PCB surface finishes is essential for best performance, reliability and board life. It protects the copper on the board from oxidation and ensures a reliable connection between the components and the board. Among other things, it also affects the manufacturing process, including the quality of soldering and assembly. Let's talk together about circuit board coatings.<h2><span>Immersion Silver (ImAg)</span></h2><p><span>This is a method of immersion plating copper with silver. This means that copper atoms are replaced by silver atoms. The process of this method involves immersing the PCB in a solution containing silver ions, which are reduced to elemental silver on the surface of the copper. </span></p><p> </p><h3><span>Advantages of immersion silver plating of copper:</span></h3><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>ImAg provides excellent solderability.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>Bonding wires, for example in medical devices, is no problem for ImAg. On the contrary, this method ensures good performance when joining wires using this method. </span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>No hazardous substances or heavy metals. ImAg contains none of these, making it more environmentally friendly. </span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>The high surface energy ensures that the components adhere to the PCB surface. </span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>If you need <strong>to save money</strong>, this method is for you. This is because ImAg is relatively inexpensive compared to other surface treatments.</span></p><h3>Disadvantages of copper immersion plating with silver:</h3><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>The surface finish is susceptible to the presence of sulphur. This causes darkening of the plates and solderability problems. </span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>Since ImAg can degrade over time, it has limited shelf life. </span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>ImAg requires careful handling during the manufacturing process to avoid contamination.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>A thin layer of this coating may not provide sufficient protection against certain types <strong>of corrosion or wear.</strong></span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>For applications that require greater thickness or a different level of protection, this coating may not be suitable.</span></p><p> </p><p> </p><h2>Immersion Gold (ENIG)</h2><p><span>After applying a thin layer of gold, the circuit board is immersed in a solution containing nickel ions. The nickel chemically displaces the gold, creating an intermetallic compound of nickel and gold. </span></p><p> </p><h3>Advantages of immersion plating copper with gold:</h3><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>Due to the protective nickel layer, ENIG exhibits<strong> excellent corrosion resistance</strong>.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>ENIG provides a uniform layer thickness, which is important for SMT surface mount technology.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>If you need to bond some conductors, ENIG is the right choice because it provides a highly conductive surface that is easy to bond to.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>ENIG provides a flat surface that is suitable for chip packaging (CSP).</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>If you need to re-melt your board multiple times, ENIG is the right choice.</span></p><p> </p><h3>Disadvantages of gold immersion plating:</h3><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>Cost: ENIG is more expensive than other finishes.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>ENIG requires careful handling during the manufacturing process. At the same time, nickel is susceptible to oxidation.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span><strong>Beware of thermal shock</strong>. Heat shocks can cause cracking and flaking of the nickel layer in the ENIG method.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>The ENIG nickel layer is difficult to visually inspect.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>Avoid high temperatures: The intermetallic compound of nickel and gold can disintegrate at elevated temperatures.</span></p><p> </p><p> </p><h2>Immersion tin (ImSn)</h2><p><span>This is a method of immersion plating copper with tin. This means that copper atoms are replaced by tin atoms. The process of this method involves immersing the PCB in a solution containing tin ions, which are reduced to elemental tin on the surface of the copper. </span></p><p> </p><h3>Advantages of tin immersion plating:</h3><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>Suitable for SMT applications due to the flat surface that tin creates.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>ImSn is well solderable.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>ImSn has a long shelf life.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>Price: ImSn is relatively <strong>cost-effective compared to other surface treatments</strong>.</span></p><p> </p><h3>Disadvantages of tin immersion plating:</h3><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>ImSn is not suitable for applications where wire splicing occurs due to its brittleness.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>ImSn has limited heat resistance.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>ImSn is <strong>susceptible to tin whiskers formation</strong>, which can lead to short circuits.