After the PCB is manufactured, it has a shelf life. If the shelf life is exceeded, the PCB needs to be baked. Otherwise, it is easy to cause the PCB to explode when the PCB is produced on the SMT. Baking can eliminate the internal stress of the PCB, which is to stabilize the size of the PCB. The baked board has a relatively large improvement in warpage. Advantages of baking: After baking, the moisture in the pad can be dried, the welding effect is enhanced, and the welding and repair rate are reduced. Disadvantages of baking: The color of the PCB board may change, affecting the appearance. The main purpose of PCB baking is to remove moisture and remove moisture from the PCB.
First, the specification of PCB management
1, PCB unpacking and storage
(1) PCB board seal can be directly used online within 2 months of unopened manufacturing date (2) PCB board manufacturing date is within 2 months, the date of unpacking must be marked after unpacking (3) PCB board manufacturing date is within 2 months, after opening, it must be used within 5 days.
2, PCB baking
(1) If the PCB is sealed and unsealed for more than 5 days within 2 months of the date of manufacture, please bake at 120 ± 5 °C for 1 hour. (2) If the PCB is more than 2 months from the date of manufacture, please bake at 120 ± 5 °C for 1 hour before going online. (3) If the PCB is more than 2 to 6 months from the date of manufacture, please bake at 120 ± 5 °C for 2 hours before going online. (4) If the PCB is more than 6 months to 1 year before the date of manufacture, please bake at 120 ± 5 °C for 4 hours before going online. (5) The baked PCB must be used within 5 days (input to IR REFLOW). After the bit is used, it needs to be baked for another hour before it can be used. (6) If the PCB exceeds the manufacturing date of 1 year, please bake at 120 ± 5 °C for 4 hours before going online, and then send it to the PCB factory for re-spraying before it can be used.
3, PCB baking method
(1) Large PCB (16 PORT and above including 16 PORT), placed in a flat format, with a maximum of 30 sheets in a stack, and the oven is opened within 10 minutes after baking. The PCB is placed in a flat and natural cooling (requires pressure to prevent the bay fixture) (2) Small and medium-sized PCB (8PORT below 8PORT) is placed flat, the maximum number of stacks is 40 pieces, the number of uprights is not limited, the oven is opened within 10 minutes after baking, and the PCB is placed flat and naturally cooled (requires pressure protection) Banwan fixtures)
Second, the preservation and baking of PCBs in different regions
The specific storage time and baking temperature of the PCB are not only related to the production capacity and manufacturing process of the PCB manufacturer, but also have a great relationship with the region.
The PCB made by the OSP process and the pure immersion gold process generally has a shelf life of 6 months after packaging, and is generally not recommended for the OSP process.
The storage and baking time of PCB has a great relationship with the area. The humidity in the south is generally heavier. Especially in Guangdong and Guangxi, there will be “returning to the south” weather every year in March and April. It is very wet at this time. The PCB must be used up within 24 hours of exposure to air, otherwise it will be easily oxidized. After normal opening, it is best to use up to 8 hours. For some PCBs that need to be baked, the baking time is longer. In the northern regions, the weather is generally dry, the PCB storage time will be longer, and the baking time can be shorter. The baking temperature is generally 120 ± 5 ° C baking, baking time is determined according to the specific circumstances.
If you need to know more about PCB drying and PCB-baked-machine machin, please contact us.
Southern Machinery (SMTHELP), which specializes in SMT machines and spare parts. SMTHELP has more than 20 years of experience in the electronics processing equipment industry. Customers all over the world, and win the trust and praise of customers. Long-term customers include BOSCH in Spain and India, DIXION in India, Panasonic in Mexico, Samsung and Cliptechin Brazil.
With the SMTHELP industry experience, philosophy and professional team, adhere to the “One-Stop Solution” belief to serve customers in the electronics processing industry, providing customers with cost-effective, high quality spare parts and equipment with stable performance from China, saving customers time And cost. truly one-stop solution services.
