M3 Phillips Countersunk Screws in Stainless Steel & Nickel-Plated — Flush-Mount Flat Head Fasteners for Metal, Wood & Plastic
When a protruding screw head is not an option — whether you're assembling a metal enclosure, mounting a panel that needs a clean surface, or building furniture where snag-free edges matter — M3 Phillips countersunk screws are the fastener that makes flush installation possible. Makers, fabricators, electronics assemblers, and woodworkers all face the same challenge: finding a flat head M3 screw in the right material and length without ordering from three different suppliers. This listing consolidates two material finishes and twelve length options into a single, flexible source.
Each order contains M3 Phillips flat head (countersunk) machine screws in your choice of Stainless Steel or Nickel-Plated finish, available in lengths from 5mm (≈3/16") to 35mm (≈1-3/8"): specifically 5mm (≈3/16"), 6mm (≈1/4"), 8mm (≈5/16"), 10mm (≈3/8"), 12mm (≈15/32"), 14mm (≈35/64"), 16mm (≈5/8"), 18mm (≈45/64"), 20mm (≈25/32"), 25mm (≈1"), 30mm (≈1-3/16"), and 35mm (≈1-3/8"). Thread is ISO metric coarse M3 × 0.5mm pitch. Pack quantities range from 50 to 500 pieces depending on material and size selected.
Typical use cases include metal enclosure and electrical panel assembly where flush-mount M3 countersunk screws prevent interference with covers and sliding components; furniture and cabinetry construction where nickel-plated flat head screws provide a clean, decorative finish on visible surfaces; and electronics and PCB chassis work where stainless steel M3 Phillips flat head screws resist corrosion in humid environments while keeping mounting surfaces smooth and snag-free.
🔩 Compatibility: ISO metric coarse thread M3 × 0.5mm pitch. Drive: Phillips (PH1). Countersunk head angle: typically 90° (standard metric). Compatible with ISO M3 hex nuts, nylon lock nuts, and tapped M3 holes. Requires a countersunk hole for flush installation. Not compatible with UNC/UNF inch-standard threads.
✅ Key Features of These M3 Phillips Countersunk Screws
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📐Flush-Mount Flat Head Design — The 90° countersunk head seats fully into a standard metric countersink, leaving the surface smooth and snag-free — essential for sliding panels, enclosure covers, and any assembly where a protruding head would interfere with fit or function.
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🧲Two Material Options in One Listing — Stainless steel M3 flat head screws offer through-material corrosion resistance for damp or outdoor-adjacent applications; nickel-plated variants deliver a bright, uniform finish suited for indoor assemblies where appearance is a priority.
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📏Twelve Length Options (5–35mm) — From 5mm (≈3/16") for thin sheet metal and PCB panels up to 35mm (≈1-3/8") for deeper structural assemblies, the range covers the most common M3 countersunk screw lengths without needing to source from multiple suppliers.
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🔧Phillips Drive for Broad Tool Compatibility — The PH1 Phillips recess works with standard screwdrivers and power drivers found in any workshop or field kit, reducing the need for specialty bits when working with M3 flat head machine screws across different job sites.
- 🛠️Stainless Steel Corrosion Resistance — The stainless steel variants resist rust and oxidation without relying on a surface coating, making them a reliable choice for outdoor enclosures, marine-adjacent hardware, and any environment where long-term fastener integrity matters.
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📦Bulk Pack Quantities Available — Choose from 50 to 500 pieces per order to match your project scale — whether you need a small pack for a single prototype or a larger quantity for production runs, assembly batches, or workshop stock replenishment.
