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    毕业论文-浅谈手机维修方法与技巧.doc

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    毕业论文-浅谈手机维修方法与技巧.doc

    毕业设计(论文)题目:浅谈手机维修方法与技巧系(院):电子通信工程系专业:通信技术班级:.姓名:.指导教师:.完成时间:2011年3月6日2008级毕业设计(论文)成绩评定表平时成绩(20分)评语:平时成绩:指导教师:(签名)年月日评阅成绩(50分)评语:评阅成绩:评阅教师:(签名)年月日答辩成绩(30分)答辩评语:答辩成绩:主持人:(签名)年月日总评成绩教研室主任(签名)答辩组成员目录摘要···························································································································1一、手机的焊接···············································································································31.1热风枪的使用··········································································································31.1.1热风枪的操作····································································································································31.2电烙铁的使用··········································································································31.2.1电烙铁的操作·······································································································41.3小元件拆卸和焊接····································································································41.3.1小元件的拆卸·····································································································································41.3.2小元件的焊接·····································································································································41.4手机贴片集成电路的拆卸和焊接··················································································41.4.1贴片集成电路的拆卸·························································································································51.4.2贴片集成电路的焊接························································································································51.5手机BGA芯片的拆卸和焊接························································································51.5.1BGA-IC拆卸·······································································································································61.5.2植锡操作·············································································································································61.5.3BGA-IC的安装···································································································································71.5.4电路板起泡的处理方法·····················································································································8二、手机常用信号的测试····································································································82.1手机常见供电电压的测试···························································································82.1.1外接电源供电电压·····························································································································82.1.2开机信号电压·····································································································································92.1.3逻辑电路供电电压·····························