文(wen)章主要是討論和分析開(kai)關電(dian)(dian)(dian)源(yuan)(yuan)印(yin)制(zhi)(zhi)板布線原(yuan)則、開(kai)關電(dian)(dian)(dian)源(yuan)(yuan)印(yin)制(zhi)(zhi)板銅皮走(zou)線的(de)一些(xie)事(shi)項、開(kai)關電(dian)(dian)(dian)源(yuan)(yuan)印(yin)制(zhi)(zhi)板大電(dian)(dian)(dian)流走(zou)線的(de)處理(li)以(yi)及反激電(dian)(dian)(dian)源(yuan)(yuan)反射電(dian)(dian)(dian)壓的(de)一個(ge)確定(ding)因素等方面，解(jie)決鋁基板在開(kai)關電(dian)(dian)(dian)源(yuan)(yuan)中的(de)應(ying)用(yong)、多層(ceng)印(yin)制(zhi)(zhi)板在開(kai)關電(dian)(dian)(dian)源(yuan)(yuan)電(dian)(dian)(dian)路(lu)中的(de)應(ying)用(yong)的(de)一些(xie)大家關注的(de)問(wen)題(ti)。

　　一、引言

　　開(kai)(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源是(shi)一種(zhong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)轉換電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，主(zhu)要的(de)(de)工作內容(rong)是(shi)升壓(ya)和(he)降壓(ya)，廣泛應用于現代電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)子產(chan)品。因為開(kai)(kai)關三極(ji)管總是(shi)工作在(zai) “開(kai)(kai)” 和(he)“關” 的(de)(de)狀(zhuang)態，所以叫開(kai)(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源。開(kai)(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源實質就是(shi)一個振蕩電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，這(zhe)(zhe)種(zhong)轉換電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)能的(de)(de)方(fang)式(shi)(shi)，不僅(jin)應用在(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，在(zai)其它的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)應用也很(hen)普遍，如液晶(jing)顯示(shi)器(qi)的(de)(de)背(bei)光電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)、日光燈等。開(kai)(kai)關電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源與(yu)變壓(ya)器(qi)相比具有效率高、穩性好、體積(ji)小等優點(dian)，缺點(dian)是(shi)功率相對較小，而且會對電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)產(chan)生(sheng)高頻干(gan)擾，變壓(ya)器(qi)反饋式(shi)(shi)振蕩電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，能產(chan)生(sheng)有規律(lv)的(de)(de)脈(mo)沖(chong)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)或電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)叫振蕩電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，變壓(ya)器(qi)反饋式(shi)(shi)振蕩電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)就是(shi)能滿足(zu)這(zhe)(zhe)種(zhong)條件的(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)。

　　開關電(dian)源(yuan)(yuan)分(fen)為(wei)，隔(ge)(ge)(ge)離與非隔(ge)(ge)(ge)離兩種形式(shi)(shi)(shi)，在這里主要(yao)談(tan)一(yi)談(tan)隔(ge)(ge)(ge)離式(shi)(shi)(shi)開關電(dian)源(yuan)(yuan)的(de)拓撲形式(shi)(shi)(shi)，在下(xia)文中，非特別(bie)說明，均指(zhi)(zhi)隔(ge)(ge)(ge)離電(dian)源(yuan)(yuan)。隔(ge)(ge)(ge)離電(dian)源(yuan)(yuan)按照結構形式(shi)(shi)(shi)不同(tong)，可分(fen)為(wei)兩大(da)類(lei)：正(zheng)(zheng)(zheng)(zheng)激(ji)(ji)(ji)(ji)式(shi)(shi)(shi)和反激(ji)(ji)(ji)(ji)式(shi)(shi)(shi)。反激(ji)(ji)(ji)(ji)式(shi)(shi)(shi)指(zhi)(zhi)在變(bian)壓(ya)器(qi)原邊(bian)(bian)(bian)導通(tong)時副(fu)邊(bian)(bian)(bian)截(jie)止，變(bian)壓(ya)器(qi)儲能(neng)。原邊(bian)(bian)(bian)截(jie)止時，副(fu)邊(bian)(bian)(bian)導通(tong)，能(neng)量釋放到負載的(de)工作狀態，一(yi)般常規(gui)(gui)反激(ji)(ji)(ji)(ji)式(shi)(shi)(shi)電(dian)源(yuan)(yuan)單(dan)管多(duo)，雙(shuang)管的(de)不常見。正(zheng)(zheng)(zheng)(zheng)激(ji)(ji)(ji)(ji)式(shi)(shi)(shi)指(zhi)(zhi)在變(bian)壓(ya)器(qi)原邊(bian)(bian)(bian)導通(tong)同(tong)時副(fu)邊(bian)(bian)(bian)感應出(chu)對應電(dian)壓(ya)輸出(chu)到負載，能(neng)量通(tong)過變(bian)壓(ya)器(qi)直接傳(chuan)遞。按規(gui)(gui)格又可分(fen)為(wei)常規(gui)(gui)正(zheng)(zheng)(zheng)(zheng)激(ji)(ji)(ji)(ji)，包(bao)括單(dan)管正(zheng)(zheng)(zheng)(zheng)激(ji)(ji)(ji)(ji)，雙(shuang)管正(zheng)(zheng)(zheng)(zheng) 激(ji)(ji)(ji)(ji)。半橋、橋式(shi)(shi)(shi)電(dian)路(lu)都屬于正(zheng)(zheng)(zheng)(zheng)激(ji)(ji)(ji)(ji)電(dian)路(lu)。

