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There is a small battery in our mobile phone, something we touch every day. Let’s take a look today.
1 Component selection criteria
Protection IC selection
High-end: MM3280H02, Seiko 8261AAGMD, Ricoh R5400N110FA
Low-end: composite IC, etc.
Special requirements of individual customers
MOSFET selection
Mid-to-high end: Panasonic MTMC8E2A0L; AON3816, Magna, etc.
Low-end: MOS 8205, etc.
Resistor-capacitor
Capacitors: use TDK, MARUTA capacitor brands, and require the material to be X5R or X7R, and do not use Y5V capacitors
Resistance: use TDK, Yageo brand, and require materials with better accuracy
ID resistance and NTC resistance
The selection of the two is to configure the resistance value and accuracy according to customer requirements. NTC thermistor also needs to determine its B value, and the package form should be determined according to the space and wiring requirements of the PCM
Fuse and PTC
When the customer requests to use, the fuse should be given priority to use 6A/0603 package
There is no requirement by the customer, but when it is needed for related certification, the use of PTC or fuse must be considered.
When the customer does not require and does not require related certification, the fuse and PTC are not used
2 Design of PCB protection board
PCB material
Fr4 is mainly used in the selection of the material of the protective board, mainly considering factors such as fire resistance, mechanical strength, and price. When the gold finger on the PCM needs to be exposed, it needs to be electroplated with a good-looking and wear-resistant metal layer, such as A thick gold standard gold plating thickness ≥ 0.25um B ordinary gold plating gold thickness ≥ 0.015um, hard plate copper skin thickness ≥ 1.0 ounce
PCB components
3 Electrical performance test standards
Measuring instrument requirements
Voltmeter requirements: The accuracy of the voltage meter should not be less than 0.5, and the internal resistance should not be less than 10KΩ/V.
Ammeter requirements: The accuracy of the meter measuring current should not be less than 0.5.
Thermometer requirements: the accuracy of the temperature measurement instrument should not be less than ±0.5 degree Celsius.
The current of the constant current source is constant and adjustable, and the current change should be within ±1%.
The voltage of the constant voltage source is adjustable, and its voltage change should be within ±0.5%
PCB quotation method
When preparing to make a PCBA board, be sure to make a form with the required materials, and place an order with confidence after detailed comparison. The steps are roughly divided into the following steps:
1. Calculate the total material cost based on BOM and Gerber files
2. Calculate the cost of SMT patches and DIP plug-ins
3. Calculate PCBA test cost (such as ICT, FCT test, etc.)
4. Packaging logistics evaluation
5. According to the customer’s area and product characteristics, cost-addition pricing is generally adopted, that is, the quotation = cost * (1x%), where x requires the above comprehensive evaluation. According to experience, x is generally within this range: 20% PCBA quotation is A kind of knowledge. The PCBA processes the insulating part composed of glass fiber, non-woven material, and resin, and then presses it with epoxy resin and copper foil to form a "prepreg". According to different technologies, it can be divided into two major types of processes: elimination and addition. . It reflects the broad vision and professional quality of sales staff, and is an important step to improve the conversion rate of potential customers.
