reference to the drawings. FIG. 9 is a schematic cross-sectional view of a conventional flow soldering apparatus using a spray type flux application method. FIG. 10 (a)
FIG. 10 is a partial sectional view taken along line YY in FIG.
FIG. 10B is a partial top view of FIG.

As shown in FIG. 9, a conventional flow soldering apparatus 60 using a spray type flux application method is used.
Is composed of a spray fluxer 60a, which is a spray type flux coating device, and a flow soldering device main body 60b. In this device 60, the flux application step is performed in a spray fluxer 60a, after which
The preheating step and the solder material supply step are sequentially performed in the apparatus main body 60b. The description of the same components as those of the conventional flow soldering apparatus and method using the foaming type flux application method will be omitted.

In the apparatus 60, first, the substrate 71 as described above is supplied to the spray fluxer 60a at the entrance 61.
Supplied from The substrate 71 is a spray fluxer 60a.
(Along the transport line shown by the dotted line in FIG. 9)
At a substantially constant speed in the direction of arrow 62, the sheet is mechanically conveyed by conveyance claws 72a and 72b (see FIGS. 10A and 10B) in the same manner as described above. When the substrate 71 thus conveyed reaches above the nozzle 63, the nozzle 6
Reference numeral 3 denotes a direction perpendicular to the transport direction of the substrate 71 (that is, the direction of the arrow 62) (that is, the direction perpendicular to the paper surface of FIG. 9), and the direction of the arrow 76 in FIGS. 10A and 10B. The flux 73 is applied to the lower surface of the substrate 71 by injecting the flux 73 together with the air while reciprocating. The nozzle 63 generally has a circular ejection port. As shown in FIG. 10A, the flux 73 ejected from the nozzle 63 is microscopically a droplet, and as a whole,
The injection port of the nozzle 63 has an upper bottom surface (or an apex), and has a truncated conical (or substantially conical) outline in which a circular region having a diameter m on the lower surface of the substrate 71 is a lower bottom surface. The substrate 71 is transported in the direction indicated by the arrow 62, and
Reciprocates in a direction indicated by an arrow 76 at a speed corresponding to the transport speed of the substrate 71 over a distance corresponding to the width W of the substrate 71. As a result, as shown in FIG. 10B, the flux 73
1 is applied to the entire lower surface of the substrate 71 while traversing the lower surface of the substrate 1. Further, since the solvent contained in the flux 73 is easily volatilized by spraying, from the viewpoint of safety, an exhaust duct (not shown) is provided above the substrate 71 to suck the solvent volatilized together with the atmospheric gas. ing.

The substrate 71 coated with the flux as described above is then mechanically transferred from the spray fluxer 60a to the apparatus main body 60b at a position 64 shown in FIG. In the same manner as described above, the substrate 71 is mechanically conveyed through the inside of the apparatus main body 60b at a substantially constant speed in the direction of arrow 65 (along the conveyance line indicated by the dotted line in FIG. 9) in the apparatus main body 60b. The solder material is heated by the pre-heater 66 in the same manner as described above, and then comes into contact with the solder jets 67 and 68 to be supplied from the lower surface of the substrate 71 and then taken out from the outlet 69.

As described above, an electronic circuit board in which electronic components are soldered to a substrate by a flow soldering process using a foaming type or spray type flux application method is manufactured.

[0012]

However, in the flux applying step of the conventional flow soldering process as described above, the edge of the substrate between the carrying claws is applied by either the foaming type or the spray type flux applying method. There is a problem in that the flux is applied to the part, which is one of the causes of the occurrence of a process failure in the post-process of the flow soldering process. More specifically,
In the conventional flux coating method, in the lower surface of the substrate, in all regions except the region covered by the transport claws, more specifically, to the edge between the transport claws that sandwiches both ends of the substrate. The flux will be applied. In the post-process of the flow soldering process, for example, in the inspection process, usually, a belt and a chain are used as a conveying member to convey while supporting a pair of edges along the conveying direction of the lower surface of the substrate from below. However, when the flux is applied to the edge of the substrate by the flux application step of the flow soldering process, rosin (resin component), which is an active component of the flux, remains on the substrate in powder form, and the residue May be peeled off from the substrate in a post-process and adhere to the transport member in the post-process as foreign matter. There is a problem that such adhesion of foreign matter to the transport member may cause a process defect such as a failure of the transport member.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a flux coating method in a flow soldering process for mounting an electronic component on a substrate using a solder material. Utilizing the flux application method, a method capable of reducing the occurrence of process failures caused by the residue of the flux applied to the substrate adhering to the conveying member as a foreign substance in the post-process of the flow soldering process It is an object of the present invention to provide a flow soldering method, an apparatus for performing the method, and an electronic circuit board manufactured by the flow soldering method.