　　正激和反激電路(lu)各有其特點，在(zai)設計電路(lu)的過程(cheng)中(zhong)為達(da)到最優性價(jia)比，可以靈活運用。一(yi)般(ban)在(zai)小功(gong)率場(chang)合可選用反激式(shi)。稍微大一(yi)些可采(cai)(cai)用單管(guan)正激電路(lu)，中(zhong)等功(gong)率可采(cai)(cai)用雙管(guan)正激電路(lu)或半橋電路(lu)，低電壓時采(cai)(cai)用推挽電路(lu)，與半橋工作狀(zhuang)態相同。大功(gong)率輸出，一(yi)般(ban)采(cai)(cai)用橋式(shi)電路(lu)，低壓也可采(cai)(cai)用推挽電路(lu)。

　　反(fan)激式電(dian)源(yuan)因其(qi)結(jie)構簡單，省掉(diao)了一(yi)個(ge)和變壓器體(ti)積大小(xiao)差不(bu)多的電(dian)感(gan)，而(er)在(zai)(zai)中(zhong)小(xiao)功(gong)率(lv)電(dian)源(yuan)中(zhong)得(de)到(dao)(dao)廣泛的應用。在(zai)(zai)有(you)些介(jie)紹中(zhong)講到(dao)(dao)反(fan)激式電(dian)源(yuan)功(gong)率(lv)只能做到(dao)(dao)幾十瓦，輸(shu)出功(gong)率(lv)超過(guo)100瓦就沒有(you)優勢，實現起來有(you)難度。本人認為(wei)一(yi)般(ban)情況下是這樣的，但也不(bu)能一(yi)概而(er)論，PI公司的TOP芯片就可(ke)做到(dao)(dao)300瓦，有(you)文章(zhang)介(jie)紹反(fan)激電(dian)源(yuan)可(ke)做到(dao)(dao)上千瓦，但沒見(jian)過(guo)實物。輸(shu)出功(gong)率(lv)大小(xiao)與(yu)輸(shu)出電(dian)壓高低有(you)關。

　　反激(ji)電(dian)(dian)源變(bian)壓(ya)(ya)器漏感是一個非(fei)常關鍵的參數，由于反激(ji)電(dian)(dian)源需要(yao)變(bian)壓(ya)(ya)器儲存能(neng)量，要(yao) 使變(bian)壓(ya)(ya)器鐵芯(xin)得到充分(fen)利用，一般都要(yao)在磁(ci)路(lu)中(zhong)開氣隙，其目的是改變(bian)鐵芯(xin)磁(ci)滯(zhi)回線的斜率，使變(bian)壓(ya)(ya)器能(neng)夠承受(shou)大的脈沖電(dian)(dian)流(liu)沖擊(ji)，而不至(zhi)于鐵芯(xin)進入飽和非(fei)線形狀(zhuang) 態(tai)，磁(ci)路(lu)中(zhong)氣隙處于高磁(ci)阻狀(zhuang)態(tai)，在磁(ci)路(lu)中(zhong)產生漏磁(ci)遠大于完全閉合磁(ci)路(lu)。

