{"id":1838,"date":"2026-10-14T09:00:00","date_gmt":"2026-10-14T01:00:00","guid":{"rendered":"https:\/\/www.jingpengpcb.com\/?p=1838"},"modified":"2026-10-08T20:14:38","modified_gmt":"2026-10-08T12:14:38","slug":"high-resolution-imaging-tech","status":"publish","type":"post","link":"https:\/\/www.jingpengpcb.com\/en\/blog\/high-resolution-imaging-tech\/","title":{"rendered":"What are the technical requirements for high-resolution PCB manufacturing? Trace pitch and copper thickness parameters"},"content":{"rendered":"<style>\n.jp-tw{overflow-x:auto;margin:26px 0;-webkit-overflow-scrolling:touch;}\n.jp-tw table{border-collapse:collapse;width:100%;min-width:560px;font-size:15px;line-height:1.65;background:#fff;}\n.jp-tw th,.jp-tw td{border:1px solid #dde3ea;padding:11px 14px;text-align:left;vertical-align:top;}\n.jp-tw thead th{background:#eef2f7;color:#1b2733;font-weight:700;white-space:nowrap;border-bottom:2px solid #c9d3de;}\n.jp-tw tbody tr:nth-child(even){background:#fafbfc;}\n.jp-tw tbody tr:hover{background:#f1f5fa;}\n.jp-tw tbody td:first-child{font-weight:600;color:#1b2733;}\n@media(max-width:767px){.jp-tw table{font-size:14px;min-width:520px;}.jp-tw th,.jp-tw td{padding:9px 11px;}}\n<\/style>\n<p>With the miniaturization and multifunctionality of electronic devices, as well as rapid advances in electronic packaging technology, the design and manufacturing of printed circuit boards (PCBs) are continuously evolving toward higher density, greater precision, and improved reliability, as well as narrower spacing, finer lines, and microvia technology. This trend poses greater challenges for PCB manufacturing technology, particularly in the production of precision patterns. This article will delve into the requirements of printed circuit board manufacturing technology and analyze the associated difficulties and challenges.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"1179\" height=\"663\" class=\"alignnone size-large wp-image-8924\" src=\"https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/the-9-basic-steps-of-cam-production.jpg\" alt=\"The 9 Basic Steps of CAM Production\" srcset=\"https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/the-9-basic-steps-of-cam-production.jpg 1179w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/the-9-basic-steps-of-cam-production-300x169.jpg 300w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/the-9-basic-steps-of-cam-production-1024x576.jpg 1024w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/the-9-basic-steps-of-cam-production-768x432.jpg 768w\" sizes=\"auto, (max-width: 1179px) 100vw, 1179px\" \/><\/p>\n<h2>1. Let\u2019s start by defining exactly what a \u201chigh-resolution PCB\u201d is.<\/h2>\n<p>In the context of PCBs, \u201chigh resolution\u201d does not refer to clarity, but rather to<strong>Minimum Line Width That Can Be Stably Reproduced After Pattern Transfer and Etching, and Its Consistency<\/strong>. It is determined by three factors:<\/p>\n<ul>\n<li><strong>Minimum Line Width \/ Line Spacing (L\/S)<\/strong>: How fine a line can be produced, and how narrow a gap can be left between lines. In the industry, 3\/3 mil (approximately 75\/75 \u03bcm) is considered standard capability; 2\/2 mil (50\/50 \u03bcm) falls into the high-resolution range; and 1\/1 mil (25\/25 \u03bcm) represents the capability threshold requiring specialized processes and equipment.<\/li>\n<li><strong>Line Width Tolerance<\/strong>: The deviation of the actual line width from the design value. High resolution isn\u2019t about \u201cbeing able to produce a 50 \u03bcm line,\u201d but rather \u201cmass-producing 1 million 50 \u03bcm lines, with 99% or more falling within \u00b110%.\u201d<\/li>\n<li><strong>Edge Quality<\/strong>: Check whether the edge is straight, whether there are any jagged edges (rat teeth), and whether there is any residual copper or over-etching. The quality of the edge directly determines impedance consistency and withstand voltage reliability.<\/li>\n<\/ul>\n<p>If you break these three points down, it becomes clear that the challenge with high resolution has never been \u201cgetting it right the first time,\u201d but rather<strong>Consistently produced under conditions of large-volume, multi-batch production<\/strong>. Mass-production yield is the real hurdle.