靜(jing)電(dian)(dian)(dian)控(kong)制(zhi)的主(zhu)要措施有:靜(jing)電(dian)(dian)(dian)的泄(xie)漏和(he)(he)耗(hao)散,靜(jing)電(dian)(dian)(dian)中和(he)(he),靜(jing)電(dian)(dian)(dian)屏(ping)蔽與接地(di),增濕(shi)等。靜(jing)電(dian)(dian)(dian)防護就(jiu)是(shi)xx靜(jing)電(dian)(dian)(dian)或(huo)把靜(jing)電(dian)(dian)(dian)壓控(kong)制(zhi)在允許的范圍,使它不致產生危害。簡單地(di)說就(jiu)是(shi)防止(zhi)靜(jing)電(dian)(dian)(dian)累積到一(yi)定程(cheng)度后(hou),去擊穿(chuan)一(yi)些(xie)電(dian)(dian)(dian)子產品(pin),造成不必要的報(bao)廢率,增加成本,造成浪費。
靜(jing)電放電可能造(zao)成(cheng)LED突(tu)發性失效(xiao)(xiao)或潛在(zai)性失效(xiao)(xiao)。突(tu)發性失效(xiao)(xiao)造(zao)成(cheng)LED的{yj}性失效(xiao)(xiao)、短路(lu)。潛在(zai)性失效(xiao)(xiao)則(ze)可使LED的性能參數劣化,例如漏電流加大,一般GaN基LED受到靜(jing)電損傷后所(suo)形成(cheng)的隱患則(ze)無(wu)法修復。
1、 靜(jing)電(dian)就是物體表面存在過剩或(huo)不足的(de)靜(jing)電(dian)荷(he),它(ta)是一種電(dian)能。
靜電(dian)(dian)是(shi)正負電(dian)(dian)荷在局部(bu)范圍內失去平衡(heng)的結(jie)果,靜電(dian)(dian)是(shi)通過電(dian)(dian)子(zi)或離(li)子(zi)轉(zhuan)移而形(xing)成的。
2、 靜(jing)電(dian)就是物體所帶相(xiang)對靜(jing)止不動的(de)電(dian)荷。
靜電的特點:
高電位:可達(da)數(shu)萬(wan)(wan)至(zhi)數(shu)十萬(wan)(wan)伏,操作時(shi)常達(da)數(shu)百和(he)數(shu)千伏。 低電量:靜電流(liu)多為(wei)微(wei)安級(ji)(uA)。 作用時(shi)間(jian)短:納秒級(ji) 。 受(shou)環境影響大:特別是濕(shi)度,濕(shi)度上升(sheng)、靜電下降。
靜電的(de)產生:
接觸、摩(mo)擦、沖(chong)流、壓電、溫差、冷凍、電解
靜(jing)電的危害:
靜(jing)電放電(ESD) 引起發光二極管PN結(jie)的(de)擊穿,是LED器件封裝和應用組(zu)裝工業中靜(jing)電危害(hai)的(de)主(zhu)要(yao)方式。靜(jing)電損傷具(ju)有如(ru)下(xia)特(te)點:
1、隱蔽性:人體不(bu)能直(zhi)接感(gan)知靜(jing)電(dian)(dian)(dian),即使發生靜(jing)電(dian)(dian)(dian)放電(dian)(dian)(dian),人體也不(bu)一(yi)定能有電(dian)(dian)(dian)擊的(de)感(gan)覺,這是因(yin)為人體感(gan)知的(de)靜(jing)電(dian)(dian)(dian)放電(dian)(dian)(dian)電(dian)(dian)(dian)壓為2-3KV。大多數情況都是通過測試(shi)或者實際應用,才(cai)能發現LED器件已受靜(jing)電(dian)(dian)(dian)損傷(shang)。
2、潛(qian)(qian)(qian)伏(fu)性(xing):靜電(dian)(dian)放電(dian)(dian)可能造成(cheng)LED突(tu)發(fa)性(xing)失(shi)效(xiao)或潛(qian)(qian)(qian)在性(xing)失(shi)效(xiao)。突(tu)發(fa)性(xing)失(shi)效(xiao)造成(cheng)LED的{yj}性(xing)失(shi)效(xiao):短路。潛(qian)(qian)(qian)在性(xing)失(shi)效(xiao)則可使LED的性(xing)能參數(shu)劣化,例如(ru)漏電(dian)(dian)流加大,一(yi)般(ban)GaN基(ji)LED受到靜電(dian)(dian)損傷(shang)后所形(xing)成(cheng)的隱患并無任(ren)何方法(fa)可xx。
