江西遂川亚恒电路有限公司JIANGXI SUICHUAN YAHENG CIRCUITS CO.,LTD. 深圳市亚恒电路有限公司SHENZHEN YAHENG CIRCUITS CO.,LTD

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pcb打样的注意事项

Views : 1758
Update time : 2017-08-12 13:12:00

板子厚度:0.8,1.0,1.2,1.6,2.0这是常用的规格,如果没有特别的要求的话就选1.6mm的板厚。

铜箔厚度:0.5,1.0,2.0这是常用规格,如果功率不是特别大的板就可以不用选,厂家一般会用0.5oz的板来做,如果功率在100W左右的功率板的话就要用到1.0以上了。

阻焊的颜色:绿,黑,红,白这是常用的,没有什么要求就用绿色,如果是自己实验用的话更应该用绿色,因为这种颜色的板线路看得最清楚。

焊盘处理:松香,抗氧化,喷锡(分为有铅和无铅两种),一般采用后面两种都可以,喷锡的保存时间会更长些。

丝印的颜色:白,黑是常用的颜色,如果是绿油的话一般选白字,这个主要是看得清楚就行了,选跟板的颜色对比度大的就可以了,如果是白色阻焊的话就要选黑字了。

板材选择:HB,94V-0,FR-4这是常用的,HB就很少用,它是不防火的板,一般单面板就用94V-0,双面板就用FR-4。


一、跑锡造成的短路

1、在退膜药水缸里操作不当引起跑锡;

2、已退膜的板叠加在一起引起跑锡。

改善方法:

(1)退膜药水浓度高,退膜时间长,抗镀膜早已掉落,可板仍在强碱溶液中浸泡,部分锡粉附在铜箔表面上,蚀刻时有一层很薄的金属锡护着铜表面,起到抗蚀作用,造成要去除的铜未除干净,从而导致线路短路。所以我们需要严格控制好退膜药水的浓度、温度、退膜时间,同时退膜时用插板架插好,板与板之间不能层叠碰在一起。

(2)已退膜的板未烘干便叠加在一起,使得板与板之间的锡浸在未烘干的退膜溶液中,部分锡层会溶解附在铜箔表面上,蚀刻时有一层很薄的金属锡护着铜表面,起到抗蚀作用,造成要去除的铜未除干净,从而导致线路短路。

二、蚀刻不净造成的短路

1、蚀刻药水参数控制的好坏直接影响到蚀刻质量,目前我司使用的是碱性蚀刻液,具体分析如下:

(1)PH值:控制在8.3~8.8之间,如果PH值低了,溶液将变成粘稠状态,颜色偏白色,蚀板速率下降,这种情况容易引起侧腐蚀,主要通过添加氨水来控制PH值。

(2) 氯离子:控制在190~210g/L之间,主要通过蚀刻盐对氯离子含量进行控制,蚀刻盐是由氯化铵和补充剂组成的。


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