<\/p>\n<h2>2. Technical Requirements for Printed Circuit Boards<\/h2>\n<p>To manufacture high-quality printed circuit boards, especially when high-density and fine-line patterns are required, a series of technical requirements must be met. These requirements include:<\/p>\n<h3>2.1 Wire pitch: 0.40 mm<\/h3>\n<h3>2.2 Inner-layer conductor: 0.05 mm<\/h3>\n<h3>2.3 Outer Conductor: 0.05\u20130.0762 mm<\/h3>\n<h3>2.4 Inner Copper Layer Thickness: 10 \u00b5m<\/h3>\n<h3>2.5 Number of floors: 10\u201320<\/h3>\n<h3>2.6 Filling Thickness: 0.05\u20130.127 mm<\/h3>\n<h3>2.7 Blind Holes and Buried Holes: 0.05\u20130.20 mm<\/h3>\n<p>These technical requirements necessitate highly precise graphic production to ensure both high product quality and reliability, while also maintaining high production efficiency and low manufacturing costs. To achieve this goal, we need to thoroughly analyze the technical challenges involved in producing precision graphics and identify ways to improve the success rate.<\/p>\n<p>To provide a clear picture of where these parameters fall on the industry capability spectrum, the following table compares common tiers:<\/p>\n<div class=\"jp-tw\">\n<table>\n<thead>\n<tr>\n<th>Ability Levels<\/th>\n<th>Minimum Line Width\/Spacing<\/th>\n<th>Thickness of the inner copper layer<\/th>\n<th>Microporous Pore Size<\/th>\n<th>Typical Applications<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>General<\/td>\n<td>\u2265100 \u03bcm (4\/4 mil)<\/td>\n<td>18\u201335 \u03bcm<\/td>\n<td>\u22650.25 mm (mechanical drill)<\/td>\n<td>Home Appliances, Industrial Control, Power Supplies<\/td>\n<\/tr>\n<tr>\n<td>Advanced<\/td>\n<td>75 \u03bcm (3\/3 mil)<\/td>\n<td>12\u201318 \u03bcm<\/td>\n<td>0.15\u20130.20 mm<\/td>\n<td>Consumer Electronics Motherboards, Networking Equipment<\/td>\n<\/tr>\n<tr>\n<td>High Resolution<\/td>\n<td>50 \u03bcm (2\/2 mil)<\/td>\n<td>9\u201312 \u03bcm<\/td>\n<td>0.075\u20130.15 mm (laser)<\/td>\n<td>Smartphones, Wearables, 5G Modules<\/td>\n<\/tr>\n<tr>\n<td>Extreme<\/td>\n<td>25\u201340 \u03bcm (1\/1.5 mil)<\/td>\n<td>5\u20139 \u03bcm (ultra-thin copper foil)<\/td>\n<td>0.05\u20130.075 mm<\/td>\n<td>IC carrier substrates, advanced packaging substrates<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>These technical requirements necessitate highly precise graphic production to ensure both high product quality and reliability, while also maintaining high production efficiency and low manufacturing costs. To achieve this goal, we need to thoroughly analyze the technical challenges involved in producing precision graphics and identify ways to improve the success rate.<\/p>\n<p>These seven parameters are not isolated; they influence one another: the pitch determines the upper limits for line width and spacing; the copper thickness determines the minimum line width that can be reliably fabricated; the dielectric thickness determines the impedance and interlayer withstand voltage; and the via diameter determines whether mechanical drilling or laser drilling is used. In particular, once microvia diameters enter the 50\u2013200 \u03bcm range, mechanical drilling is no longer sufficient, and laser drilling must be used instead. For a complete interconnect process flow, please refer to<a href=\"\/en\/hdi-pcb\/\">HDI (High-Density Interconnect) Circuit Boards<\/a>\u3002<\/p>\n<p>To provide a clear picture of where these parameters fall on the industry capability spectrum, the following table compares common tiers:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"1280\" height=\"720\" class=\"alignnone size-large wp-image-8635\" src=\"https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/copper-foil-pcb.jpg\" alt=\"Copper Foil: The Lifeline of PCBs\" srcset=\"https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/copper-foil-pcb.jpg 1280w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/copper-foil-pcb-300x169.jpg 300w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/copper-foil-pcb-1024x576.jpg 1024w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/copper-foil-pcb-768x432.jpg 768w\" sizes=\"auto, (max-width: 1280px) 100vw, 1280px\" \/><\/p>\n<h2>3. Layout: From design data to physical traces on the copper foil<\/h2>\n<p>Regardless of the final line width, the outer-layer traces all pass through the same main link; understanding this link is key to identifying where the bottleneck lies:<\/p>\n<ol>\n<li><strong>Preprocessing<\/strong>: Grind or micro-etch the board to remove oxidation and contaminants from the copper surface, while creating a microscopic roughness to ensure the adhesion of the photoresist.<\/li>\n<li><strong>Coating<\/strong>: Apply the photosensitive resist to the copper surface (by roller coating, spray coating, curtain coating, or applying a dry film).<\/li>\n<li><strong>Exposure<\/strong>: A design pattern is projected onto the photoresist using ultraviolet light, causing a photochemical reaction in the exposed areas.<\/li>\n<li><strong>Development<\/strong>: Use developer to dissolve the unreacted (or reacted, depending on whether the image is positive or negative) areas, exposing the copper to be etched.