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>Handling Caution: ImSn is sensitive to handling and requires careful handling.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>Harsh environments are not conducive to this finish. In fact, ImSn provides only limited corrosion resistance.</span></p><p> </p><p> </p><h2>Organic Soldering Preservatives (OSP)</h2><p><span>An environmentally friendly surface treatment that applies a layer of organic material to copper plates. OSP is a water-based organic compound that forms a protective layer on copper. </span></p><p> </p><h3>Benefits of OSP coating</h3><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>The absence of heavy metals makes this coating environmentally friendly.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>OSP coating is <strong>relatively simple to apply</strong>. </span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>The cost of this coating is very affordable.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>OSP provides a flat finish on the circuit board.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>No extra thickness due to the OSP method.</span></p><p> </p><h3>Disadvantages of OSP surface treatment</h3><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>Over time, the surface finish will begin to degrade.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>It is easily damaged by handling and can be affected by contaminants.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>Avoid high temperature applications: OSP can break down and lose its protective properties.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>OSP is difficult to reprocess because the organic layer can be damaged during reprocessing.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>OSP provides only <strong>limited protection against corrosion</strong>.</span></p><p> </p><p> </p><h2>LF-HASL surface treatment</h2><p><span>Full name Lead-Free Hot Air Solder Leveling. Exposed copper surfaces are coated with a thin layer of molten solder, which is then leveled with hot air knives. LF-HASL is a lead-free alternative to the traditional HASL process.</span></p><p> </p><h3>Advantages of LF-HASL</h3><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>Relatively low cost makes this method an attractive choice.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>LF-HASL offers good solderability due to its thin solder layer.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>LF-HASL can be stored for a long time </span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>LF-HASL is suitable for the use of <strong>fine-pitch components</strong></span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>The hot air leveling process produces a uniform surface which helps prevent component placement problems.</span></p><p> </p><h3>Disadvantages of LF-HASL</h3><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>High frequency applications can be a problem for the LF-HASL method. This is due to the thick layer of solder that is used in the LF-HASL method.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>The thickness of the solder layer can vary and cause deviations from design specifications.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>Despite the absence of lead, the LF-HASL method is not environmentally friendly. It still involves the use <strong>of hazardous chemicals</strong> such as flux that can be harmful to the environment.</span></p><p> </p><p> </p><h2>Surface finish HASL (tin-lead)</h2><p><span>Hot Air Solder Leveling (HASL) is a common surface treatment used on printed circuit boards. Coating the copper surface with a layer of tin-lead alloy and then leveling with hot air creates a flat and uniform surface for soldering.</span></p><p> </p><h3>Benefits of HASL treatment:</h3><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>Need a strong and reliable solder joint? HASL surface treatment is a good candidate for this application.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>HASL is a relatively inexpensive finish compared to other alternatives.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>HASL has a <strong>wide range of applications</strong>.</span></p><p><!--[if !supportLists]--><span><span>+<span> </span></span></span><!--[endif]--><span>Long shelf life due to the fact that HASL retains its properties for a longer period of time.</span></p><p><span> </span></p><h3>Disadvantages of HASL treatment:</h3><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>The lead contained in HASL is hazardous to the environment and human health.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>HASL is not suitable for fine pitch components and for SMT technology.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>The thickness of the HASL surface may vary depending on the size and shape of the PCB.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span>The cost of HASL can be higher than for OSP and ENIG treatment.</span></p><p><!--[if !supportLists]--><span><span>-<span> </span></span></span><!--[endif]--><span><strong>The use of HASL treatment is not RoHS compliant</strong>.</span></p><p> </p><p> </p><p><span>Each of these methods has advantages and disadvantages. When selecting a finish, it is important to carefully consider factors such as solderability, wire bonding, corrosion resistance, durability, and cost.</span></p><p> </p><drupal-media data-align="center" data-entity-type="media" data-entity-uuid="0fc6e179-462d-440f-a98c-f340d88b26fa"></drupal-media><p> </p><p> </p><p> </p>
