First, the resistance
1) Visual inspection, the incoming packaging should be intact and intact, and the marking is clear;
2) The color of the color ring is clear and easy to identify. The color of the color ring is consistent with the nominal resistance value. The pins are not oxidized or blackened; the digital labels are correct.
3) The resistance value is consistent with the color circle identification.
4) The resistor is not broken, and the coating layer is peeled off;
5) There must be no oil, water stains or other dirt on the surface. Dust caused by the transport material and capable of being blown away by the air is receivable.
6) Measure the resistance with a multimeter.
7) Use a 30W or 40W soldering iron to tin the resistor pins. The solder should be able to completely wrap the pins.
Second, the capacitor
1. Firstly, determine whether the specifications, capacity, error, withstand voltage value, temperature resistance value and error value required by the BOM single are consistent with the incoming materials.
2. The actual measured value of the capacitance (measured with LCR METER) must be within the range of the standard value ± error value.
3. The spacing between the capacitor leads must be consistent with the technical data requirements.
4. The capacitor trademark must be clear and complete, the paint must be clear, there must be no pollution, and the shape must be intact.
5, the lead-tin alloy plating layer in the capacitor lead-out foot is bright and uniform, and there is no sign of oxidation such as spots.
6. The spacing between the capacitor leads is less than 1mm, and the strip arrangement must be uniform and uniform. There must be no jaggedness.
7. Is the measurement capacity (plug-in capacitance) within the error range, and determine whether the type and specification are correct.
A. Electrolytic capacitors have experienced the phenomenon of skin peeling and misalignment after wave soldering (4.7UF/16V package error is 47UF/16V skin), the pitch of the resin capacitor is wrong, and the wrong size leads to excessive volume. assembly,
B. Common plug-in capacitors are electrolytic capacitors, ceramic capacitors, metal film capacitors, safety capacitors, polyester capacitors, monolithic capacitors. The main point of checking plug-in capacitors is its type and specifications. Which type should be used before inspection. Then, measure the specifications (including volume, pitch) as required, and try to install it under certain conditions.
8. Refer to the BOM to measure its diameter and height with a caliper.
9. Refer to the BOM single-use regulated power supply for forward resistance to piezoelectric resistance.
10. Measure the capacity with a capacitance tester.
11. The positive and negative signs of the capacitor cannot be reversed, and the capacity of the mark should be consistent with the actual capacity. Chip capacitors:
12. Check the appearance to see if there is oxidation and damage.
13. Use a capacitance meter to measure whether its capacity is within the error range.
14. For special requirements customers, such as Kangchuang should also pay attention to whether the color and shape are different or different from the previous one. If there is any difference, the customer should be notified in time to confirm the use and notify relevant personnel to follow up.
A. Pay attention to the color and shape (volume, thickness) when checking the chip capacitance. If there are several colors and shapes found in the same incoming material, or if it does not match the last incoming material, it should be written immediately. The form is contacted with the customer, and it can be used after confirmation. For each incoming material and the difference in color and shape of the last incoming material, samples must be left for the next comparison to facilitate production and inspection. Check the electrode of the capacitor for damage. The error, specification and pressure value are not the same as the BOM. If you find it, you should contact the customer immediately.
B. Self-purchasing chip capacitors must not be sloppy. Ask the same type and customer before checking. Find the corresponding BOM and sample. Check the label on the tray carefully, whether it is consistent with the BOM or consistent with the customer's incoming materials, and then carefully observe. Shape (volume, thickness), whether the color is consistent with the sample, the undetermined reflection to the quality control section chief, and the relevant units to confirm, and leave the sample.
C. The filming of different customers cannot be misappropriated. Be careful when confirming the filming of the production class. You must ask the investigation to be clear before you can draw conclusions.
D. For two PCBs, the same two capacities are the same, but the error is not the same. To make a targeted record, leave the sample for tracking.
E. Record the brand of chip capacitors and understand their performance.
F, enamel patch capacitors, should pay attention to the silk screen side is positive, there are four common enamel capacitor specifications:
Type A, B, C, D, type A is the smallest; type B is the largest, if the material is unclear, it is best to find the PCB board, check the tantalum capacitor should pay attention to whether there is damage, or a PCBA Two kinds of tantalum capacitors of the same capacity, there are special requirements for tantalum capacitors, for example: RS0404A-UK
The control board 100UF/16V LOW ESR is a low-impedance meaning. It should be yellow. The Qingde tantalum capacitor has been wrong for common capacitors and models. G, the representative symbol on the tray:
CC41 1805 CG 102 K 500 T N
Type Specification Material Capacity Error Pressure value Packaging The material of the end material H and the chip capacitor are divided into: NPO (good), X7R (general), and Y5V (poor).
Third, the inductance
1. Appearance: The surface is free from dirt and damage. The inductance is complete, clear, and the model specifications are correct. The lead pins are free from oxidation, bending and deformation.
(visual method)
2. Structure size: The size of the inductor body and the size of the lead pins should meet the assembly or sample requirements.