<\/li>\n<li><strong>Etching<\/strong>: The exposed copper is dissolved by the etching solution, while the copper beneath the resist is left intact to form the circuit.<\/li>\n<li><strong>Film Removal<\/strong>: Remove the remaining photoresist to reveal the final circuit.<\/li>\n<\/ol>\n<p>Of these six steps,<strong>Coating uniformity determines thickness consistency; exposure determines pattern accuracy; development determines edge steepness; and etching determines the final line width.<\/strong>. If any step gets out of control, the effects will be magnified later in the process. For specific parameter controls during the etching stage, see<a href=\"\/en\/blog\/etching\/\">A Detailed Explanation of the Etching Process in PCB Manufacturing<\/a>\u3002<\/p>\n<h2>4. Image Formation and Distortion<\/h2>\n<p>During the image formation process, the use of high-quality film, a thin photosensitive resist layer, and ultra-thin copper foil is critical to ensuring the high quality of the circuit patterns. However, image distortion is a common problem that can lead to inaccurate trace widths. For example, if a trace width is allowed to increase to 0.05 mm within a 0.05 mm spacing, short circuits can easily occur. Image distortion is typically associated with the surface condition of raw materials and quality defects during the manufacturing process. Issues such as pits, protrusions, and contamination can all reduce the adhesion of the photosensitive resist, resulting in circuit patterns that deviate significantly from the original design requirements.<\/p>\n<p>If we break down the above passage into actionable troubleshooting steps, the causes of image distortion can generally be categorized into five types:<\/p>\n<div class=\"jp-tw\">\n<table>\n<thead>\n<tr>\n<th>Sources of Distortion<\/th>\n<th>Performance<\/th>\n<th>Root Cause<\/th>\n<th>Countermeasures<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Film Defects<\/td>\n<td>Broken lines, jagged edges<\/td>\n<td>Scratches on the film, specks of dirt, and dimensional drift due to temperature and humidity<\/td>\n<td>Switch to LDI (Laser Direct Imaging) and eliminate the use of physical film<\/td>\n<\/tr>\n<tr>\n<td>Condition of the Copper Surface<\/td>\n<td>Some lines are too thin or broken<\/td>\n<td>Dents, bumps, oxidation, fingerprints<\/td>\n<td>Enhance pretreatment to control brush marks and micro-etching on the grinding plate<\/td>\n<\/tr>\n<tr>\n<td>Uneven Coating<\/td>\n<td>Systematic Deviation in Line Width Within a Board<\/td>\n<td>Inconsistent photoresist thickness and varying exposure latitude<\/td>\n<td>Switch to spray or roller coating, and monitor the wet film thickness<\/td>\n<\/tr>\n<tr>\n<td>Exposure Deviation<\/td>\n<td>The overall line width is too thick or too thin<\/td>\n<td>Exposure Energy Drift, Alignment Offset<\/td>\n<td>Perform daily Stouffer bar calibration<\/td>\n<\/tr>\n<tr>\n<td>Incomplete development<\/td>\n<td>Residual adhesive between wires causes a short circuit<\/td>\n<td>Insufficient developer concentration, temperature, or spray pressure<\/td>\n<td>Monitor the breakpoint at 40\u201360%<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h2>5. Measure changes in the image<\/h2>\n<p>After image transfer, we can measure changes in the circuit pattern. By measuring variations in line width and spacing, we can evaluate differences between individual lines during the manufacturing process. The curve representing these image changes quantifies the frequency of variations in line width and spacing. Analysis of the Modulation Transfer Function (MTF) indicates that the quality of the circuit pattern is directly related to the processing characteristics. When the MTF and image quality level drop below 1, the calculated frequency of paired lines is referred to as the breakage frequency, indicating that the lines are in a state between reliable and unreliable processing. To improve the reliability of the output, it is essential to implement the fewest possible yet most effective process steps.<\/p>\n<p>This section discusses how to use statistical methods to quantify graphical capabilities. In production environments, this is typically done as follows:<\/p>\n<ul>\n<li><strong>Sampling<\/strong>: Take one set of line width\/spacing samples at each of the four corners and the center of the board, with each set containing at least 30 lines; avoid using only data from the edges of the board.<\/li>\n<li><strong>Measurement<\/strong>: Measure the wire using a wire width gauge or a cross-section microscope<strong>Top Width<\/strong>\u4e0e<strong>Bottom Width<\/strong>, and the difference between the two reflects the degree of side etching.