3、復雜(za)(za)性:在靜(jing)(jing)電(dian)(dian)(dian)(dian)(dian)(dian)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)情況下,起(qi)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)(dian)(dian)源是空間電(dian)(dian)(dian)(dian)(dian)(dian)荷,因而它所儲存的(de)能量(liang)是有限的(de),不像外加電(dian)(dian)(dian)(dian)(dian)(dian)源那樣具有持續放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)能力,故(gu)它僅能提供短暫(zan)發(fa)生的(de)局(ju)部擊穿能量(liang)。雖然靜(jing)(jing)電(dian)(dian)(dian)(dian)(dian)(dian)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)的(de)能量(liang)較(jiao)小, 但其放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)波形很(hen)復雜(za)(za),控制起(qi)來也比較(jiao)麻(ma)煩。另外,LED極為(wei)精細,失(shi)效分(fen)析(xi)難度(du)大(da),使人(ren)容易(yi)誤把靜(jing)(jing)電(dian)(dian)(dian)(dian)(dian)(dian)損傷(shang)失(shi)效當作其它失(shi)效,在對靜(jing)(jing)電(dian)(dian)(dian)(dian)(dian)(dian)放(fang)(fang)電(dian)(dian)(dian)(dian)(dian)(dian)損害未充分(fen)認識之前,常(chang)常(chang)歸咎于(yu)早期失(shi)效或情況不明(ming)的(de)失(shi)效,從而不自覺的(de)掩蓋了失(shi)效的(de)真(zhen)正原因。
4、嚴重性(xing):ESD潛在(zai)性(xing)失效只引起部分參數劣變,如果不(bu)超(chao)過(guo)(guo)合格(ge)范圍,就(jiu)意味著被損(sun)傷的(de)LED可(ke)能毫(hao)無(wu)察覺地通過(guo)(guo){zh1}測試,導致出現過(guo)(guo)早(zao)期失效,這對各(ge)層(ceng)次的(de)制造商來說,其結(jie)果是(shi)最損(sun)聲譽(yu)的(de)。 ESD以(yi)極高(gao)的(de)強(qiang)度很迅速地發生(sheng),放電(dian)(dian)電(dian)(dian)流(liu)流(liu)經LED的(de)PN結(jie)時,產生(sheng)的(de)焦耳熱使芯片(pian)PN兩(liang)極之間局(ju)部介質熔融,造成PN結(jie)短路或漏電(dian)(dian)。防靜電(dian)(dian)區設計原則 抑制靜電(dian)(dian)荷的(de)積(ji)累和靜電(dian)(dian)壓的(de)產生(sheng)。如設備、儀器(qi)、工裝(zhuang)不(bu)使用塑料(liao)、有機(ji)玻璃、普通塑料(liao)袋。
1. 安全、迅速(su) ,有效地xx已產生的靜(jing)電(dian)荷 ,使用有繩防(fang)靜(jing)電(dian)腕防(fang)靜(jing)電(dian)椅 、車、箱。
2. 地面防(fang)靜電地面,防(fang)靜電水磨石,防(fang)靜電地板,敷設地線(xian)網。
3. 工位臺面、工作椅、凳面應采用(yong)ESD保護材(cai)料。
4. 人體 穿防(fang)靜電服、鞋、腕等(deng)。
5. 接地
a、防(fang)(fang)靜電(dian)(dian)(dian)工(gong)作區(qu)必須有安全(quan)可靠的(de)防(fang)(fang)靜電(dian)(dian)(dian)接地(di)(di)(di)(di)裝置,地(di)(di)(di)(di)電(dian)(dian)(dian)阻小于4。防(fang)(fang)靜電(dian)(dian)(dian)地(di)(di)(di)(di)線(xian)不得與(yu)電(dian)(dian)(dian)源零線(xian)相接,不得與(yu)防(fang)(fang)雷地(di)(di)(di)(di)線(xian)共用(yong),使用(yong)三相五(wu)線(xian)制(zhi)的(de)供電(dian)(dian)(dian)時,其地(di)(di)(di)(di)線(xian)可以作防(fang)(fang)靜電(dian)(dian)(dian)地(di)(di)(di)(di)線(xian)。
