當一個金屬電(dian)極(ji)同(tong)時存在(zai)陰(yin)極(ji)反(fan)應和陽極(ji)反(fan)應這兩種性質時，這個金屬電(dian)極(ji)就稱為雙性電(dian)極(ji)。在(zai)雙性電(dian)極(ji)的兩個不同(tong)表面上同(tong)時發(fa)生(sheng)陰(yin)陽極(ji)反(fan)應的現(xian)象(xiang)稱為雙極(ji)性現(xian)象(xiang)。
簡(jian)樸(pu)原(yuan)理(li)(li)(li)如(ru)下(以最常(chang)見的(de)(de)(de)(de)鍍銅為例(li)(li))：在(zai)(zai)(zai)電(dian)(dian)(dian)(dian)(dian)(dian)解槽(cao)(cao)中電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)從(cong)金(jin)(jin)(jin)屬(shu)(陽極(ji)(ji)(ji)(ji)(ji)銅球)流(liu)入(ru)電(dian)(dian)(dian)(dian)(dian)(dian)解液(鍍液)中為陽極(ji)(ji)(ji)(ji)(ji)，電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)從(cong)電(dian)(dian)(dian)(dian)(dian)(dian)解液中流(liu)入(ru)金(jin)(jin)(jin)屬(shu)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)為陰極(ji)(ji)(ji)(ji)(ji)。(實(shi)在(zai)(zai)(zai)，在(zai)(zai)(zai)電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)學理(li)(li)(li)論中，專業(ye)術語是第一(yi)類(lei)導體(例(li)(li)如(ru)：金(jin)(jin)(jin)屬(shu))和第二類(lei)導體(例(li)(li)如(ru)：電(dian)(dian)(dian)(dian)(dian)(dian)解液)。假如(ru)在(zai)(zai)(zai)電(dian)(dian)(dian)(dian)(dian)(dian)解槽(cao)(cao)中的(de)(de)(de)(de)陰、陽極(ji)(ji)(ji)(ji)(ji)之間放置一(yi)個(ge)不(bu)與(yu)外(wai)(wai)電(dian)(dian)(dian)(dian)(dian)(dian)源(整(zheng)流(liu)器)連接的(de)(de)(de)(de)金(jin)(jin)(jin)屬(shu)A將電(dian)(dian)(dian)(dian)(dian)(dian)解槽(cao)(cao)隔為二個(ge)槽(cao)(cao)，則陰陽極(ji)(ji)(ji)(ji)(ji)之間的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)不(bu)能(neng)完全通過電(dian)(dian)(dian)(dian)(dian)(dian)解液從(cong)陽極(ji)(ji)(ji)(ji)(ji)流(liu)向陰極(ji)(ji)(ji)(ji)(ji)，必(bi)需從(cong)A借道”。因(yin)此(ci)，當電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)由陽極(ji)(ji)(ji)(ji)(ji)到達(da)A表面(mian)時，此(ci)時，該(gai)表面(mian)就產(chan)生(sheng)(sheng)了(le)陰極(ji)(ji)(ji)(ji)(ji)反(fan)應(對分歧(qi)錯誤?電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)從(cong)電(dian)(dian)(dian)(dian)(dian)(dian)解液中流(liu)入(ru)金(jin)(jin)(jin)屬(shu)了(le))，而在(zai)(zai)(zai)A的(de)(de)(de)(de)另一(yi)表面(mian)就產(chan)生(sheng)(sheng)了(le)陽極(ji)(ji)(ji)(ji)(ji)反(fan)映(電(dian)(dian)(dian)(dian)(dian)(dian)流(liu)從(cong)金(jin)(jin)(jin)屬(shu)中流(liu)入(ru)電(dian)(dian)(dian)(dian)(dian)(dian)解液了(le))。