Automated optical inspection machine (AOI) is a new type of testing technology. It has developed very rapidly in recent years. The structure of AOI consists of four parts: workbench, CCD camera system, electromechanical control and system software. When testing, firstly, the circuit board to be tested is placed on the workbench of the AOI machine, and the detection procedure of the product to be detected is called out through positioning. The X/Y workbench will send the circuit board under the lens according to the command of the setting program. With the help of the special light source, the lens will capture the image required by the AOI system and analyze it, then the processor will move the lens toward the lens. The next position is collected for the next image and then analyzed, and the image is subjected to continuous analysis and processing to obtain a higher detection speed. The process of AOI image processing essentially digitizes the extracted image, and then compares it with the pre-stored “standard”. After analysis and judgment, it finds the defect to make a position prompt, and at the same time generates image text, and the operator further confirms or sends the repair station. Overhaul
WARNING Do not perform any preventive maintenance with power on unless specifically instructed otherwise. Failure to observe this warning may result in personal injury.
CAUTION When performing machine maintenance, wear a wrist strap connected to ground to prevent electrostatic discharge damage to printed circuit boards.
500,000 Cycles Check: Perform Maintenance:
Clean the clinch scrap tube with the pipe cleaner (40940101) twice daily (every 250,000 cycles).
3,000,000 Cycles Check: Perform Maintenance:
Check for excessive wear on the pins 1. Lubricate the cutter linkage pins with Magnalube and linkage. Replace if necessary. (40833809).
12,000,000 Cycles Check: Perform Maintenance:
Check for worn cutters and bushings on 1. Replace if necessary. the cut and clinch by observing the quality of the production board component leads. 2. Lubricate the clinch lead screw with Super Blue (BLKM07680). 3. Replace the O-rings and bumpers in the cutter cylinders on the cut and clinch assembly. 4. Lubricate the three surfaces of the notch in the rocker guide Kendall Super Blue (BLKM07680).
48,000,000 Cycles Check: Perform Maintenance: 1. Lubricate the anvil slides with Kendall Super Blue (40833838) and grease gun (47408201).
① PCB coordinate document template, it is the CSV file.
②Open control system main interface – > file – > new file – > import coordinate.
③ The CSV file, PCB general has Top layer and Bottom layer element coordinates, please confirm the current PCB is the top layer or the bottom layer, choose in the lower left corner coordinates. Then click the lower right corner → the import button.
Import the coordinate file function instructions:
Import the coordinate file function instructions
Choose the Top layer and Bottom layer to import coordinate
Select this option, will perform PCB flip horizontal coordinates
When coordinate file have the margin, import coordinate indicates a blank space, must be made to modify the file and then import, avoid programming error.
Select this option, will ignore the coordinate file integrity, errors
may result in mounting components.
Grab the coordinate file by hand
Main interface in the upper right corner click open control system→Grab the coordinate To manually add the new coordinates
Manually add the new coordinates
① X Y positioning equipment function
X Y positioning equipment function
Choose the cursor, nozzle 1, nozzle 2 to grab positioning tool of the coordinate.
Back to Home
Machine return to original state
② Stepping set and X Y movement Function
Stepping set and X Y movement Function
Alternatively the step size of the X Y directions
X Y movement
Up and Down, Leaf and Right button could Operate X Y direction positioning, In operation, please don’t close to the machine tool
③ Manual input coordinate function
Manual input coordinate function
General is number, To manager the PCB program more
clearly, fill the PCB current anchor element bit number.
Fill the PCB current anchor element component package.
Note: After setting the above operation,, click “OK” to record coordinate current bit number. And then to do the next one. Directly to the center of the moving direction key to enter a number to setting, Click “OK” to finish record
coordinate current bit number.
Material Stack Configuration
Coil stock and tray stock
Coil stock: For the coil stock component putting.
tray stock: For the tray stock and tube IC component putting.
Material stack configuration function
Material stack configuration function
Material stack configuration function
According to the material stack number
Click and choice of material stack put components corresponding
component model, choose components are not allowed to repeat
Click into the system of material select stack corresponding packaging material with
Click into the system components and system interface to select material
Refers to the suction nozzle picking up speed, Normal: 20000pps.
The smaller data , the slower pick up speed
Refers to the suction nozzle distance with the end face contact material stack material when pick up the component, Through the calibration can get picked up depth data, Special component separately select pickup
To some special material stack, setting the speed the depth separately.
