JP2004200282A - Method of mounting electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of mounting electronic component by which residues can be removed sufficiently and a component mounting substrate can be cleaned sufficiently, and then, the cost of an electronic component mounting device can be lowered. <P>SOLUTION: This method of mounting electronic component includes an applying step of applying a coating agent to the surfaces of the substrate 11 of the component mounting substrate and an electronic component 12, a heating step of soldering the component 12 to the substrate 11 by heating the component mounting substrate after the substrate 11 is coated with the coating agent, and a cleaning step of cleaning the component mounting substrate with a cleaning agent selected correspondingly to the coating agent. Since the cleaning agent is selected correspondingly to the coating agent, residues adhering to the surface of the component mounting substrate can be removed sufficiently as the component mounting substrate is cleaned with the cleaning agent. Consequently, the component mounting substrate can be cleaned sufficiently. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic component mounting method.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, for example, in an electronic component mounting apparatus that manufactures a control board as an electronic component mounted product on which an electronic component is mounted, an electronic component (bare chip) is positioned so that leads are aligned with a board on which solder paste is printed in advance. Is mounted, the board with the electronic components mounted thereon, that is, the component mounting board is sent to a reflow furnace, and the component mounting board is heated in the reflow furnace so that the electronic component is soldered to the board. ing.
[0003]
In the reflow furnace, the component mounting board is preliminarily heated with a predetermined temperature profile while being conveyed in the furnace by a belt conveyor, is then heated properly, the solder of the solder paste is melted, and the The component and the board are soldered. Subsequently, the component mounting board is cooled and then discharged from the reflow furnace.
[0004]
By the way, in the reflow furnace, as the solder is melted, scattered solder is generated, and solder fine particles, that is, micro solder balls adhere to the surface of the component mounting board as a residue. . In this case, depending on the portion to which the residue is attached, the substrate and the electronic component are electrically short-circuited to cause a problem, or the residue is caught in the sliding surface in a subsequent wire bonding step, and the wire bonding is performed. Yields low.
[0005]
Therefore, by spraying steam on the surface of the component mounting board, the residue is softened by heating the component mounting board, and the residue is removed by spraying a cleaning agent at a high pressure to clean the component mounting board. (For example, see Patent Document 1).
[0006]
[Patent Document 1]
JP 2000-332153 A
[Problems to be solved by the invention]
However, in the conventional electronic component mounting apparatus, since the size of the residue is extremely small, when the cleaning solution is sprayed at a high pressure, a force for removing the residue by the cleaning solution is applied to the component mounting board. It cannot be larger than the adhesive force to be attached. Therefore, the residue cannot be sufficiently removed, and the component mounting board cannot be sufficiently cleaned.
[0008]
Furthermore, it is necessary to spray steam on the surface of the component mounting board for cleaning, to heat the component mounting board, or to spray a cleaning agent at high pressure. Need to be provided separately, which increases the cost of the electronic component mounting apparatus.
[0009]
The present invention solves the problems of the conventional electronic component mounting apparatus, can sufficiently remove the residue, can sufficiently clean the component mounting board, and can reduce the cost of the electronic component mounting apparatus. It is an object of the present invention to provide an electronic component mounting method capable of performing the above.
[0010]
[Means for Solving the Problems]
Therefore, in the electronic component mounting method of the present invention, in the application step of applying a coating agent to the surface of the component mounting board substrate and the electronic component, heating the component mounting board in a state where the coating agent is applied, to the substrate On the other hand, the method includes a heating step of soldering the electronic component and a cleaning step of cleaning the component-mounted board in a state where the soldering has been performed, using a cleaning agent selected according to the coating agent.
[0011]
In another electronic component mounting method of the present invention, the coating agent is a flux for soldering. The cleaning agent contains a solvent for dissolving the flux.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0013]
FIG. 1 is a cross-sectional view of a component mounting board according to an embodiment of the present invention, FIG. 2 is a perspective view of the component mounting board according to the embodiment of the present invention, and FIG. FIG. 4 is a cross-sectional view of a reflow furnace according to an embodiment of the present invention, FIG. 5 is a conceptual diagram of an electronic component mounting apparatus according to an embodiment of the present invention, and FIG. It is a process drawing of an electronic parts mounting method.
