JPH11163511A - Method for soldering - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for soldering wherein melting of a solder under irradiation with an optical beam at constant output can be performed within an appropriate temperature range. SOLUTION: This soldering method comprises a first irradiation process wherein an optical beam scanning is performed from a first irradiation start position K1 near the center of pads 22a-22f toward the pad 22a arranged at one end part; and a second irradiation process wherein an optical beam scanning is performed from a second irradiation start position K2 which is, located near the center of the pads 22a-22f and is closer to the side of one end part than the first irradiation start position K1, toward the pad 22f arranged at the other end part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for soldering an electronic component to a printed circuit board by using a light beam.

[0002]

2. Description of the Related Art One of the methods for soldering and mounting electronic component leads to pads on a printed circuit board is to scan a pad with a light beam and heat the pad. FIG.
FIG. 3 is a diagram showing a conventional heating method using a light beam. 4, reference numeral 10 denotes an electronic component, 11 denotes a component main body in which an integrated circuit is housed, and 12a to 12f denote leads provided on one side of the component main body 11. Each of the leads 12a to 12f
Are similarly provided on the four sides of the component body 11.

In FIG. 4, reference numeral 20 denotes a printed circuit board, 21 denotes a substrate body made of epoxy resin having a surface coated with a solder resist, and 22a to 22f denote pads. Also,
Each of the pads 22a to 22f is connected to a wiring pattern (not shown) arranged on the back surface of the substrate body. In the figure, S
Indicates a solder paste.

In a conventional heating method using a light beam, first, a solder paste S is applied to a substrate body 11 of a printed circuit board 10.
It is supplied by a dispenser to pads 12a to 12f provided at predetermined intervals above. Next, each of the leads 12a-12
It is mounted so that f is located on predetermined pads 22a to 22f. Next, a spot heat source such as a light beam is scanned at a constant speed from the pad 12a to the pad 12f as indicated by L in FIG. When the heating by the light beam is completed, the solder paste S on the pads 12a to 12f solidifies, and the soldering connection is completed.

[0005]

The above conventional soldering method has the following problems. That is,
When the light beam is continuously irradiated, the temperature of the printed circuit board rises, and the surface temperature of the position on the printed circuit board where the light beam is irradiated gradually becomes higher than the temperature of the position where the light beam irradiation is started. Therefore, a sufficient amount of heat is not applied to the pad near the irradiation start position, and there is a possibility that unsolder is generated. On the other hand, if light beam irradiation is performed at a temperature sufficient to melt the solder at the start of irradiation, the printed circuit board is overheated near the end of the irradiation end position, and thermal damage such as measling occurs.

On the other hand, by changing the output of the light beam during scanning or by changing the moving speed of the light beam, the above problem can be solved, but there is a problem that the apparatus becomes complicated. . Therefore, an object of the present invention is to provide a soldering method capable of performing solder melting by irradiation of a light beam with a constant output in an appropriate temperature range.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems and achieve the object, the invention described in claim 1 provides a plurality of leads provided in a row at a predetermined interval on an electronic component and the leads. Correspondingly, in a soldering method for soldering and connecting a plurality of pads formed on a printed circuit board respectively, one end from a first irradiation start position located near the center of the plurality of pads in a row. A first irradiation step of scanning a light beam in a direction of a pad arranged on the first pad;
And a second irradiation step of scanning the light beam from the second irradiation start position on the one end side to the pad arranged on the other end with respect to the irradiation start position.

According to a second aspect of the present invention, in the first aspect, the distance between the first irradiation start position and the second irradiation start position is at least larger than the spot diameter of the light beam. Is also set large.

According to a third aspect of the present invention, a plurality of leads provided in a row at predetermined intervals on an electronic component and a plurality of pads formed on a printed circuit board corresponding to the leads are soldered. In the soldering method for attaching and connecting, an irradiation step is provided which has a predetermined angle with respect to a direction perpendicular to a direction in which the plurality of leads extend and scans a light beam along the plurality of pads.

[0010] As a result of taking the above measures, the following effects are produced. That is, in the invention described in claim 1, in the first irradiation step, the light beam is directed from the first irradiation start position located near the center of the plurality of rows of pads to the pad arranged at one end from the first irradiation start position. In the second irradiation step, the second irradiation step is located near the center of the plurality of rows of pads, and is the other end from the second irradiation start position on one end side of the first irradiation start position. Since the light beam is irradiated in the direction of the pad arranged in the pad, the pad located near the center of the plurality of pads is irradiated with the light beam in the first irradiation step and the second irradiation step in an overlapping manner. Become. Therefore, even when the irradiation intensity of the light beam is controlled so that the irradiation amount at the irradiation end position is appropriate, the amount of heat given to the pad does not become insufficient, and the soldering can be performed properly. it can.

