RU226002U1 - LASER SOLDER MODULE - Google Patents

Abstract

The utility model relates to the field of mechanical engineering, in particular to devices for automated selective laser soldering, for example, to laser soldering installations for small-scale and medium-scale production and can be used for soldering electronic components: SMD, DIP, pin connectors, sockets, wires and other electronic components technology, as well as composite materials and precious metals. The module for laser soldering of electronic components of printed circuit boards contains a housing, a pyrometer, a video camera, a device for changing the size of the laser spot and its displacement, an optical system, a lens, while in the upper part of the housing there is a hole for input of laser radiation, the pyrometer and video camera are partially located above the housing. A device for changing the size of the laser spot and its displacement is located inside the housing in the path of the collimated beam of laser radiation, and it contains a movable collecting lens, a stationary scattering lens and an electric motor. The optical system consists of lenses, translucent and reflective mirrors. The lens is located in the lower part of the housing and focuses the output laser radiation in the soldering area and receives visible and thermal radiation going to the pyrometer and video camera. Attached to the side of the housing is a wire feed mechanism with a spool of solder wire and a guide tube. Increases the productivity of the soldering process of electronic components. 6 ill.

Description

Field of technology to which the utility model relates

The utility model relates to the field of mechanical engineering, in particular to devices for automated selective laser soldering, for example, to laser soldering installations for small-scale and medium-scale production and can be used for soldering electronic components: SMD, DIP, pin connectors, sockets, wires and other electronic components technology, as well as composite materials and precious metals.

State of the art

The Seica FireFly laser soldering device is known from the prior art (see https://2shemi.ru/lazernaya-payka-pechatnyh-plat/?ysclid=lr7bdvbaly359891549#Device_for_laser_soldering), which is available in two versions, with a soldering head above or below the printed circuit fee. The soldering head contains a radiation energy source, an optical system, a CCD camera for monitoring the process, a pyrometer for analyzing the thermal power supplied to the board, and a solder dispenser. This set of tools allows you to fully control the soldering process.

However, the device does not allow you to change the size of the solder spot. This device focuses laser radiation into a ring-shaped spot and is designed for soldering round holes, while the power density has an uneven distribution. As a result, the thin film of metallization will heat up significantly above the wire lead, which can lead to a failed connection.

A laser soldering module is known (see patent RU No. 183152, IPC B23K 1/005, published September 12, 2018), which contains a laser head including a system of focusing lenses and beam splitters, a pyrometer and a device for feeding solder.

However, this module does not allow automatic shifting of the spot when its size changes and requires additional adjustment of the wire feed mechanism each time the spot size changes.

Disclosure of the essence of the utility model

The technical problem is to create a device, a laser soldering module, that allows you to control the soldering mode with high accuracy, preventing overheating of components and contact pads, as well as to carry out optical control of the soldering process.

The technical result is to increase the productivity of the soldering process of electronic components.

The technical result is achieved in that the laser soldering module, according to the solution, contains a housing, in the upper part of which there is a hole for input of laser radiation and a pyrometer and a video camera are built-in, wherein the pyrometer and video camera are partially located above the housing, inside the housing, in the path of the collimated beam of laser radiation a device is placed for changing the size of the laser spot and its displacement, containing a movable collecting lens, a stationary diverging lens and an electric motor, an optical system consisting of lenses, translucent and reflective mirrors, and a lens located in the lower part of the body, which focuses the output laser radiation into soldering area and receives visible and thermal radiation going to the pyrometer and video camera, while a wire feed mechanism, including a coil of solder wire and a guide tube, is attached to the side of the body.

Brief description of drawings

The utility model is illustrated by drawings, where: FIG. 1 - shows the inventive device, Fig. 2 - optical diagram of the laser soldering module, Fig. 3 - shows an example of soldering a component lead with a small spot; Fig. 4 - shows the intensity distribution of laser radiation in the area of a small solder spot; Fig. 5 is an example of soldering a lead through a hole with a large spot; in FIG. 6 - shows the distribution of laser radiation intensity in the area of a large solder spot.

Positions in the drawings indicate:

1. entrance hole for input of laser radiation;

2. pyrometer;

3. video camera;

4. video camera eyepiece;

5. solder wire coil;

6. solder wire feeding mechanism;

7. guide tube for solder wire;

8. PCB plane;

9. laser soldering module lens;

10. translucent mirror;

11. reflective mirror;

12. device for changing the size of the laser spot;

13. movable collecting lens;

14. fixed diverging lens;

15. collimating lens.