[0014]

According to one aspect of the present invention, a flux is supplied from below a substrate by a flux supply means used in a flow soldering process for mounting an electronic component on a substrate using a solder material. A flux application method for applying to a lower surface of a substrate, wherein the substrate is transported while the substrate is positioned above the flux supply means, directly below a pair of edges of the lower surface of the substrate along the transport direction of the substrate. Supplying the flux from the flux supply means to the lower surface of the substrate while covering each edge with a pair of covers respectively located on the lower surface of the substrate, thereby applying the flux to the lower surface of the substrate excluding the pair of edges. Is provided.

In this specification, the "edge" of the substrate refers to a peripheral region on the main surface of the substrate. The term "directly below" means that the cover covers each edge and can function so as to substantially prevent the application of the flux to the edge. Even if it is in contact with the lower surface, a slight gap may be provided between the cover and the lower surface of the substrate.

According to the method of the present invention, a flux is applied to the lower surface of the substrate except for a pair of edges along the transport direction of the substrate, and a pair of the lower surfaces is covered with a pair of covers. No flux is applied to the edges of the pair, so that no active ingredient (such as rosin) of the flux remains on the pair of edges. Therefore, in a later stage of the flow soldering process, if the substrate is brought into mechanical contact with a conveying member such as a belt in the region of the pair of edges, the residual flux remains on the pair of edges. Since no substance is attached, it is possible to avoid the residue of the flux from adhering to such a conveying member, and it is possible to reduce the occurrence of a process defect due to this.

In a preferred embodiment, each of the pair of covers is an angle plate-shaped elongated member having an L-shaped cross-sectional shape defined by two sides, and the substrate is located above the flux supply means. Each edge of the lower surface of the substrate such that one side of the L-shaped cross section defines, at its end, a boundary between the edge and the lower surface of the substrate excluding a pair of edges. , And the other side of the L-shaped cross section is disposed below the edge. In this way, the cover
Abutting against the edge to define a boundary between the edge and the lower surface of the substrate excluding a pair of edges (ie, the area where the cover contacts the lower surface of the substrate and the cover covers the lower surface of the substrate) Is defined as an “edge”, and an uncovered area is defined as “a lower surface of the substrate excluding a pair of edges”, and a boundary between the “edge” and the “lower surface of the substrate excluding a pair of edges” is defined. It is preferred to isolate the pair of edges from the area where the flux is supplied, but the invention is not limited to this, as long as no flux is applied to the pair of edges. A gap may be provided between the cover and the lower surface of the substrate. Further, the cross-sectional shape of the cover is not limited to the L-shape as described above. For example, a T-shaped portion in which one side is joined to the inside of the end of the other side.
It may have any suitable shape, such as having a letter shape or a curved contour.

[0018] In a further preferred aspect, each of the pair of covers has an inclined portion that transitionally connects to an end of the one side at a portion that first comes into contact with the substrate, and the substrate is provided with a flux supply means. When the substrate is transported upward, the front edge of the lower surface of the substrate comes into contact with the inclined portion, and as the substrate is further transported above the flux supply means, the lower surface of the substrate slides along the inclined portion. While pressing down the cover, the one side abuts the edge at its end when the substrate is located above the flux supply means. By providing such an inclined portion (or a tapered portion) on the cover, the cover is moved at one end of the lower surface of the substrate by using the movement of the cover itself conveyed above the flux supply means. To abut
You can move the cover. For this cover, at least a part thereof may use a member having elasticity, for example,
Those utilizing a leaf spring or the like can be used. However, the present invention is not limited to this, and the cover may be moved by other mechanical means or the like, or may be fixed without moving.

