汽車已經(jīng)成為人們出行的必不可少的交通工具，為汽車電子設(shè)備選擇高可靠性的電容器已然是工程師的工作日常。首先必須清晰的了解每種不同規(guī)格電容器的技術(shù)參數(shù)和性能特征，其次要根據(jù)汽車電子的環(huán)境和特殊應(yīng)用場景，才能選擇最具性價比和最可靠的解決方案。
Automobile has become an indispensable means of transportation for people to travel, and it is the daily work of engineers to select high reliability capacitors for automotive electronic equipment. First of all, we must clearly understand the technical parameters and performance characteristics of each capacitor with different specifications. Secondly, we must select the most cost-effective and reliable solution according to the environment and special application scenarios of automotive electronics.
電容在汽車電子方面的應(yīng)用通?？梢钥偨Y(jié)歸納為以下六個應(yīng)用領(lǐng)域：
The application of capacitors in automotive electronics can generally be summarized into the following six application areas:
1.動力系統(tǒng)控制：電動機(jī)、變速器和排放控制。如今電動汽車的蓬勃發(fā)展為電源轉(zhuǎn)換和控制電子設(shè)備增加了許多新的機(jī)會。
Power system control: motor, transmission and emission control. Nowadays, the vigorous development of electric vehicles has increased many new opportunities for power conversion and control electronic equipment.
2.車輛控制：防抱死制動、主動懸架、牽引力控制、動力和四輪驅(qū)動轉(zhuǎn)向。
Vehicle control: anti lock braking, active suspension, traction control, power and four-wheel drive steering.
3.安全性、舒適性和便利性：安全氣囊執(zhí)行器、防撞、溫濕度控制、巡航控制和防盜。
Safety, comfort and convenience: airbag actuator, anti-collision, temperature and humidity control, cruise control and anti-theft.
4.車內(nèi)娛樂系統(tǒng)
In car entertainment system
5.駕駛員信息顯示和聲音警告系統(tǒng)
Driver information display and audible warning system
6.診斷和維修
Diagnosis and maintenance
那么如何根據(jù)汽車的主要工作環(huán)境和應(yīng)用領(lǐng)域來選擇適合的電容器呢？通常，大多數(shù)電容器屬于兩種基本結(jié)構(gòu)類別之一：靜電(聚合物薄膜和陶瓷電容)和電解(鉭和鋁)電容器。靜電電容器是非極化器件，通常表現(xiàn)出非常低的等效串聯(lián)電阻(ESR)和阻抗。電解電容器通常具有更高的電容值，但會被極化。
So how to choose the appropriate capacitor according to the main working environment and application fields of the car? In general, most capacitors fall into one of two basic structural categories: electrostatic (polymer film and ceramic capacitors) and electrolytic (tantalum and aluminum) capacitors. Electrostatic capacitors are nonpolarized devices, which usually exhibit very low equivalent series resistance (ESR) and impedance. Electrolytic capacitors usually have higher capacitance values but are polarized.
鉭電解電容
tantalum electrolytic capacitor
鉭電解電容一般是額定電壓從2.5VDC至63VDC的貼片器件，采用125V軸向引線。注意：為了獲得最高的可靠性，固體鉭電容的實(shí)際施加電壓降額至額定電壓的50%，鉭聚合物和濕塊狀軸向鉭電容則降額至80%。
Tantalum electrolytic capacitor is generally a chip device with rated voltage from 2.5VDC to 63VDC, and 125V axial lead is used. Note: In order to obtain the highest reliability, the actual applied voltage of solid tantalum capacitors is derated to 50% of the rated voltage, and tantalum polymer and wet bulk axial tantalum capacitors are derated to 80%.