································································································92.1.4、射频电路供电电压··························································································································92.1.5SIM卡电路供电电压·······················································································································102.2手机常见信号波形的测试·························································································102.2.113MHz时钟和32.768kHz时钟信号波形························································································102.2.2发射VCO控制信号····························································································································112.2.3RXUQ、TXUQ信号······························································································································112.2.4接收使能RXON发射使能TXON信号······························································································112.2.5CPU输出的频率合成器数据SYNDAT时钟SYNCLK和使能SYNEN(SYNON)信号·························112.2.6卡数据SIMDAT卡时钟SIMCLK和卡复位SIMRST信号·······························································122.2.7显示数据SDATA和时钟SCLK波形··································································································122.2.8、受话器两端的信号························································································································122.2.9振铃两端的信号·······························································································································12三、手机电路的读图········································································································12四、故障分类················································································································133.1引起手机故障的原因·······························································································133.2不拆开手机只从手机的外表来看其故障,可分为三大类:···············································133.3拆开手机,从机芯来看其故障,也可分为三大类:·························································143.4常见电子元器件的故障特点······················································································143.5故障检修步骤········································································································153.6手机维修的一般流程·······························································································16致谢····································································································错误!未定义书签。参考文献······················································································································181摘要手机维修的市场潜力是巨大的,而且是长久的,通过介绍热风枪的使用电、烙铁的使用、小元件拆卸和焊接、手机贴片集成电路的拆卸和焊接、手机BGA芯片的拆卸和焊接、手机常见供电电压的测试来说明手机维修的方法与技巧关键词:手机维修焊接热风枪电烙铁BGA信号测试2前言手机维修行业的出现是在上世纪90年代初,在中国快速发展已经了十几年了,据有关部门统计,目前我国手机拥有量4.15亿,这意味着平均每三个中国人就拥有一部手机,手机由于随身携带属于移动中的产品,难免会出现故障。从目前中国的消费水平看来,还远没达到用坏就扔的程度,这就给维修带来了巨大的工作量。而手机产品技术含量很高,相对于自行车、煤气灶等物品来说,维修难度要大得多,即使是家用电器的维修人员不经过专门的学习,也很难胜任对手机的维修工作,从而造成维修技术人员大量缺乏,庞大的手机市场带来了巨大的维修量,这给手机维修市场注入了勃勃生机。按我国有关规定,电子产品的标准故障率应低于3。