Surface plating of flexible printed circuits (FPCs) is a critical step in their manufacturing process, directly affecting product quality and reliability. This article provides a detailed overview of the key technical aspects of FPC surface plating and its application in PCBA manufacturing.<\/p>\n
Prior to FPC electroplating, the exposed copper conductor surface may be contaminated with adhesives and ink, as well as suffer from oxidation and discoloration caused by high-temperature processes. To achieve a dense, strongly adherent coating, the conductor surface must be cleaned to remove contaminants and oxidation layers. Sometimes, certain contaminants adhere tightly to the copper conductors and cannot be removed with mild cleaning agents; therefore, alkaline abrasives and medium-gauge polishing brushes are typically used for treatment. However, these polishing agents may adversely affect the coating adhesive, particularly since epoxy adhesives have poor alkali resistance. During the FPC electroplating process, the plating solution may seep under the edges of the coating, causing the coating to peel off; therefore, pretreatment is of critical importance.<\/p>\n
The thickness of the FPC plating is typically related to the electric field strength: the narrower the line width and the closer the distance between electrodes, the greater the electric field strength, and the thicker the plating. Since the widths of the conductors on flexible printed circuits vary significantly, this can lead to uneven plating thickness. To address this issue, shunt cathode patterns can be added around the circuit to distribute the current evenly and improve the uniformity of the plating thickness. Therefore, this aspect must be taken into account when designing the electrode structure. Standards impose strict requirements on areas where high plating thickness uniformity is essential, while standards for other areas are relatively lenient.<\/p>\n
Sometimes, after electroplating an FPC, the surface may appear flawless at first, but stains, dirt, and discoloration may develop over time. This is caused by chemical reactions between the plating solution that has not been completely rinsed away and the surface of the plating layer; this problem is particularly common on flexible printed circuits. To prevent this, thorough rinsing and drying must be performed to ensure the plating is fully cured.<\/p>\n
Isolated conductors on flexible printed circuits cannot be used as electrodes for electroplating; therefore, only electroless plating methods can be used. The electroless gold plating process is a typical example of this. However, this process requires the use of an alkaline aqueous solution with a very high pH, which can easily cause the plating solution to seep beneath the plating layer\u2014a problem that is particularly likely to occur when the plating quality is inconsistent. Consequently, the conditions for electroless plating are relatively harsh, making it difficult to achieve ideal plating results.<\/p>\n
Hot-air leveling was originally designed for rigid PCBs, but it is also suitable for flexible PCBs. In this process, the board is immersed vertically into a bath of molten lead-tin, and then excess solder is blown away using hot air. However, for flexible PCBs, the process conditions are quite demanding. If the flexible PCB cannot be immersed in the solder, it must be clamped between a metal mesh made of titanium steel and then immersed in the molten solder. Since flexible PCBs are prone to absorbing moisture, the moisture absorbed may evaporate upon rapid heating during the hot-air leveling process, causing the coating to bubble or peel. Therefore, flexible PCBs must be thoroughly dried and treated to prevent moisture absorption before hot-air leveling.<\/p>\n
Overall, the manufacturing and design of flexible printed circuits (FPCs) involve numerous complex processes, of which surface plating is an indispensable part. Understanding and carefully managing the details of these plating processes is crucial for ensuring the quality of FPCs, particularly in the field of PCBA manufacturing, as the quality of the circuit boards directly impacts the overall performance and reliability of the product.<\/p>","protected":false},"excerpt":{"rendered":"
\u67d4\u6027\u7ebf\u8def\u677f\uff08FPC\uff09\u7684\u8868\u9762\u7535\u9540\u662f\u5176\u5236\u9020\u5de5\u827a\u4e2d\u7684\u5173\u952e\u73af\u8282\uff0c\u76f4\u63a5\u5f71\u54cd\u4ea7\u54c1\u8d28\u91cf\u548c\u53ef\u9760\u6027\u3002\u672c\u6587\u5c06\u8be6\u7ec6\u4ecb\u7ecdFPC\u8868\u9762\u7535\u9540 […]<\/p>\n","protected":false},"author":1,"featured_media":6579,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"slim_seo":{"title":"A Detailed Explanation of the Surface Plating Process for FPC Flexible Printed Circuit Boards","description":"How is surface plating performed on FPCs? This article explains the key points of pretreatment (degreasing), plating thickness control, and contamination prevention, and compares the differences in applicability between electroless nickel-gold plating and hot-air leveling on flexible circuits."},"_slim_seo_primary_term_category":0,"_slim_seo_primary_term_post_tag":0,"footnotes":""},"categories":[26],"tags":[54],"class_list":["post-3759","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","tag-fpc"],"_links":{"self":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/3759","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/comments?post=3759"}],"version-history":[{"count":1,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/3759\/revisions"}],"predecessor-version":[{"id":13113,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/3759\/revisions\/13113"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/media\/6579"}],"wp:attachment":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/media?parent=3759"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/categories?post=3759"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/tags?post=3759"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}