铜或铜合金的镀银– Silver Properties
镀银铜或铜合金的是用于传递热和电跨宽呼吸产业利用的高功能的光洁度。自19世纪后期onelectrical开关，把它传递电流的其他组件银得到了应用。近年来铜电子部件，包括连接器和端子的镀银已经在电子，汽车和电动汽车（EV）的市场内迅速增长。镀银具有许多独特的性能这使得需要对这些应用。主要的原因是，银具有任何金属，这有利于电力和热能的高效传输的最高电和热传导性。此外，银是一种相对较软的金属，其允许银沉积到压缩和形式围绕一个配合连接器填充小空隙和微粗糙度。这增加导致较少的整体连接器电阻的有效接触面积。
图1：银的导电性比铜和其他金属
银has excellent lubricity and resists galling in switching, sliding or rotary applications. However, high pressure wear surfaces such as blade-style stab connectors can be susceptible to silverwear. In applications such as this, a higher deposit thickness of silver is recommended as well as the use of a nickel or electroless nickel underplate. Thinner silver plating without a nickel underplate is best used on static joints or low duty cycle connectors that are mated and unmated relatively infrequently.
之一的镀银历史关注的是硫化银化合物，通常被称为银失泽的形成。银的失泽主要是一种化妆品关注，因为它仅产生在导电性的相对较小的减少。然而，对于微电子和低压连接器，用于失泽的电位应占用抗晦暗抑制的适当选择。有提供给许多不同的防变色剂avoid silver tarnish执行得非常好，包括有机，硫醇基和锡浸渍系统。
铜特性
铜材料一直是电子电器行业内的工作，马材料一个多世纪。这是因为，如银，铜也有很多可取性能such as excellent electrical and thermal conductivity, which makes it great for handling high voltages and high currents. Copper is also a relatively noble metal which reduces the potential for corrosion when in contact with metals such as tin, nickel or silver. For this reason, silver plating of copper provides many design benefits since the properties of the two metals complement each other. Numerous copper alloys are available today which provide a range of mechanical and electrical properties. Many of the common grades of copper used in manufacturing today include C101 (Oxygen Free), C110 (ETP – Electrolytic Tough Pitch), C145 (Tellurium), C147 (Sulfur Bearing), C172 (Beryllium), and C182 (Chromium). All these different grades of copper can be silver plated to increase the electrical performance in its designated application.
镍侵的好处
The use of a nickel underplate prior to silver plating copper can improve the performance of the overall deposit in several ways. A few of the benefits of nickel underplate are summarized below:
- 扩散阻挡层：When silver is plated on copper a natural solid-state diffusion of the copper into the silver will occur over time. The rate of diffusion is accelerated greatly at elevated temperatures. As copper diffuses into silver it forms a hybrid copper/silver eutectic layer which negatively affects adhesion, solderability and electrical performance. Nickel forms an effective diffusion barrier to prevent this copper/silver migration from occurring. This intermediate layer of nickel is highly recommended in most specifications and even required in some such asASTM B700(Section 6.3.4) andQQ-S-365（第3.3.5节）。
- 腐蚀性能：银通过形成环境和铜基板之间的阻挡层保护铜免于氧化;这种类型的防腐蚀保护的是通常被称为阻挡腐蚀保护。在加入之前，镀银镍托板的有助于形成铜基和环境之间的更有效的屏障，因为它限制了整体存款孔隙率。由于镍是更便宜的金属比银，镍的重存款可用于提高耐蚀性能比单独增加银的厚度成本的影响要小得多。
- Load/Bearing Durability:The use of a nickel underplate helps provide a rigid structure for which the silver layer can be deposited upon. This helps reduce the wear of the silver in high contact pressure switching and wear applications such as fuse stabs or high voltage switch gear.
- Solder Base:The use of a proper nickel underplate prior to silver plating can help improve the solderability of a copper component; this is especially true if soldering copper alloys. In addition, since the nickel helps reduce the diffusion of copper into the silver, a nickel underplate can extend the shelf-life of solderability and reduce the overall amount of silver that needs to be plated to successfully solder a copper component.