(Test or measure with a vernier caliper.)
3, plug-in inductor pin bending resistance: after bending, the lead pin is not loose, falling off.
(Fold the lead pin 900 from the root of the lead leg and fold it back and forth five times.)
4. Electrical performance: The inductance, impedance and quality factors meet the requirements of the product specification.
(measured with LCR tester)
5. Solderability: After the solderability test, the tin surface of the lead immersion tin should be above 98%.
(The inductor lead is immersed in the tin furnace for 3-5S and then taken out (the tin furnace temperature is 245±5°C))
Fourth, the diode
First, the appearance inspection
1 Whether the main body is damaged, broken or deformed.
2 Whether the pin is oxidized, rusted or peeled off.
3 Whether the printing is blurred or falling off.
4 Positive or negative identification is wrong.
Second, functional testing
Functional detection of common diodes
1 ordinary diode forward voltage drop detection
The diode to be tested is connected into the circuit, and the adjustable voltage source voltage is adjusted to make the current value displayed by the ammeter reach the specification. At this time, the voltage displayed by the voltmeter is the forward voltage drop of the diode, or a digital multimeter is used. The forward voltage detection circuit diode position is directly tested, and the displayed value should be within the required range.
Such as IN4148
The forward voltage drop is generally 0.1~0.3V
Silicon tube
The forward voltage drop is generally 0.5~0.7V
Common diode reverse current detection
The diode to be tested is connected into the circuit, and the adjustable voltage source voltage is adjusted so that the voltage value displayed by the voltmeter reaches the specification. At this time, the current value displayed by the ammeter is the reverse current of the diode.
Functional detection of Zener diode
Zener diode voltage regulation detection.
Connect the diode to be tested into the line, adjust the adjustable regulated power supply voltage, and make the current displayed by the ammeter reach the specification. At this time, the voltage displayed by the voltmeter is the regulated voltage of the diode.
Detection of reverse current of Zener diode (detection of reverse current of common diode)
Third, the solder test
Use a 30W soldering iron to test the tin on its pins, and it should be able to eat tin well within 3 seconds.
Five, triode
Inspection items and technical requirements
1 Appearance: The surface is not damaged, the specifications and model identification are clear, there is no mixing, and the pins are not oxidized.
(visual method)
2 Structure size: Each structure size should meet the assembly or sample requirements.
(Test or measure with a vernier caliper.)
3 Plug-in triode lead pin bending resistance: After bending, the pin is not loose and broken.
(Fold the lead pin 900 from the root of the lead leg and fold it back and forth five times.)
4 Electrical performance: test Vbes parameters, Vces parameters, BVceo parameters, hFE parameters
5 Solderability: After soldering, the upper tin surface requirement is greater than 98%
(The inductor lead is immersed in the tin furnace for 3-5S and then taken out (the tin furnace temperature is 245±5°C))
Sixth, MOS tube
structure
1. Check the structural dimensions and specifications of the MOS tube according to the template, and it must not affect the dimensional deviation of the assembly or the specifications do not meet the requirements;
2. The connection between the pin and the tube body is reliable, and it can't be loose or fall off. When the pin is welded for more than 5 times, it can't be loose or fall off;
3. The PIN pin of the MOS tube meets the type of product design requirements;
4. Trial: When the MOS tube and the corresponding PCB board are tested, they cannot be inserted.
performance
1. Dip the MOS tube pin into a 235 °C tin furnace and add tin for 2-3s. The solder can completely wrap the pin, and there should be no pins on the tin or less than 80% on the tin;
2. On-machine test: Install the MOS tube on the test light board, and illuminate the light on the power. The power of the lamp meets the design requirements. The temperature of the lamp will not rise suddenly and will not flash above 80V. After cooling at room temperature, it cannot be There are phenomena such as bursting.
3. MOS tube measurement:
Electrical performance (Vbes/Vces/BVceo/HEF) parameters must comply with the corresponding specification or acknowledgment requirements
MOS tube: Vgs (V), Rds (on), Id (mA), Vdss parameters must meet the requirements of the corresponding acknowledgment.
4. The magnification of the triode should meet the requirements of the specification or the acknowledgment
Exterior
1. The surface of the MOS tube is smooth and clean, and there is no heat dissipation aluminum sheet splitting, pin detachment or deformation;
2. MOS tube can not be dirty;
3. The corresponding specifications and parameters on the MOS tube are consistent with the confirmation template, and there should be no errors or omissions;
4. MOS tube pins are smooth and can't be oxidized and blackened.
package
1. The MOS tube component is packed into the paper box by tube or tray to ensure that it will not be pressed during handling and storage.
Broken foot
2. The carton logo is correct and clear.
Seven, power IC
package
1: The package is not marked, and the external label is inconsistent with the actual object.
2: The package is damaged and severely dirty, and the packaging is poor.
3: Mixed with different models and specifications
Visual inspection
1: IC surface is clean and free of dirt
2: IC silk screen font is clear, no blur
3: The IC pin is bright and the surface is not oxidized.
