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Basic working principle of wave soldering

S-WS450 Wave Soldering machine

一、Wave soldering machine

Wave solderingis a kind of solder wave with a specific shape formed on the surface of molten liquid solder by means of pump pressure. When mounted components pass through the solder wave at a fixed angle, solder joints are formed in the lead solder zone. The component is preheated in the preheating zone of the welding machine (the preheating of the component and the temperature to be reached are still controlled by the predetermined temperature curve) in the process of conveyor belt conveyor. In actual welding, the preheating temperature of the assembly surface is usually controlled, so many devices have added corresponding temperature detection devices (such as infrared detectors). After preheating, the components enter the lead slot for welding. Tin trough contains molten liquid solder. The nozzle at the bottom of the trough determines the shape of the solder. Thus, the solder wave is heated when the welding surface of the component passes through the wave. At the same time, the solder wave wets the welding zone and expands and fills the welding process.

wave soldering process

wave soldering process

二、Basic working principle

Wave soldering is based on the principle of convection heat transfer to the welding area heating. The molten solder wave acts as a source of heat. On the one hand, it flows to wash out the pin welding area, on the other hand, it acts as a heat conduction. The pin welding area is heated under this effect. When the silver lead solder is used, the melting solder temperature is usually controlled at about 245 degrees Celsius. In order to ensure the temperature of the welding zone, the solder wave usually has a fixed width, so that when the welding surface of the component passes through the wave, there is sufficient time for heating and wetting. In traditional wave soldering, a wave is adopted and the wave is relatively flat. With the use of lead solder, double wave mode is adopted at present.

wave soldering pot

三、The welding spot

The pin of the component provides a way to immerse the liquid solder into the metal through hole. When the pin contacts the solder wave, the liquid solder climbs up along the pin and the hole wall with the help of the surface tension. The capillary action of metallized through-hole improves the climb of solder. When the solder reaches the PcB part, the surface tension of the pad is expanded. The rising solder discharges flux gas and air from the through hole, filling the through hole and forming a solder joint after cooling.

四、What’s the difference between wave soldering and reflow oven?


The mainly different are in heating source and solder supply mode.
In wave soldering, the solder is pre-heated and melted in the trough. The solder wave pumped by the pump plays a dual role of heat source and solder supply. The solder wave of solder solder solder causes the through holes, pads and component pins of the PcB to be heated, and also provides the solder needed to form solder joints. In reflow soldering, solder paste is pre-quantitatively assigned to the solder zone of PCB. The role of heat source in reflow is to re-melt the solder.

五、Main components and working principle of wave soldering

A wave soldering machine is mainly composed of conveyor belt, heater, tin trough, pump, flux foaming (or spraying) device, etc. It is mainly divided into flux adding area, preheating zone and welding area.

The solder in the solder tank, heated by a heater, gradually melts, and the molten liquid solder, under the action of a mechanical pump (or electromagnetic pump), forms a specific shape of solder wave on the surface of the solder tank, which becomes a wave. The PCB with mounted elements is placed on the conveyor and solder joints are welded by passing through the solder wave at a certain angle and at a certain immersion depth, so it is called wave soldering.

For a single wave, there is only one wave, called the advection wave. For double waves, the first wave is called the disturbing wave, and the second wave is called the advection wave (Ping Huabo).

The role of spoiler: SMT element welding and prevent leakage welding, it ensures the proper distribution of solder through the circuit board. The solder is penetrated through the slit at a relatively high speed, thus leading to narrow gap. The direction of the jet is the same as that of the circuit board. For SMT components, the disturbance wave can basically be welded. But for through-hole components, the spoiler wave itself can not properly weld the components, it leaves the weld unevenness and excess solder, so the need for a second wave – advection wave.

The role of advection wave is to eliminate burr and weld bridge generated by the disturbance wave. Advection wave is actually the wave used by the single wave soldering machine. Therefore, when the traditional through-hole components are welded on the dual-wave machine, the disturbing wave can be turned off and the soldering can be completed by advection wave. The entire wavefront of the advection wave is basically horizontal, like a mirror. At first glance, it looks as if the tin wave is static, but in fact the solder is flowing continuously, but the wave is very smooth.