用作托板银的最常见的镍是电解氨基磺酸镍要么electroless nickel。镍托板的类型的选择取决于许多因素，包括零件的几何形状，设计防腐性能，成本，可焊性和均匀磁场的担忧。先进的电镀技术的工程或技电子游艺棋牌术销售人员的成员可以帮助选择最佳的镍托板以及推荐的沉积厚度协助。
铜或铜合金的电镀银 - 电镀周期和治疗前的注意事项
Figure 2: C101 Copper Crimp Connector Commonly Silver Plated
在银电镀铜合金，在合金成分的微小差别会具有很大的影响电镀周期，以确保高质量的最终银沉积。即使大多数铜合金具有多数由铜制成的组合物的，合金元素的小百分比可需要特定的治疗前或撞击层，以确保最终的银层是粘附。的一些因素的简要总结在下面列出了许多常见的铜和铜合金。
C101的镀银（无氧）和C110（ETP）铜
铜合金C101和C110是最简单的铜等级到板为99.9％或更纯的铜。对于这两种合金，建议他们都接收碱性清洗预处理清洁部件，以及一个酸泡菜以从铜表面上除去任何氧化物。这导致容易接受“有效的”铜表面，以接收后续的镀敷步骤。接着将铜可以接收镍托板后跟一个银冲击和最后镀银（如果指定）。银罢工层是非常重要的，以实现粘附银层，避免银浸泡，会导致如果铜立刻被镀银无罢工。
The above steps will be referred to as thestandard method的，因为这种方法通常只需要稍微改变，以适应其他的铜合金。
C145（碲）铜镀银
碲铜为铜的具有优良的电特性的高度可加工合金。出于这个原因，碲铜是当该组件通过机械加工操作，如车削或铣削制造中最常用的铜合金中的一个。碲铜需要一个唯一的预处理，由于在合金中的0.5％的碲。因为碲这种材料不能暴露于氰电镀溶液。如果发生这种情况的不溶性碲/氰化合物的结果，将不会接受随后的镀覆。由于大多数银触击银电镀浴是氰化物配制剂;碲铜必须首先用一个非氰化物处理侵如镍，铜酸或锡。一旦以这种方式侵，预处理工艺的其余部分是相同的标准方法。
Due to the need for an acid-based strike prior to silver plating, alternative machinable coppers such as C147 sulfur copper may be preferred to C145 tellurium copper in certain applications. These would include specifically applications with deep, ID features that may be difficult to fully plate with the acid-based strike without affecting part dimensions and tolerances. Advanced Plating Technologies’ sales and engineering staff can help provide input to assist with design for manufacturability to ensure the best material is selected from a finishing standpoint.
镀银的C147 (Sulfur) Copper
图3：光亮镀银机械加工C147铜手指接触
C147 Copper is essentially pure copper with only about 0.4% sulfur added. However, this small addition of sulfur gives C147 much improved machinability over that of C101 or C110 copper. In fact, C147 copper has the same machinability rating as that of C145 tellurium copper (85% of free-cutting brass)2。从镀层的角度来看，C147铜大大优于C145铜，因为在该合金无碲。由于C147是碲可用，则可以进行预处理和电镀，而不需要用于与上面提到的标准方法相一致的酸击。这样，可以C147提供超过该C145碲铜为镀银的相当大的节约成本;如果部分有复杂的几何形状，这是尤其如此。
C172的镀银和C173（铍）铜
铍铜，很像碲铜，获取因为1.9％铍，它包含了一个特殊的预处理。因为铍含量的这种铜合金的表面趋向于具有氧化铍必须镀覆部分之前被去除。另外，C172和C173铜常常热电镀导致必须电镀前除去的热处理规模之前处理。最常用的方法，以除去氧化物的层/标尺是光亮浸渍处理（几个氨基酸的混合物）。一个适当的光亮浸渍将去除该氧化物层和富铍区域留下一个活性的铜表面。之后光亮浸渍铍铜，通常可以使用的标准镀敷法。由于光亮浸渍操作通常进行离线和不在线与典型的电镀工艺;铍铜合金的银镀层可以比其它铜合金更昂贵。
C182（铬），铜镀银
铬铜合金化与铬的小百分比（〜0.8％）。这看似很小加入铬使这种铜合金能够被热处理，并同时提高强度和硬度。添加铬的必要的初始清洁和酸洗之后使用特定的电解镍活化。激活材料后，将标准镀铜方法得到遵守。所使用的镍催化剂是一种非常低效的过程，不需要内的部分的小ID特征达到良好。这样，具有复杂几何形状C182铬铜部件可能带来独特的挑战之前镀银来激活。
镀银的C260 (Cartridge) Brass
图4：镀银机械加工C360黄铜连接器
C260弹壳黄铜可以被认为是黄铜的基本形式，因为它是唯一的和锌铜的组合。锌通常大约占材料的，其余为铜组成的30％。C260黄铜是很受欢迎，因为它提供了良好的耐腐蚀性和黄色黄铜的最高延展性。C260黄铜通常用于制造该被冲压或拉伸元件。尽管该合金在组合物中的差异显著，C260黄铜预处理非常类似于C102和C110铜。然而，必须小心在合金不overclean的材料作为该合金中的锌可以反应的激活。除了该变形例中，基本标准电镀方法适用于C260黄铜的镀银。
C360的镀银（免费加工）黄铜
C360 Brass is different from C260 for several reasons. The first is that the zinc content is higher (about 37%) and the second is that it also contains lead (about 3%). The addition of the lead helps make C360 brass one of the most machinable copper alloys available and is commonly used for turning and milling applications. A side effect of the addition of lead is that it requires modification to the pretreatment for this alloy. A duplex acid pickle must be used in which the first acid removes the standard copper/zinc oxides from the surface and the second alloy removes any lead inclusions present on the surface. As with C260 brass, care must be taken not to overclean the brass since the zinc in the substrate makes the alloy more delicate than a pure copper alloy. Beyond these modifications, the standard method applies to silver plating C360 brass.