Multi-line batch modification Description
Multi-line batch modification Description
Description: Bit column number , hold down the left button to select a number of modifications can
make the following batch modify.
batch settings calibration center X coordinate of material stack
batch settings calibration center Y coordinate of material stack
batch settings Broaching partial X coordinate of material stack
batch settings Broaching partial Y coordinate of material stack
Pick up depth
batch settings pick up depth of material stack
batch settings adapter nozzle of material stack
Material stack debugging tools, data checking function description
Material stack debugging tools, data checking function description
Material stack test
Pick up test for calibration finished material station configuration
station to the file
Save the material station file for calibration finished material station configuration list, it could make it easy for the nest use.
Loading the material station
from the file
Can be loaded directly with the saved material station.
Check no material
Check the Program Component in the material station
configuration list for no material.
Check the Program Component in the material station
configuration list for double material.
Mount setting function and introduction
Programming parameters automatically get in after the second material Stack Configuration.
① Click the Align program into the coordinate system origin correction interface.
② Calibration Make sure whether the splint placed parallel to the PCB in place, subject to the plywood base point, and then calibrate.
③ Calibrating the far two point coordination ( reduce the error), Click OK after finished
Setting Mark point ( This setting must be completed – after operating alignment program origin )
Set Mark Point, choose a more independent square or circular Mark point as calibration points.( (Note: Mark point usage; in the fourth programming due to the PCB board or puzzle on the origin lead to error, click Mark point to automatic correct board )
Calibration ( This setting must be completed – after operating alignment program origin )
Calibration is used to correct a separate placement coordinate with the actual Mark-point calibration.
① Reset the default placement coordination, mounting XY coordinate reply for source file coordination.
② Check invalid pick up material station, check whether the configuration is complete.
Puzzle calibration Make sure whether the splint placed parallel to the PCB in place, subject to the plywood base point, and then calibrate.
① Manual correction: Click the PCB list of coordinates to enter the calibration correction, respectively coordinate 2 far point calibration.( reduce the error), If there is the puzzle PCB, then do the first PCB, and send and so no. The same way to calibrate.
② Mark point automatic correction: one-time auto-complete according to automatic Mark point on board.
Program option function 5.1.1 Function
Base plate Depth
Nozzle and plywood PCB contact distance, setting through the
Dual stepper reel, can improve the placement rate.
Please read the instructions carefully before user operation
First of all, we sincerely thank you for choosing the SMT peripheral automation machine produced by our company. This company specialized production: conveyor, automatic feeding detection machine, vacuum suction machine, stacked on the machine, parallel transfer, angle conveyor, turning machine,machine, double buffer for the same reflow furnace system, a series of automated production machine. According to the customer’s requirements, we can develop and design a series of automation machine, in order to meet the customer’s high efficiency, energy saving, downsizing and other production needs. This manual describes the use of methods and machine maintenance and precautions, in front of the machine, please carefully read this manual, and it will be properly preserved, wrong operation may cause the device does not operate normally or damaged parts. Due to man-made machine failure or parts damage, will not apply to the company’s exemption free warranty service range. Without permission of the company, please do not disassemble or replace the machineparts, nor applicable to the company’s free warranty warranty service range. As to the improvement and partial renewal of the product, we will not make further instructions. If you have any doubts, please contact our company for consultation.
一、Important matters and safety instructions
When using this Cleaning Machine, you must abide by these safety devices.
All attention should be taken to avoid accidents and damage to the instrument.
1. please read and understand the user’s manual carefully before using or operating this machine.
2. non – instrument maintenance personnel and untrained personnel should not use this machine at will.
3. please avoid the use of this machine in the vicinity of the strong electromagnetic interference source.
4. please avoid the use of this machine in the environment with high humidity.
5. maintenance, please turn off the power, to prevent damage to components.
6. instruments are used, they should be kept stable to prevent falling.
1、Liquid storage tank：
When the cleaning liquid is completely unused, the liquid can be added, and the addition method is referred to the addition of the solution step.
After pressing the emergency switch, PLC is out of power and the equipment stops working
Store the cleaned liquid and put out of the liquid in time.
