- Entry Board
- A thin sheet placed on top of the PCB stack before drilling. It guides the drill bit on entry, suppresses top-side burr, and dissipates heat. The industry standard is 1100 H18 full-hard aluminum, 0.15–0.20 mm thick. View products →
- Backup Board
- A rigid board placed under the PCB panel during drilling. It supports the exit side of the hole, controls exit burr height, absorbs drill heat, and extends bit life. Common types include HDF, Melamine, and Phenolic grades. View products →
- Back-drill
- A secondary controlled-depth drilling pass that removes the unused stub (barrel) of a through-hole via. Required on high-speed digital PCBs (≥10 Gbps) to reduce signal reflection caused by the via stub. Learn more →
- Stub
- The remaining unused portion of a via barrel after back-drilling. A shorter stub means better signal integrity. Production back-drilling typically leaves 0.15–0.25 mm residual stub. The industry capability target is CpK ≥1.67 for critical high-speed links.
- CpK (Process Capability Index)
- A statistical measure of how consistently a process produces output within specification limits. In PCB drilling, CpK is commonly used for stub depth (target ≥1.33 for standard, ≥1.67 for critical), hole location accuracy, and coating thickness. A CpK of 1.67 means the process is well-centred with minimal variation.
- HDI (High Density Interconnect)
- A PCB technology using finer lines, smaller microvias (≤Ø0.15 mm), and higher layer density than conventional boards. HDI drilling requires coated/lubricant entry boards for precise microvia location and low-smear backup boards. View HDI solution →
- IC Substrate
- A specialized PCB used as the package base for semiconductor chips. IC substrates demand extremely fine hole diameters (≤Ø0.10 mm), tight location tolerance, and ultra-clean hole walls. They typically require Phenolic or high-end Melamine backup boards. View solution →
- Microvia
- A very small blind or buried via, typically ≤Ø0.15 mm, used in HDI PCBs to connect adjacent layers. Microvia drilling requires coated entry sheets to hold the drill on centre and prevent resin smear.
- Exit Burr
- The raised collar of copper that forms around the bottom of a drilled hole when the drill exits into a soft or unsupported surface. Exit burr can break electrical continuity or cause short circuits. Control is primarily through backup board density, flatness, and moisture content. Learn more →
- Hole Location Accuracy
- The precision with which a drilled hole's centre matches its design position, typically measured in micrometres. For HDI boards, ±25 µm is common; for standard multilayer ±50 µm. The entry board's flatness and alloy temper directly affect location accuracy.
- L.C.O. (Lubricant Coated Aluminum)
- A coated aluminum entry sheet with a thermoset (220°C) or water-soluble resin layer that lubricates the drill flute, reduces heat, and improves chip evacuation. Recommended for HDI, BGA, and IC substrate microvia drilling. YUESHAN's green thermoset-coated is a direct alternative to legacy L.C.O. brands. View products →
- HDF (High Density Fiberboard)
- A cost-effective backup board made from compressed wood fibres. HDF 880 (880±30 kg/m³) is the workhorse grade for standard 2–12 layer PCB drilling, delivering ≤0.05 mm exit burr at 40–80% lower cost than Melamine alternatives. View HDF →
- Melamine Backup Board
- A high-performance backup board made from melamine-impregnated paper layers. UV Melamine 950 resists moisture, warpage, and delivers low resin smear — ideal for HDI, automotive, and 5G boards from 2–24 layers. View UV Melamine →
- Phenolic Backup Board (PHE)
- A dense, thermoset backup board used for IC substrate drilling, routing worktables, and thick copper applications. Offers the highest flatness stability and cleanest exit quality among backup board families. View Phenolic PHE →
- Back-drill Aluminum
- A one-piece, margin-reserved coated aluminum sheet (0.16–0.19 mm) designed specifically as the entry plane for the back-drilling pass. Its tight thickness tolerance and coating CpK hold the Z-reference stable for consistent stub depth. View products →
- REACH / RoHS
- European regulations governing chemical safety (REACH — Registration, Evaluation, Authorisation and Restriction of Chemicals) and restriction of hazardous substances (RoHS). YUESHAN materials are REACH and RoHS compliant, with declarations provided on request.
- SGS Certification
- Third-party inspection and certification by SGS (Société Générale de Surveillance), a leading testing and verification company. YUESHAN products are SGS-certified for material composition, physical properties, and compliance.
- Desmear
- A chemical or plasma process that removes resin smear from the hole wall after drilling, ensuring reliable copper plating adhesion. Low-smear backup boards (UV Melamine 950, Phenolic PHE) reduce the desmear burden and improve plating quality.
- PPAP (Production Part Approval Process)
- A standard automotive industry qualification process (IATF 16949) that validates a production process can consistently meet specifications. YUESHAN can supply PPAP-style documentation — including lot traceability and material declarations — on request for qualified programs. View automotive solution →
- AOI (Automated Optical Inspection)
- An automated visual inspection system used post-drilling to detect defects such as exit burr, smear, and misregistration. AOI threshold for exit burr is typically ≤0.05 mm on standard lines and tighter on HDI/automotive.
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