<\/li>\n<li><strong>Statistics<\/strong>: Calculate the mean and standard deviation, and use Cpk to measure process capability. High-resolution production lines generally require a line width Cpk of \u2265 1.33.<\/li>\n<li><strong>Differences in Judgment<\/strong>: A bimodal distribution indicates the presence of two types of systematic deviations (typically due to uneven exposure or coating), while a long tail indicates the presence of random defects (typically related to cleanliness or the copper surface).<\/li>\n<\/ul>\n<p>Deviations in line width not only affect appearance but also directly alter impedance and current-carrying capacity; the quantitative relationship between the two is shown in<a href=\"\/en\/blog\/the-relationship-between-pcb-line-width-and-current\/\">Relationship Between PCB Trace Width and Current<\/a>\u3002<\/p>\n<h2>6. Changes in Raw Materials for the Production of Fine-Line Circuit Patterns<\/h2>\n<p>The key to achieving high-yield, high-resolution circuit patterning lies in selecting the correct photoresist. The photoresist is a critical factor in image formation. New process equipment, enhanced process control, and the skilled expertise of the staff also play a crucial role in achieving high-quality circuit patterning. Currently, roller coating and spray coating are the primary methods used to manufacture high-density PCBs. However, these methods require significant investment and still present challenges in terms of reliability. In particular, for the fabrication of fine-line patterns, liquid photoresists are not necessarily a completely reliable or feasible process technology.<\/p>\n<p>The three variables on the raw material side often have a greater impact on resolution than those on the device side:<\/p>\n<ul>\n<li><strong>Copper Foil Thickness and Contour<\/strong>: The thinner the copper foil and the lower its surface roughness (Rz), the less side etching occurs during etching. Conventional electrolytic copper foil has an Rz of approximately 5\u20138 \u03bcm, while ultra-low-profile copper foil (VLP\/HTE) can achieve 2\u20133 \u03bcm, which is a prerequisite for producing lines narrower than 50 \u03bcm. For detailed selection guidelines, see<a href=\"\/en\/blog\/pcb-circuit-board-materials\/\">PCB Materials<\/a>\u3002<\/li>\n<li><strong>Resist Thickness<\/strong>: The thinner the photoresist, the smaller the effects of diffraction and scattering during exposure, and the higher the resolution. However, if it is too thin, it can lead to pinholes and reduced etch resistance. In actual production, dry films are typically 15\u201325 \u03bcm thick, while the coating thickness of liquid photoresists is controlled at 8\u201315 \u03bcm.<\/li>\n<li><strong>Dimensional Stability of the Substrate<\/strong>: Expansion and contraction of the laminated panels after lamination can directly cause alignment errors. High-resolution panels typically require the substrate to undergo a pre-baking process to limit expansion and contraction to within 100 ppm.<\/li>\n<\/ul>\n<h2>7. High-Throughput, High-Resolution Photoresist Technology<\/h2>\n<p>When creating circuit patterns, selecting the right photoresist is crucial. The quality of the photoresist directly affects the quality of the image. By controlling the exposure light source and fully utilizing the high resolution of the photoresist, it is possible to improve the yield of fine-line fabrication. Using<a href=\"\/en\/hdi-pcb\/\">HDI<\/a>The (Hot Development Inhibition) process can increase the contrast of the photoresist, thereby improving resolution. The basic principle of HDI is to immerse the exposed film in hot water, which helps enhance the hardness and stability of the photoresist. However, further research and development are needed to determine whether the HDI process is suitable for all photoresists.<\/p>\n<p>It should be noted that, in the current PCB industry terminology,<strong>The more common meaning of HDI is High Density Interconnect.<\/strong>, refers to an interconnect structure characterized by micropores, fine lines, and thin dielectric layers; the term \u201cHot Development Inhibition\u201d mentioned above is used in specific process literature to refer to a processing technique that enhances photoresist contrast through heat treatment. Although the two terms share the same abbreviation, their meanings differ; when reading materials, be sure to distinguish between them based on context. For a complete high-density interconnect process flow, please refer to<a href=\"\/en\/blog\/hdi-manufacturing-process\/\">A Comprehensive Analysis of the HDI PCB Manufacturing Process<\/a>\u3002<\/p>\n<p>The practical differences between the two technical approaches for photoresists:<\/p>\n<div class=\"jp-tw\">\n<table>\n<thead>\n<tr>\n<th>Comparison Items<\/th>\n<th>Dry Film Photoresist<\/th>\n<th>Liquid Photoresist (Liquid \/ LPI)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Coating Method<\/td>\n<td>Hot-Roll Laminating Film<\/td>\n<td>Roll Coating \/ Spray Coating \/ Band Coating<\/td>\n<\/tr>\n<tr>\n<td>Thickness Uniformity<\/td>\n<td>Okay, the thickness is determined by the membrane material.