JPH0446669A - Method and device for laser beam soldering - Google Patents

Abstract

PURPOSE:To accurately perform soldering by bringing a reed into contact with solder cream applied by pressing circuit parts, irradiating the solder cream with a laser beam to melt it and then, pressing the circuit parts. CONSTITUTION:The cream is applied to a wiring pattern for joining the circuit parts formed on a substrate. The reed of the circuit parts in aligned with the wiring pattern by using an FPIC3. The reed is brought into contact with the solder cream applied by pressing the aligned circuit parts with the specified pressing force by using the FPIC3 and a pusher 10. A contact part between the solder cream and the reed is irradiated with the laser beam by using a laser beam scanning mechanism 12 to melt the solder cream. After the solder cream is molten, the circuit parts are again pressed by the pusher 10. Consequently, all reeds of the circuit parts aligned with the wiring pattern are stuck and can be fixed.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to laser soldering, and particularly to a method and apparatus for laser soldering of multi-legged circuit components such as flat package semiconductor integrated circuits. .

(Prior Art) Generally, circuit components are mounted on a printed wiring board by attaching various predetermined circuit components to the solder-coated wiring pattern of the printed wiring board, and then soldering them by dip or reflow methods. This is done by attaching. However, when trying to solder a multi-legged circuit component having multiple leads in parallel, such as a flat package semiconductor integrated circuit (hereinafter abbreviated as FPIC) using this method, as shown in FIG. ) Since the solder coating (2) that covers the wiring pattern (2) has a chevron shape, it is not possible to accurately align the leads with the wiring pattern (1), and as a result, as shown in Figure 6, the FPI
The lead (4) of C(3) is likely to be soldered to the wiring pattern (1) in a misaligned state.

To prevent such misalignment, apply masking ink or masking tape to the PPIC mounting area to prevent it from being covered with solder.
When soldering the FPIC after applying a solder coating to other parts, the masking is removed, solder cream is applied, and the FPIC is positioned on the solder cream and soldered.

(Problem to be Solved by the Invention) As mentioned above, as a method for soldering multi-legged circuit components such as PPIC, masking ink or masking tape is applied to the PPIC mounting part in advance, and the wiring pattern is coated with solder. When soldering multi-legged circuit components, the method is to remove the masking, apply solder cream, and then solder.

However, this method has the following problems.

(b) Before soldering PPIC, it is necessary to apply masking ink or masking tape and then remove it, making it difficult to automate the masking work and requiring human labor. Precision is required to prevent solder from coating the surface. When you peel it off again,
If it is not removed carefully, some of the masking material, such as the adhesive, will remain, leading to poor soldering and reduced soldering reliability. In particular, this problem is a major problem in automating pprc mounting because it depends on the skill of the operator (c) Masking ink and masking tape are expensive, so this invention increases the cost of mounted components.
The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a soldering method and apparatus that can solder multi-legged circuit components such as FPICs without shifting their positions.

[Structure of the Invention] (Means for Solving the Problems) In a laser soldering method for soldering a multi-legged circuit component to a wiring pattern for connecting circuit components formed on a board, applying solder cream to the wiring pattern, Align the leads of the circuit components with the wiring pattern coated with this solder cream, press the aligned circuit components, and bring the leads into contact with the applied solder cream with a predetermined pressing force. After melting the solder cream by irradiating the contact area between the cream and the lead with a laser beam, the circuit components were again pressed and soldered.

Another method is to use a pressure sensor to detect the reaction force of the circuit component lead that is generated when the circuit component is pressed and brought into contact with the solder cream applied to the wiring pattern for connecting the circuit component. The pressing force on the circuit components is controlled based on the detection output of the sensor.

The soldering device also includes a pusher that presses the circuit component whose leads are aligned with the wiring pattern for connecting the circuit component coated with solder cream, and a pusher that drives the pusher to a predetermined position relative to the circuit component. a second pusher drive mechanism whose driving source is a fluid actuator that drives the pusher driven by the first pusher drive mechanism until the lead of the circuit component contacts the solder cream with a predetermined pressure; , a pressure sensor that detects the reaction force of the lead generated when the lead of the circuit component contacts the solder cream with a predetermined pressure from the fluid pressure of the fluid actuator; a laser scanning mechanism that guides the lead of the circuit component and the solder cream into contact with the solder cream at a predetermined pressure and scans this contact region; The control device controls the drive of the second pusher drive mechanism and also controls the drive of the second pusher drive mechanism for pressing the circuit component after the solder cream is melted by scanning with the laser beam.

