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What is the difference between SMT patch red rubber steel wire mesh and solder paste steel wire mesh? Is the process different? The price is not used? Still different? In fact, the difference between the two is just the difference. When opening the steel mesh, open the solder paste mesh in the original solder pad, and open the red plastic mesh in the center of the two solder pads, and the hole can be elongated to have a double point and bone shape.
1. Red SMT patch plastic is used for the thickness and opening requirements of the template.
(1) The thickness of the red rubber net is usually: 0.18mm, 0.2mm, 0.25mm, etc.
(2) The opening requirements of the red plastic template: The opening width of the IC is 1/2 of the width of the two pads, and multiple small round holes can be opened.
2. Design requirements for SMT patches of red plastic equipment:
(1) The long axis of the chip assembly must be perpendicular to the conveying direction of the wave soldering machine; the long axis of the IC device must be parallel to the conveying direction of the wave soldering machine.
(2) In order to avoid the shadow effect, arrange the ends of the same size components in parallel with the direction of the welding wave; components of different sizes must be staggered; small components should be arranged in front of the large components; the main body can protect the welding tip and welding pins. When the arrangement cannot be made according to the above requirements, there must be a gap of 3 to 5 mm between the components.
(3) The characteristic directions of the components must be consistent. For example, the polarity of the electrolytic capacitor, the anode of the diode and the single-pin end of the transistor should be perpendicular to the transmission direction, the first level of the integrated circuit, etc.
3. The opening and pad design of the red plastic SMT patch component:
(1) The component holes must be arranged in the basic grid, 1/2 basic grid and 1/4 basic grid. The gap between the plug hole and the pin diameter of the inserted part is good for wetting the solder.
(2) For the wiring of high-density components, an oval ground pattern should be used to reduce tin connections.
The basic requirements of components and printed circuit boards in the wave soldering process.
(1) Three-layer surface mounting components should be selected. The component body and solder joints can withstand the temperature shock of more than two soldering per 260 degrees Celsius wave. After soldering, the device body is not damaged or deformed, and there is no coating on the chip component end.
(2) The SMT substrate must be able to withstand the heat resistance of 260 degrees Celsius / 50s. The copper foil has good peel strength, and the solder-resistant layer still has sufficient adhesion at high temperatures, and the solder-resistant layer does not wrinkle after soldering.
SMT placement machine classification and maintenance knowledge
SMT patch belt classification: steel wire T-shaped track, main belt, motor belt, X-axis belt, Y-axis belt, RN-axis synchronous belt: input plate drive belt, CP33L conveyor belt, CP40L conveyor belt, CP45FV / NEO conveyor belt, R-axis Belt, SM321 conveyor belt, toothed belt, Z-axis belt, JUKI2050 T-axis belt, wide belt, conveyor belt.
SMT patch strap specifications: (thickness: 0.6mm 0.8mm 0.9mm 1.0mm 1.1mm 1.2mm 1.3mm 1.5mm 2.0mm)
How to fix the SMT patch belt:
1. Turn off the power, remove the protective cover, then loosen the mounting bolts on the motor base, and move the motor back and forth.
2. Shake the motor to make the belt loose enough for easy disassembly. Do not use tools to slide the SMT patch belt.
3. Remove the old belt and check for abnormal wear. Excessive wear may mean problems with transmission design or maintenance.
4. Clean the SMT patch belt and pulley: clean the cloth with a small amount of non-volatile liquid. Do not soak in detergent or use detergent to rub the belt. Do not use sandpaper or scratch the belt with sharp objects. Before installation, the belt must be kept dry.
5. To check whether the belt is broken or worn, the easiest way is to use a wheel groove gauge to check. If it is excessively worn, the pulley should be replaced.
6. Check the remaining transmission components, such as symmetry, durability and lubrication of bearings and bushings.
SMT patch places extremely high requirements on conveyor belts, especially antistatic requirements. In the manufacturing process of electronic products, electrostatic discharge can change the characteristics of semiconductor devices, causing damage or unstable performance, resulting in damage to the final product or improper use.
