{"id":1223,"date":"2025-09-27T20:54:06","date_gmt":"2025-09-27T12:54:06","guid":{"rendered":"https:\/\/ulpcb.com\/?p=1223"},"modified":"2025-09-27T21:03:43","modified_gmt":"2025-09-27T13:03:43","slug":"guarantee-for-high-frequency-and-low-loss","status":"publish","type":"post","link":"https:\/\/ulpcb.com\/tr\/guarantee-for-high-frequency-and-low-loss\/","title":{"rendered":"The Core Links from Base Materials to Finished Products"},"content":{"rendered":"
The performance and reliability of printed circuit boards (PCBs) depend not only on the inherent characteristics of the base materials but also on the precise control of the manufacturing process. Different types of boards, due to their compositional and performance differences, require distinct process routes. Standardized processes can be used for mass – production of common FR – 4 boards, while customized processes are needed to break through for ceramics and flexible substrates. This article, combined with industry practical cases, disassembles the core characteristics of four commonly used types of boards and their corresponding manufacturing processes.<\/div>\n

I. Four Commonly Used Types of PCB Boards8 layer pcb<\/a>: Characteristics and Application Scenarios<\/p>\n

    \n
  1. Epoxy – resin – based Boards: FR – 4 and High – TG Boards<\/a> (Accounting for over 70%)<\/strong>\n
    <\/div>\n

    As the most basic rigid boards, FR – 4 is made by impregnating brominated epoxy resin and pressing with fiberglass cloth as the reinforcing material. Its dielectric constant (Dk) ranges from 4.0 – 4.7, and the flame – retardant grade is UL 94 V – 0. The cost is only 1\/5 – 1\/10 of that of special boards. The glass – transition temperature of high – TG FR – 4 is increased to over 170\u2103, replacing ordinary FR – 4 in high – temperature scenarios such as automotive electronics.<\/p>\n

    <\/div>\n

    Typical applications: Xiaomi mobile phone motherboards, Haier refrigerator control boards, automotive central control systems.<\/li>\n

  2. Metal Substrates: Aluminum – based and Copper – based (Special for Heat Dissipation)<\/strong>\n
    <\/div>\n

    With an aluminum alloy or pure copper as the base, a surface – composite insulating dielectric layer and copper foil are added. The thermal conductivity of an aluminum substrate is 20 – 30W\/(m\u30fbK), and that of a copper substrate can reach over 200W\/(m\u30fbK), which can quickly conduct away the heat from power devices. However, metal substrates are relatively brittle, and mechanical stress needs to be controlled during processing.<\/p>\n

    <\/div>\n

    Typical applications: 100W LED street lights, new – energy vehicle OBC modules, industrial power supplies.<\/li>\n

  3. High – frequency Boards: PTFE and BT Resin Boards (Low – signal Loss)<\/strong>\n
    <\/div>\n

    Polytetrafluoroethylene (PTFE) boards have a low dielectric constant of 2.0 – 2.2 and a dielectric loss (Df) < 0.001, making them the core base material for 5G millimeter – wave radars. BT resin boards have a dielectric constant of 3.0 – 3.5, heat – resistance above 260\u2103, and the cost is only 60% of that of PTFE, suitable for mobile phone RF modules.<\/p>\n

    <\/div>\n

    Typical applications: Tesla autopilot radars, Huawei 5G base – station power amplifiers.<\/li>\n

  4. Flexible Boards: PI Polyimide Boards (Bendable)<\/strong>\n
    <\/div>\n

    The thickness can be as thin as 12\u03bcm, and it can withstand 100,000 times of 180\u00b0 bending. Its performance is stable in the environment from – 20\u2103 to 150\u2103. PI substrates account for 45% of the material cost in flexible PCBs. However, PI materials have weak chemical corrosion resistance, and the concentration of the etchant needs to be strictly controlled in the process.<\/p>\n

    <\/div>\n

    Typical applications: The hinge of Huawei Mate X5 folding screen, smart bracelet flex cables.<\/li>\n<\/ol>\n

    II. General Manufacturing Process: Taking an FR – 4 Four – layer Board as an Example (Standardized Process)<\/h3>\n
    The manufacturing of FR – 4 boards has formed a mature industrial chain. The process of a four – layer board covers 9 core steps, and the daily production capacity can reach tens of thousands of pieces:<\/div>\n
    <\/div>\n
      \n
    1. Base – material Pretreatment and Layout Transfer<\/strong>\n
        \n
      • Board Cutting and Cleaning<\/strong>: Cut the FR – 4 copper – clad laminate into the designed size and remove oil stains through ultrasonic cleaning to avoid subsequent circuit short – circuits.<\/li>\n
      • Photosensitive Imaging<\/strong>: Coat a photosensitive film on the copper – foil surface, irradiate it with a UV lamp to cure the light – transmitting areas, and wash the uncured parts with an alkaline solution to expose the copper foil to be etched.<\/li>\n
      • Etching into Circuits<\/strong>: Etch the exposed copper foil with a NaOH solution. After removing the film, inner – layer circuits are formed with an accuracy of up to \u00b13\u03bcm.<\/li>\n<\/ul>\n<\/li>\n
      • Lamination and Drilling<\/strong>\n
          \n
        • Core – board Inspection<\/strong>: Use an AOI device to automatically compare the circuits with the design drawing, and the defect rate needs to be controlled below 0.1%.<\/li>\n
        • Lamination Assembly<\/strong>: Stack in the order of “copper foil – prepreg – inner – layer core board – prepreg – copper foil”. The prepreg melts at high temperatures to form an insulating adhesive layer.<\/li>\n
        • Positioning Drilling<\/strong>: Use an X – ray drilling machine for positioning and drill inter – layer connection holes with an aperture tolerance of \u00b15\u03bcm.<\/li>\n<\/ul>\n<\/li>\n
        • Via Metallization and Outer – layer Processing<\/strong>\n
            \n
          • Electroless Copper Plating<\/strong>: Deposit a 1\u03bcm conductive layer on the hole wall to ensure the insulating hole wall is conductive, and then electro – plate to thicken it to 25\u03bcm.<\/li>\n
          • Outer – layer Imaging<\/strong>: Transfer the outer – layer circuits using the positive – film process. Electro – plate a tin layer to protect the circuits, and after etching, remove the tin to expose the copper foil.<\/li>\n
          • Surface Treatment and Shaping<\/strong>: Spray tin or plate gold to prevent oxidation. Cut the shape with a CNC milling machine and finally test the conductivity.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n