According to another aspect of the present invention, a flux is supplied from below the substrate by a flux supply unit and applied to the lower surface of the substrate for use in a flow soldering process for mounting an electronic component on the substrate using a solder material. And a flux supplying device for supplying flux from below the substrate; and a substrate along a transport direction of the substrate when the substrate is located above the flux supplying device. Applying a flux to the lower surface of the substrate except for the pair of edges, the apparatus including a pair of covers respectively positioned immediately below the pair of edges of the lower surface of the substrate. Provided.

In a preferred embodiment, each of the pair of covers is an angle plate-shaped elongated member having an L-shaped cross-sectional shape defined by two sides, and the substrate is positioned above the flux supply means. Each edge of the lower surface of the substrate such that one side of the L-shaped cross section defines, at its end, a boundary between the edge and the lower surface of the substrate excluding a pair of edges. , And the other side of the L-shaped cross section is disposed below the edge.

In a further preferred aspect, each of the pair of covers has an inclined portion that transitionally connects to an end of the one side at a portion that first comes in contact with the substrate, and the substrate is provided with a flux supply means. When it is not above, the end of the one side is located above the surface through which the lower surface of the substrate should pass without applying external force to the cover, and the inclined portion is formed of the flux supply means. The lower surface of the substrate is located intersecting with the surface to be passed so as to first contact the substrate conveyed upward, and when the substrate is above the flux supply means, the lower surface of the substrate is By applying a pressing force to the one side that abuts, the cover is pushed down while being in contact with the edge at the end of the one side.

Such a flux applying apparatus of the present invention is suitably used for carrying out the above-described flux applying method of the present invention, and can obtain the same effects as the flux applying method of the present invention.

In a preferred embodiment of the flux applying method and the flux applying apparatus according to the present invention, each of the pair of edges has a width of 2 to 15 mm, more preferably about 5 mm. On the edge having such a width, electronic components are not usually arranged, and there is no need to apply a flux. In addition, since the width of such an edge is generally larger than the width (width from the edge of the substrate) that can be brought into contact with the transfer member in a subsequent step of the flow soldering process, the width of the Adhesion of flux residue to the member can be avoided.

The flux supplying means in the flux applying method and apparatus of the present invention includes a foaming type flux supplying means (for example, a foaming fluxer) for bringing a foamy flux into contact with a substrate and a spraying type flux for blowing a mist-like flux onto the substrate. Any of supply means (for example, a spray fluxer) may be used, or a combination of a foaming type and a spray type flux application method may be used.

According to another aspect of the present invention, there is provided a flow soldering method (or process) and a flow soldering apparatus each including the above-described flux applying method and flux applying apparatus of the present invention. The effect can be obtained.

According to still another aspect of the present invention, there is provided an electronic circuit board on which electronic components are mounted on a board by a flow soldering process using a solder material, wherein the lower surface of the board is taken along the board conveying direction. An electronic circuit board is provided wherein the flux is applied to the lower surface of the substrate except for a pair of edges, preferably a pair of edges each having a width of 2 to 15 mm.

In the present invention, "flux" refers to a metal (for example, a land) to which a solder material is to be supplied.
A material applied for the purpose of removing the oxide from the surface of the surface and improving the wettability of the solder material on the surface,
It contains an active ingredient for removing oxides and a solvent for facilitating handling of the active ingredient. The active ingredient may be, for example, about 3-20% by weight and the solvent may be about 80-97% by weight. Such active ingredients include rosin, matting agents,
Organic solvents and the like are included, and the solvent includes isopropyl alcohol and the like.

Examples of the solder material that can be used in the present invention include Sn—Pb, Sn—Cu, and Sn—Ag—Cu.
System, Sn-Ag system, Sn-Ag-Bi system, and Sn-
Ag-Bi-Cu-based solder materials are exemplified.