📐 Technical Specifications — M3 Phillips Flat Head Countersunk Machine Screws
| Thread Standard |
ISO Metric Coarse — M3 × 0.5mm pitch |
| Thread Diameter |
M3 (3mm / ≈0.118") |
| Head Type |
Flat Head (Countersunk) — 90° head angle (standard metric) |
| Drive Type |
Phillips (PH1) |
| Available Lengths |
5mm (≈3/16"), 6mm (≈1/4"), 8mm (≈5/16"), 10mm (≈3/8"), 12mm (≈15/32"), 14mm (≈35/64"), 16mm (≈5/8"), 18mm (≈45/64"), 20mm (≈25/32"), 25mm (≈1"), 30mm (≈1-3/16"), 35mm (≈1-3/8") |
| Material Options |
Stainless Steel (corrosion-resistant alloy) | Nickel-Plated (carbon steel core with nickel finish) |
| Stainless Steel Grade |
Contact us to confirm |
| Surface Finish |
Stainless Steel: natural brushed/polished | Nickel-Plated: bright silver |
| Corrosion Resistance |
Stainless Steel: through-material resistance | Nickel-Plated: surface coating, suited for indoor use |
| Pack Quantity Options (SS) |
50, 100, 150, 250, 400, 500 pcs |
| Pack Quantity Options (Nickel-Plated) |
100, 200, 300, 400, 500 pcs |
| Countersink Requirement |
Requires countersunk hole (90°) for flush installation |
⚠️ Note: Flat head screws require a properly countersunk hole to sit flush. Without a countersink, the head will protrude above the surface. Nickel-plated screws are not recommended for prolonged outdoor or high-humidity exposure — select stainless steel for those applications. Avoid overtightening in soft materials to prevent stripping the countersink recess.
❓ Frequently Asked Questions
How do I choose the right length for an M3 countersunk screw?
Measure the total thickness of the material(s) being fastened, then add the depth of the countersink. The screw should pass fully through the top layer and engage the base material or nut by at least 2–3 times the thread diameter — for M3, that is typically 6–9mm of thread engagement. For example, fastening a 3mm panel to a 5mm base generally calls for an M3×10mm (3/8") or M3×12mm (15/32") screw. Always account for the countersink depth, which reduces the effective clamping length compared to a round head screw of the same nominal length.
What is the difference between stainless steel and nickel-plated M3 screws?
Stainless steel M3 screws are made from a corrosion-resistant alloy throughout, making them suitable for damp, outdoor, or marine-adjacent environments where long-term rust resistance is needed. Nickel-plated screws have a carbon steel core with a nickel coating that provides a bright, uniform finish and moderate corrosion resistance — they are generally suited for indoor applications where appearance matters and exposure to moisture is limited. For outdoor or high-humidity use, stainless steel is generally the more durable choice.
Are these screws suitable for outdoor use?
The stainless steel variants are generally suitable for outdoor and damp environments, as stainless steel resists rust and oxidation without a surface coating. The nickel-plated variants are better suited for indoor use — the nickel coating can wear or chip over time in wet or corrosive conditions, exposing the carbon steel core to rust. For outdoor furniture, enclosures, or any application with regular moisture exposure, select the stainless steel option.
What thread standard do these M3 flat head screws follow, and are they compatible with standard nuts?
These screws follow the ISO metric coarse thread standard: M3 × 0.5mm pitch. They are compatible with standard ISO M3 hex nuts, nylon lock nuts, threaded inserts, and tapped M3 holes. They are not compatible with UNC/UNF inch-standard threads. The countersunk head angle is typically 90°, which is the standard for metric flat head screws — confirm your countersink tool matches this angle for a proper flush fit.
Do I need a countersunk hole to use flat head screws?
Yes. Flat head (countersunk) screws are designed to sit flush with or below the surface of the material. To achieve this, the receiving hole must be countersunk — typically at a 90° angle for metric screws — so the tapered head seats fully into the recess. Without a countersink, the head will protrude above the surface. A standard M3 countersink bit or a stepped drill bit sized for M3 will create the correct recess in most materials including metal, wood, and plastic.
How strong are M3 Phillips flat head screws in metal-to-metal applications?
M3 stainless steel screws generally have a tensile strength in the range of 500–700 MPa, making them suitable for light-to-medium duty fastening in metal, wood, and plastic assemblies. They are not rated for structural or high-vibration applications without additional locking hardware such as lock washers or nylon lock nuts. For applications requiring specific load ratings, contact us to confirm the grade and mechanical properties before ordering.
Which length should I choose for fastening thin sheet metal or PCB panels?
For thin sheet metal (typically 1–3mm) or PCB panels, shorter lengths in the M3×6mm (1/4") to M3×10mm (3/8") range are generally the right starting point. The screw should pass through the panel and engage a nut or threaded standoff with at least 2–3 thread diameters of engagement (6–9mm for M3). For stacked panels or thicker assemblies, step up to M3×12mm (15/32") or longer. When in doubt, measure your total stack height including any spacers or standoffs before selecting a length.
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