Implementation of a utility model.

The laser soldering module contains a housing, in the upper part of which there is a hole for input of laser radiation transmitted through a fiber-optic waveguide 1, and a pyrometer 2 and a video camera 3 are built-in. Moreover, the pyrometer and video camera are partially located above the housing (Fig. 1).

In the lower part of the housing there is a hole for the lens 9, which focuses the outgoing laser radiation into the soldering area on the printed circuit board 8 and receives thermal and visible radiation entering the pyrometer 2 and video camera 3.

Attached to the side of the body is a wire feed mechanism (solder wire) 6, consisting of a coil of solder wire 5 and a guide tube 7 (Fig. 1).

Inside the housing there are: a device for changing the size of the laser spot and its displacement 12, containing a movable collecting lens 13, a fixed diverging lens 14, and an electric drive mechanism (electric motor, not shown in Fig 2); an optical system consisting of a collimating lens 15, eyepiece lenses of a video camera 4, translucent mirrors 10 and reflective mirrors 11, and an objective lens 9 (Fig. 2).

The electric drive mechanism is designed to move the movable collecting lens 13 along the optical axis at the required angle. The drive mechanism is represented by a stepper motor with a worm gear; signals for moving the moving lens are generated by a microcontroller according to commands from the control computer.

The device works as follows.

The laser soldering module is installed on a manipulator, which is capable of providing movement in space with the required accuracy. For example, a laser soldering module is placed on the Z-axis carriage of a gantry manipulator. The printed circuit board is located motionless on the table, and the laser soldering module moves from above the printed circuit board according to specified coordinates. On the portal of the manipulator there is a carriage that moves the laser soldering module along the Y axis along the portal, respectively, the movement of the portal moves the laser soldering module along the X axis. Electromechanical movement drives are made using servomotors, ball screw transmission of movement along linear guides on ball carriages, which ensures high speed, accuracy and reproducibility of movement to a given point in the workspace according to commands from the control computer.

Installation of the laser soldering module is possible on a robotic arm or any manipulator that provides the necessary precision of movement.

A printed circuit board is placed on the table with electronic components attached (pins up if the components are soldered through a hole in the board).

Using a test printed circuit board, the operator creates a table in the software for automatic soldering of a series of printed circuit boards of the same type or solders each connection individually. By moving the manipulator to specified points above the printed circuit board (position control is carried out through a video camera), the coordinates and soldering modes for these coordinates are stored in the table. The parameters of the soldering mode (temperature profile, size of the heated spot, amount and speed of solder supply) are adjusted if necessary and can be checked by the operator by starting the soldering process individually for a specific connection. When moving to the next soldering point, the laser soldering module can be set to a safe height at which there are no obstacles that could damage it or the elements of the electronic circuit. A table with coordinates of soldering locations, soldering modes and reference points can be saved in a file and loaded for use. Coordinates for solder points can be obtained either directly from the test board or from a file format (Gerber file format).

When installing the next printed circuit board using reference points, the coordinates in the table for automatic soldering are corrected. The manipulator sequentially moves along the calculated coordinates and, in accordance with the specified mode, carries out the soldering process. When the spot size changes, the movable lens 13 moves up or down with a simultaneous displacement away from the optical axis, which results in a displacement of the laser-heated spot on the printed circuit board. The size of the spot is chosen in such a way that the entire contact pad is heated, and in the case of a wire lead coming out of the hole in the printed circuit board, the solder is supplied to the area of the corner (gap) of Fig. 5 preventing the solder wire from colliding with the hard terminal of the electronic component. During the soldering process, the specified heating temperature profile is controlled by a pyrometer built into the laser soldering module, and the laser radiation power is changed so that the temperature in the soldering area corresponds to the specified one. The feed rate and amount of solder are matched to the heating profile so that when the solder wire contacts the solder area, there is no solder sticking, deformation, or melting to form a solder ball at the solder tip.

The spot size is changed by moving the movable collecting lens 13 using an electric motor installed inside the laser soldering module housing (stepping motor), not shown in Fig. 2. The axis of movement of the lens is tilted at a certain angle from the optical axis and when moving the lens moves not only up or down, but shifts to the side, which leads to a displacement of the laser spot on the board synchronously with a change in its size. A fixed diverging lens together with a movable collecting lens and optical elements of lens 15 and objective 9 make it possible to form the laser spot sizes necessary for soldering different contact pads while maintaining a constant distance from the laser soldering module to the printed circuit board. Thus, there is no need to adjust the wire feeder for soldered joints of different sizes.