As the substrate that can be used in the present invention, for example, a substrate made of paper phenol-based material, glass epoxy-based material, polyimide film-based material, ceramic-based material, or the like can be used. Further, the electronic components to be bonded to the substrate may be inserted components (for example, semiconductors, capacitors, resistors, coils, connectors, etc.) and / or surface mount components (for example, semiconductors, capacitors, resistors,
Coil or the like). However, these are merely examples, and the present invention is not limited thereto.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1)
One embodiment will be described with reference to the drawings. The present embodiment relates to a foaming type flux applying method and a flux applying apparatus using a foaming fluxer as a flux supplying means. The flux applying method and apparatus according to the present embodiment relate to the flux applying step of the conventional flow soldering method and apparatus described with reference to FIGS. FIG. 1 (a) and (b)
FIG. 3 is a partial cross-sectional view in a direction perpendicular to a substrate transport direction above a flux supply unit, illustrating a flux applying method of the present embodiment, and was referred to for describing the conventional flux applying method described above. FIG. 9 is a diagram corresponding to FIG. Here, FIG. 1A shows a state where there is no substrate above the flux supply means, and FIG. 1B shows a state where there is a substrate above the flux supply means.
FIG. 2 is a partial top view of FIG. 1B, and FIG. 8 referred to explain the above-described conventional flux coating method.
It is a figure corresponding to (b). FIG. 3 (a) and (b)
FIGS. 2A and 2B are partially enlarged perspective views of FIGS. 1A and 1B, respectively.

FIG. 1 shows a flux coating apparatus according to this embodiment.
As partially shown in (a) and (b), transport claws 2a and 2b connected to chains 4a and 4b respectively rotating around conveyor frames 5a and 5b, a guide 6 and a foaming device (not shown) Fluxer). The transport claws 2a and 2b
The substrate 1 is transported in a transport direction 9 (ie, a direction perpendicular to the paper surface of FIGS. 1A and 1B and facing from the back of the paper surface to the front surface) with the substrate 1 sandwiched from above and below at both ends. The foaming fluxer is a flux supplying means for supplying the flux 3 to the lower surface 11 of the substrate 1 located above the foaming fluxer. These members are the same as those described with respect to the conventional flow soldering apparatus described with reference to FIGS. 7 and 8, and therefore description thereof will be omitted.

Further, as shown in FIGS. 1 (a) and 1 (b), the flux coating device of
conveyor frames 5a and 5b by a and 7b
Has a pair of covers 8a and 8b respectively attached thereto, which is different from the conventional one in this point. These covers 8a and 8b are provided on a surface perpendicular to the transport direction 9 of the substrate 1 transported by the transport claws 2a and 2b (that is, FIG. 1).
(A) and (b) of the drawing), it is composed of an angle plate-shaped elongated member having an L-shaped cross section. These covers 8a and 8b are arranged symmetrically with respect to a plane (not shown) passing through the center of the substrate and perpendicular to the main surface of the substrate. Hereinafter, the cover 8a will be described in detail.
b also has a similar configuration and function.

The cover 8a is, as shown in FIG.
It has an L-shaped cross-sectional shape defined by two sides A and B. The sides A and B respectively refer to a vertical portion and a horizontal portion of the cover 8a, and each have a plate-like shape having a predetermined thickness cross section. Sides A and B may be joined using separate members of separate or identical materials or may be integrally formed of the same material to provide an L-shaped cross section . As shown in FIG. 2, the cover 8a extends over a distance L longer than the length l of the opening of the guide 6 of the foaming fluxer, and when the substrate 1 is located above the opening of the guide 6, the width of the cover 8a is small. At the edge 11a of the substrate 1 having W, they are arranged so as to overlap each other by the width d. When the substrate 1 is positioned above the guide 6 of the foaming fluxer as the flux supply means, FIG.
As shown in FIG. 4 and FIG. 4, one side A of the L-shaped cross section of the cover 8a has, at its end 10, the edge 11a and the lower surface 11c of the substrate excluding the pair of edges 11a and 11b. Edge 1 of lower surface 11 of substrate 1 so as to define the boundaries between
1a, and the other side B of the L-shaped cross section is
, Preferably spaced apart from each other. Here, a pair of edges 11a and 11b on the lower surface 11 of the substrate 1 along the transport direction 9 of the substrate 1 is preferably about 2 to 15 m.
m, more preferably a width d of about 5 mm, but different widths may be selected as appropriate in some cases.