In the invention described in claim 2, the interval between the first irradiation start position and the second irradiation start position is set to be at least larger than the spot diameter of the light beam. And soldering failure can be prevented.

According to the third aspect of the present invention, there is provided an irradiation step having a predetermined angle with respect to a direction perpendicular to the direction in which the plurality of leads extend, and scanning the light beam along the plurality of pads. Therefore, the light beam is applied to the part on the tip end side of the lead and the part on the electronic component side. For this reason, since heat is evenly applied to the pads, high-strength soldering can be performed.

[0013]

FIG. 1 is a view showing a main part of an electronic component 10 and a printed circuit board 20 according to a first embodiment of the present invention, wherein (a) is a plan view and (b) is a front view. FIG.
In FIG. 1, reference numeral 10 denotes an electronic component, 11 denotes a component main body containing an integrated circuit, and 12a to 12f denote leads provided on one side of the component main body 11. Each of the leads 12a to 12a
f is similarly provided on the four sides of the component body 11.

In FIG. 1, reference numeral 20 denotes a printed circuit board, 21 denotes an epoxy resin substrate body having a surface coated with a solder resist, and 22a to 22f denote pads. Each of the pads 22a to 22f is connected to a wiring pattern (not shown) arranged on the back surface of the substrate body. In the drawing, S indicates a solder paste, and L indicates an irradiation spot of a light beam.

In FIG. 1, K1 is the first irradiation start position,
Reference numeral 2 denotes a second irradiation start position, and the distance between the first irradiation start position K1 and the second irradiation start position K2 is set to be larger than the diameter of the light beam irradiation spot L.

The mounting of the electronic component 10 and the printed circuit board 20 thus configured by soldering using a light beam is performed as follows. That is, after positioning the substrate body 21 at a predetermined position, the pads 22a to 22
f. Solder paste S using a dispenser (not shown)
Supply.

Each of the leads 1 of the electronic component 10 will be described below.
2a to 12f correspond to the corresponding pads 22a to 22f, respectively.
Place on. Next, scanning with a light beam (not shown) is performed. First, a light beam is scanned from the right side K1 of the pad 22d in FIG. 1 in the direction of the pad 22a (first irradiation step). Next, a light beam is scanned from the left side K2 of the pad 22c in the direction of the pad 22f (second irradiation step). Then, the melted solder paste S spreads on the pads 22a to 22f.

For this reason, the pads 22c and 22d between the first irradiation start position K1 and the second irradiation start position K2 have two pads.
Since irradiation is performed twice, a sufficient amount of heat for melting the solder is given by the light beam, and no soldering failure occurs.

As described above, according to the soldering method according to the first embodiment, the irradiation amount at the irradiation end position is adjusted to be appropriate (the substrate is not damaged at the irradiation end position, such as measling. Even if the irradiation intensity of the light beam is set, the amount of heat applied to the pads 22c and 22d near the irradiation start position does not become insufficient, so that the soldering can be performed properly, and the irradiation is completed. The substrate can be prevented from causing thermal damage such as measling at the position.

Further, since the distance between the first irradiation start position K1 and the second irradiation start position K2 is set to be at least larger than the spot diameter of the light beam, a sufficient overlapping irradiation distance can be secured. In addition, soldering defects can be prevented. In addition, when the overlapping irradiation distance cannot be sufficiently ensured, it is possible to cope with the problem by reducing the scanning speed of the light beam in the overlapping portion.

FIGS. 2A and 2B are diagrams showing main parts of an electronic component 10 and a printed circuit board 30 according to a second embodiment of the present invention, wherein FIG. 2A is a plan view and FIG. 2B is a front view. 2, the same functional portions as those in FIG. 1 are denoted by the same reference numerals, and the detailed description thereof will be omitted.

In FIG. 1, reference numeral 30 denotes a printed circuit board, 31 denotes a substrate main body made of epoxy resin having a surface coated with a solder resist, and 32a to 32f denote pads. Each of the pads 32a to 32f is connected to a wiring pattern (not shown) arranged on the back surface of the substrate body. Further, 33a,
33b and 33c, 33d indicate dummy pads, and these dummy pads 33a to 33d are not connected to the wiring pattern. In the drawing, S indicates a solder paste, and L indicates an irradiation spot of a light beam.

The mounting of the electronic component 10 and the printed circuit board 30 thus configured by soldering using a light beam is performed as follows. That is, after positioning the substrate main body 31 at a predetermined position, the pads 32a to 32
The solder paste S is supplied to the f and the dummy pads 33a to 33d by a dispenser (not shown).