铜或铜合金的镀银– Thickness of Silver Plating
镀银of copper or copper alloys usually falls within one of four thickness ranges: flash, commercial, moderate, severe or轴承应用。每个这些不同类别的使用了不同的范围内的厚度所必需的零件，以满足设计要求的镀层。
| 银范畴 | 银厚度 | 描述 |
| 闪 | 0.00005英寸（1.25um） | 非常轻型，无磨损或腐蚀的担忧 |
| 广告 | 0。0001-0.0003 inches (2.5-7.5um) | Light duty connectors and contacts with limited wear and corrosion resistance for mild interior applications only |
| 中等 | 0.0003-0.0008英寸（7.5-20uin） | 中等duty connectors with higher switching and contact loads; moderate exterior corrosion applications |
| 严重 | 0.0008-0.002英寸（20-50um） | 高耐磨重型接触载荷;高腐蚀环境，包括暴露于化学侵蚀 |
| Bearing | >0.002英寸（> 50um的） | 高压/中石化负荷轴承，重型设备或航天应用 |
铜或铜合金的电镀银 - 桶VS挂镀方法
图5：小电镀银桶常用于电镀铜电子元器件
One of the largest factors impacting the cost of silver plating is whether a component must be barrel or rack plated. These two methods are the most common way to plate “loose piece” copper components. In barrel plating parts are mass loaded into a vessel that rotates during processing while passing current into the load. In rack processing the components are individually fixtured on a framework that passes current into the parts. Barrel plating offers considerable labor savings since the parts can be handled in mass which makes this plating method a much more cost effective way to silver plate smaller copper components. However, the parts must be smaller and amendable to tumbling which limits the size and type of component that can be barrel plated.
滚镀可与各种桶尺寸和配置来进行。小桶可以是2” 的直径和4” 长而较大的桶可以是一样大的直径和48” 14” 长。桶的选择将取决于零件尺寸/配置是多少产品被镀。如果你有零件的体积足以填补约30％-50％的容器滚镀才有效。出于这个原因，如果部件用筒镀方法引用，它是典型的，以列出MOQ（最小订单数量）成功地筒身板。
Figure 6: Racked Silver Plated Parts
The ability to barrel silver plate a copper component depends on three primary variables: the size of the part, the weight of the part and surface finish requirements. Typically, parts must be less than 3” in any dimension and less than 0.75” in diameter as a very general rule. Most commonly, copper components must be less than approximately 0.1lbs to barrel plate; however, the part geometry matters as well. For example, soft copper parts with exposed male threads can be damaged during barrel plating. In addition, parts that can interlock, stick together or nest during tumbling often cannot be barrel plated. The final consideration is the surface finish of the part. Since parts are tumbled during barrel plating, highly machined surface finishes (< 30uin) can be increased by the tumbling action of barrel plating. Again, the part size/weight must also be considered when reviewing surface finish as smaller parts with a low surface finish are more likely to be successfully barrel plated than larger copper parts.
对于不能被桶镀铜的部分，挂镀是一种可行的选择。部分通常镀架because they are either too large for barrel plating or the parts might nest/interlock or otherwise become damaged while tumbling. One consideration when rack plating is that a rack mark or lack of full plating coverage will result where the part is contacted by the plating fixture. There are ways to minimize this contact point; however, this needs to be discussed during the development phase of a new application. Although rack plating is higher cost process than barrel plating, it can be used to successfully plate very large parts of nearly any geometry of configuration
铜及铜合金镀银 - 结论
铜和铜合金的镀银两端产生一个范围的产业中利用的高导电性，润滑和耐腐蚀涂层。上铜的银涂层的组合提供了一个表面，其导电性高的热和电性使这个组合的最佳选择份该传递热量或电力。铜合金的多样性提供了广泛的机械性能的增加可以被利用铜的应用程序。铜的合金必须进行预处理，并且其中可以在方法和镀银的成本具有影响独特的方式被激活。underplates和银厚度的适当选择是用于镀银铜部件的功能，以确保该应用程序是否满足预期使用寿命的关键。最后，铜部件的尺寸，几何形状和表面光洁度要求会影响它是否可以是桶或机架镀银。
对于铜或其他应用，镀银的更多信息，请联系a member of Advanced Plating Technologies’ engineering or technical sales staff.
博客，作者：：多米尼克·斯卡尔迪诺，估计工程师
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