Step: the tank is pulled out, carefully put out the liquid.
1. connect the power supply (220V, 50HZ) and gas supply (0.6MPa), turn on the power switch.
2.Check whether there is a liquid on the left level (the grooves pipe), if it‘s no,then add liquid (detailed please refer the step of adding the liquid).
3. Switch is normal opening , and the touch screen appears as the Figure 3.1 interface
4. Click Figure 3.1 [into system], and appear on the interface, such as Figure 3.2. If you need to set parameters, enter the manual tool interface for parameter settings (detailed please refer the parameter settings).When you set it up, Hit [save parameter].
Note: first use the parameters set first ( refer parameter settings) and then do the next step.
5. When nozzle is placed well,closed the door tightly ,and set the parameters(can skip). Confirm that the suitable angle is adjusted well, that is, the nozzle is aligned with the suction nozzle center, otherwise it can’t be cleaned.
6. Click Figure 3.2 [reversion], then click Figure 3.2 [auto start] (after click finish is displayed as automatic stop) or press the boot button of the device
1. click the [manual tool] as shown in Figure 4.1, as shown in Figure 4.2
Input signal monitor(click the interface of Figure 4.2 [ input and monitor].)
Manual control interface(click the interface of Figure 4.2 [ control debug].)
2. click on Figure 4.2 [parameter settings], appear as shown in Figure 4.5, according to actual needs, set up relevant parameters, click figure 4.5 [bottom parameter], the password is 4 “8888”, and then appear as shown in Figure 4.6.
1) nozzle: set the number of nozzle (according to the jig can install the number of nozzle to set)
2) clean time: setting up a single nozzle cleaning time (according to the actual situation)
3) air-dry time: setting the time to complete the air-dry of a single nozzle (according to the actual situation)
4) save parameter: after setting the complete parameter, you need to click the [save parameter].
1) Original correction: to confirm the suitable angle, that is, the angle of the nozzle and the nozzle center to be rearranged, and the setting is set up.
2) Power on air storage time: set according to the actual situation
3) Air storage time before clean: it refers to the setting of the gas storage time before each cleaning, according to the actual situation.
4) Interval air storage time: express the later that later chose not to select the display as “yes”, For example, the clean time is 3 S, and interval air storage time is set to 1S, after cleaning 1S, gas storage for 1 S, and then clean for 1 S.
5) Impulse quantity: it express the impulse quantity for the turn of the turntable to 1o. If the device is not at its origin, it will increase the impulse quantity if it arrives at the origin. If it is found that the device is not at its origin, if it exceeds the origin, it will increase or decrease.
6) Continuous jet: express choose whether to continue the actual situation as yes” no choice later, shown as “no” is that he has chosen to continue.
五、Adding liquid steps
1. after the start of the machine，enter the standby state and enter the interface shown in Figure 5.1.
2. click [pressure relief] has been holding down the nozzle, until no gas ejected and then release the hand off power.
3. open the tank cover, a funnel into the washing solution until close to the reservoir until canful.
4. closed storage tank cover, power off, re-work.
Note: the cleaning solution will never be allowed to splash into the equipment, otherwise the controller will burn out.
六、Daily maintenance project
the water must be emptied after each use.
the water must be cleaned up on the platform after each use.
check whether there is water leakage in the pneumatic cabinet and electrical cabinet.
check the looseness of the screws in each movement mechanism.
check whether the external electrical connector is loose.
cleaning the dust and debris in the electric cabinet and the pneumatic cabinet.
check the air leakage of the pneumatic components and the joint of the trachea.
check the oil mist special oil in the oil mist is too small, less is added.
check whether the internal joint of the electric cabinet is loose.
check the entrainment wheel, whether the belt wear out.
lubricating grease for all bearings of each device.