Next, each of the leads 12a to 12a of the electronic component 10
f are placed on the corresponding pads 32a to 32f, respectively. Next, scanning with a light beam (not shown) is performed. First, FIG.
The light beam is scanned from the right side K1 of the pad 32d toward the pad 32a (first irradiation step), and then the light beam is scanned from the left side K2 of the pad 32c toward the pad 32f (second irradiation step).
Solder paste S melted by the irradiation step)
Spread over the pads 32a to 32f, respectively.

For this reason, the pads 32c and 32d between the first irradiation start position K1 and the second irradiation start position K2 have two pads.
Since irradiation is performed twice, a sufficient amount of heat for melting the solder is given by the light beam, and no soldering failure occurs.

On the other hand, since the dummy pads 33a to 33d absorb the heat of the pads 32a and 33f, which are relatively high in temperature because they are close to the irradiation end position of the light beam, an abnormal rise in temperature can be prevented. Damage can be prevented.

As described above, according to the soldering method according to the second embodiment, it is possible to obtain the same effect as the effect obtained by the soldering method according to the first embodiment, and it is also possible to obtain the position at both ends. Thermal damage to the pad can be prevented.

FIGS. 3A and 3B show an electronic component 40 to which a soldering method according to a third embodiment of the present invention is applied.
FIG. 2 is a diagram showing a printed circuit board 50. In FIG. 3, reference numeral 40 denotes an electronic component; 41, a component body containing an integrated circuit;
Reference numerals 42d denote leads provided on the side 41a of the rectangular component body 41. These leads 42 a to 42 d are attached at an angle θ to the side 41 a of the component body 41. The leads 42a to 42d are similarly provided on the four sides of the component body 31.

In FIG. 3, reference numeral 50 denotes a printed circuit board; 51, a substrate body made of epoxy resin having a surface coated with a solder resist; and 52a to 52d, pads. Each of the pads 52a to 52d is connected to a wiring pattern (not shown) arranged on the substrate body 51. In the drawing, S indicates a solder paste.

The mounting of the electronic component 40 and the printed circuit board 50 thus configured by soldering using a light beam is performed as follows. That is, after positioning the substrate body 51 at a predetermined position, the pads 52a to 52
d. Solder paste S using a dispenser (not shown)
Supply.

Next, the leads 42a to 4d of the electronic component 40
2d are placed on the corresponding pads 52a to 52d, respectively. Next, scanning with a light beam (not shown) is performed. At this time, the light beam is applied to the portion α on the tip side of each of the leads 42a to 42d and the portion β on the component body side. Therefore, the solder paste S is sufficiently melted at both the portions α and β. Therefore, high-strength soldering can be performed. It should be noted that the present invention is not limited to each embodiment, and it is needless to say that various modifications can be made without departing from the spirit of the present invention.

[0032]

According to the soldering method of the present invention, good soldering can be performed.

[Brief description of the drawings]

FIG. 1 is a view showing an electronic component and a printed board to which a soldering method according to a first embodiment of the present invention has been applied.

FIG. 2 is a view showing an electronic component and a printed circuit board to which a soldering method according to a second embodiment of the present invention is applied.

FIG. 3 is a view showing an electronic component and a printed circuit board to which a soldering method according to a third embodiment is applied.

FIG. 4 is a diagram showing an example of a conventional method for soldering an electronic component and a printed circuit board.

[Explanation of symbols]

 10, 40: electronic components 20, 30, 50: printed circuit boards

Claims (3)

[Claims] 1. A soldering method for soldering and connecting a plurality of leads provided in a row at predetermined intervals to an electronic component and a plurality of pads formed on a printed circuit board so as to correspond to the leads. A first irradiation step of scanning a light beam from a first irradiation start position located near the center of the plurality of rows of pads to a pad arranged at one end; A second irradiation which is located near the center and scans a light beam in a direction from a second irradiation start position on one end side of the first irradiation start position to a pad arranged on the other end; And a soldering method. 2. The solder according to claim 1, wherein an interval between the first irradiation start position and the second irradiation start position is set to be at least larger than a spot diameter of the light beam. Attachment method. 3. A soldering method for soldering and connecting a plurality of leads provided in a row at predetermined intervals to an electronic component and a plurality of pads formed on a printed circuit board so as to correspond to the leads. A soldering method, comprising: an irradiation step having a predetermined angle with respect to a direction perpendicular to a direction in which the plurality of leads extend and scanning a light beam along the plurality of pads.