對(dui)電路中(zhong)電容元(yuan)件的選用應該考慮以下幾個因素(su)：

電子開發電容耐壓選擇

電子(zi)產品開發在選用電容時(shi)，元(yuan)件的耐壓(ya)一定要高于實際電路(lu)中的工作(zuo)電壓(ya)，尤其值得注(zhu)意的是電子(zi)電路(lu)中要考慮到(dao)可能(neng)產生的高壓(ya)。

電子開發電容電容量選擇

在電(dian)(dian)子電(dian)(dian)路(lu)，電(dian)(dian)容(rong)(rong)(rong)量是(shi)根據(ju)某些性能指標確(que)(que)定的(de)，在確(que)(que)定容(rong)(rong)(rong)量時要根據(ju)標稱系列(lie)選擇。如果通過(guo)(guo)標稱系列(lie)找不到(dao)該電(dian)(dian)容(rong)(rong)(rong)的(de)容(rong)(rong)(rong)量數值，可以(yi)(yi)通過(guo)(guo)串并聯的(de)方(fang)法解決或(huo)通過(guo)(guo)修(xiu)改(gai)設(she)計方(fang)案(an)中其他(ta)參數加以(yi)(yi)解決。在更(geng)換電(dian)(dian)路(lu)中的(de)電(dian)(dian)容(rong)(rong)(rong)時最好選用(yong)原參數的(de)電(dian)(dian)容(rong)(rong)(rong)或(huo)性能指標優于原電(dian)(dian)路(lu)電(dian)(dian)容(rong)(rong)(rong)的(de)元件。

電子開發電容介質選擇

電(dian)(dian)容介(jie)(jie)質(zhi)不(bu)同，其特性差異較大，用(yong)途也不(bu)完全(quan)相同。在選用(yong)電(dian)(dian)容的(de)介(jie)(jie)質(zhi)時，要(yao)首先(xian)了解各介(jie)(jie)質(zhi)的(de)特性，然后確定適用(yong)何種場合。下面分別介(jie)(jie)紹幾種常用(yong)的(de)固定電(dian)(dian)容的(de)使用(yong)。

電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)(dian)(dian)(dian)容是以鋁(lv)等金屬為(wei)正極(ji)(ji)，在其表面形成(cheng)(cheng)一層氧化(hua)膜(mo)為(wei)介質(zhi)，介質(zhi)與電(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)成(cheng)(cheng)為(wei)不(bu)可分的(de)整(zheng)體；負極(ji)(ji)是固體或非固體電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)質(zhi)。由于構成(cheng)(cheng)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)(dian)(dian)(dian)容的(de)兩電(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)的(de)材料(liao)不(bu)同(tong)，因此(ci)它的(de)正負電(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)分別標出(chu)，使用時一定(ding)要正極(ji)(ji)端(duan)接(jie)電(dian)(dian)(dian)(dian)(dian)(dian)路的(de)高電(dian)(dian)(dian)(dian)(dian)(dian)位，負極(ji)(ji)端(duan)接(jie)電(dian)(dian)(dian)(dian)(dian)(dian)路的(de)低電(dian)(dian)(dian)(dian)(dian)(dian)位，否則會引起電(dian)(dian)(dian)(dian)(dian)(dian)容的(de)損壞。按照電(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)材料(liao)的(de)不(bu)同(tong)有鋁(lv)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)(dian)(dian)(dian)容、鉭電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)(dian)(dian)(dian)容和鈮(ni)電(dian)(dian)(dian)(dian)(dian)(dian)解(jie)電(dian)(dian)(dian)(dian)(dian)(dian)容等幾種。

云母電(dian)容是以云母片(pian)為介(jie)質(zhi)的電(dian)容。它絕緣性能好、損(sun)耗小、溫(wen)度(du)穩定性好、電(dian)容量精確(que)度(du)高，常用(yong)在高頻(pin)振(zhen)蕩(dang)電(dian)路(lu)中。

