[Repost] Popular Science of Components: Complete Component Selection Specifications

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[Repost] Popular Science of Components: Complete Component Selection Specifications [Copy link]

Electronic components are the basic parts of electronic systems. They are the basic circuit units that can complete the predetermined functions and cannot be divided. Due to the large number and variety of electronic components, their performance, reliability and other parameters have a great impact on the technical indicators such as system performance, reliability and life cycle of the entire electronic product.

Therefore, correctly and effectively selecting and using electronic components is an important task to improve the reliability level of electronic products. The reliability of electronic components is divided into inherent reliability and use reliability. Intrinsic reliability is mainly guaranteed by design and manufacturing, which is the task of component manufacturers.

However, domestic and foreign failure analysis data show that nearly half of component failures are not due to the low inherent reliability of components, but due to improper selection or incorrect use of components by users. Therefore, in order to ensure the reliability of electronic products, the selection and application of electronic components must be strictly controlled.

I. General Principles of Material Selection

1. The selected devices shall follow the company's normalization principle. Under the premise of not affecting the function and reliability, the types of materials shall be selected as few as possible.

2. Materials with "preferred level" of "A" in the material coding library shall be given priority.

3. Devices with a growing and mature life cycle shall be given priority.

4. Select the devices that are born or declining to go through the special approval process.

5. Carefully select the devices whose life cycle is declining. Do not use the discontinued devices.

6. For power devices, give priority to the package models with small RjA thermal resistance and larger Tj junction temperature.

7. Do not use the devices with package size less than 0402 (inclusive).

8. The ESD resistance must be at least 100V, and anti-static measures must be taken in the design.

9. The MSL (moisture sensitivity level) of the selected components cannot be greater than level 5 (inclusive).

10. Models with sealed vacuum packaging are preferred. For models with MSL (moisture sensitivity level) greater than level 2 (inclusive), sealed vacuum packaging must be used.

11. Models with tape and reel packaging and tray packaging are preferred. If the device is of moisture sensitivity level 2 or above, it is required to be packaged in a plastic tape, which must be able to withstand a high temperature of 125°C. 12. For key components, at least two brands of models can replace each other, and some should also consider solution-level replacement. 13. The materials used must meet the requirements of anti-static, flame retardant, anti-corrosion, anti-oxidation and safety regulations. 2. Selection rules for various materials General rules for chip selection 1. Sn63Pb37 alloy is preferred for leaded BGA solder balls, and SnPb alloy with high lead (lead content ≈ 85%) can also be selected. SnAgCu alloy is selected for lead-free BGA solder balls. 25)]2. For SMD and integrated circuit devices with leads, the metal material of the lead wires must be copper, copper alloy, valve alloy, 42 alloy material, the surface alloy coating must be uniform and the thickness must meet the relevant standards (4 to 7.6μm), and the coating must not contain metallic bismuth. Tin-lead pin plating: SnPb; Lead-free pin plating: Preferred: Matte-Sn, SnAgCu, Ni/Au, Ni/Pd/Au; Sn plating: For pure Sn plating, the Sn plating thickness is ≈7.6μm (electroplating process), or ≈2.5μm (melting process after electroplating), or ≈5.1μm (immersion tin process), or ≈0.5μm (chemical plating process); Barrier layer Ni: thickness ≈3μm; SnCu plating: SnCu plating thickness ≈3μm; Ni/Pd plating: Pd plating thickness ≈0.075μm, Ni plating thickness is above 3μm; Ni/Pd/Au plating: Ni thickness ≈3μm, Pd thickness ≈0.075μm, Au thickness is 0.025～0.10μm

3. Be careful when choosing CPU and power chips from Taiwan.

[color=rgb(25, 25,4. Do not use QFN packaged components. If only QFN packaged components can be used, they must be reviewed. Any QFN packaged chips must be approved by the deputy general manager before they can be used. 5. For IC, SMD packaged devices with a foot spacing of at least 0.5MM are preferred. 6. SMD packaged devices are preferred, and DIP packaged devices are carefully selected. 7. Try not to use BGA packaged components. Use them only when you have to. If BGA is selected, the BGA ball spacing must be greater than or equal to 0.8mm, preferably greater than or equal to 1.0mm. And try to choose models that use leaded BGA ball devices and use leaded soldering processes.

8. Do not use CPUs that do not support online programming.

9. Try not to use Samsung chips.

Resistor selection rules

1. The resistance value should preferably be 10 series, 12 series, 15 series, 20 series, 30 series, 39 series, 51 series, 68 series, and 82 series. 2. The preferred packages of chip resistors are 0603 and 0805. Packages below 0402 are prohibited. 3. The preferred pin resistors are 0.25W, 0.5W, 1W, 2W, 3W, 5W, 7W, 10W, and 15W.

4. For the temperature drift of the resistor, the temperature drift of the J gear cannot exceed 500ppm/℃, the temperature drift of the F gear cannot exceed 100ppm/℃, and the temperature drift of the B gear cannot exceed 10ppm/℃.