(Function) As described above, when the leads of the circuit components are brought into contact with the solder cream applied to the wiring pattern for connecting the circuit components with a predetermined pressing force, the leads of the circuit components aligned with the wiring pattern will not be misaligned. Holding the solder cream in place, the contact area between the solder cream and the lead of the circuit component can be irradiated with a laser beam to melt the solder cream, and then suppressed again to ensure accurate and reliable soldering. .

In particular, by using a pressure sensor to detect the reaction force of the lead that occurs when the lead of a circuit component is brought into contact with solder cream, and controlling the pressing force against the circuit component based on the detected output, other special means can be used. Various circuit components can be soldered without the need for soldering, and better results can be obtained.

(Example) Hereinafter, the present invention will be described based on an example with reference to the drawings.

First, a laser soldering device for soldering PPIC according to one embodiment will be described.

This soldering device can be used on an X-Y table or
A moving mechanism such as a robot that can move at least in the X-Y direction, a head mounted on the moving mechanism, and a control unit (not shown) that controls the operations of the moving mechanism and the head. Become.

As shown in FIG.
a pusher (lO) for pressing the
1) and F when pressed by the pusher (10)
A pressure sensor (not shown) detects the reaction force generated in the lead of the PIC (3), and a laser beam emitted from a laser oscillator is guided in the direction of the lead of the FPIC aligned with the wiring pattern, and the laser beam is The main component is a laser scanning mechanism (12) for scanning.

The pusher (10) has a rod shape with its central axis in the Z direction, and its base end is attached to a support (14) that transmits the drive of the pusher drive section (11).

A pusher drive unit (
11) includes a first pusher drive mechanism (16) whose drive source is a pulse motor (15), and an air cylinder (17).
and a second pusher drive mechanism (18) whose drive source is a fluid actuator such as the above.

The first pusher drive mechanism (16) has a pulse motor (19) and a feed mechanism 20) whose center axis is in the Z direction and which transmits the rotational torque of the pulse motor (19),
A support portion (22) that supports the drive source of the second pusher drive mechanism (18) is attached to a feed nut (21) that is screwed into the feed nut (20). The air cylinder (17), which is the drive source of the second pusher drive mechanism (18), is attached to the support part (22) so that the central axis of the operating rod (23) is in the Z direction.
A support (14) for supporting the proximal end of the bunya (10) is attached to 23).

These first and second pusher drive mechanisms (1B).

Among (18), the first pusher drive mechanism (IB) is
The pusher (10) is moved largely forward and backward in the Z direction, and the second pusher drive mechanism (18) moves the pusher (10) lowered by its first pusher drive mechanism (6).
This is for finely adjusting the position of 10) with respect to PPIC (3).

The pressure sensor that detects the reaction force generated on the lead of the PPIC (3) due to the pressure of the pusher (10) measures the gas pressure that operates the air cylinder (17) of the second pusher drive mechanism (18). , is attached to a gas supply pipe (not shown) connected to the air cylinder (I7).

The laser scanning mechanism (12) directs a laser beam from a laser oscillator (not shown) guided to the head section by an optical fiber (25) to the leads of the PPIC (3) aligned with the wiring pattern of the printed wiring board. Mirror leading upwards (2B
) and a mirror swinging mechanism (27) that swings a mirror (2B) so that the guided laser beam scans a plurality of parallel leads of the PPIC (3). For example, a galvanometer is used as a swing source for the mirror swing mechanism (27). In addition, in the laser scanning mechanism (12) of this example, the laser beam emitted from the laser oscillator is designed so that the laser beam can be guided simultaneously to the leads extending in four directions from each side of the rectangular PPIC (3). is guided to the head part by two pairs (four) of optical fibers (25), and the laser light from the two pairs of optical fibers (25) is extended from the opposite side of the PPIC (3) by one mirror (2B). Two mirrors (26) are arranged to guide the leads in two directions.