瓷(ci)(ci)介(jie)電(dian)容(rong)(rong)(rong)的介(jie)質是陶瓷(ci)(ci)，根(gen)據(ju)陶瓷(ci)(ci)成分(fen)(fen)不同(tong)可分(fen)(fen)為(wei)(wei)高頻瓷(ci)(ci)介(jie)電(dian)容(rong)(rong)(rong)和(he)(he)低(di)(di)(di)頻瓷(ci)(ci)介(jie)電(dian)容(rong)(rong)(rong)兩種(zhong)（高頻的用(yong)CC表(biao)示，低(di)(di)(di)頻的用(yong)CT表(biao)示）。高頻瓷(ci)(ci)介(jie)電(dian)容(rong)(rong)(rong)容(rong)(rong)(rong)量(liang)在(zai)零點幾(ji)皮法(fa)至幾(ji)百皮法(fa)之間。常使(shi)用(yong)于(yu)要求(qiu)損耗小(xiao)、電(dian)容(rong)(rong)(rong)量(liang)穩定(ding)的場合和(he)(he)在(zai)高頻電(dian)路(lu)(lu)中(zhong)作調諧電(dian)容(rong)(rong)(rong)、振蕩回路(lu)(lu)電(dian)容(rong)(rong)(rong)和(he)(he)溫度補償電(dian)容(rong)(rong)(rong)。電(dian)容(rong)(rong)(rong)耐(nai)壓有(you) 160V、250V和(he)(he) 500V等幾(ji)種(zhong)。容(rong)(rong)(rong)量(liang)誤差分(fen)(fen)為(wei)(wei)2%、5%、10%和(he)(he)20%幾(ji)種(zhong)。低(di)(di)(di)頻瓷(ci)(ci)介(jie)電(dian)容(rong)(rong)(rong)容(rong)(rong)(rong)量(liang)從300pF到22000pF之間，適用(yong)于(yu)低(di)(di)(di)頻電(dian)路(lu)(lu)中(zhong)。

紙介電容生產(chan)工藝簡單，成本(ben)低，電壓范圍較(jiao)寬；缺點是電容量不(bu)易控制，損(sun)耗較(jiao)大，穩定性較(jiao)差，電感最大，通常不(bu)適宜在高頻下使(shi)用。

滌(di)綸電(dian)容(rong)又叫聚酯(zhi)電(dian)容(rong)。它是以(yi)滌(di)綸薄(bo)膜做介質的(de)(de)電(dian)容(rong)。它可(ke)用于各種電(dian)子儀器(qi)儀表(biao)，電(dian)視(shi)機(ji)、收錄機(ji)的(de)(de)耦(ou)合、退(tui)耦(ou)、旁路、隔直流等電(dian)路中。

聚(ju)苯(ben)乙(yi)(yi)烯(xi)電(dian)容(rong)(rong)(rong)是以聚(ju)苯(ben)乙(yi)(yi)烯(xi)薄膜為介質制(zhi)成的(de)(de)電(dian)容(rong)(rong)(rong)。聚(ju)苯(ben)乙(yi)(yi)烯(xi)電(dian)容(rong)(rong)(rong)的(de)(de)最大特(te)點(dian)是絕緣電(dian)阻(zu)高(gao)。這種(zhong)電(dian)容(rong)(rong)(rong)的(de)(de)高(gao)頻損(sun)耗小(xiao)，電(dian)容(rong)(rong)(rong)量(liang)穩定，是目前應用廣泛的(de)(de)一(yi)種(zhong)電(dian)容(rong)(rong)(rong)，由于其(qi)精(jing)度高(gao)，在濾(lv)波器及對容(rong)(rong)(rong)量(liang)要求精(jing)確(que)的(de)(de)電(dian)路(lu)中（如(ru)電(dian)子(zi)琴(qin)電(dian)路(lu)）多采(cai)用。它的(de)(de)缺點(dian)是工作溫度范(fan)圍不(bu)寬，上限為+75℃。因此焊(han)接時(shi)烙鐵的(de)(de)接觸時(shi)間(jian)不(bu)宜過長(chang)，以免因過熱損(sun)壞薄膜。