六、Wave soldering machine welding spot molding

Solder Joint Forming: When PCB enters the front end of the wave, the substrate and pin are heated, and before leaving the wave, the whole PCB is immersed in the solder, that is, bridged by the solder, but at the moment of leaving the wave end, a small amount of solder is attached to the pad due to the effect of wetting force, and due to surface tension, it will come out. At present, the shrinkage of the lead wire is small, and the wetting force between the solder and the pad is greater than the cohesion of the solder between the two pads. Therefore, a full, round solder joint will be formed, leaving the excess solder at the end of the wave, and due to gravity, it will fall back into the tin bath.

S-WS250 Wave Soldering machine

How to choose laser marking machine in SMT production line

The most important choice of laser marking machine is its laser.So today I’m gonna to tell  you something about four most common lasers.

 

S-UV-300 laser marking machine for PCB
laser marking machine for PCB

1. CO2 laser /(CO2 laser marking machine)

1)Principle

CO2 laser marking machine principle: CO2 laser marking machine, or carbon dioxide laser marking machine (CO2 is carbon dioxide). It is a laser galvanometer marking machine using CO2 gas as working medium. CO2 laser marking machine is a CO2 laser with CO2 gas as the medium, CO2 and other auxiliary gases are charged into the discharge tube on the electrode to add high voltage, the discharge tube produces glow discharge, so that the gas emits a wavelength of 10.64um laser, laser energy amplified, after the galvanometer scanning and F-Theta mirror focusing, under the control of computer and laser marking control card. The marking of images, words, numbers and lines can be carried out on the workpiece according to the requirements of users.

2)Constitution

CO2 laser marking machine consists of CO2 laser, 10.64 field mirror, 10.64 beam expander, CO2 laser power supply, scanning galvanometer, control computer, laser control card, laser control software, laser frame, laser circulating water system, circuit control system and other parts.

3)Advantages and application areas

The main features of CO2 laser marking machine are: using carbon dioxide laser, belonging to the general model, post-focusing mode, small size, high integration.

This machine is suitable for marking most non-metallic materials, such as paper packaging, plastic products, label paper, leather cloth, glass and ceramics, resin and plastic, bamboo and wood products, PCB board, etc. CO2 laser is a gas laser with a wavelength of 10.64 um in the far infrared optical band. CO2 gas filled discharge tube is used as the medium to produce laser. When high voltage is applied to the electrode, glow discharge is produced in the discharge tube. The gas molecule can release the laser, and the laser beam is formed after amplifying the laser energy.

Auto-Laser marking machine
Auto-Laser marking machine

2.Green laser /(Green laser marking machine)

1)Principle

Green laser marking machine uses high-power multi-mode laser diode pumped to produce green laser beam after laser frequency doubling, and then through computer control of high-speed scanning galvanometer deflection marking or cutting. Two laser beams are projected from different angles into transparent objects (such as glass, crystal, etc.), accurately intersecting at a point. Because two laser beams interfere and cancel at the intersection point, their energy is converted from light energy to internal energy, releasing a lot of heat, melting the point into a tiny hole. The machine accurately controls the intersection of two laser beams at different locations, creating a large number of tiny holes that eventually form the desired pattern.

 

2)Advantages and application areas

The green laser with 532 nm wavelength has obvious advantages: smaller spot diameter, more concentrated energy, high electro-optic conversion efficiency, good beam quality, marking accuracy below 10 micron level, neat marking frame, no explosion point, no thermal deformation. Mainly used in glass, crystal products, surface and internal marking, ceramics, metals, electronics, plastics and other products. It belongs to the category of cold light. It is also suitable for some products with high heat reaction and high precision.

3.Ultraviolet laser/(Ultraviolet laser marking machine)

1)Principle

Through photochemical ablation, that is, by laser energy to break the bonding between atoms or molecules, making it into small molecules gasification, evaporation. The focus spot is very small and the heat affected zone is very small, so it can be used for superfine marking and special material marking.