The control section includes a control means for controlling the operation of each part of the moving mechanism section and the head section. In particular, in the control section of the soldering apparatus of this example, the pusher (IO) is connected to the FPIC (FPIC).
3) From the output of the pressure sensor that measures the gas pressure in the air cylinder when pressing the gas pressure, the reduction in the reaction force of the pp+c(a) lead that occurs when the solder cream melts by laser scanning is determined by measuring the gas pressure ( The pusher drive mechanism includes a control means for detecting a decrease in gas pressure) and controlling the drive of the second pusher drive mechanism (18) based on the detection signal.

Next, a method of soldering PPIC will be explained.

First, as shown in FIG.
Using a metal mask in which openings corresponding to the leads of the PPIC are formed, solder cream (30) is applied to the mounting portion with a squeegee or the like. Next, the FPIC is mounted on the applied solder cream (30), and the wiring pattern (1) is applied with this solder cream (30).
Align the pp+c leads to.

Next, the soldering device is operated to position its head portion on the aligned PPIC. Then, first operate the first pusher drive mechanism and
), the tip of the pusher (10) is lowered to a position where it is slightly spaced or slightly in contact with the aligned PPIC (3). Then, the second pusher drive mechanism is operated. Then, a pressure sensor detects a pressure change (pressure increase) in the air cylinder based on a reaction force generated in the lead (4) of the PPIC (3) due to the pressing force of the pusher (10) that descends due to the drive of the second pusher drive mechanism. Then, when all the leads (4) are in close contact with the solder cream (30) and the pressurizing force of the air cylinder reaches a certain value, the drive of the second pusher drive mechanism is stopped based on the detection output from the pressure sensor. let The pressing force of the pusher at this time is 120 to 130 per lead for FPIC in which the leads (4) extend in four directions.
mg, and the reaction force generated on the lead is approximately 50a+g.

Next, a laser beam is emitted from a laser oscillator, and the FPIC (3) glued (
4) While guiding the above FPI upward, move the mirror back and
The parallel leads (4) of C (3) are scanned.

In addition, in the soldering apparatus of this example, all the leads (4) extending in four directions from the periphery of the PPIC (3) are simultaneously scanned by laser light branched by four optical fibers.

By scanning this laser beam, the solder cream (30) melts, and the resulting drop in reaction force is detected by a pressure sensor from the drop in gas pressure in the air cylinder, and based on the detection output of the pressure sensor at that time. , the scanning of the laser beam is stopped, and the second pusher drive mechanism is operated at the same time, as shown in (C), the pusher (10
) to connect the FPIC (3) to the wiring pattern (1) at a constant pressure.
) and solder it.

After the soldering part has cooled and the molten solder has solidified, the first and second pusher drive mechanisms are operated to separate the pusher (10) from the PPIC (3).

FIG. 3 is a time chart showing the operation of each part in this soldering method.

By the way, when soldering as mentioned above, the first
and a second pusher drive mechanism (1B).

(18) to lower the pusher (10) until all the leads (4) of the PPIC (3) are in close contact with the solder cream (30), and then the solder cream (21) is soldered by laser beam scanning. When it melts, repeat the second
Operate the pusher drive mechanism (18) to remove the PPIC (3).
), the lead (
4) Solder cream (30) without displacing the
All the leads (4) can be fixed in close contact with each other, and the solder cream (30) can be melted and accurately soldered while maintaining their alignment. In addition, it is possible to eliminate the pasting and peeling of relatively expensive masking ink and masking tape, which was conventionally performed.Furthermore, this soldering method uses a pressure sensor to detect a pusher (lO) for the FPIC (3) based on the detection output. Since it controls the pressing force of various FPICPs with different heights (
For 3), lead (4) and solder cream (30)
It is possible to properly bring them into close contact with each other without causing too much or too little. Therefore, according to this soldering method, it is possible to easily solder an FPIC (3) having a plurality of parallel leads (4), which was difficult in the past, and it is also possible to automate the soldering. can.

Next, other embodiments will be described.

In the above example, the pressure sensor was used to control the drive of the second pusher drive mechanism so that all the leads of the FPIC came into close contact with the solder cream, or for FPICs of the same type, the height from the top surface of the FPIC to the leads was Since the soldering temperature is constant, FPI that is trying to solder roughly.
By measuring the height of C and storing it in the control unit, all the leads of the FPIC can be brought into proper contact with the solder cream without using a pressure sensor. can be attached.

