JPH0744332B2 - Terminal connection method and device - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a plurality of terminals arranged in parallel of an electric component such as a flat package type integrated circuit (hereinafter referred to as FPIC) and a printed circuit board. The present invention relates to a method and an apparatus for connecting a conductor on a substrate such as a plate.

[Background of the Invention] While heating a solder interposed between a plurality of terminals arranged in parallel in an electric component and a conductor on a substrate by a non-contact electrode part heating means, It is melted by scanning in a direction across a plurality of terminals, and then, by solidification, the terminals are connected to the conductors by using this brazing medium ("Electronic Technology", Vol. 25). No. 8 "YAC laser soldering").

Many of the electrical parts using semiconductors such as FPIC are destroyed when the package receives heat of about 140 ° C. According to the above method, the package and the terminals and conductors do not heat much. Since the brazing filler metal present between them can be melted by raising it to the eutectic point of 183 ° C. or higher, there is almost no fear that the electric components will be broken by the heat during brazing.

However, in the heating method using the non-contact electrode part heating means, a high density of energy is suddenly applied to speed up the work, so that the brazing material scatters, which electrically connects adjacent terminals or conductors. I had to do it.

The above document also shows that such a problem can be solved by preheating. However, there is no disclosure of how this preheating was done.

Generally, preheating is performed by putting both the substrate and the electric components in a preheating tank. As a matter of course, the electric parts also receive heat from the package part, so that preheating can be performed up to about 120 to 135 ° C. this is,
There is a considerable difference up to 183 ° C, which is the eutectic point of tin-lead solder. When eutectic solder is used, preheating to a temperature as close as possible not to exceed the eutectic point of 183 ° C can reduce the scattering of brazing filler metal that occurs during main heating.

When using a solder other than eutectic solder, which is a tin-lead system, it may be in a semi-molten state during the change from solid to liquid state, and the temperature in this semi-molten state is eutectic point 183
Higher than ℃, depending on the combination of tin and lead 183 ℃
To 327 ° C.

Therefore, when a brazing filler having a semi-molten state is used, it cannot be preheated to a semi-molten state by a method of putting it in a preheating tank for preheating.

In the case of preheating with the preheating tank, no matter how well the work proceeds, it takes a long time to get out of the preheating tank and perform the main heating for brazing. The temperature is considerably cooled. This reduces the effect of preheating and causes a large energy loss.

The state diagram of tin-lead solder is "Electronic Technology" VOL.22 No7
See "Solder Material" for more details.

[Object of the Invention] The present invention has been made in view of the above points, and an object of the present invention is to prevent electrical destruction of an electric component.
Another object of the present invention is to provide a terminal connection method capable of suppressing occurrence of a short circuit between terminals, a short circuit between conductors, and the like, and moreover, preheating and main heating can be efficiently performed by one laser irradiation means. The object of the present invention is to provide a terminal connecting device that can accurately implement the above method.

[Summary of the Invention] In the method of the present invention, a wax interposed between a plurality of terminals arranged in parallel in an electric component and a conductor on a substrate is heated by laser light from a laser output section, and In the method of scanning the laser output section across a plurality of terminals of an electric component and connecting each terminal to a conductor on a substrate by the brazing, when the laser output section sequentially scans each terminal of the electric component. A preheating step in which the distance between the laser output portion and the substrate is changed for each terminal, and the brazing is heated in a state where the brazing material is not melted due to a change in energy density of the laser beam irradiated on the substrate, and the preheating step Then, the main heating step of melting the brazing material is performed for each terminal, and the preliminary heating step and the main heating step are repeated for each terminal to connect the terminal to the conductor.

Further, in the device of the present invention, the substrate supporting means for supporting the substrate on which the electric component is mounted, the laser output part, and the distance of the laser output part to the substrate are changed to change the energy density of the laser light with which the wax on the substrate is irradiated. Scanning driving means for scanning the laser output portion in a direction traversing each of the plurality of terminals on the substrate are provided, each having energy changing means for changing the energy density. The energy density changing means places the laser output portion in a preheating position so that the laser output portion preheats the brazing filler metal so that it does not melt when the laser driving portion scans the terminals on the substrate by the scan driving means. Positioning means, means for positioning the laser output portion to the main heating position so that the laser output is in the molten state for the wax and main heating, and these preheating position positioning means and main heating position positioning means are repeatedly executed for each terminal. And means for making it.

In the present invention, the molten state of wax means a liquid state and does not include a semi-molten state.