　　脈沖電(dian)(dian)(dian)(dian)(dian)壓(ya)連(lian)線(xian)盡(jin)可能短(duan)，其(qi)中輸(shu)(shu)(shu)入(ru)開關管到(dao)(dao)(dao)(dao)變(bian)壓(ya)器(qi)(qi)連(lian)線(xian)，輸(shu)(shu)(shu)出變(bian)壓(ya)器(qi)(qi)到(dao)(dao)(dao)(dao)整流管連(lian)接線(xian)。脈沖電(dian)(dian)(dian)(dian)(dian)流環(huan)路盡(jin)可能小如輸(shu)(shu)(shu)入(ru)濾波電(dian)(dian)(dian)(dian)(dian)容正到(dao)(dao)(dao)(dao)變(bian)壓(ya)器(qi)(qi)到(dao)(dao)(dao)(dao)開關管返回電(dian)(dian)(dian)(dian)(dian)容負。輸(shu)(shu)(shu)出部分(fen)變(bian)壓(ya)器(qi)(qi)出端到(dao)(dao)(dao)(dao)整流管到(dao)(dao)(dao)(dao)輸(shu)(shu)(shu)出電(dian)(dian)(dian)(dian)(dian)感到(dao)(dao)(dao)(dao)輸(shu)(shu)(shu)出電(dian)(dian)(dian)(dian)(dian)容返回變(bian)壓(ya)器(qi)(qi)電(dian)(dian)(dian)(dian)(dian)路中X電(dian)(dian)(dian)(dian)(dian)容要盡(jin)量接 近開關電(dian)(dian)(dian)(dian)(dian)源(yuan)輸(shu)(shu)(shu)入(ru)端，輸(shu)(shu)(shu)入(ru)線(xian)應(ying)(ying)避(bi)免與(yu)其(qi)他(ta)電(dian)(dian)(dian)(dian)(dian)路平(ping)行，應(ying)(ying)避(bi)開。Y電(dian)(dian)(dian)(dian)(dian)容應(ying)(ying)放(fang)置在機(ji)殼接地端子或(huo)FG連(lian)接端。共摸電(dian)(dian)(dian)(dian)(dian)感應(ying)(ying)與(yu)變(bian)壓(ya)器(qi)(qi)保持(chi)一定距離，以避(bi)免磁偶(ou)合。

　　輸出(chu)(chu)電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)一(yi)般(ban)可(ke)(ke)采用兩只(zhi)(zhi)(zhi)(zhi)一(yi)只(zhi)(zhi)(zhi)(zhi)靠近(jin)整流管另一(yi)只(zhi)(zhi)(zhi)(zhi)應靠近(jin)輸出(chu)(chu)端子，可(ke)(ke)影(ying)響(xiang)電(dian)(dian)(dian)(dian)(dian)源輸出(chu)(chu)紋波指(zhi)標，兩只(zhi)(zhi)(zhi)(zhi)小(xiao)容(rong)(rong)量電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)并(bing)聯效(xiao)果應優于用一(yi)只(zhi)(zhi)(zhi)(zhi)大(da)容(rong)(rong)量電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)。發熱器(qi)件要和電(dian)(dian)(dian)(dian)(dian)解 電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)保持一(yi)定距(ju)離(li)(li)，以延長整機壽命，電(dian)(dian)(dian)(dian)(dian)解電(dian)(dian)(dian)(dian)(dian)容(rong)(rong)是開關電(dian)(dian)(dian)(dian)(dian)源壽命的(de)瓶勁，如變(bian)壓器(qi)、功(gong)率(lv)管、大(da)功(gong)率(lv)電(dian)(dian)(dian)(dian)(dian)阻要和電(dian)(dian)(dian)(dian)(dian)解保持距(ju)離(li)(li)，電(dian)(dian)(dian)(dian)(dian)解之間(jian)也須留出(chu)(chu)散熱空間(jian)，條件允許可(ke)(ke)將其放置在(zai)進風口。

