Hi
Take cross-section on the pads and observe the nickel layer by SEM, for black pad, you could see the nickel corrosion.
Best regards,
Gary Yu
-----Original Message-----
From: TGAsia 代理 Benjamin Chen
Sent: 30/7/2007 [Mon] 17:04
To: [log in to unmask]
Cc:
Subject: Re: [TGA] (瑞星提示-此邮件可能是垃圾邮件)Re : [TGA] (瑞星提示-此邮件可能是垃圾邮件)Re : [TGA] (瑞星提示-此邮件可能是垃圾邮件)[ TGA ] 答 复: (瑞星提示-此邮件可能是垃圾邮 件)[T GA ] 答复: [TGA]
在白老師同一章節內有提到一些方法:
1. (焊接前)可以透過將具有黑墊(金色呈現稍微的暗紅)與不具黑墊的ENIG處理之顏色在強光下作對照比較, 不過文中提到比色法相當困難
2. (焊接前)可透過不會攻擊鎳層與不會攻擊黑墊層的除金層藥水將金層除去, 觀察黑墊的存在性. 不過文章內並沒有提到適合的藥水成分
3. (焊接前後)可切片觀察鎳層的晶格邊界狀況併EDX分析, 也可觀察到是否有磷與氧化鎳複合物含量異常的狀況與黑墊的存在
Hope this helps.
zgfeng <[log in to unmask]>
Sent by: TGAsia <[log in to unmask]>
07/30/2007 04:40 PM
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Re: [TGA] (瑞星提示-此邮件可能是垃圾邮件)Re: [TGA] (瑞星提示-此邮件可能是垃圾邮件)Re : [TGA] (瑞星提示-此邮件可能是垃圾邮件)[TGA ] 答 复: (瑞星提示-此邮件可能是垃圾邮件)[T GA ] 答复: [TGA]
谢谢你，可惜在大陆看不到白先生的这本书。
另外还想问一下，出现这种情况常常是无法在焊接前发现的，焊接后发现了损失也很大的，怎么样能在焊接之后判别是否是"Black pad"呢？
冯志刚
----- Original Message -----
From: Benjamin Chen <mailto:[log in to unmask]>
To: [log in to unmask] <mailto:[log in to unmask]>
Sent: Monday, July 30, 2007 4:08 PM
Subject: (瑞星提示-此邮件可能是垃圾邮件)Re: [TGA] (瑞星提示-此邮件可能是垃圾邮件)Re : [TGA] (瑞星提示-此邮件可能是垃圾邮件)[TGA ] 答 复: (瑞星提示-此邮件可能是垃圾邮件)[T GA ] 答复: [TGA]
各位好,
下列是參考白蓉生老師在其"電路板與無鉛焊接"(由台灣電路板產業學院出版)一書中第十章化鎳浸金無鉛銲點之強度關於黑墊的形成.
化鎳浸金的黑墊成分主要是製程後的磷與氧化鎳的複合物. 幾乎是現行ENIG製程再加上SAC高溫銲錫所很難避免的結果. 已經有一些公開的解決方案, 如利用一部分還原金代替全部換金, 或是在化鎳上鍍上薄化學鈀, 似乎是可行的替代方案, 不過更改製成的成本均相當高. 另外也有一些新的製程如錫銅鎳噴錫, 化鎳化銅上再加上薄的OSP似乎也是可替換ENIG的表面處理.
詳細的黑墊形成原理, 白老師在其書中有詳述, 皆基於公開的論文資料, 大家看看應該會有所幫助
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Tel: 886-2-2896-7790 ext. 62267, Fax: 886-2-2896-6140
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zgfeng <[log in to unmask]>
Sent by: TGAsia <[log in to unmask]>
07/30/2007 02:42 PM
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"Black pad"和"黑盘＂应该指的是同一种现象吧,可能是中文和英文的不同称谓。
----- Original Message -----
From: Benjamin Chen <mailto:[log in to unmask]>
To: [log in to unmask] <mailto:[log in to unmask]>
Sent: Monday, July 30, 2007 9:42 AM
Subject: (瑞星提示-此邮件可能是垃圾邮件)Re: [TGA] (瑞星提示-此邮件可能是垃圾邮件)[TGA ] 答 复: (瑞星提示-此邮件可能是垃圾邮件)[T GA ] 答复: [TGA]
請問指的是"Black pad"嗎?