Embodiments of the Invention Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall construction of an embodiment of a terminal connecting device for carrying out the method of the present invention, in which 1 is an unbrazed substrate stack for stacking substrates 2a to be brazed, and 3 is already This is a brazed substrate stack that stacks the substrates 2b that have been brazed. The stack 1 is constructed so that the substrate to be next worked is lifted to a certain height and stands by, and the stack 3 finishes the brazing work and positions the newly transferred substrate at a certain height. In order to receive the substrate, the previously received substrates are sequentially lowered.

Although only one is shown in the figure between the stack 1 and the stack 3, two belts 4 are provided in parallel, and the substrates 2a and 2b are placed on the belt 4 to stack the stacks 1 to 3 It is configured to be transported to. Stack 1
A limit switch (not shown) for detecting the arrival of the substrate 2a is provided between the stack and the stack 3, and when the limit switch is activated, both sides of the substrate 2a being conveyed are grasped and slightly lifted to raise the substrate 2a. Away from belt 4,
Substrate supporting means for supporting is provided. Since the above-mentioned structure of the substrate supporting means is known, the illustration is omitted. In FIG. 1, the substrate 2 between the stacks 1 and 3 is in a state of being supported by the substrate supporting means.

Reference numeral 5 is a horizontal articulated assembly robot as a scanning drive means. This assembly robot 5 has a base 5a and this base
A column 5b that extends vertically on 5a, a first arm 5c that can rotate 200 ° horizontally with the column 5b as a fulcrum, and a first arm 5
Second arm that can rotate horizontally by 152.5 ° with c as a fulcrum
5d, a vertical shaft 5e having a stroke of 200 mm in the vertical direction on the second arm 5d, and a twist shaft 5f which is located at the lower end of the vertical shaft 5e and is rotatable about the vertical axis by 360 °. Further, a laser output portion 8 serving as a non-contact pole portion heating means is attached to the twist shaft 5f. The laser output section 8 is configured to emit a YAG laser beam to the solder 20 located between the conductor on the board, that is, the printed pattern 17 and the terminal 19 of the FPIC 18, and the assembly robot 5 is configured to emit the YAG laser beam. 1 arm 5c,
By operating the second arm 5d, the vertical shaft 5e, and the twist shaft 5f, scanning is performed so as to cross each of the plurality of terminals 19 arranged in parallel with the FPIC 18.

Further, the assembling robot 5 causes the laser output section 8 to repeat the vertical movement of the vertical axis 5e during scanning of the laser output section 8 so that the laser output section 8 is sawtooth-shaped with respect to the surface of the wax 20 as shown in FIG.
While moving away from or closer to 85 as a whole, it scans in the F6 direction across each terminal 17 as a whole. That is, the vertical axis
5e keeps the laser output unit 8 away from the wax 20,
Is preheated to such an extent that the
To perform main heating for heating the wax 20 to a molten state, and thus changing the distance of the laser output section 8 to the substrate 2 for each terminal 19 to change the energy density of the laser light to the wax 20. Work as a means. Therefore, the laser output unit 8 is attached to the vertical axis 5e.
A preheating position of the laser output unit 8 so that the laser can be preheated to a state in which it is not melted, and a position where the laser output unit 8 performs main heating so that the laser output unit 8 melts the wax 20 and performs main heating.
It is preset for each terminal.

What is important in this embodiment is that the laser output 8 is focused above the surface of the wax 20. When the laser output unit 8 approaches the wax 20, it is also important that the laser output unit 8 approaches in a linear form perpendicular to the surface of the substrate 2.

Since the terminal connecting device of the embodiment has the above-mentioned structure, one embodiment of the method of the present invention will be described with reference to the operation thereof.
When scanning a plurality of terminals 19 arranged in parallel with each other on the 18 side, the laser output section 8 is repeatedly moved away from or closer to the brazing wire 20 by the vertical axis 5e, so that the laser output section 8 is further separated from the substrate 2. 20 when you are far apart
Is not melted but is simply preheated. When the laser output part 8 comes closest to the substrate 2 or when it is located near the substrate 2, it becomes a main heating process for bringing the brazing material 20 into a molten state. Therefore, preheating and main heating are performed. And can be performed in one step.

As a result, in the method of the present invention, it is not necessary to put it in a preheating tank to preheat it as in the prior art, and it is possible to efficiently perform preheating and main heating without destroying the FPIC 18, and further, to the substrate 2. On the other hand, since the distance of the laser output unit 8 is changed and the heat of preheating is continuously used for main heating,
It will no longer be said that the wax 20 will be heated rapidly
20 can be prevented from scattering like in the prior art, and it can be prevented that adjacent terminals or printed patterns 19 are electrically connected to each other. Moreover, since the position of the laser output unit 8 with respect to the wax 20 is simply changed, the structure can be simplified.