Further, as shown in FIG.
a of the first contact with the substrate 1 is a side A of the L-shaped cross section.
Is provided with an inclined portion (or taper) 10 ′ that transitionally connects to the end portion 10 of the optical disk. FIG.
FIG. 1A shows an open state where no external force is applied, and FIG.
It is preferable that at least a part of the cover 8a and / or the attachment 7a has sufficient elasticity so as to be able to shift between a state of being pressed down by the substrate 1 as shown in FIG. For example, a leaf spring or the like can be used for the cover 8a. The same applies to the cover 8b and the attachment 7b.

More specifically, when the substrate 1 is not above the guide 6 of the foaming fluxer, which is a flux supply means, the cover 8a is in an open state receiving no external force as shown in FIG. The end 10 of the side A (vertical portion) of 8a is located above a surface through which the lower surface 11 of the substrate 1 should pass (a surface indicated by a dotted line in the figure, hereinafter also referred to as a reference surface), and , The inclined portion 10 ′ (FIG. 3) intersects with the reference plane so as to first come into contact with the substrate 1 conveyed toward above the guide 6. On the other hand, when the substrate 1 is above the guide 6, the cover 8a is in a pressed state receiving an external force as shown in FIG.
However, by applying a pressing force to the side A that comes into contact with this at the end 10, the cover 8 a
1 is pressed down while being in contact with the edge.

Hereinafter, a flux coating method using such a flux coating device will be described. First, FIG.
As shown in FIG. 3A and FIG. 3A, the substrate 1 is sandwiched between the transport claws 2a and 2b from above and below at both ends thereof above the opening of the guide 6 where no external force is applied to the covers 8a and 8b. To transport in the transport direction 9. When the substrate 1 is conveyed above the opening of the guide 6, the front edge of the substrate 1 first comes into contact with the inclined portions 10 'of the covers 8a and 8b, and the substrate 1 is placed above the opening of the guide 6. As the substrate 1 is further conveyed, the lower surface 11 of the substrate 1
Push down covers 8a and 8b while sliding along 0 '. Then, the front edge of the substrate 1 passes over the inclined portion 10 ', and slides on the end 10 of the side A of the covers 8a and 8b as shown in FIGS. 1B and 3B. The end 10 of the side A comes into contact with the edge of the lower surface 11 of the substrate 1. Thereby, the covers 8a and 8b are adapted to define the boundary between the edges 11a and 11b shown in FIG. 4 and the lower surface 11c of the substrate excluding the pair of edges.
a and 11b at an end 10 and a pair of edges 11
a and 11b are covered with covers 8a and 8b that are in contact with the lower surface 11 of the substrate 1 so as to be isolated from the region where the flux is supplied. Thus, the pair of edges 11a
When the flux 3 is supplied to the lower surface 11 of the substrate 1 located above the opening of the guide 6 in a state where the fluxes 3 and 11b are covered with the pair of covers 8a and 8b, respectively, the substrate excluding the pair of edges 11a and 11b The flux 3 is applied to the lower surface 11c, and the flux is not applied to the pair of edges 11a and 11b.

Further, one of the conveyor frames 5 is provided so that the width W of the substrate 1 can be changed depending on the substrate.
a, and the other conveyor frame 5b is perpendicular to the direction of substrate transport and parallel to the fixed conveyor frame 5a (i.e., left and right in the plane of FIGS. 1 (a) and 1 (b)).
The transport claws 2a and 2b that slide and hold the substrate 1
It is preferable that the width between the slides can be adjusted. In this case, since the cover 8b is connected to the conveyor frame 5b by the attachment 7b as in the present embodiment, the cover 8b is moved as the conveyor frame 5b slides.
Also slides the same distance. Therefore, the width W of the substrate 1
Only by appropriately setting the conveyor frame 5b in accordance with the condition, the cover 8b does not need to be set individually, and the edge d
Can be maintained at a predetermined value.

