{"id":2643,"date":"2025-11-01T16:06:09","date_gmt":"2025-11-01T08:06:09","guid":{"rendered":"https:\/\/www.jingpengpcb.com\/?p=2643"},"modified":"2026-10-02T16:48:35","modified_gmt":"2026-10-02T08:48:35","slug":"pcb-solder-pad-design-for-cob","status":"publish","type":"post","link":"https:\/\/www.jingpengpcb.com\/en\/blog\/pcb-solder-pad-design-for-cob\/","title":{"rendered":"Design Requirements for COB PCB Solder Pads"},"content":{"rendered":"

COB (Chip on Board) technology is a packaging technique widely used in the electronics manufacturing industry. It involves mounting the chip directly onto a PCB (Printed Circuit Board) without using traditional IC packaging.<\/p>\n

\"Design<\/p>\n

This technology requires special attention to the design of PCB solder pads to ensure their performance and reliability.<\/p>\n

In this article, we will take an in-depth look at the design requirements and considerations for COB PCB solder pads.<\/p>\n

1. Surface treatment: Gold plating or ENIG<\/h3>\n

First, the PCB for a COB must undergo a gold plating or ENIG surface treatment. This treatment not only requires the presence of a metal layer but also requires that the metal layer be thicker than that of a typical PCB to provide sufficient die-bonding strength.<\/p>\n

This ensures that gold wires, aluminum wires, and even the latest copper wires can be successfully soldered, thereby avoiding soldering issues.<\/p>\n

2. Solder Pad Routing Location<\/h3>\n

Special attention must be paid to the routing of the solder pad traces outside the COB die pad. The length of each solder trace should be kept as consistent as possible to avoid short circuits caused by intersecting solder joints. Therefore, the distance from the die to the PCB solder pad should be consistent.<\/p>\n

We recommend eliminating the diagonal pad layout; instead, reduce the spacing between PCB pads or use elliptical pad shapes to evenly distribute the relative positions of the wires.<\/p>\n

3. Design of Positioning Points<\/h3>\n

COB wafers require at least two positioning marks; it is preferable to use cross-shaped positioning marks rather than traditional circular ones. This is because automated wire bonding machines typically use straight lines for positioning. Therefore, the design of the positioning marks must take machine performance into account to ensure bonding accuracy.<\/p>\n

4. Die Pad Size<\/h3>\n

The die pad on the PCB should be slightly larger than the actual die. This helps limit the die\u2019s offset within the die pad and prevents excessive rotation of the die within the die pad. It is recommended that the die pads on each side be 0.25 to 0.3 mm larger than the actual die.<\/p>\n

5. Through-Hole Processing<\/h3>\n

It is best to avoid having through-holes in the areas where COB requires adhesive application. If this cannot be avoided, instruct the PCB manufacturer to completely seal these through-holes to prevent the epoxy from seeping through to the other side of the PCB during the adhesive application process, which could cause problems. This will ensure that the adhesive application process proceeds smoothly.<\/p>\n

6. Mark the dispensing area<\/h3>\n

We recommend printing silkscreen markings on the areas where dispensing is required to facilitate the dispensing process and control the shape of the dispensed material. This helps ensure the accuracy and consistency of the dispensing.<\/p>\n

COB technology is widely used in modern electronics manufacturing, but its successful implementation requires careful design of PCB pads to ensure performance and reliability.<\/p>\n

The design requirements and considerations mentioned above will help you better understand the design of PCB pads for COB and ensure the smooth progress of your project.<\/p>\n

\n

Frequently Asked Questions<\/strong><\/h2>\n

1. How does COB technology differ from traditional IC packaging?<\/h3>\n

COB technology involves mounting the chip directly onto the PCB, without using traditional IC packaging. This reduces the package size, improves performance, and lowers manufacturing costs.<\/p>\n

2. Why choose electroplated gold or ENIG as a surface treatment?<\/h3>\n

Electrolytic gold plating or ENIG surface treatments have sufficient metal layer thickness to provide the energy required for die bonding, ensuring the successful bonding of gold wires, aluminum wires, and other materials.<\/p>\n

3. Why is it necessary to eliminate the diagonal pad design?<\/h3>\n

Eliminating diagonal pad designs helps maintain consistent spacing between solder joints and reduces the risk of short circuits caused by overlapping joints.<\/p>\n

4. Why use cross-shaped alignment marks?<\/h3>\n

Cross-shaped positioning marks facilitate automatic positioning in wire bonding machines, ensuring bonding accuracy. Traditional circular positioning marks may not be suitable for this application.<\/p>\n

5. Why should \u201cSilkscreen\u201d be marked in the dispensing area?<\/h3>\n

Silkscreen markings facilitate the dispensing process, ensure precise control over the shape of the dispensed material, and improve dispensing quality.<\/p>","protected":false},"excerpt":{"rendered":"

COB\uff08Chip on Board\uff09\u6280\u672f\u662f\u4e00\u79cd\u5e7f\u6cdb\u5e94\u7528\u4e8e\u7535\u5b50\u5236\u9020\u9886\u57df\u7684\u5c01\u88c5\u6280\u672f\uff0c\u5b83\u5c06\u82af\u7247\u76f4\u63a5\u5b89\u88c5\u5728PCB\uff08Pr […]<\/p>\n","protected":false},"author":1,"featured_media":12265,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"slim_seo":{"title":"Design Requirements for COB PCB Solder Pads","description":"How should PCB solder pads for COB packaging be designed? This article explains the key design considerations and their impact on reliability, covering everything from surface treatment selection, routing placement, and positioning mark setup to die pad size and via handling."},"_slim_seo_primary_term_category":0,"_slim_seo_primary_term_post_tag":0,"footnotes":""},"categories":[26],"tags":[375],"class_list":["post-2643","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","tag-cob"],"_links":{"self":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/2643","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=2643"}],"version-history":[{"count":1,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/2643\/revisions"}],"predecessor-version":[{"id":19293,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/2643\/revisions\/19293"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/media\/12265"}],"wp:attachment":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/media?parent=2643"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/categories?post=2643"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/tags?post=2643"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}