In the device of the present invention, the assembly robot 5 uses the laser output shaft 8
Is scanned across the terminals 19 arranged on the FPIC 18, preheating and main heating are performed by moving the laser output section 8 away from or near the wax 20 on the substrate 2 by the operation of the vertical axis 5e. Since it is configured to be repeatedly performed, the laser output 8 can easily and surely bring the density of the laser light into contact with the wax 20, and the above method can be accurately performed with a simple configuration.

The illustrated embodiment shows an example in which the laser output unit 8 focuses the laser light above the surface of the brazing material 20, but as shown in FIG. May be down. That is, when the focus is down,
As shown by the sawtooth wave 86 in FIG. 5, the laser output portion 8 is operated in the direction opposite to that of the embodiment shown in FIG. 4 and is raised to gradually increase the heat energy density with respect to the wax 20. Even if the preheating and the main heating are performed by repeating this, the same effect can be obtained.

[Effects of the Invention] As described above, according to the method of the present invention, when the laser output unit scans the terminals of the electric component arranged in parallel, the distance of the laser output unit to the substrate is changed for each terminal, Since the preheating and the heating are repeatedly performed by changing the energy density of the laser beam applied to the wax on the substrate by the output unit, the preheating and the main heating can be performed by one laser output unit. Further, there is an effect that preheating and main heating can be efficiently performed without destroying the electric parts, and further, short circuit between terminals, short circuit between conductors and the like can be suppressed.

According to the apparatus of the present invention, the apparatus further comprises a substrate supporting means, a laser output section, and a scanning driving section having an energy density changing section, and the energy density changing section uses the scanning driving section to output the laser output section on the substrate. A means for positioning the laser output portion at a preheating position so as to preheat the laser output portion to a state in which the brazing material does not melt when scanned in the direction across each terminal;
It has a means for positioning the laser output portion at the main heating position so that the laser output is in the molten state for the main heating and a main heating position, these preheating position positioning means, main heating position positioning means, and means for repeatedly executing each terminal. Since it was configured
There is an effect that the above method can be implemented accurately.

[Brief description of drawings]

FIG. 1 is an overall view of an embodiment of a terminal connecting device for carrying out the method of the present invention, FIG. 2 is a perspective view showing the relationship between a part of a printed board and a flat package integrated circuit, and FIG. 3 is a laser. FIG. 4 is a sectional view of a main part showing a light irradiation state, FIG. 4 is an explanatory view showing a scanning locus of a laser output portion, and FIG. 5 is an explanatory view showing another scanning locus of a laser output portion. 1 ... Terminal connection device, 2 ... Substrate, 5 ... Assembling robot as scanning drive means, 5a ... Base, 5b ... Post, 5c
...... First arm, 5d ...... Second arm, 5e ...... Vertical axis as energy density changing means, 5f ...... Twist axis, 8 ...... Laser output section, 17 ...... Print pattern, 18 ...... Flat package type Integrated circuit, 19 ... Terminal, 20 ...

Claims (2)

[Claims] 1. A braze interposed between a plurality of terminals arranged in parallel with an electric component and a conductor on a substrate is heated by laser light from a laser output section and the laser output section is , A method of scanning across a plurality of terminals of an electric component and connecting each terminal to a conductor on a substrate by the brazing, when the laser output unit sequentially scans each terminal of the electric component, By changing the distance of the laser output portion to the substrate and changing the energy density of the laser light with which the wax on the substrate is irradiated, the preheating step in which the wax is heated in a non-melting state, and the preheating step is followed by the preheating step. And a main heating step for melting each of the terminals is performed, and the preliminary heating step and the main heating step are repeated for each terminal to connect the terminals to the conductor. 2. A solder interposed between a plurality of terminals arranged in parallel with an electric component and a conductor on a substrate is heated by laser light from a laser output section, and the laser output section is A device for scanning across a plurality of terminals of an electric component and connecting each terminal to a conductor on the substrate by the brazing, substrate supporting means for supporting the substrate on which the electric component is mounted, a laser output unit, and The laser output section is provided with energy density changing means for changing the distance to the substrate to change the energy density of the laser light with which the wax on the substrate is irradiated, and the laser output section has a plurality of terminals on the substrate. A scanning drive means for scanning in a transverse direction, the energy density changing means, when the laser output section is scanned by the scanning drive means in a direction traversing each terminal on the substrate,
A means for positioning the laser output portion at a preheating position so that the laser output portion preheats the wax in a non-melting state; and a means for positioning the laser output portion at the main heating position so that the laser output makes the wax in a molten state and performs main heating. A terminal connecting device, comprising: a preheating position positioning means and a main heating position positioning means for repeatedly executing each terminal.