When the flux is applied using the flux applying method and the coating apparatus of the present embodiment as described above,
Since the flux is not applied to the pair of edges of the substrate, it is possible to prevent the residue of the flux from adhering to the transporting member in the subsequent process, and it is possible to reduce the occurrence of process defects due to this. Becomes

The flux coating device of the present embodiment
Like the conventional flow soldering apparatus described with reference to FIGS. 7 and 8, it can be integrated into the flow soldering apparatus, but is separately and independently configured outside the flow soldering apparatus main body. Is also good.

In this embodiment, a cover having an L-shaped cross-sectional shape and a tapered portion is brought into contact with (or in contact with) the lower surface of the substrate by utilizing the elasticity, thereby making the cover 1
Although the pair of edges are separated from the flux supply unit, the present invention is not limited to this, and when the substrate is located above the flux supply means, a pair of edges on the lower surface of the substrate along the transport direction of the substrate. It will be readily apparent to those skilled in the art that modifications can be made to the extent that each edge can be covered by a pair of covers located directly below the portion. Specifically, it is also possible to modify the cross-sectional shape of the cover to, for example, a T-shape, to make the inclined portion curved, or to make the cover move up and down mechanically so as to contact the lower surface of the substrate. It is possible. Even if the cover does not contact the lower surface of the substrate, a gap may be provided between the cover and the lower surface of the substrate such that the flux is not substantially applied to the pair of edges.

(Embodiment 2) This embodiment corresponds to Embodiment 1.
And a flow soldering method including a flux application method and apparatus. The flow soldering apparatus according to the present embodiment is configured such that the flux coating apparatus described in detail in the first embodiment is integrally incorporated as in the conventional flow soldering apparatus described with reference to FIG. Apparatus for supplying the pre-heater and the solder material in the form of a jet except for the flux applying apparatus may be any appropriate one,
For example, the one shown in FIG. 7 can be used. By using such a flow soldering apparatus, a flux is applied in the same manner as in the first embodiment, and then subjected to a preheating (preheating) step and a solder material supply step in the same manner as in the above-described conventional method. The flow soldering process (method) is completed, and an electronic circuit board on which electronic components are mounted is obtained. The obtained electronic circuit board is sent to a step subsequent to the flow soldering process, for example, an inspection step. However, since no flux is applied to a pair of edges of the electronic circuit board, the electronic circuit board is described in Embodiment 1. As described above, in the post-process, it is possible to reduce the occurrence of process defects caused by the flux residue adhering to the transport member.

Embodiment 3 Next, another embodiment of the present invention will be described with reference to the drawings. The present embodiment relates to a spray-type flux coating method and a flux coating apparatus using a spray fluxer as a flux supply unit. The flux applying method and apparatus according to the present embodiment relate to the flux applying step of the conventional flow soldering method and apparatus described with reference to FIGS. FIGS. 5A and 5B are partial cross-sectional views of a flux application method according to the present embodiment, in a direction perpendicular to the substrate transport direction above the flux supply means. FIG. 10 referred to explain the coating method
It is a figure corresponding to (a). Here, FIG. 5A shows a state where there is no substrate above the flux supply means.
(B) shows a state when the substrate is located above the flux supply means. FIG. 6 is a partial top view of FIG. 5B and corresponds to FIG. 10B referred to for describing the above-described conventional flux application method.

The flux coating device of the present embodiment, which is partially shown in FIGS. 5A and 5B, is the same as the flux coating device of the first embodiment, but instead of a foaming fluxer as a flux supply means, Using a spray fluxer used in the conventional flow soldering apparatus described with reference to FIGS. 9 and 10, an exhaust duct (not shown) for sucking an atmospheric gas in the same manner as the apparatus of FIGS. 9 and 10. ) Is provided above the substrate.