b、工(gong)(gong)作臺面(mian)、地(di)板墊、坐椅、凳和(he)其它(ta)導靜電(dian)的ESD保護(hu)措施均應通過限流電(dian)阻接到(dao)地(di)線,腕帶等(deng)應通過工(gong)(gong)作臺頂面(mian)接地(di)點與地(di)線連(lian)接,工(gong)(gong)作臺不可(ke)相互串聯接地(di)。
c、防靜電(dian)(dian)工(gong)作(zuo)區(qu)接地系統,包括限流電(dian)(dian)阻(zu)和連接端子應連接可靠并具有一定載流能力,限流電(dian)(dian)阻(zu)阻(zu)值選擇應保證漏(lou)泄電(dian)(dian)流不(bu)超(chao)過5mA,下限值取為1M Ω。
6. 濕度 小于(yu)60%時,須建防靜電(dian)操作系統。
7. 電離器不能(neng)有(you)效地泄放(fang)靜電荷的場合,可(ke)采(cai)用電離器通過空氣中的正負離子來防止和(he)中和(he)元器件和(he)其它(ta)物體(ti)上電荷積(ji)累,電離能(neng)力(li)大于250V/s。
8. 增濕(shi) 增濕(shi)器可使潮(chao)濕(shi)空氣(qi)流,防止靜電荷積累(lei),此(ci)法不適;增濕(shi)后(hou)產生(sheng)有害影響的(de)場地。
9. 包裝(zhuang) 靜(jing)(jing)電(dian)敏感器件應采取保(bao)護性包裝(zhuang); 靜(jing)(jing)電(dian)敏感器件包裝(zhuang)器具必須采用防(fang)靜(jing)(jing)存放(fang)盒,防(fang)靜(jing)(jing)電(dian)塑料袋。
10. 運輸、貯存(cun) SSD必須放在防靜電(dian)容器(箱、袋)內,并用(yong)防靜電(dian)運輸工具(車)。 庫房滿(man)足防靜電(dian)操作系統(tong)要求(qiu),SSD須放防靜電(dian)容器內,貯運中要遠離(li)靜電(dian), 電(dian)磁場(chang)或(huo)放射場(chang)的位置。
11、SSD元器(qi)件應分類(lei)拿放,靜(jing)電(dian)敏感符(fu)(fu)號 符(fu)(fu)號符(fu)(fu)合(he)GJB1649規定。 E、防靜(jing)電(dian)材料的度測方法(fa)與時效(xiao)性 1、摩擦起電(dian)法(fa):棉布120次/分 20次。 2、電(dian)阻率測量(liang)法(fa),小于1010W為好。 3、衰減(jian)常數 RC紅(hong)色(se)塑料袋(dai)與紅(hong)色(se)泡沫時效(xiao)期半年,不能在(zai)陽光下曬,黑(hei)色(se)防靜(jing)電(dian)箱5年,裝IC塑料管、也有(you)時效(xiao)性。 F、生產(chan)系統現場(chang)存(cun)在(zai)的問題(ti)
LED組(zu)裝靜靜電防護{zd1}要
1.環境
空氣濕度的控制(zhi),小于(yu)60%時(shi),須加(jia)強(qiang)防(fang)靜電操作系統(tong)。
工作臺面防靜電桌(zhuo)布良好接地,定期檢查有效性。
2.機(ji)臺、設備、工具
機臺、設備、工具(ju)良(liang)好接地線。(不可與人體靜電(dian)地線共用,防止(zhi)機臺、設備、工具(ju)漏電(dian)電(dian)擊(ji)人員(yuan))
3.人體
人體配有繩防靜(jing)電腕,良好接地,每天定期測(ce)試有效性能。 檢查靜(jing)電腕與人體皮膚良好接觸,接地端與地線良好接觸。
4.其它
除了(le)(le)測(ce)試(shi)(shi)儀(yi)接地外,還要(yao)了(le)(le)解測(ce)試(shi)(shi)儀(yi)的測(ce)試(shi)(shi)線(xian)路,特別(bie)是恒(heng)流測(ce)試(shi)(shi)的電(dian)源(yuan)開路電(dian)壓(ya)不(bu)能(neng)過(guo)高,以免LED受到負反饋脈(mo)沖(chong)電(dian)壓(ya)的沖(chong)擊而失效
5.避免和減少材(cai)料堆積及磨擦
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