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深圳山旭電路有限公司Shenzhen Shanxu Pcb Co.,ltd.

English

檢測柔性線路板的9個(gè)常識(shí)

Views : 11680
Update time : 2017-01-25 10:22:00

1、嚴(yán)禁在無隔離變壓器的情況下,用已接地的測試設(shè)備去接觸底板帶電的電視、音響、錄像等設(shè)備來檢測柔性線路板。

嚴(yán)禁用外殼已接地的儀器設(shè)備直接測試無電源隔離變壓器的電視、音響、錄像等設(shè)備。雖然一般的收錄機(jī)都具有電源變壓器,當(dāng)接觸到較特殊的尤其是輸出功率較大或?qū)Σ捎玫碾娫葱再|(zhì)不太了解的電視或音響設(shè)備時(shí),首先要弄清該機(jī)底盤是否帶電,否則極易與底板帶電的電視、音響等設(shè)備造成電源短路,波及集成電路,造成故障的進(jìn)一步擴(kuò)大。

2、檢測柔性線路板要注意電烙鐵的絕緣性能。

不允許帶電使用烙鐵焊接,要確認(rèn)烙鐵不帶電,最好把烙鐵的外殼接地,對(duì)MOS電路更應(yīng)小心,能采用6~8V的低壓電烙鐵就更安全。

3、檢測柔性線路板前要了解集成電路及其相關(guān)電路的工作原理。

檢查和修理集成電路前首先要熟悉所用集成電路的功能、內(nèi)部電路、主要電氣參數(shù)、各引腳的作用以及引腳的正常電壓、波形與外圍元件組成電路的工作原理。如果具備以上條件,那么分析和檢查會(huì)容易許多。

4、測試柔性線路板不要造成引腳間短路。

電壓測量或用示波器探頭測試波形時(shí),表筆或探頭不要由于滑動(dòng)而造成集成電路引腳間短路,最好在與引腳直接連通的外圍印刷電路上進(jìn)行測量。任何瞬間的短路都容易損壞集成電路,在測試扁平型封裝的CMOS集成電路時(shí)更要加倍小心。

5、檢測柔性線路板測試儀表內(nèi)阻要大。

測量集成電路引腳直流電壓時(shí),應(yīng)選用表頭內(nèi)阻大于20KΩ/V的萬用表,否則對(duì)某些引腳電壓會(huì)有較大的測量誤差。

6、檢測柔性線路板要注意功率集成電路的散熱。

功率集成電路應(yīng)散熱良好,不允許不帶散熱器而處于大功率的狀態(tài)下工作。

7、檢測柔性線路板引線要合理。

如需要加接外圍元件代替集成電路內(nèi)部已損壞部分,應(yīng)選用小型元器件,且接線要合理以免造成不必要的寄生耦合,尤其是要處理好音頻功放集成電路和前置放大電路之間的接地端。

8、檢測柔性線路板要保證焊接質(zhì)量。

焊接時(shí)確實(shí)焊牢,焊錫的堆積、氣孔容易造成虛焊。焊接時(shí)間一般不超過3秒鐘,烙鐵的功率應(yīng)用內(nèi)熱式25W左右。已焊接好的集成電路要仔細(xì)查看,最好用歐姆表測量各引腳間有否短路,確認(rèn)無焊錫粘連現(xiàn)象再接通電源。

9、檢測柔性線路板不要輕易斷定集成電路的損壞。

不要輕易地判斷集成電路已損壞。因?yàn)榧呻娐方^大多數(shù)為直接耦合,一旦某一電路不正常,可能會(huì)導(dǎo)致多處電壓變化,而這些變化不一定是集成電路損壞引起的,另外在有些情況下測得各引腳電壓與正常值相符或接近時(shí),也不一定都能說明集成電路就是好的。因?yàn)橛行┸浌收喜粫?huì)引起直流電壓的變化。


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