[0014]
In the drawing, reference numeral 10 denotes a component mounting board as a processing object, and the component mounting board 10 includes one or more electronic components (bare chips) such that leads are aligned with a board 11 on which solder paste is printed in advance. 12 is formed. Further, 21 is a reflow furnace as a heating furnace, 41 is a transfer device for transferring the component mounting board 10 in the direction of arrow A, and the transfer device 41 is composed of a walking beam and drives a transfer driving unit (not shown). Then, the component mounting board 10 is moved in the direction of arrow A, and is sent to the reflow furnace 21.
[0015]
Then, a heating step is performed in the reflow furnace 21, the component mounting board 10 is heated, and the electronic component 12 is soldered to the board 11.
[0016]
To this end, as shown in FIG. 4, the reflow furnace 21 includes a housing 23 formed to extend in a longitudinal direction along a transport path 22 of the component mounting board 10. The body 23 includes a front wall 24 located on the entrance side of the transport path 22, a rear wall 25 located on the exit side of the transport path 22, left and right side walls, a top wall 27 and a bottom wall 28. And an outlet 32 is formed in the rear wall 25.
[0017]
In the housing 23, a plurality of hot plates hi (i = 1, 2,..., 5) are arranged in a line along the transport path 22, and the component mounting board 10 is placed on each hot plate hi. Can be placed. In the present embodiment, five hot plates hi are arranged, but any number of hot plates hi can be arranged. A heater (not shown) as a first heating member is embedded in each of the hot plates h1 to h4, and the heater can be energized to heat the component mounting board 10 by heat transfer.
[0018]
Further, the inside of the furnace, that is, the inside of the housing 23 is partitioned into first to third regions AR1 to AR3, and a preheating unit that preliminarily heats the component mounting board 10 by the first region AR1 is provided in the second region. The area AR2 constitutes a heating section for properly heating the component mounting board 10, and the third area AR3 constitutes a cooling section for cooling the component mounting board 10. In addition, in the first and second regions AR1 and AR2, the top wall 27 is opposed to the hot plates h1 to h4 to heat the component mounting board 10 by radiating radiation. An infrared heater 37 as a second heating member is attached, and a cooling fan (not shown) as a cooling member is disposed adjacent to the hot plate h5 in the third area AR3. In the present embodiment, the infrared heater 37 is attached to the top wall 27 of the first and second regions AR1 and AR2, but the infrared heater 37 is not always required.
[0019]
The pre-heat treatment means of the control unit (not shown) performs pre-heat treatment, energizes the heater to heat each of the hot plates h1 and h2, heats the component mounting board 10 by heat transfer, and turns on the infrared heater 37. Electric current is generated to generate infrared rays, radiate them to the component mounting board 10, and preheat the component mounting board 10 by radiation. Further, the heating processing means of the control unit performs a heating process, energizes the heater to heat each of the hot plates h3 and h4, heats the component mounting board 10 by heat transfer, and energizes the infrared heater 37. Then, infrared rays are generated, radiated to the component mounting board 10, and the component mounting board 10 is heated by the radiation.
[0020]
Therefore, the component mounting board 10 that has entered the housing 23 via the entrance 31 is preliminarily heated to the temperature T1 in the first area AR1, and to the temperature T2 in the second area AR2. As described above, and is cooled to room temperature in the third region AR3.
[0021]
As described above, in the reflow furnace 21, the component mounting substrate 10 is preliminarily heated with a predetermined temperature profile in the preheating unit while being conveyed in the furnace by the conveyance device 41, and then is properly regulated in the heating unit. Heat is applied to melt the solder of the solder paste, and the electronic component 12 and the substrate 11 are joined by solder. Then, the component mounting board 10 is discharged from the reflow furnace 21 after being cooled in the cooling section.
[0022]
By the way, as described above, the component mounting board 10 is formed by mounting the electronic components 12 on the board 11 on which the solder paste is printed in advance so that the leads are aligned, and is sent to the reflow furnace 21. In the reflow furnace 21, as the solder is melted, scattered solder is generated, and micro solder balls adhere to the surface of the component mounting board 10 as a residue 38. In this case, depending on the portion where the residue 38 adheres, the substrate 11 and the electronic component 12 are electrically short-circuited to cause a problem, or the residue 38 is caught on the sliding surface in a subsequent wire bonding step, and This lowers the yield of bonding.
[0023]
Therefore, a coating device 51 is provided at a coating position set on the upstream side of the reflow furnace 21 in the transport direction of the component mounting board 10, and a cleaning device 52 is provided at a cleaning position set on the downstream side of the reflow furnace 21. .
