一. Printed circuit board graphic alignment
Align the optical positioning point (MARK point) of the substrate and the stencil on the worktable through the printer camera, and then fine-tune the X, Y, Θ of the substrate and the stencil to make the substrate land pattern and the stencil opening The graphics completely overlap.
二. Explanation of the angle between the squeegee and the circuit board during printing
The smaller the angle between the squeegee and the steel mesh, the greater the downward pressure, and it is easier to inject the solder paste into the mesh, but it is also easier for the solder paste to be squeezed onto the bottom surface of the steel mesh, causing the solder paste to stick. Generally 45~60 °. At present, most automatic and semi-automatic printing machines use 60°。
三. The input amount of solder paste at one time when smt solder paste printing machine is working (rolling diameter of solder paste)
1. The rolling diameter of solder paste ∮h ≈10~15mm is more appropriate.
2. If the rolling diameter ∮h is too small, it is easy to cause the solder paste to miss printing and the amount of tin is small.
3. The rolling diameter ∮h is too large. When the printing speed is constant, too much solder paste can easily cause the solder paste to fail to form a rolling motion, and the solder paste cannot be scraped cleanly, resulting in poor printing and demolding, and thick solder paste after printing, etc. Poor printing; and too much solder paste exposed to the air for a long time is detrimental to the quality of the solder paste.
4. During production, the operator visually inspects the amount of solder paste on the screen every half an hour, and moves the solder paste outside the stroke of the squeegee on the stencil to within the stroke of the squeegee of the stencil every half an hour and distributes it evenly. Solder paste, but cannot be shoveled into the openings of the steel mesh.
四, the pressure of the squeegee when the smt solder paste printing machine is working
Squeegee pressure is also an important factor affecting printing quality. The pressure of the squeegee actually refers to the depth of the descent of the squeegee. If the pressure is too small, the squeegee is not close to the surface of the steel mesh, which is equivalent to increasing the printing thickness. In addition, if the pressure is too small, a layer of solder paste will remain on the surface of the stencil, which is likely to cause printing defects such as printing and forming adhesion (bridging).
五, the printing speed of smt solder paste printing machine when working
1. Since the squeegee speed is inversely proportional to the viscosity of the solder paste, the speed will be slower when there is a narrow spacing. If the speed is too fast, the time for the squeegee to pass through the stencil opening is relatively too short, and the solder paste cannot fully penetrate into the opening, which may easily cause printing defects such as insufficient solder paste molding or missing printing.
2. There is a certain relationship between printing speed and squeegee pressure. Decreasing the speed is equivalent to increasing the pressure. Appropriately reducing the pressure can increase the printing speed.
3. The ideal scraper speed and pressure should be just to scrape the solder paste from the surface of the steel mesh.
六, the printing gap when smt solder paste printing machine is working
The printing gap is the distance between the stencil and the PCB, which is related to the amount of solder paste remaining on the PCB after printing.
七, the separation speed of the stencil and PCB when the smt solder paste printing machine is working
After the solder paste is printed, the instantaneous speed at which the stencil leaves the PCB is the separation speed, which is a parameter related to the printing quality, and is the most important in fine-pitch and high-density printing. In advanced printing machines, when the stencil leaves the solder paste pattern, there is one (or more) minute staying process, that is, multi-stage demolding, which can ensure the best printing and forming.
When the separation speed is too high, the adhesive force of the solder paste decreases, and the cohesion between the solder paste and the pad is small, so that part of the solder paste sticks to the bottom surface of the stencil and the wall of the opening, causing printing defects such as less printing and tin collapse.
When the separation speed slows down, the viscosity and cohesive force of the solder paste are large, so that the solder paste is easily separated from the stencil opening wall, and the printing state is good.
八. Cleaning mode and cleaning frequency of smt solder paste printing machine
Cleaning the bottom surface of the stencil is also a factor to ensure the printing quality. The cleaning mode and cleaning frequency should be determined according to the solder paste, stencil material, thickness, and opening size. (Set dry cleaning, wet cleaning, one reciprocation, wiping speed, etc.).
Keywords:
SMD Production Line, SMT Line Equipment, PCB Stencil Printer,Semi Auto Stencil Printer, Reflow Machine, PCB Oven, Wave Soldering Desktop Machine, Patch Placement Machine And Heat Seal, High Speed Smart Placement Machine, SMT Coating Machine For PCB, SMT Coating Machine For PCB LED, Coating Spraying Gluing Machine For PCB LED, PCB Board Cutting And Marking Machine, PCB Off-Cut Remover Machine, PCB Reject Conveyor, PCB Router Drill Bits Set With Shank 3.175MM, Solder Soldering Robot, Soldering Robot Welding Soldering, Two Heads Double Solder Soldering Robot
I.C.T is a manufacturer of SMT machines. It mainly provides customers with SMT production lines including SMT Stencil Printers, Pick and place machines, Reflow Oven, AOI Machine, Wave Soldering Machine and PCB Handling Machine etc. I.C.T has more than 25 researches on SMT and DIP technology, for the world Customers provide SMT total solutions. There are successful cases of SMT technical team in Asia, Europe, America, Africa, and Australia.
I.C.T provide SMT solutions at various stages according to the different needs of customers. I.C.T is not only a provider of SMT equipment and technology, but also is the customer's escort in the field of SMT and DIP.
Welcome more people to discuss with us about SMT technologies and solutions, please contact us for more information:
Tel: +86 13670124230 (WhatsApp/Skype/WeChat)
Email: etasmt@foxmail.com