<\/td>\n<td>Due to the coating equipment, there is a slightly greater variation within the panel.<\/td>\n<\/tr>\n<tr>\n<td>Filling Capacity<\/td>\n<td>Poor; insufficient filling of surface depressions can easily cause bubbles.<\/td>\n<td>Okay, it can adhere to irregular surfaces.<\/td>\n<\/tr>\n<tr>\n<td>Resolution<\/td>\n<td>Due to film thickness limitations, stability is generally achieved at 50 \u03bcm or more.<\/td>\n<td>Can be applied in thinner layers, down to 25\u201330 \u03bcm<\/td>\n<\/tr>\n<tr>\n<td>Capital Expenditures<\/td>\n<td>\u4f4e<\/td>\n<td>High (Coating Line + Cleanroom)<\/td>\n<\/tr>\n<tr>\n<td>Applicable Scenarios<\/td>\n<td>Standard Boards, Inner Layers, High-Volume Production<\/td>\n<td>High-Resolution Outer Layers, Fine Pitch, HDI<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h2>8. High-Density Image Resolution Processing Program<\/h2>\n<p>To reduce image distortion and produce conductors with a width of 0.10\u20130.15 mm, new manufacturing processes, such as HDI, must be adopted. The principle behind this process is to immerse the film in hot water after exposure to improve the resolution of the photoresist. This method reduces image distortion and ensures that the edges of the conductors are neat and free of deformation. The application of the HDI process increases the hardness of the resist after exposure, providing greater stability and helping to improve resolution.<\/p>\n<p>On today's production lines, the mainstream approach to improving resolution has shifted from \"post-processing enhancement\" to \"upgrading the exposure method\"\u2014that is, replacing traditional film exposure with LDI:<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"1280\" height=\"720\" class=\"alignnone size-large wp-image-8588\" src=\"https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/comparison-between-ldi-and-ccd-exposure-machines-1.jpg\" alt=\"A Comparison of LDI and CCD Exposure Systems\" srcset=\"https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/comparison-between-ldi-and-ccd-exposure-machines-1.jpg 1280w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/comparison-between-ldi-and-ccd-exposure-machines-1-300x169.jpg 300w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/comparison-between-ldi-and-ccd-exposure-machines-1-1024x576.jpg 1024w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/comparison-between-ldi-and-ccd-exposure-machines-1-768x432.jpg 768w\" sizes=\"auto, (max-width: 1280px) 100vw, 1280px\" \/><\/p>\n<ul>\n<li><strong>LDI (Laser Direct Imaging)<\/strong>: By using a laser beam to scan and image directly onto the photoresist according to the design data, the need for physical film is eliminated, thereby removing an entire category of defects\u2014such as film warping, scratches, and dust spots\u2014while also allowing for adjustments based on the actual expansion and contraction of the board surface.<strong>Real-Time Zoom Compensation<\/strong>, with positioning accuracy within \u00b110 \u03bcm.<\/li>\n<li><strong>CCD Alignment Exposure System<\/strong>: It still uses film, but uses a CCD to automatically align the target, offering higher precision than manual alignment and lower costs than LDI; it is suitable for medium-resolution batch production.<\/li>\n<li><strong>Traditional Manual\/Semi-Automatic Exposure<\/strong>: Relies on manual alignment; suitable for standard boards with line widths of 100 \u03bcm or greater; yield rates are difficult to guarantee when producing fine lines.<\/li>\n<\/ul>\n<p>For a detailed comparison of the three methods, see<a href=\"\/en\/blog\/comparison-between-ldi-and-ccd-exposure-machines\/\">A Comparison of LDI and CCD Exposure Systems<\/a>. For information on process windows and capability boundaries, see<a href=\"\/en\/capabilities\/\">PCB Manufacturing Capabilities<\/a>\u3002<\/p>\n<h2>9. The Etching Process: The Ultimate Determinant of Resolution<\/h2>\n<p>No matter how precise the exposure is, fine lines cannot be produced if the etching process is out of control. The key to etching is<strong>Etch Factor<\/strong>\u2014The ratio of etch depth to lateral etch rate. The higher the etch factor, the steeper the line edges, and the better the design line width is maintained.