[0024]
The coating device 51 includes a nozzle portion 33 such as a dispenser or a spray, and can discharge a liquid flux 53 for soldering from the nozzle portion 33 toward the component mounting board 10 as a coating agent. Further, the cleaning device 52 includes a cleaning tank (not shown). The cleaning tank contains a cleaning agent containing an alcohol-based solvent selected according to the flux 53, and is provided with a predetermined circulation device (not shown). The cleaning agent is lubricated.
[0025]
Next, an electronic component mounting method will be described.
[0026]
First, in the application step, the component mounting substrate 10 is transported by the transport device 41, stopped at the application position, and the flux 53 discharged from the nozzle unit 33 is applied to the surfaces of the substrate 11 and the electronic component 12. At this time, the coating film 35 with the flux 53 is formed on the surfaces of the substrate 11 and the electronic component 12.
[0027]
Next, in the heating step, the component mounting board 10 on which the flux 53 has been applied is sent to the reflow furnace 21 by the transfer device 41, heated in the reflow furnace 21, and soldered on the board 11 to the electronic component 12. Is attached. In this case, since the coating film 35 is formed, it is possible to prevent the micro solder balls from adhering to the surface of the component mounting board 10 as the residue 38. In FIG. 1, reference numeral 36 denotes a solder portion formed as the soldering is performed.
[0028]
Then, in the cleaning process, the component mounting board 10 in a state where soldering has been performed is transported by the transport device 41 and discharged from the reflow furnace 21, and is immersed (coughed) in the cleaning tank at the cleaning position. It is cleaned by the cleaning agent circulated in the inside. In this case, the cleaning agent is selected according to the flux 53 and contains an alcohol-based solvent, so that the flux 53 is easily dissolved in the cleaning agent.
[0029]
That is, since the cleaning agent is selected according to the flux 53, the coating film 35 can be removed by the cleaning agent. Accordingly, the adhesive force of the residue 38 attached to the surface of the component mounting board 10 is rapidly reduced, so that the residue 38 attached to the surface of the component mounting board 10 can be sufficiently removed. The component mounting board 10 can be sufficiently cleaned.
[0030]
Further, when a cleaning agent containing a solvent for easily dissolving the flux 53 is selected, as the flux 53 dissolves in the cleaning agent, the adhesive force of the residue 38 attached to the surface of the component mounting substrate 10 is further increased. Since the size is reduced, the residue 38 attached to the surface of the component mounting board 10 can be more sufficiently removed, and the component mounting board 10 can be more sufficiently cleaned.
[0031]
Since there is no need to heat the component mounting substrate 10 by spraying steam onto the surface of the component mounting substrate 10 or to spray a cleaning agent at a high pressure, a steam injection device and a cleaning agent spray device are used. There is no need for separate installation. As a result, the cost of the electronic component mounting apparatus can be reduced.
[0032]
It should be noted that the present invention is not limited to the above-described embodiment, but can be variously modified based on the gist of the present invention, and they are not excluded from the scope of the present invention.
[0033]
【The invention's effect】
As described above in detail, according to the present invention, since the cleaning agent is selected in accordance with the coating agent, the cleaning agent is attached to the surface of the component mounting substrate as the component mounting substrate is cleaned by the cleaning agent. The residue can be sufficiently removed, and the component mounting substrate can be sufficiently cleaned.
[Brief description of the drawings]
FIG. 1 is a sectional view of a component mounting board according to an embodiment of the present invention.
FIG. 2 is a perspective view of a component mounting board according to the embodiment of the present invention.
FIG. 3 is a perspective view showing a main part of the electronic component mounting apparatus according to the embodiment of the present invention.
FIG. 4 is a sectional view of the reflow furnace according to the embodiment of the present invention.
FIG. 5 is a conceptual diagram of an electronic component mounting apparatus according to an embodiment of the present invention.
FIG. 6 is a process chart of the electronic component mounting method according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Component mounting board 11 Substrate 12 Electronic component 53 Flux

Claims (2)

A coating step of applying a coating agent to the surface of the component mounting board and the electronic component, a heating step of heating the component mounting board in a state where the coating agent is applied, and soldering the electronic component to the board; A cleaning step of cleaning the component-mounted board in a state where soldering has been performed with a cleaning agent selected in correspondence with the coating agent. The electronic component mounting method according to claim 1, wherein the coating agent is a flux for soldering, and the cleaning agent contains a solvent for dissolving the flux.

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