2)Constitution

The main components of UV laser marking machine are: focusing system, trigger type, computer control system, laser power supply, laser, galvanometer field mirror scanning system, marking control software.

3)Advantages and application areas

Ultraviolet laser marking machine with its unique low-power laser beam, especially suitable for ultra-fine processing of the high-end market.iPhone, cosmetics, pharmaceuticals, food and other polymer packaging bottle surface marking; flexible PCB board; silicon wafer micro-hole, blind hole processing; LCD liquid crystal glass, glassware surface, metal surface coating, plastic buttons, electronic components, Communications Equipment,  and other fields.

Laser marking machine
Laser marking machine

4.Optical fiber laser/(Optical fiber laser marking machine)

1)Principle

Optical fiber laser marking machine principle: Optical fiber laser marking machine is the use of laser beams in a variety of different substances on the surface of permanent marking. Marking effect is through the evaporation of the surface material to expose the deep material, or through the light energy causes the chemical and physical changes of the surface material to “engrave” out the trace, or through the light energy burns off part of the material, showing the desired etched patterns, text, bar code and other graphics. The so-called fiber laser marking machine refers to the use of fiber laser marking machine, fiber laser with small size (no water-cooled device, using air-cooled), light is good quality (base mode), maintenance-free and so on.

2)Constitution

Fiber laser marking machine is mainly composed of fiber laser, high-speed scanning mirror, marking software, industrial computer and cabinet. Fiber laser is the core part.

3)Advantages and application areas

Mainly used in: plastics, electronics, metals, ceramics, tobacco and other materials marked out the required text, pattern, bar code and other graphics. Optical fiber laser marking machine easy to operate, fast marking, clear and other advantages, making the production efficiency of enterprises more efficient. Our commonly used pulsed lasers are 10W, 20W, 30W and 50W.

laser marking machine sample1
laser marking machine sample 1

Summary

We design and manufacture automatic machine for the PCB/SMT and Thru-hole industries in Shenzhen China. We help companies looking to low cost equipment with smart, ROI-driven assembly equipment solutions.Contact us today to learn how we can help you。

Methods and measures to improve the production efficiency of SMT production line

Abstract

Nowadays, the market competition is more and more intense, how PCB assembly plant in such an environment can to be invincible. The first point is to reduce its production costs. To achieve this goal, the most important way is to improve the production efficiency of the production line. This paper discusses some measures and measures to improve the efficiency of SMT production line based on the author’s work practice.

S-K 100 LED SMT line

 

一. Processing of chip mounting program

SMT production line consists of a number of equipment, including screen printing machine, chip mounter, reflow soldering and so on, but in fact the speed of the production line is determined by the chip mounter. A SMT production line usually consists of a high-speed machine and a high-precision chip mounter, the former mainly mounting chip components, while the latter mainly mounts IC and Odd-form components. The entire SMT production line has the maximum production capacity when the two patch machine completes an affixed time (hereinafter referred to as the mounting time) and the hourly hour. In order to achieve this goal, we can process the mounting procedure according to the following methods.

  1. Load distribution balance. Reasonable distribution of the number of mounting components of each device, so as to make the installation time of each device equal. When we first assign the number of mounting components for each equipment, there is a large gap in the mounting time. This requires the adjustment of the production load of all the equipment on the production line according to the mounting time of each equipment, and the part of the equipment on the equipment is moved one part to the other. The balance of current load distribution.
  2. Equipment optimization. Each patch machine has a maximum value of the patch speed, for example, the YV100 of YAMAHA is called 0.25 seconds / slice, but in fact the speed value is realized under certain conditions. To optimize the numerical control program for each equipment, it is to make the chip mounter meet these conditions as much as possible in the production process, so as to achieve the highest speed mounting and reduce the installation time of the equipment. The principle of optimization depends on the structure of the equipment. The placement machine for X/Y structure is usually optimized according to the following principles.

