PCB News - LED light strip SMT processing requirements and solutions

LED light strip (flexible circuit board FPCB) SMT processing requirements and solutions
At present, the country has higher and higher requirements for environmental protection and greater efforts in link governance. This is a challenge but also an opportunity for PCB factories. If PCB factories are determined to solve the problem of environmental pollution, then FPC flexible circuit board products can be at the forefront of the market, and PCB factories can get opportunities for further development.
The Internet era has broken the traditional marketing model, and a large number of resources have been gathered together to the greatest extent through the Internet, which has also accelerated the development speed of FPC flexible circuit boards, and then as the development speed accelerates, environmental problems will continue to appear in PCB factories. In front of him. However, with the development of the Internet, environmental protection and environmental informatization have also been developed by leaps and bounds. Environmental information data centers and green electronic procurement are gradually being applied to the actual production and operation fields.
Common sense of LED lights:
At present, the most commonly used specifications for led strips are 12V and 24V. The 12V is a three-string multi-parallel structure, and the 24V is a 6-string multi-parallel structure. Because the LED strip is a series-parallel structure, when a short circuit occurs in a certain group of circuits, it will cause the voltage of other LEDs in the same group to increase, the brightness of the LED will increase, and the corresponding heat generation will also increase. . For example, in a 5050 light strip, when any chip loop of the 5050 light strip is short-circuited, the current of the short-circuited lamp bead will double, that is, 20mA becomes 40mA, and the brightness of the lamp bead will become It is very bright, but at the same time the heat generation will increase sharply, and the circuit board will be burnt in a few minutes. If the staff in charge of the test only pays attention to whether the LED is shining, and does not check the abnormal brightness, or does not do the appearance inspection but only conducts the electrical test, this problem will often be ignored.

LED light strip SMT processing solution:
1. Production process:
A/. When printing solder paste, try not to allow solder connection between the pads to avoid solder short circuit caused by poor printing;
B. Avoid short circuits when patching
C. Check the placement of the patch before reflow
D. Perform visual inspection after reflow to make sure that the light strip is not short-circuited, and then perform electrical test and re-examination. During the re-examination, pay attention to whether the LED is abnormally bright or abnormally dark.

It is also worth noting that SMT processing of LED light strips is a relatively simple product in electronic product foundry. Many foundry technical engineers are easy to take it lightly and often cause mass quality accidents.
The following are the points that the foundry technical engineers need to pay attention to:
1. Lamp beads and resistors need to be baked in an oven for 4-8 hours;
2. The furnace temperature must be tested, and different plate thicknesses must be treated differently to avoid cold welding accidents.
3. In the SMT processing of LED products, the most fatal and common quality problem is the production of tin beads. It is very necessary to prepare a steel mesh to prevent tin beads in advance.
4. For the selection of solder paste, it is best to use the LED special solder paste of the respective solder paste manufacturer. With the correct furnace temperature curve, the soldering effect will be more reliable.
5. LED anti-sulfurization and other related measures must also be in place to avoid contact between LEDs and all sulfur-containing substances. Pay attention to product innovation in terms of energy saving and emission reduction. PCB factories must learn to attach importance to Internet technology and realize the practical application of automated monitoring and intelligent management in production through the integration of overall industry knowledge.