　　二、印制板布線的一些原則

　　印(yin)(yin)制板設(she)計(ji)(ji)時，要(yao)考(kao)慮到(dao)干擾(rao)(rao)對(dui)(dui)系(xi)統的(de)(de)影(ying)響，將(jiang)電(dian)(dian)路(lu)(lu)(lu)(lu)的(de)(de)模(mo)擬部(bu)分(fen)(fen)和(he)數字部(bu)分(fen)(fen)的(de)(de)電(dian)(dian)路(lu)(lu)(lu)(lu)嚴格分(fen)(fen)開(kai)，對(dui)(dui)核心電(dian)(dian)路(lu)(lu)(lu)(lu)重點防(fang)護(hu)，將(jiang)系(xi)統地線環繞，并(bing)布線盡可能(neng)粗，電(dian)(dian)源增加濾(lv)波電(dian)(dian)路(lu)(lu)(lu)(lu)，采用(yong)DC-DC隔(ge)(ge)離(li)，信(xin)號采用(yong)光電(dian)(dian)隔(ge)(ge)離(li)，設(she)計(ji)(ji)隔(ge)(ge)離(li)電(dian)(dian)源，分(fen)(fen)析(xi)容(rong)易產(chan)生(sheng)干擾(rao)(rao)的(de)(de)部(bu)分(fen)(fen)（如(ru)時鐘電(dian)(dian)路(lu)(lu)(lu)(lu)、通訊電(dian)(dian)路(lu)(lu)(lu)(lu)等）和(he)容(rong)易被(bei)干擾(rao)(rao)的(de)(de)部(bu)分(fen)(fen)（如(ru)模(mo)擬采樣(yang)電(dian)(dian)路(lu)(lu)(lu)(lu)等），對(dui)(dui)這兩種(zhong)類(lei)型的(de)(de)電(dian)(dian)路(lu)(lu)(lu)(lu)分(fen)(fen)別(bie)采取(qu)措施(shi)。對(dui)(dui)于干擾(rao)(rao)元件(jian)采取(qu)抑(yi)制措施(shi)，對(dui)(dui)敏感(gan)元件(jian)采取(qu)隔(ge)(ge)離(li)和(he)保護(hu)措施(shi)，并(bing)且(qie)將(jiang)它們在空間(jian)和(he)電(dian)(dian)氣上拉(la)開(kai)距離(li)。在板級(ji)設(she)計(ji)(ji)時，還要(yao)注意元器件(jian)放置(zhi)要(yao)遠離(li)印(yin)(yin)制板邊(bian)沿(yan)，這對(dui)(dui)防(fang)護(hu)空氣放電(dian)(dian)是有利的(de)(de)。樣(yang)電(dian)(dian)路(lu)(lu)(lu)(lu)的(de)(de)原理(li)圖(tu)設(she)計(ji)(ji)參見(jian)圖(tu)1。

　　圖1 樣電路的原(yuan)理圖設計原(yuan)理圖

　　線間距(ju)：隨著印制(zhi)線路板制(zhi)造(zao)工(gong)藝的(de)不斷完(wan)善和提高，一(yi)般加工(gong)廠制(zhi)造(zao)出(chu)線間距(ju)等(deng)于甚(shen)至小(xiao)于0.1mm已(yi)經不存在(zai)什么問題，完(wan)全能夠(gou)滿足大多數(shu)應用場合。考慮 到開關電源(yuan)所采用的(de)元器件及(ji)生產工(gong)藝，一(yi)般雙(shuang)面(mian)板最(zui)(zui)小(xiao)線間距(ju)設(she)為0.3mm，單面(mian)板最(zui)(zui)小(xiao)線間距(ju)設(she)為0.5mm，焊盤(pan)與焊盤(pan)、焊盤(pan)與過(guo)孔或過(guo)孔與過(guo)孔，最(zui)(zui)小(xiao) 間距(ju)設(she)為0.5mm，可避免在(zai)焊接操作(zuo)過(guo)程中出(chu)現(xian)“橋(qiao)接”現(xian)象。，這樣大多數(shu)制(zhi)板廠都能夠(gou)很輕松滿足生產要求(qiu)，并可以把(ba)成品率控制(zhi)得非常高，亦可實(shi)現(xian)合理 的(de)布線密度(du)及(ji)有一(yi)個較經濟的(de)成本。