  • As far as possible, the mounting head can be picked up at the same time.
  • When arranging the mounting program, the same type of components are arranged together to reduce the number of changing suction nozzles when the mounting head picks up the components and save mounting time.
  • More supplies should be placed near the material station near the PCB.
  • During the process of picking up and releasing, try to collect materials only from the front or rear material stations, so as to reduce the moving distance of the head.
  • In every cycle of collection and circulation, the head should be loaded.

Notice: Some principles will conflict when optimizing the program, which requires compromise consideration to select the best optimization plan. Optimization software can be used in load distribution and equipment optimization. The optimization software includes equipment optimization program and production line balance software. The optimization procedure of the equipment is mainly to optimize the placement procedure and the configuration of the feeder. After the components BOM and CAD data are obtained, the mount program and the feeder configuration table can be generated. The optimization program will optimize the movement path of the mounting head and the configuration of the feeder, and reduce the moving distance of the mounting head as much as possible, thus saving the time of the mounting. The production line balancing software is an effective tool for the optimization of the whole production line. The optimization software adopts a certain optimization algorithm. The current optimization software has been intellectualized, and the optimization process can be completed faster and better.

Customer scene IN Brazil 2

二.Eliminating of bottlenecks

The SMT production line is made up of a number of automatic equipment. When a certain equipment is slower than other equipment, the device will be the bottleneck for the speed improvement of the whole SMT production line. According to a sample of 19 factories (Table 1), bottlenecks are often found in chip mounters, and only by adding chip mounters can they be eliminated. Of course, this requires a large amount of capital investment, but it can make full use of the production capacity of other equipment, far more than the investment of a SMT production line. What type of patch machine is added depends on the bottleneck of the production line. In general, it is best to buy a high speed, multi-functional chip mounter machine, because it has the features of both high speed and high precision machines. The range of mounting components covers the high precision machine and the high speed machine. It can solve the problem caused by the high speed machine or the high precision machine. Bottleneck problem. At present, the development trend of chip mounter is also developing in this direction to meet the needs of the market.

Bottleneck of process steps Percentage
High precision chip mounter 32
High Speed Chip Mounter 21
Online testing (ICT) 16
functional testing 16
Other 15
Total 100

Table 1 –Distribution of the most common bottlenecks in a factory

Adding a patch machine to the production line can solve the bottleneck problem and speed up the pace rate. This method provides more production capacity and more feeder position to better balance the production line without significantly increasing the complexity of production line management, which is much more than a single increase in the production capacity of a chip mounter machine. It’s much more powerful.

Sample of SMT Line Configuration

三.Implementing strict and effective management measures

1.SMT equipment is a precision equipment of mechatronics. Strict and effective management measures are an important way to improve the efficiency of SMT production line. If the components to be supplemented in advance are installed on the standby feeder, the production line will assemble the last few pieces of the batch number in front of the front, and do well the preparation of the next batch of products on the production line and so on.

2.The SMT production line is a large production line, and the output value is calculated in seconds. And the fluency of production and quality of products, besides equipment and environmental factors, human factors play a very important role. For example, if the operator is familiar with the equipment, it will take less time to eliminate problems in the production process, and it will also save production time and improve production efficiency. Therefore, we must attach great importance to the training of employees. In addition to regular professional training, some professional SMT books and periodicals should be used as teaching materials to organize the staff to learn, to cultivate the love of SMT and to improve the comprehensive business level of each person.

3.Regular inspection and maintenance of SMT equipment is also a powerful guarantee to ensure its full effect. Many companies often neglect this because of their heavy production tasks. Once the equipment fails to produce normally, the loss caused by the shutdown is far greater than the cost of regular shutdown inspection and maintenance of the equipment. Therefore, we must emphasize the regular inspection and maintenance of the equipment, so that the equipment is in good condition.

Vacuum loader &Buffer unloader (1.5 M)

Summary

SMT production needs high investment, but if the management and use is appropriate, and pay attention to several aspects mentioned above by editor , It will fully tap the production potential of the SMT production line, improve production efficiency, in a few years will take back all of the investment, to achieve “high input, high output”.

Smart factory--Loader & unloader from Southern Machinery