Furthermore, in the above embodiment, the FPIC was soldered by applying solder cream on the wiring pattern coated with solder.
Mask the p+c mounting part and apply solder coating,
It can also be applied to the case where solder cream is applied to the wiring pattern without the solder coating and soldered.

Furthermore, in the above embodiment, a case was described in which all the leads extending in four directions of the PPIC were soldered at the same time. It can also be applied to PPIC.

Note that the present invention is applicable not only to FPIC but also to soldering of other circuit components having a plurality of parallel leads.

[Effects of the invention] Solder cream is applied to the circuit component connection wiring pattern formed on the board, the leads of the circuit component are aligned with the wiring pattern coated with the solder cream, and the circuit component is pressed. , Bring the lead of the circuit component into contact with the applied solder cream with a predetermined pressing force, irradiate the contact area between the solder cream and the lead with a laser beam to melt the solder cream, and then press the circuit component again. When soldering is performed, all the leads of the circuit component aligned with the wiring pattern can be closely fixed, and soldering can be performed accurately in the aligned state.

In particular, if a pressure sensor is used to detect the reaction force when the lead of a circuit component is brought into contact with solder cream, and the pressing force against the circuit component is controlled based on the detection output of this pressure sensor, other special means may be used. It can be applied to various circuit components without requiring it, and better results can be obtained.

[Brief explanation of drawings]

Figures 1 to 4 are detailed explanatory diagrams of this invention.
Figures (a) and (b) are an example of F
FIGS. 2(a) to 2(c) are perspective views showing the head section and its first and second pusher drive mechanisms of a laser soldering device used for soldering PICs, respectively. An explanatory diagram of the soldering method, Figure 3 is a diagram showing the time chart, Figure 4 is a diagram showing the soldering method.
The figure shows a time chart for another soldering method, Figure 5 shows the shape of the solder coating applied to the wiring pattern of the printed wiring board, and Figures 6 (a) and (b) respectively show the solder coating. FPIC on the wiring pattern with
FIG. 4 is a plan view and a side view showing lead deviation when soldering. 1... Wiring pattern, 2-... Solder coating, 3...
PPIC, 4... Lead, 10... Pusher 12... Laser scanning mechanism, 16... First pusher drive mechanism, 17... Air cylinder 18... Second pusher drive mechanism, 26. ··mirror

Claims (3)

[Claims] (1) A step of applying solder cream to the circuit component connection wiring pattern formed on the board, a step of aligning the leads of the circuit component to the wiring pattern coated with the solder cream, and a step of aligning the leads of the circuit component to the wiring pattern to which the solder cream has been applied. a step of pressing the circuit component to bring the lead into contact with the applied solder cream with a predetermined pressing force; and a step of irradiating the contact portion between the solder cream and the lead with a laser beam to melt the solder cream. . A laser soldering method comprising the steps of: pressing the circuit component again after the solder cream has melted. (2) A pressure sensor detects the reaction force of the lead that is generated when the circuit component is pressed and the lead of the circuit component comes into contact with the solder cream applied to the wiring pattern for connecting the circuit component; 2. The laser soldering method according to claim 1, wherein the pressing force on the circuit component is controlled based on the output. (3) A pusher that presses a circuit component whose leads are aligned with the circuit component connection wiring pattern coated with solder cream, and a first pusher drive mechanism that drives this pusher to a predetermined position relative to the circuit component. a second pusher drive mechanism whose drive source is a fluid actuator that drives the pusher driven by the first pusher drive mechanism until the lead of the circuit component contacts the solder cream with a predetermined pressure; and the circuit component. A pressure sensor detects the reaction force of the lead generated when the lead contacts the solder cream at a predetermined pressure from the fluid pressure of the fluid actuator, and a laser beam emitted from a laser oscillator is brought into contact with the solder cream at the predetermined pressure. A laser scanning mechanism that guides the lead to the contact area between the lead of the circuit component and the solder cream and scans this contact area, and a detection output of the pressure sensor in response to the reaction force of the lead. the second pusher drive mechanism for controlling the driving of the second pusher drive mechanism so as to contact the circuit component with a predetermined pressure, and for pressing the circuit component after the solder cream is melted by scanning with the laser beam; A laser soldering device comprising: a control device for controlling driving of the laser soldering device;