In this embodiment, the flux 3 is
The flux can be applied to the substrate by the same method as in the first embodiment, except that the flux is supplied from the nozzle 12 reciprocating in the direction of the arrow 13 to the substrate 1. Also in this embodiment, as in the first embodiment, the flux 3 is applied to the lower surface 11 of the substrate 1 in a state where the pair of edges of the substrate 1 are covered by the covers 8a and 8b. The flux 3 is applied to the lower surface of the substrate excluding the portions, and the flux 3 is not applied to a pair of edges. As a result, the same effects as in the first embodiment can be achieved in the present embodiment.

The flux coating device of the present embodiment is
Like the conventional flow soldering apparatus described with reference to FIGS. 9 and 10, it can be separately and independently provided outside the flow soldering apparatus main body, but is integrated into the flow soldering apparatus. Is also good. In the second embodiment, it is also possible to carry out the flow soldering by using the method of the present embodiment instead of the flux applying method and apparatus of the first embodiment. Furthermore, the foam type flux applying method and apparatus of the first embodiment may be used in combination with the spray type flux applying method and apparatus of the present embodiment.

[0046]

According to the present invention, there is provided a flux coating method used in a flow soldering process for mounting an electronic component on a substrate using a solder material, wherein a flux residue applied to the substrate is removed by a flow soldering process. Provided are a method and an apparatus for performing the method, which are capable of reducing the occurrence of process defects due to foreign matter adhering to a conveying member in a post-process of a soldering process. Further, according to the present invention, there are provided a flow soldering method using the flux applying method, an apparatus for performing the method, and an electronic circuit board manufactured by the flow soldering method. According to the present invention, a flux is applied to the lower surface of the substrate except for a pair of edges along the transport direction of the substrate, and a pair of edges covered with a pair of covers is provided on the lower surface of the substrate. Since the flux is not applied, the residue of the flux can be prevented from adhering to the transporting member in the post-process of the flow soldering process, and the occurrence of process defects due to this can be reduced.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view of a flux application method according to one embodiment of the present invention, in a direction perpendicular to a substrate transport direction, above a flux supply unit.
1A shows a state where there is no substrate above the flux supply means, and FIG. 1B shows a state where there is a substrate above the flux supply means.

FIG. 2 is a partial top view of FIG. 1 (b).

FIGS. 3 (a) and 3 (b) correspond to FIGS.
It is a partial expansion perspective view of (a) and (b).

FIG. 4 is a perspective view of the substrate on which the flux is applied according to the embodiment of FIG. 1 as viewed from the lower surface side.

FIG. 5 is a partial cross-sectional view of a flux application method according to another embodiment of the present invention, in a direction perpendicular to the substrate transport direction, above the flux supply means, and FIG. FIG. 5B shows a state in which there is no substrate above the flux supply means, and FIG. 5B shows a state in which there is a substrate above the flux supply means.

FIG. 6 is a partial top view of FIG. 5 (b).

FIG. 7 is a schematic cross-sectional schematic view of one conventional flow soldering apparatus.

8A is a partial cross-sectional view taken along line XX of FIG. 7, and FIG. 8B is a partial top view of FIG. 8A.

FIG. 9 is a schematic cross-sectional schematic view of another conventional flow soldering apparatus.

FIG. 10A is a partial cross-sectional view taken along line YY of FIG. 9, and FIG. 10B is a partial top view of FIG. 10A.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Board | substrate 2a, 2b Transport nail | claw 3 Flux 4a, 4b Chain 5a, 5b Conveyor frame 6 Guide 7a, 7b Attachment 8a, 8b Cover 9 Arrow (transport direction) 10 End part 10 'Inclined part 11 Lower surface 11a, 11b Edge 11c The lower surface of the substrate excluding a pair of edges d The width of the edge L The length of the cover l The length of the guide opening W The width of the substrate w The width of the opening of the guide

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shunji Hibino 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 72) Inventor Tatsuo Okuchi 1006 Kadoma Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 1006 Kadoma Kadoma Matsushita Electric Industrial Co., Ltd. (72) Inventor Mikiya Nakata 1006 Kadoma City Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd.F-term (reference)

Claims (16)

