I. failure reason of SMD inductive power:
1. The magnetic core will not release if the magnetic flux density is too high during the processing;
2. When there are impurities or hollow materials in the magnetic core, the magnetic permeability of the magnetic core will be deviated because the magnetic field of the magnetic core will be affected.
3. Sintering crack caused by sintering;
4. When the copper wire is connected to the copper belt, the part of the coil splashed on the tin liquid will melt the insulation layer of the paint wire and cause a short circuit.
5. The copper wire is thin, resulting in false welding and open circuit fault when connected with the copper strip.
Ii. Methods for prolonging the life of SMD inductor power electrolytic capacitor:
1. Plan to extend its life
In fact, in order to extend the life of the electrolytic capacitor, the method is very simple, because its long-term voice is mainly due to the effect of evaporation of liquid electrolyte. It is assumed that the sealing performance of the electrolytic capacitor is improved, and evaporation is not allowed, and the life of the electrolytic capacitor is also naturally prolonged. In addition, electrolyte losses can be greatly reduced by using a well-wound phenolic cover with electrodes and two layers of special gaskets that are tightly sealed to the aluminum shell.
What is the function of the chip sensor? Inductance is an electronic element whose main function is electromagnetic induction conversion. Relatively simple inductance can be a lead and can be used as an antenna. Can be used in frequency selection circuit and rf emission circuit, can also be used in filtering and energy storage type I inductance.
Is the SMT inductor vulnerable to damage? Inductive elements are not easily damaged. But there are times of damage.
Three, SMT inductive power is easy to damage reason analysis:
1. Magnetic core inductance, magnetic core is more brittle, do not cover the outer cover, hard floor fell to the hard floor, the ring is easy to damage, the protection in transportation and impact force will also lead to the damage of the magnetic core.
2. When the power required by the circuit is greater than that of the chip inductor, the inductor will be damaged by heat.
3. There is a short circuit in the latter part of the output circuit, resulting in the heat and loss of the ring.
4. SMD inductance power weldability test:
When the reflux temperature is reached, silver (ag) reacts with tin (sn) to form a eutectic, which cannot be directly tinned on the silver end of the inductance of the chip. The silver head is then plated with nickel (ca. 2 m) to form an insulating layer, followed by tin (4-8um).
Isn’t it? Clean the tip of the chip inductor with alcohol for the weldability test. Solderability is acceptable if the tip of the SMT inductor has 90% or more solder coverage.
1. Poor weldability:
Tip oxidation: when the tip is affected by high temperature, humidity, chemicals, oxidizing gases (SO2, NO2, etc.), or stored for too long, the metal Sn at the tip is oxidized to SnO2 and the tip of the tip becomes dark. Due to SnO2, Sn, Ag, Cu, etc. To produce a common melt, leading to the reduction of SMT inductor weldability. Shelf life of chip inductor: half a year. If the tip of the patch is contaminated, such as oily substances, solvents, etc., can reduce the weldability.
2. The nickel plating layer is too thin:
If the nickel plating layer is too thin to isolate. In reflow welding, Sn at the end of SMT inductor and its own Ag first react, which affects the fusion of Sn on SMT inductor and solder paste on the pad, resulting in the erosion of silver, and the reduced solderability of SMT inductor.
Method: dip the chip sensor into a molten solder tank for a few seconds and then remove it. If the end of the hole or even exposed porcelain is found, it can be considered edible silver.
3. Internal stress of poor welding:
If there is a large internal stress in the manufacturing process of the chip inductor, and no measures are taken to eliminate the stress, in the process of reflow welding, the installed chip inductor will be due to the impact of internal stress, commonly known as the tablet effect.