<\/p>\n<div class=\"jp-tw\">\n<table>\n<thead>\n<tr>\n<th>Copper Thickness<\/th>\n<th>Typical Etching Factors<\/th>\n<th>Unilateral Drilling and Erosion Volume<\/th>\n<th>Stable Minimum Line Width<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>5 \u03bcm (ultra-thin)<\/td>\n<td>4.0\u20135.0<\/td>\n<td>1.0\u20131.3 \u03bcm<\/td>\n<td>25 \u03bcm<\/td>\n<\/tr>\n<tr>\n<td>9 \u03bcm (1\/4 oz)<\/td>\n<td>3.0\u20134.0<\/td>\n<td>2.3\u20133.0 \u03bcm<\/td>\n<td>40 \u03bcm<\/td>\n<\/tr>\n<tr>\n<td>18 \u03bcm (1\/2 oz)<\/td>\n<td>2.5\u20133.0<\/td>\n<td>6.0\u20137.2 \u03bcm<\/td>\n<td>75 \u03bcm<\/td>\n<\/tr>\n<tr>\n<td>35 \u03bcm (1 oz)<\/td>\n<td>2.0\u20132.5<\/td>\n<td>14\u201317.5 \u03bcm<\/td>\n<td>100 \u03bcm<\/td>\n<\/tr>\n<tr>\n<td>70 \u03bcm (2 oz)<\/td>\n<td>1.5\u20132.0<\/td>\n<td>35\u201346 \u03bcm<\/td>\n<td>200 \u03bcm<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p>This table explains why thin copper is used in almost all high-resolution boards:<strong>If the copper thickness is halved, the line width can generally be halved as well.<\/strong>. For the three key control points in the etching process, see<a href=\"\/en\/blog\/three-key-points-of-pcb-etching-process\/\">Three Key Points of the PCB Etching Process<\/a>For specific techniques on line width and spacing, see<a href=\"\/en\/blog\/pcb-fine-line-manufacturing-techniques\/\">Analysis of Techniques and Challenges in Precision PCB Line Width and Spacing<\/a>\u3002<\/p>\n<h2>10. Verification: How to Confirm That It Was Actually Done<\/h2>\n<p>High-resolution boards cannot rely solely on visual inspection of finished products; checkpoints must be established at three key stages:<\/p>\n<ul>\n<li><strong>AOI (Automated Optical Inspection)<\/strong>: After etching, perform a full-board scan to detect short circuits, notches, copper residue, and pinholes. For fine-line boards, the AOI system requires higher pixel resolution, and detection thresholds must be set individually based on line width.<\/li>\n<li><strong>Line Width Measurement<\/strong>: For each batch of random inspections, record the top\/bottom line widths and Cpk; if any abnormal trends are detected, stop the machine and make adjustments.<\/li>\n<li><strong>Microsection<\/strong>: Measuring the copper thickness, dielectric thickness, copper thickness on the hole walls, and wire edge morphology of the cross-section under a microscope serves as the ultimate basis for determining whether the process truly meets the specifications. Key points for observing micro-sections are outlined in<a href=\"\/en\/blog\/19-pcb-reliability-and-microsection-points\/\">Key Points for PCB Reliability and Microsection Inspection<\/a>\u3002<\/li>\n<li><strong>Electrical Testing<\/strong>: Perform a comprehensive open-circuit and short-circuit test. The risk of open circuits and short circuits in fine-pitch circuit boards is significantly higher than in standard boards, so this step cannot be skipped.<\/li>\n<\/ul>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"1920\" height=\"1080\" class=\"alignnone size-large wp-image-12801\" src=\"https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2025\/12\/high-density-interconnect-pcb.jpg\" alt=\"HDI (High-Density Interconnect) Circuit Boards\" srcset=\"https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2025\/12\/high-density-interconnect-pcb.jpg 1920w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2025\/12\/high-density-interconnect-pcb-300x169.jpg 300w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2025\/12\/high-density-interconnect-pcb-1024x576.jpg 1024w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2025\/12\/high-density-interconnect-pcb-768x432.jpg 768w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2025\/12\/high-density-interconnect-pcb-1536x864.jpg 1536w\" sizes=\"auto, (max-width: 1920px) 100vw, 1920px\" \/><\/p>\n<h2>11. Balancing Cost and Yield<\/h2>\n<p><img loading=\"lazy\" decoding=\"async\" width=\"981\" height=\"571\" class=\"alignnone size-large wp-image-10088\" src=\"https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/the-relationship-between-pcb-line-width-and-current.jpg\" alt=\"Relationship Between PCB Trace Width and Current\" srcset=\"https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/the-relationship-between-pcb-line-width-and-current.jpg 981w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/the-relationship-between-pcb-line-width-and-current-300x175.jpg 300w, https:\/\/www.jingpengpcb.com\/wp-content\/uploads\/2023\/08\/the-relationship-between-pcb-line-width-and-current-768x447.jpg 768w\" sizes=\"auto, (max-width: 981px) 100vw, 981px\" \/><\/p>\n<p>With each increase in resolution, costs rise exponentially rather than linearly. When selecting a model, you must strike a balance among the following four factors:<\/p>\n<ul>\n<li><strong>Copper Foil Grades<\/strong>: Ultra-low-profile copper foil costs 1.5\u20132.5 times as much as standard copper foil.