3. 2. Installation accessories, required energy and precautions
1) The source pressure is : 0.4Mpa~0.6Mpa
2)Taken the air over diameter for ?: 12mm, a quick joint is needed
3) The top of the equipment is designed ?: The 125mm exhaust port shall be connected to the outside by independent air duct
4) matters need attention: In order to ensure safe production, customers must ensure that the following security measures are installed in place. Otherwise, the company does not assume any responsibility for security
?It is at least 3 meters away from the electric equipment, away from fire source and heat source
?The ground wire must be connected, and the earth shall not be connected to any other electrified equipment
?The exhaust duct of this equipment shall not be connected to any equipment that can produce heat source. (such as reflow soldering wave soldering of SMT, etc.)
3.3 installation space
To facilitate the maintenance and replacement of spare parts for equipment operation, please leave more than one meter space around the equipment
4.0 Operations Guide
A Preparation before operation
4.1.1 connect the air source to the machine, the gas source is connected well, the display lamp is highlighted and the subsequent work can be continued
4.1.2 check if air pressure in the standard rating (04-0.6 MPa) range. Lower than 0.4mpa will affect the cleaning effect and reduce production efficiency (too low will not activate the machine).
Higher than 0.6mpa can result in damage to the mechanical gas system and all parts of the system.
Adjust the pressure method: pull upward gently to adjust the knob and rotate to the right————- Increase pressure
Go to the right ————– reduce stress
After reaching the required pressure, press the adjusting knob, air pressure lock and pressure to complete the gas connection, and the lamp is highlighted
4.1.3 check whether the top exhaust duct is unblocked or unblocked, which will result in damage to the environment and other consequences of the cleaning effect
4.1.4 check the glass viewport of the door panel through the liquid road to check the solvent reserves. The normal state is above the M position, and the machine can meet the various cleaning effects. The amount of liquid stored in this model is the maximum amount (40L).
4.1.5 if the solvent is not enough, please add adding method in time: see adding solvent method
4.1.6 the pump access panel is opened with a randomly attached triangle key to check whether the ball valves are in normal condition
Ball (the ball valve of pump outlet filter) A ball valve D (pump inlet connection of the reservoir fluid Xiang ball valve) opens, B ((the ball) of white PE tube pump discharge ball valve C (white PE tube pump inlet ball valve) closed
4.2 time setting
4.2.1The setting of the cleaning time (see figure below), gently rotate the timer protection cap to the left and pull up the cover.
General cleaning time is
Minutes, depending on the actual situation, will be different.
This timer is measured in seconds (S) with a range of 10-999 seconds (S).
It can be set to 0, otherwise the machine will not start and may damage the timer and other components.
4.2.2 setting of drying time
Operation method and cleaning time setting.
The general drying time is 4-6 minutes depending on the actual situation.There will be an elongation of the aqueous solvents.
4.2.3The cleaning and drying time are automatic reset.
That is, one set, multiple times (N times).
When the pressure is less than the required number, the timer can be reset and the device cannot be started.
At this point, the black reset button on the upper row of the timer can be reset manually.
4.2.4The counter’s use of this counter is the increment counter, each cleaning a steel net, automatically into the system,
One of them is going up.
The count range is 0-999999.
Mainly used for cleaning work statistics, timely replacement of consumables (filter element), etc.
The filter cartridge should be changed when cleaning up to 1500.
Specific visual cleaning products are different and different.
When the counter displays the number to reach the target number, press the 4.2.3 method to open the cover, then press the black reset button on the left of the timer and the counter is reset.
4.3 placement of steel mesh
4.3.1 press the inner door safety button to open the cleaning room
4.3.2 lift the steel net with http://topmednorx.com both hands, gently place the front in the cleaning room chute roller and push it gently forward to the sliding channel steel
Fixed fixture on the net.
The steel net is in the middle of the fixture and chute. The top of the steel net is at the top of the cleaning room
Steel mesh fixture middle.(see below.)
4.3.3 when placing the steel mesh, the steel mesh shall not be in contact with the door to avoid damaging the steel net and sealant
4.3.4After the steel net is placed, close the cleaning door.
The inner door should be kept in good condition, otherwise, the solvent will be expelled outside, causing machine damage or environmental damage, more likely to cause personal injury
4.3.5 after the inside door is closed, continue to close the outer security door.
The security door is closed and the light is on, so that the following operation can be continued.
If the security door is not closed, the lamp will be retracted and the machine will not be able to start.