但据一家不愿透露姓名的手机零售商称,我国手机故障率(返修率)已经达到1015,有些甚至在50以上。手机维修的市场潜力是巨大的,而且是长久的。手机从当年的“身份象征大哥大”演变为今天百姓必备的实实在在的通讯工具,再到将来融通讯与多媒体为一体的个人电子商务、生活助理,都与人们的日常生活越来越密不可分。现在人们手机的拥有量和前几年比可谓多得惊人,而且还在逐年增长。这一点不用翻看报纸杂志上枯燥的统计数字,你只需看一看身边的人手机拥有量就足以说明问题了。手机是精密的电子产品,而且是随身携带的,除了一些设计缺陷和正常老化,还难免磕磕碰碰,受潮进水,它的故障发生率要高出家电和电脑几倍甚至几十倍。不得不指出的是,在庞大的农村手机市场中我们的农民朋友们大多使用的为品牌低下的国产机、杂牌机、水货机,所反映出的手机问题比较多。庞大的市场拥有量决定着一个潜在的庞大市场维修量,庞大的市场维修量意味着包含一个巨大的市场利益空间!手机这种通讯工具在日常工作及生活里发挥着巨大的无可替代的作用!总的来说,手机维修行业是朝阳产业而绝非昔日黄花。3毕业设计(论文)正文一、手机的焊接手机的焊接在手机维修里是最基本,但又是最重要的,因为手机维修经常要替换元件,如果手机焊接技术不行,手机维修也无从谈起。1.1热风枪的使用热风枪是一种贴片元件和贴片集成电路的拆焊、焊接工具,热风枪主要由气泵、线性电路板、气流稳定器、外壳、手柄组件组成。性能较好的850热风枪采用850原装气泵。具有噪音小、气流稳定的特点,而且风流量较大一般为27Lmm;NEC组成的原装线性电路板,使调节符合标准温度(气流调整曲线),从而获得均匀稳定的热量、风量;手柄组件采用消除静电材料制造,可以有效的防止静电干扰。由于手机广泛采用粘合的多层印制电路板,在焊接和拆卸时要特别注意通路孔,应避免印制电路与通路孔错开。更换元件时,应避免焊接温度过高。有些金属氧化物互补型半导体(CMOS)对静电或高压特别敏感而易受损。这种损伤可能是潜在的,在数周或数月后才会表现出来。在拆卸这类元件时,必须放在接地的台子上,接地最有效的办法是维修人员戴上导电的手套,不要穿尼龙衣服等易带静电的服装。1.1.1热风枪的操作(1)将热风枪电源插头插入电源插座,打开热风枪电源开关。(2)看元件类型和方位调节热风枪风速。(3)看元件类型和方位调节热风枪的温度开关。(4)必要时用一个小挡板把元件挡住,要不过高的温度把元件吹坏!1.2电烙铁的使用与850热风枪并驾齐驱的另一类维修工具是936电烙铁,936电烙铁有防静电(一般为黑色)的,也有不防静电(一般为白色)的,选购936电烙铁最好选用防静电可调温度电烙铁。在功能上,936电烙铁主要用来焊接,使用方法十分简单,只要用电烙铁头对准所焊元器件焊接即可,焊接时最好使用助焊剂,有利于焊接良好又不造成短路。41.2.1电烙铁的操作(1)将电烙铁电源插头插入电源插座,打开电烙铁电源开关。(2)将电烙铁的温度开关调节到适当的位置,一般为370度。(3)用完之后一定要加锡,要不电烙铁会氧化变坏!1.3小元件拆卸和焊接手机电路中的小元件主要包括电阻、电容、电感、晶体管等。由于手机体积小、功能强大,电路比较复杂,决定了这些元件必须采用贴片式安装(SMD),片式元件与传统的通孔元器件相比,贴片元件安装密度高,减小了引线分布的影响,增强了搞电磁干扰和射频干扰能力。对这些小元件,一般使用热风枪进行拆卸和焊接(焊接时也可使用电烙铁),在拆卸和焊接时一定要掌握好风力、风速和风力的方向,操作不当,不但将小元件吹跑,而且还会“殃及鱼池”,将周围的小元件也吹动位置或吹跑。1.3.1小元件的拆卸在用热风枪拆卸小元件之前,一定要将手机线路板上的备用电池拆下(特别是备用电池离所拆元件较近时),否则,备用电池很容易受热爆炸,对人身构成威胁。将线路板固定在手机维修平台上,打开带灯放大镜,仔细观察欲拆卸的小元件的位置。用小刷子将小元件周围的杂质清理干净,往小元件上加注少许松香水。安装好热风枪的细嘴喷头,打开热风枪电源开关,调节热风枪温度和风速。只手用手指钳夹住小元件,另一只手拿稳热风枪手柄,使喷头离欲拆卸的小元件保持垂直,距离为2至3cm,沿小元件上均匀加热,喷头不可触小元件。待小元件周围焊锡熔化后用手指钳将小元件取下。1.3.2小元件的焊接用手指钳夹住欲焊接的小元件放置到焊接的位置,注意要放正,不可偏离焊点。若焊点上焊锡不足,可用电烙铁在焊点上加注少许焊锡。打开热风枪电源开关,调节热风枪温度和风速。使热风枪的喷头离欲焊接的小元件保持垂直,距离为2至3cm,沿小元件上均匀加热。待小元件周围焊锡熔化后移走热风枪喷头。焊锡冷却后移走手指钳。用无水酒精将小元件周围的松香清理干净。1.4手机贴片集成电路的拆卸和焊接手机贴片安装的集成电路主要有小外型封装和四方扁平封装两种。小外型封装又称SOP封装,其引脚数目在28之下,引脚分布在两边,手机电路中的码片、字库、电子开关、频率合成器、功放等集成电路常采用这种SOP封装手集成电路。四方扁平封装适用于高频电路和引脚较多的模块,简单QFP封装,四边都有引脚,其引脚数目一般为20以上。如许多中频模块、数据处理器、音频模块、微处理器、电源模块等都采用QFP封装。5这些贴片集成电路的拆卸和安装都必须采用热风枪才能将其拆下或焊接好。和手机中的一些小元件相比,这些贴片集成电路由于相对较大,拆卸和焊接时可将热风枪的风速和温度调得高一些。1.4.1贴片集成电路的拆卸在用热风枪拆卸贴片集成电路之前,一定要将手机线路板上的备用电池拆下(特别是备用电池离所拆集成电路较近时),否则,备用电池很容易受热爆炸,对人身构成威胁。将线路板固定在手机维修平台上,打开带灯放大镜,仔细观察欲拆卸集成电路的位置和方位,并做好记录,以便焊接时恢复。用小刷子将贴片集成电路周围的杂质清理干净,往贴片集成电路管脚周围加注少许松香水。调好热风枪的温度和风速。用单喷头拆卸时,应注意使喷头和所拆集成电路保持垂直,并沿集成电路周围管脚慢速旋转,均匀加热,喷头不可触及集成电路及周围的外围元件,吹焊的位置要准确,且不可吹跑集成电路周围的外围小件。待集成电路的管脚焊锡全部熔化后,用医用针头或手指钳将集成电路掀起或镊走,且不可用力,否则,极易损坏集成电路的锡箔。1.4.2贴片集成电路的焊接将焊接点用平头烙铁整理平整,必要时,对焊锡较少焊点应进行补锡,然后,用酒精清洁干净焊点周围的杂质。将更换的集成电路和电路板上的焊接位置对好,用带灯放大镜进行反复调整,使之完全对正。先用电烙铁焊好集成电路的四脚,将集成电路固定,然后,再用热风枪吹焊四周。焊好后应注意冷却,不可立即去动集成电路,以免其发生位移。冷却后,用带灯放大镜检查集成电路的管脚有无虚焊,若有,应用尖头烙铁进行补焊,直至全部正常为止。用无水酒精将集成电路周围的松香清理干净。1.5手机BGA芯片的拆卸和焊接随着全球移动通信技术日新月异的发展,众多的手机厂商竞相推出了外形小巧功能强大的新型手机。在这些新型手机中,普遍采用了先进的BGAIC(Balldarrays球栅阵列封装),这种已经普及的技术可大大缩小手机的体积,增强功能,减小功耗,降低生产成本。但万事万物一样有利则有弊,BGA封装IC很容易因摔引起虚焊,给维修工作带来了很大的困难。

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