鉭電解電容隨著時間和溫度的變化具有非常穩(wěn)定的電氣特性
Tantalum electrolytic capacitors have very stable electrical characteristics as time and temperature change
貼片鉭電容的容量最高為2,200μF，軸向濕塊鉭電容的最大容量可達(dá)10,000μF。
The maximum capacity of chip tantalum capacitor is 2200 μ F. The maximum capacity of axial wet block tantalum capacitor can reach 10000 μ F。
浪涌測試/篩選和更大的貼片外殼尺寸(低ESR值和大電容值)。
Surge test/screening and larger chip enclosure size (low ESR value and large capacitance value).
在正常電壓降額使用條件下的典型失效率為5FIT至15FIT(每10億小時失效數(shù))。
Typical failure rates under normal voltage derating service conditions are 5FIT to 15FIT (failures per billion hours).
鋁電解電容
Aluminum electrolytic capacitor
貼片式鋁電解電容的額定電壓從6.3VDC至450VDC，大罐式鋁電容則有更高的電壓。
The rated voltage of the chip type aluminum electrolytic capacitor is from 6.3VDC to 450VDC, and the large tank type aluminum capacitor has a higher voltage.
溫度等級有85℃、105℃或120℃。
The temperature grade is 85 ℃, 105 ℃ or 120 ℃.
貼片式鋁電容的最大容量為10mF。
The maximum capacity of chip type aluminum capacitor is 10mF.
無需浪涌電流篩選。
No surge current screening is required.
鋁電解電容具有自然磨損機(jī)制，在完全額定電壓和最高溫度條件下的使用壽命將限制為5,000小時。如果降額至額定電壓的80%，使用壽命可延長兩倍。
The aluminum electrolytic capacitor has a natural wear mechanism, and its service life under fully rated voltage and maximum temperature conditions will be limited to 5000 hours. If the rating is reduced to 80% of the rated voltage, the service life can be extended twice.
陶瓷電容
Ceramic capacitor
陶瓷電容的額定電壓從6.3VDC到5,000VDC(大多數(shù)使用場合為100V或更低)；電壓無需降額使用，但必須考慮電容的電壓系數(shù)。在額定電壓或接近額定電壓下工作時，多層陶瓷電容(MLCC)的有效電容值可能最多會損失40%。
The rated voltage of ceramic capacitor ranges from 6.3VDC to 5000VDC (100V or less for most applications); The voltage does not need to be derated, but the voltage coefficient of the capacitor must be considered. When working at or near the rated voltage, the effective capacitance value of multilayer ceramic capacitor (MLCC) may lose up to 40%.
陶瓷電容的工作溫度可以超過150℃。
The working temperature of ceramic capacitor can exceed 150 ℃.
無極化(在高速插入時可大電流充電)。
No polarization (it can be charged with large current during high-speed insertion).
陶瓷電容具有非常低的ESR和直流漏電流。
Ceramic capacitors have very low ESR and DC leakage current.
典型失效率小于1FIT；典型失效模式是短路或參數(shù)漂移。
Typical failure rate is less than 1FIT; The typical failure mode is short circuit or parameter drift.
聚合物薄膜電容
Polymer film capacitor
額定電壓從16VDC至2,000VDC；無需降額工作。
Rated voltage from 16VDC to 2000VDC; No derating is required.
大多數(shù)聚合物薄膜電容的最高工作溫度為105℃(PPS電容為125℃)。
The maximum operating temperature of most polymer film capacitors is 105 ℃ (PPS capacitors are 125 ℃).
超低的ESR和直流漏電流
Ultra low ESR and DC leakage current
典型失效率小于5FIT；典型失效模式是開路或參數(shù)漂移。
Typical failure rate is less than 5FIT; Typical failure modes are open circuit or parameter drift.
汽車應(yīng)用中表貼型號產(chǎn)品比較有限。
The surface mounted products are limited in automotive applications.
確定哪種電容器類型最適合給定應(yīng)用并不總是那么容易。除了以上的各種參數(shù)、性能等因素，還要綜合考慮成本、尺寸和可制造性同樣很重要。
It is not always easy to determine which capacitor type is best suited for a given application. In addition to the above parameters, performance and other factors, it is also important to comprehensively consider the cost, size and manufacturability.