[Claims] 1. A flux application method for supplying a flux from below a substrate by a flux supply means and applying the flux to a lower surface of the substrate, which is used in a flow soldering process for mounting an electronic component on the substrate using a solder material, While transporting the substrate, when the substrate is positioned above the flux supply means, one of the lower surfaces of the substrate along the substrate transport direction
Flux is supplied from the flux supply means to the lower surface of the substrate while each edge is covered with a pair of covers located immediately below the pair of edges, whereby the lower surface of the substrate excluding the pair of edges is removed. A method comprising applying a flux to a substrate. 2. Each of the pair of edges has a length of 2 to 15 mm.
The method of claim 1, having a width of 3. Each of the pair of covers is an angle plate-shaped elongated member having an L-shaped cross-sectional shape defined by two sides, and when the substrate is positioned above the flux supply means, One side of the L-shaped cross section abuts each edge of the lower surface of the substrate such that at one end thereof defines a boundary between the edge and the lower surface of the substrate excluding a pair of edges,
3. The method according to claim 1 or 2, wherein the other side of the L-section is located below the edge. 4. Each of the pair of covers has an inclined portion transitionally connected to the end of the one side at a portion where the cover first comes in contact with the substrate, and the substrate is moved upward from the flux supply means. When transported, the front edge of the lower surface of the substrate contacts the inclined portion, and as the substrate is further transported above the flux supply means, the lower surface of the substrate slides down the inclined portion and pushes down the cover, 4. The method of claim 3, wherein said one side abuts an edge at its end when the substrate is positioned above the flux supply means. 5. The method according to claim 1, wherein the flux supplying means is a foaming type flux supplying means for bringing a foamy flux into contact with the substrate. 6. The method according to claim 1, wherein the flux supply means is a spray-type flux supply means for spraying a mist-like flux onto the substrate. 7. A flux application apparatus for applying a flux from below a substrate by a flux supply means and applying the flux to a lower surface of the substrate, the flux application apparatus being used in a flow soldering process of mounting an electronic component on a substrate using a solder material: Transport means for transporting the substrate, flux supply means for supplying flux from below the substrate, and a pair of edges on the lower surface of the substrate along the transport direction of the substrate when the substrate is located above the flux supply means And a pair of covers respectively positioned directly under the cover and covering each edge,
An apparatus for applying a flux to a lower surface of a substrate excluding a pair of edges. 8. Each of the pair of edges is 2-15 mm.
8. The device of claim 7, having a width of. 9. Each of the pair of covers is an angle plate-shaped elongated member having an L-shaped cross-sectional shape defined by two sides, and when the substrate is positioned above the flux supply means, One side of the L-shaped cross section abuts each edge of the lower surface of the substrate such that at one end thereof defines a boundary between the edge and the lower surface of the substrate excluding a pair of edges,
9. Apparatus according to claim 7 or claim 8, wherein the other side of the L-section is located below the edge. 10. When each of the pair of covers has an inclined portion transitionally connected to an end of the one side at a portion where the cover first comes in contact with the substrate, and the substrate is not above the flux supply means. The end of the one side is located above the surface through which the lower surface of the substrate should pass, and the inclined portion is conveyed toward above the flux supply means without external force being applied to the cover. The lower surface of the substrate is positioned to intersect with the surface through which the lower surface of the substrate is to pass, so that the lower surface of the substrate is positioned above the flux supply means so that the lower surface of the substrate first contacts the substrate to be contacted.
Apparatus according to claim 9, wherein the cover is pushed down against the edge at the end of one side by applying a pressing force to the one side abutting the same. 11. The apparatus according to claim 7, wherein the flux supplying means is a foaming type flux supplying means for bringing a foamy flux into contact with the substrate. 12. The apparatus according to claim 7, wherein the flux supply means is a spray-type flux supply means for spraying a mist-like flux onto the substrate. 13. A flow soldering method including the flux applying method according to claim 1. 14. A flow soldering device including the flux coating device according to claim 7. Description: 15. An electronic circuit board on which electronic components are mounted on a board by a flow soldering process using a solder material, wherein one of the lower surfaces of the board along the board conveying direction is provided.
An electronic circuit board in which flux is applied to the lower surface of the board except for the edge of the pair. 16. Each of the pair of edges is 2-15 m.
The electronic circuit board according to claim 15, having a width of m.