After closing the door again, the machine can be started
For the last 20 years any odd-form components that did not come pre-packaged have been assembled BY HAND. Any PCB Assembly in today’s market can gain quick advantages by automating their assembly line. Huge costs are spent unnecessarily on labor and import fees.
If you are considering automation of odd-form components in your PCBA, consider these questions:
Does your desired component come available in a package?
Is your lead to hole ratio appropriate for automating?
Is the quality and repeatability of the component suitable for automation?
Does your component require lead preparation prior to insertion?
Does your process require that the component is clinched?
Need help with these questions? Let us know and we will help design your Odd-Form Assembly tailored to your needs!
The solder paste should be fully stirred before using Purpose: To make the flux and tin powder evenly distributed, give full play to various characteristics; Mixing method: manual mixing or machine mixing can be; mixing time: manual: about 4 minutes machine: 1 ~ 3 minutes 1) Manual Mixing: Remove the solder paste from the freezer and open the cover until it returns to room temperature (about three to four hours at 25 ° C). Stir the solder paste with a stirring knife. If the cover is broken, tin The cream will become tin pieces by absorbing moisture. 2) with automatic mixer:. If the solder paste is removed from the freezer, there is only a brief warm-up period and you will need to use an automatic mixer to use automatic mixing without affecting the solder paste characteristics. After a period of agitation, the solder paste will. Gradual warm-up If the mixing time is too long, it may cause the solder paste to be higher than the operating room temperature, causing the solder paste to be poured over the board in one piece, and flow (bleeding) during printing, so be careful. Due to different machines, room temperature and other conditions change, will result in different mixing time, so before proceeding, please prepare enough test. Stirring effect of the judge: Scraping part of the solder paste with a scraper blade tilt, if the solder paste can slide down smoothly, that is, the right to meet the requirements of the appropriate mixing time due to the mixing method, the device and the ambient temperature and other factors vary, should Do more experiments in advance to determine.
We have a fully automatic tin paste mixer which can solve these problems：
In 80s the use of far infrared reflow has the characteristics of fast heating, energy saving, stable operation, but because the printed circuit board and various components for different material, color and thermal radiation absorption rate to have very big difference, caused by a variety of different components and different parts of the circuit temperature is not uniform, the local temperature difference. For example, the black plastic package of integrated circuit will be overheated due to the high radiant absorption rate, and the welding part of it will lead to false welding on the silver lead instead of low temperature. In addition, the heat radiation blocked on printed boards, such as welding pins or small components in the shadow parts of big (high) components, will cause poor welding due to insufficient heating.
Full hot air reflow oven is a welding method by which the flow of airflow is forced through a convective nozzle or a heat-resistant fan, so that the welded parts are heated. This kind of equipment began to rise in 90s. Due to the adoption of this heating mode, the temperature of PCB and components is close to the temperature of the given heating area, which completely overcomes the temperature difference and shadowing effect of infrared reflow soldering, so it is widely applied now. In all hot air reflow oven equipment, the convection velocity of the circulating gas is very important. In order to ensure that the circulating gas acts on any area of the printed board, the air flow must have a fast enough speed. To a certain extent, it is easy to cause the jitter of the printed board and the displacement of the components. In addition, in terms of heat exchange, the efficiency is poor and the power consumption is more.
This kind of reflow oven is a more ideal heating method, which is based on the IR oven with hot air to make the temperature even more uniform insaide the oven. The characteristics of this kind of equipment to make full use of the infrared penetration, high thermal efficiency, energy saving, and effectively overcome the temperature difference of infrared reflow soldering and shadowing effect, and make up the influence of hot air reflow on gas flow caused by excessive demand, therefore at international this kind of IR+Hot reflow is used most commonly at present .
With the increase of assembly density and the appearance of fine spacing assembly technology, a reflow oven furnace with nitrogen protection has appeared. Welding under nitrogen protection conditions can prevent oxidation, improve welding wetting power and speed up wetting speed. It is more suitable for uncleaning process to reduce the welding force and reduce welding beads.
2 The establishment of temperature curve
The temperature curve is the curve of the temperature of a point on the SMA will change over time when SMA through the reflow oven. The temperature curve provides an intuitive method to analyze the temperature change of a component during the whole reflowprocess. This is very useful for obtaining the best weldability, avoiding damage to the components due to overheating, and ensuring the quality of the welding.