4: The IC body is not damaged or broken.
5: There is no bending or deformation of the IC pin.
6: IC silk screen font, whether the package form meets the specification requirements
7: There is no short circuit in the IC pin, and the length of the pin is the same.
Dimensions
1: IC body length, width and height meet the requirements of the specification
2: IC pin length, width, height and spacing meet the specification requirements
Solderability
1: The surface of the IC pin should be bright after being tinned.
1: The surface of the IC pin should be bright after being tinned.
performance
Installed test aging
Eight, transformer
Focus on flyback
1. Does the primary inductance meet the requirements?
2. Primary to secondary analogy, primary versus feedback
3. The capacitance between the primary and secondary, the capacitance of the primary feedback, and the capacitance between the secondary feedback. The smaller the better, the average is only a few dozen P
4. Coupling degree: Primary secondary coupling coefficient, coupling coefficient between primary feedbacks
5. Phase
6. Withstand voltage, primary secondary withstand voltage, primary feedback withstand voltage, all coils with magnetic withstand voltage
7. Leakage
8. Appearance
9. Solderability
10. Transformer label
11. Whether the core and the skeleton meet the requirements, especially for the skeleton.
The above test requires the use of a transformer integrated tester and pressure tester.
How to test the coupling degree, withstand voltage and primary and secondary capacitance, what is the criterion for judging?
Transformer comprehensive tester, the larger the coupling reading, the better, the maximum 100%, I think the transformer can not reach this value, generally more than 80%, below 90%
Withstand voltage: look at the standards of various manufacturers, generally the primary secondary 3750VAC 1 minute set current 3mA, no breakdown, no flashover, no excessive noise
Diurnal capacitance: the smaller the better (for the flyback transformer)
supplement
For multi-winding transformers, it is sometimes necessary to consider the short-term problems between the same sides, such as:
1. Poor manufacturing of the enameled wire (pinhole phenomenon);
2. Various coil products are damaged in the enameled wire during production and processing. The thickness of the enameled wire is different, and the setting of the test voltage is also different;
Nine, safety capacitor
Exterior
Check whether the appearance is damaged, deformed, oxidized, etc. The mark must be clear and correct, and whether the whole foot meets the requirements of the plug-in.
The card can be admitted) (visual inspection)
size
The dimensions of each part are measured according to the specifications and must meet the actual assembly requirements.
capacitance
After being placed at room temperature (25 ° C) for 1H, the capacitance is tested at 1KHz/0.3V.
No within the specification.
DF value
After setting the room temperature (25 ° C) environment for 1H, test the DF value at 1KHz/0.3V.
Within the specification range.
Eat tin
Immerse the capacitor pin in a (245 ° C ± 5 ° C) tin furnace for 3 seconds, the pin must be 95%
Eat tin above.
Withstand voltage
According to the specification, apply the corresponding AC/DC voltage, and there is no pressure tolerance.
phenomenon.
Insulation resistance
In room temperature (25 ° C) environment, add 500V DC voltage between terminals, measure its insulation
The resistance value must meet the specifications.
Arc test
Capacitor withstand voltage between terminals at room temperature (25 ° C)
(Y1: 4KV/Y2: 2.2KV), the sensitivity is set to 6, and it must meet the specifications.
Seeking. (Y capacitor only)
Terminal load
Apply corresponding tension and torque between the capacitor terminals according to the requirements of the specification.
There is a break in the terminal or damage to the body.
Life test
Manufacturer attached inspection report
Some detailed supplements for X2 capacitors
1. Capacitor capacity, generally three gears +/-20% +/- 10% +/-5%
Loss
X2 capacitors generally less than 0.47uF are not to exceed 0.001 at 1KHz and less than 0.002 at 10KHz.
Generally, the X2 capacitor of 0.47-1uF is not to exceed 0.002 at 1KHz and less than 0.007 at 10KHz.
Generally, the X2 capacitor is larger than 1uF. The loss cannot exceed 0.003 at 1KHz.
3. Withstand voltage
The rated pressure is AC275V, AC310V, AC400V
Withstand DC voltage, generally less than 1uF is 2200V, the test voltage rise rate is required, can not exceed 1000V/us, the withstand voltage above iuF is lower, generally only 1800V, the test time is 1 minute, the shell to capacitor head withstand voltage is generally AC2120V ,1 minute
4. Appearance Clear writing, no oxidation or rust on the pins. High-grade capacitors are copper feet. Generally, the capacitors are iron feet or alloy feet. There should be no impurities in the package material.
5. Insulation resistance The insulation resistance between 2 feet is greater than 15000 megohms, and the foot-to-shell is greater than 30,000 megohms. Test voltage 100V
6. Mechanical shock, mechanical vibration, temperature, flame retardant characteristics, general factory does not test or verify
7. Under normal input voltage, the noise of the capacitor itself is not described in the general specification, but it does not mean that the X2 capacitor does not sound, especially at the high end of the specified AC voltage.
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