zgfeng <[log in to unmask] <mailto:[log in to unmask]> >
Sent by: TGAsia <[log in to unmask] <mailto:[log in to unmask]> >
07/27/2007 05:30 PM
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ENIG工艺中有一种叫"黑盘＂的现象，能解释一下是什么吗？看了资料说是由于P浓度过低引起的，会导致可焊性不良。多谢了！
冯志刚
----- Original Message -----
From: Gong Lijun <mailto:[log in to unmask]>
To: [log in to unmask] <mailto:[log in to unmask]>
Sent: Thursday, July 26, 2007 12:08 PM
Subject: (瑞星提示-此邮件可能是垃圾邮件)[TGA] 答复: (瑞星提示-此邮件可能是垃圾邮件)[T GA] 答复: [TGA]
电镀镍金和化学镍金只是加工方式上不同，一个是化学镀一个是电镀，都有镍层和金层，厚度标准也够一样，镍层3-5微米，金层0.025-0.1微米。
我个人的观点，局部可焊性不好，不会是这个加工过程引起的，是PCB问题的话，应该是阻焊显影时局部显影不净导致问题的可能性更大。
-----原始邮件-----
发件人: zgfeng [mailto:[log in to unmask]]
发送时间: 2007年7月26日 11:30
收件人: Asia Committe Task Group Forum; [log in to unmask] <mailto:[log in to unmask]>
主题: Re: (瑞星提示-此邮件可能是垃圾邮件)[TGA] 答复: [TGA]
谢谢两位的回复。
还是有些不明白的地方，水金和沉金工艺除了工序不同以外，还有什么区别？是否沉金工艺中不镀镍？还是镀金层的厚度不同？
回流焊后出现不润湿的情况后，用电烙铁手工加锡也不行，这可以反映出焊盘的可焊性应该是有问题。
另外，是否有可能是金层太薄，造成镍氧化，或是在镀金前镍已氧化？不清楚PCB工艺，乱猜的。
冯志刚
----- Original Message -----
From: Gong Lijun <mailto:[log in to unmask]>
To: [log in to unmask] <mailto:[log in to unmask]>
Sent: Thursday, July 26, 2007 11:14 AM
Subject: (瑞星提示-此邮件可能是垃圾邮件)[TGA] 答复: [TGA]
冯工：
您好！
您指的加工工艺应该是全板电镀水金（镍金）或全板化学沉金。不知具体是何种工艺。
从PCB加工讲，化学沉金都是整板进行的，并且是在阻焊加工完成之后进行，如果出现可焊性的问题，逻辑上应该是全板都会出现不良，不会是局部的问题。因此焊接的工艺应该好好分析一下。
如果是电镀水金会复杂些，由于是先整板镀镍金，然后再进行阻焊加工，镀金也是全板进行，局部的可焊性不好，不会是镀金过程引起的，但有可能会因为绿油显影不净出现局部可焊性不好的情况。具体还要仔细进行分析。
宫立军
兴森快捷
-----原始邮件-----
发件人: 李娅婷 [mailto:[log in to unmask]]
发送时间: 2007年7月26日 10:54
收件人: [log in to unmask]
主题: [TGA]
冯先生：
你好！镀金我们在业内一般称之为硬金，由于金层的致密性远高于化学浸金的金层，所以可能会出现局部的上金不良问题。但是我们公司的镀金工艺仅只有针对金手指的接插件，所以对于镀层的可焊性不良不是很清楚。
如果是化金的板件，如果贵司加工的时候没有污染，就可能是供应商的问题了！
深南电路
李娅婷
--------- Original Message --------
From: "Asia Committe Task Group Forum" <[log in to unmask]>
To: <[log in to unmask]>
Subject: [TGA]
Date: 2007/07/26 10:45
最近碰到一批板，焊盘表面是镀金处理，回流焊接后发现每片板上都有不同程度的不润湿现象，但在每块板上出现的区域不同，出现的位置也不同，同一片板上，有些位置润湿情况还是良好的（通过40倍放大镜观察）。
怀疑是PCB厂商在表面处理的工艺中做得有问题，不知镀金工艺中出现这种问题如何分析原因？还请快捷和深南的几位专家解答一下。
冯志刚
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