            III. Process Breakthroughs for Special Boards: Customized Solutions<\/h3>\n
            Due to their special characteristics, special boards need to optimize key links based on the general process:<\/div>\n
            <\/div>\n
              \n
            1. Metal Substrates: Temperature Control and Anti – oxidation Processes<\/strong>\n
                \n
              • Lamination Pressure Control<\/strong>: The lamination pressure of aluminum substrates needs to be 30% higher than that of FR – 4 to avoid bubbles in the dielectric layer. Shenlian Circuit has increased the lamination yield to 99.2% through a vacuum hot – press.<\/li>\n
              • Reflow – soldering Control<\/strong>: Use nitrogen reflow – soldering with an oxygen content < 1000ppm and a peak temperature controlled at 235 – 245\u2103 to prevent aluminum oxidation.<\/li>\n
              • Cutting Protection<\/strong>: The V – cut depth should not exceed 1\/3 of the metal layer. Add a 3mm process edge to the panel to enhance strength.<\/li>\n<\/ul>\n<\/li>\n
              • Ceramic Substrates: Laser Processing and Metallization Technologies<\/strong>\n
                  \n
                • Laser Drilling<\/strong>: Aluminum nitride ceramics have high hardness and need to be drilled step – by – step with an ultraviolet laser. The minimum aperture can reach 50\u03bcm. The efficiency is 40% lower than mechanical drilling but with higher precision.<\/li>\n
                • Thick – film Metallization<\/strong>: Screen – print silver paste and sinter it at 850\u2103 to form a conductive layer, replacing traditional electro – plating to adapt to the non – conductive characteristics of ceramics.<\/li>\n<\/ul>\n<\/li>\n
                • Flexible PI Substrates: Low – stress Process Design<\/strong>\n
                    \n
                  • Etching and Thinning<\/strong>: Reduce the copper – foil thickness from 18\u03bcm to 9\u03bcm through multiple shallow – etching processes to reduce stress concentration during bending.<\/li>\n
                  • Cover – film Lamination<\/strong>: Use a PI cover – film to protect the circuits. Control the lamination temperature at 180\u2103 and the pressure at 0.3MPa to avoid substrate deformation.<\/li>\n
                  • Bending Test<\/strong>: The finished product needs to pass 100,000 times of 180\u00b0 bending tests with a circuit resistance change rate < 10%.<\/li>\n<\/ul>\n<\/li>\n<\/ol>\n

                    IV. Core Principles of Process Selection: The Triangle Balance of Board – Performance – Cost<\/h3>\n
                    \n
                    \n\n\n\n\n\n\n\n\n\n
                    Board Type<\/th>\nKey Process Differences<\/th>\nYield Control Points<\/th>\nCost Ratio (Relative to FR – 4)<\/th>\n<\/tr>\n<\/thead>\n
                    Ordinary FR – 4<\/td>\nStandardized etching\/lamination<\/td>\nDrilling positioning accuracy<\/td>\n1x<\/td>\n<\/tr>\n
                    High – TG FR – 4<\/td>\nIncrease lamination temperature to 200\u2103<\/td>\nResin curing degree detection<\/td>\n1.2x<\/td>\n<\/tr>\n
                    Aluminum substrate<\/td>\nNitrogen reflow – soldering\/V – cut control<\/td>\nDielectric layer adhesion<\/td>\n3x<\/td>\n<\/tr>\n
                    PTFE board<\/td>\nPlasma surface roughening<\/td>\nCopper – free defects on the hole wall<\/td>\n8x<\/td>\n<\/tr>\n
                    PI flexible board<\/td>\nCover – film lamination\/bending test<\/td>\nCircuit stress concentration<\/td>\n5x<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>","protected":false},"excerpt":{"rendered":"

                    The performance and reliability of printed circuit boards (PCBs) depend not only on the inherent characteristics of the base materials<\/p>","protected":false},"author":1,"featured_media":1150,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-1223","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news"],"_links":{"self":[{"href":"https:\/\/ulpcb.com\/tr\/wp-json\/wp\/v2\/posts\/1223","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ulpcb.com\/tr\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ulpcb.com\/tr\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ulpcb.com\/tr\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ulpcb.com\/tr\/wp-json\/wp\/v2\/comments?post=1223"}],"version-history":[{"count":2,"href":"https:\/\/ulpcb.com\/tr\/wp-json\/wp\/v2\/posts\/1223\/revisions"}],"predecessor-version":[{"id":1225,"href":"https:\/\/ulpcb.com\/tr\/wp-json\/wp\/v2\/posts\/1223\/revisions\/1225"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ulpcb.com\/tr\/wp-json\/wp\/v2\/media\/1150"}],"wp:attachment":[{"href":"https:\/\/ulpcb.com\/tr\/wp-json\/wp\/v2\/media?parent=1223"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ulpcb.com\/tr\/wp-json\/wp\/v2\/categories?post=1223"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ulpcb.com\/tr\/wp-json\/wp\/v2\/tags?post=1223"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}