5. Metal film resistors of 1W and above are prohibited, and metal film resistors of 750k and above are prohibited.

6. Axial type power resistors above 7W are prohibited.

7. Choose the potentiometer carefully. If it cannot be avoided, choose multi-turn ones, and use BOURNS as the brand. The electronic potentiometer is operated according to the chip selection specifications. 8. The preferred resistor brands are YAGEO, MK, and Bedis. Capacitor selection rules  Aluminum electrolytic capacitor selection rules 1. In ordinary applications, select standard type with a life of 1000HR~3000HR (for price considerations, carefully select long-life type). For aluminum electrolytic capacitors, try to choose a life of 2000Hr. 2. For the withstand voltage of aluminum electrolytic capacitors, 10V is used for 3.3V system, 10V is used for 5V system, 25V is used for 12V system, 50V is used for 24V system; 100V is used for systems above 48V. 3. Aluminum electrolytic capacitors must have an operating temperature of 105 degrees. 4. For the capacitance of aluminum electrolytic capacitors, 10, 22, and 47 series are preferred; 224, 105, and 475 capacitance models are prohibited below 25V (use chip multilayer ceramic capacitors or tantalum electrolytic capacitors instead). 5. For high-voltage aluminum electrolytic capacitors, 400V is reserved. Non-polar aluminum electrolytic capacitors are prohibited.

6. Ordinary aluminum electrolytic capacitors should use the brand "SAMWHA" (Sanhe), and high-end aluminum electrolytic capacitors should use NCC (Black King Kong) or other Japanese brand aluminum electrolytic capacitors.

7. It is forbidden to use surface-mount aluminum electrolytic capacitors.

Tantalum electrolytic capacitor selection rules

1. Tantalum electrolytic capacitors with a withstand voltage of more than 35V are prohibited. 2. Pin-type tantalum electrolytic capacitors are prohibited. 3. For the withstand voltage of tantalum electrolytic capacitors, 10V is used for 3.3V system, 16V is used for 5V system, and 35V is used for 12V system. 10V, 16V, and 35V are preferred, while 4V, 6.3V and 50V are prohibited (replace with aluminum electrolytic capacitors).

4. For the capacitance of tantalum electrolytic capacitors: 10, 22, and 47 series are preferred. Tantalum electrolytic capacitors with a capacitance below 105 are prohibited (replace with ceramic capacitors).

5. Tantalum electrolytic capacitor brands: KEMET, AVX.

Selection rules for chip multilayer ceramic capacitors

1. Choose high-Q ceramic capacitors with caution; only use them in RF circuits. 2. Chip multilayer ceramic capacitor package: 0603 and 0805 are preferred, 1206 and 1210 are carefully selected, and 1808 and above are prohibited. 3. Withstand voltage of chip multilayer ceramic capacitors: 25V, 50V, and 100V are preferred; the withstand voltage of 106 (inclusive) and above is not greater than 25V. 4. Capacitance of chip multilayer ceramic capacitors: 10, 22, 33, 47, and 68 series are preferred. 5. Materials of chip multilayer ceramic capacitors: NPO, X7R, and X5R are preferred; others are prohibited.

6. Brands of chip multilayer ceramic capacitors: TAIYO, MURATA, KEMET, TEMEX (high Q ceramic capacitors).

Pin multilayer ceramic capacitor selection rules

1. It is forbidden to use this type of capacitor for new products (use chip multilayer ceramic capacitors instead).

Relay selection rules

1. Brand selection: PANASONIC, OMRON, FINDER.

2. It is forbidden to use relay sockets.

Diode selection rules

1. It is forbidden to use glass-encapsulated diodes. 2. The LEDs should preferably have a 5mm diameter pin. SMD LEDs should preferably have a soldered frame, and the ESD/MSL levels should follow the above standards. 3. Rectifier diodes: For the same current level, the highest reverse voltage model should be selected. For example, 1N4007 should be selected for 1A or less, and IN5408 for 3A. 4. Schottky diodes: For the same current level, the highest reverse voltage level is reserved, such as: 1N5819 is reserved, 1N5817 is prohibited, SS14 is reserved, SS12 is prohibited; M7, 30BQ060, S5G are reserved. 5. LEDs with edges and short legs are preferred; in order to maintain the consistency of the company's products, red-red, green-green and other models are preferred, and white-red, white-green and other models are carefully selected; if there are no special requirements, try not to use long-legged and edgeless ones.

6. The preferred brand of light-emitting diodes is "Everlight".

7. The preferred brands of transient suppression diodes are PROTEK and SEMTECH.

Transistor selection rules

1. For the 901X series transistors, use 9012 and 9013.

Connector selection rules

1. Do not use IC sockets. If you cannot avoid using IC sockets, you must use round hole IC sockets.

2. Use three-sided contact for the pin holder. Do not use two-sided contact. Except for special requirements such as PC104.