因(yin)此(ci)，朝旭日極(ji)(ji)(ji)(ji)(ji)的(de)(de)(de)(de)一(yi)面(mian)被鍍上了(le)金(jin)(jin)(jin)屬(shu)，而另外(wai)(wai)一(yi)側(ce)面(mian)向陰極(ji)(ji)(ji)(ji)(ji)的(de)(de)(de)(de)金(jin)(jin)(jin)屬(shu)A有可能(neng)發生(sheng)(sheng)溶解。原(yuan)理(li)(li)(li)如(ru)斯，在(zai)(zai)(zai)實(shi)踐中，按電(dian)(dian)(dian)(dian)(dian)(dian)化(hua)學理(li)(li)(li)論，某一(yi)特(te)定(ding)的(de)(de)(de)(de)陽極(ji)(ji)(ji)(ji)(ji)或陰極(ji)(ji)(ji)(ji)(ji)反(fan)應必(bi)需達(da)到一(yi)定(ding)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)(ji)(ji)(ji)電(dian)(dian)(dian)(dian)(dian)(dian)位(不(bu)是電(dian)(dian)(dian)(dian)(dian)(dian)壓(ya))才能(neng)開(kai)始反(fan)應。
以(yi)鍍銅為例：一(yi)般的(de)，酸銅電(dian)(dian)鍍只要(yao)在(zai)(zai)0.6V左(zuo)右的(de)電(dian)(dian)壓差下就(jiu)(jiu)會(hui)發生陰(yin)極(ji)反應(銅離子被還(huan)原到金屬上)。假設(she)，垂直(zhi)電(dian)(dian)鍍槽中的(de)一(yi)個(ge)鈦(tai)籃(lan)因(yin)為和導電(dian)(dian)銅巴接觸不良，有電(dian)(dian)阻(zu)存在(zai)(zai)，那么這(zhe)個(ge)鈦(tai)籃(lan)和相臨的(de)二(er)個(ge)鈦(tai)藍之(zhi)間就(jiu)(jiu)會(hui)有電(dian)(dian)位差，只要(yao)這(zhe)個(ge)電(dian)(dian)位差超(chao)過(guo)一(yi)定的(de)值，這(zhe)時該鈦(tai)藍就(jiu)(jiu)成了(le)上文中的(de)A，成了(le)一(yi)個(ge)雙極(ji)性電(dian)(dian)極(ji)了(le)。面向隔壁鈦(tai)藍方(fang)向被鍍上銅，而(er)面向陰(yin)極(ji)方(fang)向的(de)還(huan)是(shi)陽極(ji)。
應(ying)對(dui)措施：明(ming)白了(le)以(yi)上(shang)的(de)原理，解決該(gai)題(ti)目就很簡樸了(le)：保證所(suo)有陽極(ji)相對(dui)陰極(ji)來說是(shi)(shi)(shi)(shi)在統一(yi)電位高度上(shang)。也(ye)就是(shi)(shi)(shi)(shi)一(yi)端接地，另一(yi)端丈量陽極(ji)的(de)各(ge)點，是(shi)(shi)(shi)(shi)不是(shi)(shi)(shi)(shi)各(ge)點都是(shi)(shi)(shi)(shi)統一(yi)電位。應(ying)用與PCB電鍍銅，該(gai)題(ti)目多(duo)發生在陽極(ji)----鈦藍上(shang)。
因此，可以(yi)采(cai)取以(yi)下(xia)措施：
1，清潔(jie)導電(dian)銅(tong)巴(ba)和鈦(tai)藍掛(gua)鉤，保證鈦(tai)藍和導電(dian)銅(tong)巴(ba)的良好電(dian)氣連接。
2，及時補加銅球，保證銅球與銅球之間的接觸(chu)緊密(mi)。
3，若陰極(ji)的夾具夾的不緊，其中(zhong)一塊基(ji)板沒(mei)有被(bei)施加電(dian)壓，則(ze)陰極(ji)(基(ji)板)上則(ze)變成雙極(ji)性電(dian)極(ji)。這時基(ji)板就會(hui)被(bei)溶解一部門。
