- 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. PCB Backup Board Manufacturer
Readers who want the full definition rather than the one-line version can start with what a PCB backup board is, including HDF, melamine and phenolic grades. The process-side entries — parameters, defects, accuracy — are collected in the drilling techniques guide.
- 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. How to Control PCB Drilling Exit Burr
- 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 / LCOA (Laminating Company of America)
- Brand of Laminating Company of America (LCOA), a long-established U.S. manufacturer of PCB drilling consumables whose coated aluminum entry sheets serve as a common industry benchmark. The abbreviation is also sometimes used loosely for thermoset-coated lubricant entry sheets in general. YUESHAN's thermoset-coated lubricant aluminum is an independently qualified alternative — benchmark both grades side by side on your own line. Lubricant-Coated Aluminum Entry Board
- 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. Back-Drill Aluminum HW600/HW900
- 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
- SGS (Société Générale de Surveillance) is an independent inspection, verification, testing and certification company. Where third-party test reports exist for a specific material grade, YUESHAN provides them on request.
- 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.
Missing a term? Contact Mr. Lucky Xu and we will add it.
Where These Terms Are Used in Practice
A definition is only useful where it is applied. Each of the pages below uses the vocabulary above in a specific decision, so the term and its consequence sit together.
- Drilling parameters in numbers — feed, spindle speed, chip load, stack height and hit count, with the ranges each term implies.
- Defect isolation by symptom — burr, smear, nail-head, ICD and stub, and which term belongs to which failure.
- The backup board material families — where hardness, density and flatness values come from.
- Material comparison for purchase decisions — how those values translate into price against yield.
- Supplier qualification and audit vocabulary — TDS, COA, SDS, declaration and traceability, used the way a buyer uses them.
- The calculator set — every term above that can be computed rather than estimated.