3. The same brand of complete sets of connectors are required, that is, the plugs and sockets must be of the same brand.

Switch selection rules

1. Do not select DIP switches.

2. The power switch is preferably a rocker switch.

Inductor selection rules

1. The preferred brands of chip inductors are "SANLI" and "SUMIDA".

CPU selection rules

1. If the selected CPU is a different model from the same series that our company has used, it needs to be approved by the production manager. If the selected CPU is a new series of CPU that our company has never used before, it must be decided by the company-level leaders in a meeting.

2. Atmega48, Atmega168, Atmega32, Atmega128 are retained. Attiny2313 and Atmega88 are prohibited for new products. 3. QFN packaged Atmega128 is not allowed to be used in new products in the future. 4. ARM7 can only use the following types: LPC2138FBD64, LPC2292FBD144, STR710FZ2T6, STR711FR2T6.

5. In the future, new products will use COLDFIRE series instead of 68000 series.

FLASH selection rules

1. The preferred parallel FLASH brands are SPANSION and SST. SAMSUNG is prohibited.

2. The preferred serial FLASH brand is ATMEL. It is prohibited to use AT45DB081B-RI in new products.

SRAM selection rules

Preferred brands are ISSI, CYPRESS, MICRON, IDT, and SAMSUNG is prohibited.

EEPROM selection rules

1. Parallel EEPROM is prohibited.

2.ATMEL and MICROCHIP are the preferred brands of serial EEPROM.

3.24LC65-I/SM is prohibited for new products.

Crystal and crystal oscillator selection rules

General technical requirements for crystal materials: AT cut (base frequency), 20pF load capacitance, temperature range -20～+70℃ (industrial temperature grade), manufacturing frequency deviation 30ppm, temperature drift 50ppm/℃, lead-free products. The preferred crystal and crystal oscillator brands are HOSONIC and EPSON.

Power supply selection rules

AC/DC selection rules

1. For products with high reliability requirements, LAMBDA and COSEL are preferred power supplies;

2. When selecting Lambda power supplies, it is convenient for normalization to require everyone to uniformly select models with JST connectors.

3. For new products, standard power supplies should be used as much as possible. Customized power supplies are not recommended.

Isolated DC/DC power supply selection rules

1. TI products are preferred for isolated DC/DC power supplies. When TI products cannot meet the requirements, C&D is preferred.

Connector selection rules

European connector selection rules

1.European connector brands are preferably HARTING, ERNI, and EPT. The plugs and sockets used in the same set of products are required to be of the same brand. Different brands are prohibited from being used together.

RJ series connector selection rules

1.If it is not necessary to use external communication signals, RJ11 and RJ12 connectors are prohibited. 2. RJ45 preferably uses round pins for connecting springs, shielding shells, or shielding shells with springs. The thickness of the gold-plated layer of the RJ45 connecting springs must not be less than 3uin. 3. It is forbidden to use RJ45 sockets with lights or transformers.

4. The preferred brand of RJ series connector is PULSE (FRE).

Selection rules for white terminals

1. Try not to use white terminals.

2. The preferred brands of white terminals are JST, AMP, and MOLEX. Selection rules for PCB board mounting screw wiring connectors 1. The preferred brand of PCB board mounting screw wiring connectors is PHOENIX. 2. The preferred brand of PCB board mounting screw wiring connectors is 2-position and 3-position terminal blocks. Connectors with other digits can be spliced using 2-position and 3-position terminal blocks. 3. 5.08mm pitch is preferred, and 5.00mm pitch is prohibited. Selection rules for other rectangular connectors 1. The preferred brands of other rectangular connectors are as follows: AMP, MOLEX, SAMTEC, HIROSE, WCON, NSTECH. 2. The thickness of the gold-plated layer of the connector pin must not be less than 3uin. 3. General connectors are preferred and customized connectors are prohibited.

Source: Internet, please delete if infringed

PCB board mounting screw terminal block brand preferred 2-position and 3-position terminal blocks, other digits of connectors can be spliced with 2-position and 3-position terminal blocks

3. 5.08mm pitch is preferred, and 5.00mm pitch is prohibited.

Other rectangular connector selection rules

1. Other rectangular connectors are preferred brands as follows: AMP, MOLEX, SAMTEC, HIROSE, WCON, NSTECH.

[color=rgb(25, 25, 2. The thickness of the gold plating layer of the connector pin must not be less than 3uin. 3. Universal connectors are preferred and customized connectors are prohibited. Source: Internet, please delete if infringed.PCB board mounting screw terminal block brand preferred 2-position and 3-position terminal blocks, other digits of connectors can be spliced with 2-position and 3-position terminal blocks

3. 5.08mm pitch is preferred, and 5.00mm pitch is prohibited.

Other rectangular connector selection rules

1. Other rectangular connectors are preferred brands as follows: AMP, MOLEX, SAMTEC, HIROSE, WCON, NSTECH.

[color=rgb(25, 25, 2. The thickness of the gold plating layer of the connector pin must not be less than 3uin. 3. Universal connectors are preferred and customized connectors are prohibited. Source: Internet, please delete if infringed.