1. Capacitor
Chip capacitors and other components in the package of 1206 and above should be used with cautions, there is a practical risk in the welding process.
Ceramic capacitors use NPO (C0G) and X7R two types which temperature coefficient control is better. Tantalum capacitors which rated voltage is lower than 25V are preferred. The forming voltage of the Aluminum Electrolytic capacitors should be 1.2 to 1.4 times of the rated voltage.
In general, the comparison of ESR values of various capacitor: aluminum capacitor > tantalum capacitor > ceramic capacitor;
The ripple current should not exceed the specifications under the high temperature, otherwise it will affect the service life; the limit value of each package is not recommended.
1.电容
慎用1206及以上封装的贴片电容等器件，焊接过程中有实效风险.
陶瓷电容选用NPO（C0G）和X7R这两类，温度系数控制较好。钽电解电容一般建议使用额定电压不超过25V产品。铝电解电容一般选取形成电压是额定电压的1.2到1.4倍。
一般情况下，各种电容ESR比较：铝电容＞钽电容＞陶瓷电容；注意高温下时的纹波电流不要超出使用规格，否则会影响使用寿命；每种封装的极限值不建议使用.
2.
Diode & triode
When selecting the diode & triodes, pay attention to whether the following parameters are sufficient in the circuit to prevent the risk of damage.
Reverse breakdown voltage Vbr, reverse repeated operating voltage Vrwm, maximum average forward average current If, Instantaneous forward voltage Vf, reverse recovery time Trr, thermal resistance Rjc, maximum junction temperature Tjm.
2.二三极管
二三极管选型时注意以下参数在电路中是否够用，防止损坏风险。
反向击穿电压Vbr，反向重复工作电压Vrwm，最大平均正向平均电流If，正向压降Vf，反向恢复时间Trr，热阻Rjc，最高节温Tjm。
3.
Crystals and crystal oscillatorsTry to use the chip package. The largest shipment in the industry is 3.2mmx2.5mm (3225) package;
the AT cut fundamental frequency is selected, the preferred range is 12MHz~15MHz; a crystal oscillator generally only drives one device.
3.晶体和晶振
尽量选用贴片封装，行业内目前出货量最大的是3.2mmx2.5mm(3225) 封装；
选择AT切基频，优选范围12MHz~15MHz；一个晶振一般只驱动一个器件。