<\/li>\n<li><strong>Exposure Methods<\/strong>: The capital investment for LDI equipment is 3\u20135 times that of traditional exposure systems, and its throughput is lower than that of film-based systems using parallel exposure.<\/li>\n<li><strong>Resist Process<\/strong>: Liquid photoresists require coating lines and a higher level of cleanliness.<\/li>\n<li><strong>Yield Loss<\/strong>: The thinner the wire width, the higher the open-circuit and short-circuit defect rates, leading to increased rework and scrap costs.<\/li>\n<\/ul>\n<p>The best practices are as follows:<strong>Set the level based on the tightest spot, not on the entire board.<\/strong>: Since only the BGA lead-out area on the entire board requires a 50 \u03bcm trace width, while 75 \u03bcm is sufficient for the rest of the board, the process should be set to 50 \u03bcm but strictly controlled only in the specific area to avoid overprocessing the entire board. For stability requirements for multilayer high-resolution boards, see<a href=\"\/en\/blog\/pcb-multilayer-board-tg\/\">Stability and Reliability of Multilayer PCBs<\/a>\u3002<\/p>\n<h2>12. Conclusion<\/h2>\n<p>Printed circuit board manufacturing technology faces significant challenges in the pursuit of high density, high precision, high reliability, and miniaturization. Image formation and distortion, variations in measurement images, fluctuations in raw materials, and photoresist technology are all critical issues that must be addressed when producing precision patterns. By adopting new process methods such as HDI, it is possible to increase yield and resolution, thereby better meeting the manufacturing demands of high-density PCBs.<\/p>\n<p>In PCB manufacturing, to maintain high quality and reliability, manufacturers must continuously research and improve their processes to meet ever-changing technical requirements. Only through scientific analysis and innovative process methods can the successful production of high-density, fine-line patterns be achieved.<\/p>\n<h2>Frequently Asked Questions<\/h2>\n<h3>1. What is the HDI process?<\/h3>\n<p>The HDI (Hot Development Inhibition) process is a manufacturing method used to produce high-density circuit patterns. It improves the resolution of the photoresist by immersing the exposed film in hot water, thereby achieving higher yields and resolution.<\/p>\n<h3>2. Why is the choice of photoresist so important?<\/h3>\n<p>\u6297\u8680\u5242\u76f4\u63a5\u5f71\u54cd\u7535\u8def\u56fe\u5f62\u7684\u8d28\u91cf\u3002\u9009\u62e9\u9002\u5f53\u7684\u6297\u8680\u5242\u53ef\u4ee5\u63d0\u9ad8\u5206\u8fa8\u7387\u548c\u56fe\u8c61\u7684\u7a33\u5b9a\u6027\u3002<\/p>\n<h3>3. \u4e3a\u4ec0\u4e48\u7cbe\u5bc6\u56fe\u5f62\u5236\u4f5c\u5982\u6b64\u91cd\u8981\uff1f<\/h3>\n<p>\u7cbe\u5bc6\u56fe\u5f62\u5236\u4f5c\u662f\u5370\u5236\u7535\u8def\u677f\u5236\u9020\u4e2d\u7684\u5173\u952e\u73af\u8282\uff0c\u5b83\u76f4\u63a5\u5f71\u54cd\u7535\u8def\u677f\u7684\u6027\u80fd\u548c\u53ef\u9760\u6027\u3002\u53ea\u6709\u901a\u8fc7\u7cbe\u786e\u5236\u4f5c\u56fe\u5f62\uff0c\u624d\u80fd\u6ee1\u8db3\u73b0\u4ee3\u7535\u5b50\u8bbe\u5907\u5bf9\u9ad8\u5bc6\u5ea6PCB\u7684\u9700\u6c42\u3002<\/p>\n<h3>4. \u6709\u54ea\u4e9b\u56e0\u7d20\u53ef\u80fd\u5bfc\u81f4\u56fe\u8c61\u5931\u771f\uff1f<\/h3>\n<p>\u56fe\u8c61\u5931\u771f\u53ef\u80fd\u4e0e\u539f\u6750\u6599\u7684\u8d28\u91cf\u3001\u52a0\u5de5\u8fc7\u7a0b\u4e2d\u7684\u8d28\u91cf\u7f3a\u9677\u4ee5\u53ca\u5149\u654f\u6297\u8680\u5242\u7684\u6027\u80fd\u6709\u5173\u3002<\/p>\n<h3>5. \u5982\u4f55\u63d0\u9ad8\u7535\u8def\u56fe\u5f62\u7684\u5206\u8fa8\u7387\uff1f<\/h3>\n<p>\u91c7\u7528HDI\u7b49\u65b0\u7684\u52a0\u5de5\u5de5\u5e8f\u53ef\u4ee5\u63d0\u9ad8\u7535\u8def\u56fe\u5f62\u7684\u5206\u8fa8\u7387\uff0c\u540c\u65f6\u9700\u8981\u9009\u62e9\u9002\u5f53\u7684\u6297\u8680\u5242\u5e76\u63a7\u5236\u66dd\u5149\u5149\u6e90\u3002<\/p>\n<h3>6. \u8bbe\u8ba1 50 \u03bcm \u7ebf\u5bbd\u65f6\uff0c\u94dc\u539a\u5e94\u8be5\u9009\u591a\u5c11\uff1f<\/h3>\n<p>\u4f18\u5148\u9009 9 \u03bcm\uff081\/4 oz\uff09\u6216\u66f4\u8584\u7684\u5185\u5c42\u94dc\u7b94\u3002\u94dc\u539a\u8d8a\u5927\u4fa7\u5411\u94bb\u8680\u8d8a\u4e25\u91cd\uff0c35 \u03bcm \u94dc\u539a\u4e0b\u505a 50 \u03bcm \u7ebf\u5bbd\uff0c\u7ebf\u8fb9\u4f1a\u4e25\u91cd\u503e\u659c\u751a\u81f3\u5f00\u8def\u3002\u82e5\u7ed3\u6784\u5f3a\u5ea6\u8981\u6c42\u5fc5\u987b\u7528\u539a\u94dc\uff0c\u5e94\u628a\u7ebf\u5bbd\u653e\u5bbd\u5230 100 \u03bcm \u4ee5\u4e0a\u3002<\/p>\n<h3>7. LDI \u76f8\u6bd4\u5e95\u7247\u66dd\u5149\u5230\u5e95\u597d\u5728\u54ea\uff1f<\/h3>\n<p>\u6838\u5fc3\u662f\u53d6\u6d88\u4e86\u7269\u7406\u5e95\u7247\uff0c\u6d88\u9664\u4e86\u5e95\u7247\u53d8\u5f62\u3001\u5212\u4f24\u3001\u810f\u70b9\u8fd9\u4e00\u7c7b\u7f3a\u9677\uff0c\u5e76\u4e14\u80fd\u6839\u636e\u677f\u9762\u5b9e\u9645\u6da8\u7f29\u505a\u5b9e\u65f6\u7f29\u653e\u8865\u507f\uff0c\u5bf9\u4f4d\u7cbe\u5ea6\u4ece \u00b150 \u03bcm \u7ea7\u63d0\u5347\u5230 \u00b110 \u03bcm \u7ea7\u3002\u7f3a\u70b9\u662f\u8bbe\u5907\u6295\u8d44\u9ad8\u3001\u5355\u677f\u66dd\u5149\u65f6\u95f4\u66f4\u957f\u3002<\/p>\n<h3>8. \u8680\u523b\u56e0\u5b50\u600e\u4e48\u7b97\uff0c\u591a\u5c11\u7b97\u5408\u683c\uff1f<\/h3>\n<p>\u8680\u523b\u56e0\u5b50 = \u8680\u523b\u6df1\u5ea6 \u00f7 \u5355\u4fa7\u94bb\u8680\u91cf\u3002\u5e38\u89c4\u677f \u22652.0 \u5373\u53ef\u63a5\u53d7\uff0c\u9ad8\u5206\u8fa8\u7387\u677f\u8981\u6c42 \u22653.0\uff0c\u8d85\u7ec6\u7ebf\uff08\u226430 \u03bcm\uff09\u8981\u6c42 \u22654.0\u3002\u4f4e\u4e8e 2.0 \u65f6\u7ebf\u8fb9\u4f1a\u660e\u663e\u5448\u68af\u5f62\uff0c\u963b\u6297\u4e0e\u8f7d\u6d41\u90fd\u4f1a\u504f\u79bb\u8bbe\u8ba1\u3002<\/p>\n<h3>9. \u7ec6\u7ebf\u677f\u4e3a\u4ec0\u4e48\u66f4\u5bb9\u6613\u51fa\u73b0\u5f00\u8def\uff1f<\/h3>\n<p>\u4e09\u4e2a\u539f\u56e0\uff1a\u4e00\u662f\u4fa7\u5411\u94bb\u8680\u5360\u6bd4\u5927\uff0c\u7ebf\u5bbd\u4f59\u91cf\u5c0f\uff1b\u4e8c\u662f\u94dc\u9762\u5fae\u5c0f\u51f9\u5751\u6216\u6297\u8680\u5242\u9488\u5b54\u5728\u7ec6\u7ebf\u4e0a\u8db3\u4ee5\u9020\u6210\u65ad\u7ebf\uff1b\u4e09\u662f\u8680\u523b\u6db2\u4ea4\u6362\u4e0d\u5145\u5206\uff0c\u5bc6\u96c6\u533a\u4e0e\u7a00\u758f\u533a\u7684\u8680\u523b\u901f\u7387\u4e0d\u4e00\u81f4\uff08\u6c34\u6c60\u6548\u5e94\uff09\u3002<\/p>\n<h3>10. \u9ad8\u5206\u8fa8\u7387\u80fd\u529b\u8981\u4e0d\u8981\u5728\u91c7\u8d2d\u65f6\u5355\u72ec\u786e\u8ba4\uff1f<\/h3>\n<p>\u8981\u3002\u677f\u5382\u6807\u79f0\u7684\u300c\u6700\u5c0f\u7ebf\u5bbd\u300d\u5f80\u5f80\u662f\u6253\u6837\u6781\u9650\u503c\uff0c\u4e0d\u7b49\u4e8e\u6279\u91cf\u80fd\u529b\u3002\u91c7\u8d2d\u65f6\u5e94\u660e\u786e\u4e09\u4ef6\u4e8b\uff1a\u6279\u91cf\u751f\u4ea7\u7684\u6700\u5c0f\u7ebf\u5bbd\/\u7ebf\u8ddd\u3001\u7ebf\u5bbd\u516c\u5dee\u6216 Cpk \u8981\u6c42\u3001\u5bf9\u5e94\u7684\u94dc\u539a\u4e0e\u68c0\u6d4b\u65b9\u6cd5\u3002\u5236\u9020\u7aef\u7684\u4e94\u4e2a\u5173\u952e\u8981\u6c42\u89c1<a href=\"\/en\/blog\/5-hdi-manufacturing-requirements\/\">5 Key Requirements and Optimization Strategies for the HDI Manufacturing Process<\/a>\u3002<\/p>\n<p><strong>Related Recommendations<\/strong>\uff1a<a href=\"\/en\/blog\/pcb-multilayer-board-tg\/\">Stability and Reliability of Multilayer PCBs<\/a> \u00b7 <a href=\"\/en\/blog\/5-hdi-manufacturing-requirements\/\">5 Key Requirements and Optimization Strategies for the HDI Manufacturing Process<\/a><\/p>","protected":false},"excerpt":{"rendered":"<p>\u968f\u7740\u5668\u4ef6\u7684\u5fae\u578b\u5316\u3001\u591a\u529f\u80fd\u5316\u548c\u7535\u5b50\u5c01\u88c5\u6280\u672f\u7684\u98de\u901f\u8fdb\u5c55\uff0c\u5370\u5236\u7535\u8def\u677f\uff08PCB\uff09\u7684\u8bbe\u8ba1\u548c\u5236\u9020\u6b63\u671d\u7740\u9ad8\u5bc6\u5ea6\u3001\u9ad8\u7cbe\u5ea6\u3001\u9ad8\u53ef [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":8924,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"slim_seo":{"title":"What are the technical requirements for high-resolution PCB manufacturing? Trace pitch and copper thickness parameters","description":"What are the technical requirements for creating high-resolution images? Explain the manufacturing challenges associated with parameters such as trace pitch, inner and outer layer trace widths, copper layer thickness, and the number of copper layers. This article provides ready-to-use values and key operational guidelines."},"_slim_seo_primary_term_category":0,"_slim_seo_primary_term_post_tag":0,"footnotes":""},"categories":[26,410],"tags":[],"class_list":["post-1838","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","category-quality-reliability"],"_links":{"self":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/1838","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=1838"}],"version-history":[{"count":6,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/1838\/revisions"}],"predecessor-version":[{"id":19882,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/1838\/revisions\/19882"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/media\/8924"}],"wp:attachment":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/media?parent=1838"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/categories?post=1838"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/tags?post=1838"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}