The following is a brief analysis of the preheating section.
2.1 preheating section
The purpose of this section is to put PCB at room temperature as soon as possible heating, to achieve second specific targets, but the heating rate should be controlled in the appropriate range, if excessive, will produce thermal shock, circuit boards and components may be damaged; if too slow, will not fully solvent, affecting the welding quality. Due to the rapid heating rate, the temperature difference in the rear section of the temperature zone is larger than that in the SMA. In order to prevent the damage of thermal shock to the component, the maximum speed is 4℃/s. However, the normal rise rate is set to 1-3℃/s. The typical heating rate is 2℃/s.
2.2 heat preservation section
The heat preservation section is the area where the temperature rises from 120℃-150℃ to the melting point of the solder paste. Its main purpose is to make the temperature of each element in the SMA stable and minimize the temperature difference.In this area, the temperature of the larger components can have enough time to catch up with the smaller components and ensure that the flux in the solder paste is fully volatile. The oxide of the soldering plate, the solder ball and the pin of the element is removed, and the temperature of the entire circuit board is balanced until the end of heat preservation section. It should be noted that all elements on the SMA should have the same temperature at the end of heat preservation section, otherwise, entering the reflux section will cause various bad welding phenomena due to the uneven temperature of each part.
In this area, the temperature of the heater is set to the highest, which makes the temperature of the component up to the peak temperature. In reflow sectionthe，the different of peak temperature is according to the solder paste to change, the general recommendation for solder melting point temperature plus 20-40℃. For 63Sn/37Pb solder paste with melting point of 183℃ and Sn62/Pb36/Ag2 solder paste with melting point of 179℃, the peak temperature is generally 210-230℃. Reflow time should not be too long to prevent adverse effects on SMA. The ideal temperature curve is the smallest area covered by the “tip zone” of the solder melting point.
As we know,reflow oven is the most important welding technology in surface mount technology. It has been widely used in many industries including mobile phones, computers, automotive electronics, control circuits, communications, LED lighting and many other industries. More and more electronic devices are converted from through hole to surface mount, and reflow oven replaces wave soldering is a obvious trend in welding industry.
So what is the role of reflow oven equipment in the increasingly mature lead-free SMT process? Let’s take a look at the whole SMT surface mount line:
The whole SMT surface mounting line consists of three parts, such as steel mesh solder paste printing machine, SMT machine and reflow oven furnace. For the machine, and compared with lead free, and no new demands on the equipment itself; for screen printing machine, and a lead-free solder paste in the physical properties there are some differences, so put forward some improvement on the device itself, but there is no qualitative change. the key of lead-free is in the reflow oven.
The lead paste (Sn63Pb37) melting point of 183 degrees, if you want to form a good weld must have the thickness of 0.5-3.5um intermetallic compounds in welding, intermetallic compound formation temperature is above the melting point of 10-15, the lead welding is 195-200. The maximum withstand temperature of the electronic device on the circuit board is generally 240 degrees. Therefore, for lead welding, the ideal welding process window is 195-240 degrees.
Because of the change of melting point of lead-free solder paste, lead-free welding has brought great changes for welding process. At present, the lead-free solder paste is Sn96Ag0.5Cu3.5 and the melting point is 217-221 degrees. Good lead-free solder must also be formed 0.5-3.5um thickness intermetallic compounds, intermetallic compound formation temperature is also above the melting point of 10-15 degrees, for lead-free welding, that is, 230-235 degrees. Since the highest temperature of lead-free solder electronic device will not change, therefore, for lead-free soldering, ideal welding process window is 230-245 degrees. The substantial reduction of process window brings great challenge to ensure welding quality, and also brings higher requirements to stability and reliability of lead-free wave soldering equipment. Because the equipment itself is coupled with the electronic device transverse temperature difference, due to differences in size of heat capacity will produce temperature difference in the heating process, so in the process control of lead-free reflow oven can be adjusted in the process of welding temperature window becomes very small, this is the real lead-free reflow to the difficulty.