The inventive device, a laser soldering module, combines a device for forming a laser spot of variable size with a proportional displacement relative to the optical axis, a pyrometer for monitoring the temperature in the soldering area, and a video camera.

Laser radiation is transmitted through a fiber optic light guide into the entrance hole 1. Lens 15 forms a collimated beam of radiation, a movable collecting lens 13 and a stationary diverging lens 14 form a device for changing the size of the laser spot 12. The reflecting mirror 11 and the translucent mirror 10 shift the laser beam, which the objective lens 9 is focused in the soldering area, for example, on the surface of the printed circuit board 8 within the solder pad. By the position of the movable collecting lens 13, the size of the heated area is selected depending on the size of the soldered joint. In fig. 2 shows the ray path to the left of the optical axis for the position of the movable lens 13’ and, accordingly, to the right of the optical axis for the position 13 of the movable lens. Designations in Fig. 2 lenses 13 and 13' correspond to the extreme positions of the movable lens 13. Translucent mirrors 10 combine laser radiation (which heats the soldered joint), visible radiation for a digital video camera 3 and thermal radiation in the near-infrared range into one optical channel, to control the temperature in the area with a pyrometer 2 rations. The solder wire feeding mechanism 6 is indicated in Fig. 2 with a fragment of guide tube 7 for supplying wire with flux to the soldering area. The pyrometer, located on the optical axis, is focused into the solder supply area regardless of the size of the laser spot, which eliminates the need for its additional adjustment when changing the size of the soldered joints. The proposed technical solution makes it possible to reduce the time of soldering printed circuit boards with connections of different sizes, eliminating additional operations to reconfigure the device, while maintaining high quality of the solder connection.

Laser heating, temperature control and visual inspection are combined into a single channel through the objective lens and focused into the solder wire feeding area. As mirrors for laser radiation, an interference dielectric multilayer coating is used on the glass, which selectively reflects laser radiation at the operating wavelength of the laser and is transparent to most of the visible and thermal radiation necessary for optical monitoring with a pyrometer and video camera. A device is placed in the path of the collimated laser beam that allows one to simultaneously change the size and position of the spot on the surface of the soldered joint without changing the position of the laser soldering module and the solder feeder.

Pyrometric temperature control and the location of the solder wire supply do not depend on the size of the heating spot by laser radiation, and the displacement of the center of the laser spot relative to the solder supply location makes it possible to eliminate a number of characteristic defects during the laser soldering method and the procedure for adjusting the solder supply location and the pyrometer when changing the size of the soldered joint.

In fig. 4 and 6 show examples of uniform distribution of radiation intensity in the area of the heating spot and its displacement from the optical axis (place of solder supply) in the extreme positions of the movable lens and the corresponding examples of Figs. 3 and 5 sections of the printed circuit board with indications of the location of solder supply and the position of the laser spot.

High quality of the solder joint is achieved by individual correction of not only the heating profile and the process of feeding solder wire for each joint, but also by the possibility of coordinated control of the size of the area heated by laser radiation and the location of the solder supply.

So, due to the automatic displacement of the area heated by laser radiation when the spot size changes, the need for additional adjustment is eliminated, since the location of the solder wire supply and the temperature control area do not change.

The video camera is used to determine the position of the soldered joint and evaluate the quality of soldering.

Claims (1)

A module for laser soldering of electronic components of printed circuit boards, characterized in that it contains a housing, a pyrometer, a video camera, a device for changing the size of the laser spot and its displacement, an optical system, a lens, while in the upper part of the housing there is a hole for input of laser radiation, a pyrometer and the video camera is partially located above the housing, the device for changing the size of the laser spot and its displacement is located inside the housing in the path of the collimated beam of laser radiation, and it contains a movable collecting lens, a fixed scattering lens and an electric motor, the optical system consists of lenses, translucent and reflective mirrors, The lens is located in the lower part of the housing and focuses the outgoing laser radiation in the soldering area and receives visible and thermal radiation going to the pyrometer and video camera, while a wire feed mechanism with a coil of solder wire and a guide tube is attached to the side of the housing.