Strike Lock PCB

Definition, scope, and who this guide is for

A Strike Lock PCB is the specialized printed circuit board designed to control the electromechanical actuation of an electric strike. Unlike standard consumer electronics, these boards operate in harsh physical environments—embedded within door frames where they are subjected to repetitive mechanical shock (door slamming), inductive voltage spikes from solenoids, and varying environmental conditions. The PCB serves as the bridge between the access control system and the physical locking mechanism, handling power distribution, signal processing for status monitoring, and fail-safe/fail-secure logic.

This guide is written for hardware engineers, product managers, and procurement leads responsible for sourcing reliable electronics for the security and access control industry. It moves beyond basic fabrication notes to address the specific reliability challenges of door hardware. Whether you are designing a new smart lock system or sourcing a replacement board for legacy infrastructure, understanding the nuances of these boards is critical to preventing field failures.

At APTPCB (APTPCB PCB Factory), we have observed that the most common failures in security hardware stem not from component selection, but from overlooking the mechanical and thermal stresses inherent to the application. This playbook provides a structured approach to defining specifications, identifying risks, and validating suppliers to ensure your Strike Lock PCB performs reliably over hundreds of thousands of cycles.

When to use Strike Lock PCB (and when a standard approach is better)

Building on the definition of the board's role, it is essential to determine if a dedicated Strike Lock PCB is necessary or if a generic driver board suffices.

Use a dedicated Strike Lock PCB when:

Space is constrained: The board must fit inside a narrow ANSI or DIN standard door strike housing, requiring non-standard shapes or rigid-flex configurations.
Inductive loads are high: You are driving high-current solenoids that generate significant back EMF, requiring dedicated flyback protection and robust trace widths close to the connector.
Smart features are required: The lock includes onboard logic for door position sensing (DPS), latch bolt monitoring (LBM), or encrypted communication (OSDP) with the controller.
Dual-voltage operation is needed: The device must auto-detect and switch between 12V and 24V DC/AC input without user intervention.
Vibration is constant: The application involves high-traffic doors where standard solder joints would fatigue and crack over time.

Stick to a standard or external controller when:

The lock is purely mechanical: The electric actuation is handled entirely by a remote power supply with no local logic required.
Space is ample: The control logic is housed in a secure box above the door rather than in the strike itself.
Cost is the only driver: For low-security, residential applications where cycle counts are low and failure consequences are minimal.

Strike Lock PCB specifications (materials, stackup, tolerances)

Once you have determined that a specialized Strike Lock PCB is required, the next step is defining the engineering parameters that ensure survival in a door frame environment.

Base Material (Laminate): Specify FR-4 with a High Tg (Glass Transition Temperature) of ≥150°C. Solenoids in electric strikes can generate significant heat during "hold open" states; standard Tg (130°C) may soften and compromise via reliability.
Copper Weight: Minimum 1 oz (35µm) finished copper on inner and outer layers. For high-inrush solenoids, consider 2 oz (70µm) to minimize resistive heating and voltage drop across the traces.
PCB Thickness: Standard 1.6mm is preferred for rigidity, but 1.0mm or 0.8mm may be necessary for compact strike housings. If thinning the board, ensure the mounting points are reinforced.
Surface Finish: Electroless Nickel Immersion Gold (ENIG) is recommended over HASL. ENIG provides a flatter surface for fine-pitch components and better corrosion resistance for door frames exposed to humidity or condensation.
Solder Mask: Green is standard, but Matte Black or Blue is often used in security products to obscure trace routing from casual visual inspection. Ensure the mask dam is sufficient (min 4 mil) to prevent solder bridging on tight driver ICs.
Trace Width & Spacing: Power traces for the solenoid must be calculated for maximum inrush current, not just holding current. Maintain minimum 0.25mm clearance for low voltage logic, but increase spacing for power lines to prevent arcing under inductive spikes.
Vias: Tented or plugged vias are preferred to prevent moisture ingress and solder wicking. In high-vibration zones, avoid placing vias directly on component pads (VIP) unless filled and plated over.
Mounting Holes: Non-plated mounting holes should have a keep-out zone of at least 0.5mm larger than the screw head to prevent crushing traces during installation.
Conformal Coating: Mandatory specification for outdoor or semi-outdoor strikes. Acrylic or Silicone coating protects against condensation and dust.
Flammability Rating: UL 94V-0 is non-negotiable for security and building infrastructure compliance.
Silkscreen: Clearly label terminal blocks (e.g., +12V, GND, NO, NC, COM) to prevent installation errors by field technicians.
Panelization: Design panels with V-score or tab-routing that minimizes stress on the PCB during depanelization, as ceramic capacitors near the edge can crack if the board is flexed.

Strike Lock PCB manufacturing risks (root causes and prevention)

Even with perfect specifications, manufacturing defects can introduce latent failures. Understanding these risks allows you to implement specific prevention strategies.

Solder Joint Fatigue (Vibration):
- Root Cause: Repeated slamming of the door transfers high G-force shock to the PCB.
- Detection: Intermittent failures in the field; cracks visible under X-ray or microscope.
- Prevention: Use larger solder pads for heavy components (connectors, relays). Apply underfill or bonding adhesive (staking) to large capacitors and inductors.
Inductive Kickback Damage:
- Root Cause: The solenoid acts as an inductor; when power is cut, it releases a high-voltage spike back into the PCB.
- Detection: Burnt MOSFETs or driver ICs; erratic logic behavior.
- Prevention: Ensure flyback diodes are placed as close to the connector as possible. Verify trace inductance is minimized in the layout.
Connector Fretting Corrosion:
- Root Cause: Micro-movements between the cable harness and PCB header due to vibration wear away the plating.
- Detection: High resistance connections; intermittent power loss.
- Prevention: Specify gold-plated headers if the mating harness is gold. Use locking connectors (e.g., JST or Molex with positive latching).
Thermal Delamination:
- Root Cause: Continuous duty solenoids heat the PCB locally, causing FR-4 layers to separate.
- Detection: Blistering on the board surface; change in board color.
- Prevention: Use thermal vias to spread heat to ground planes. Ensure the enclosure allows for some heat dissipation.
ESD (Electrostatic Discharge):
- Root Cause: Users touching the door frame or lock faceplate discharge static electricity into the PCB.
- Detection: Logic lockups; permanent damage to microcontrollers.
- Prevention: Place TVS diodes on all I/O lines. Ensure the mounting screws provide a solid path to earth ground if the chassis is metal.
Moisture Ingress (Electrochemical Migration):
- Root Cause: Condensation inside the door frame creates dendrites between closely spaced traces.
- Detection: Short circuits; "ghost" triggering of the lock.
- Prevention: Conformal coating (Type AR or SR). Increase spacing between high-voltage and low-voltage nets.
Component Cracking (Depanelization):
- Root Cause: Mechanical stress during PCB separation cracks MLCC capacitors.
- Detection: Short circuits on power rails immediately or after thermal cycling.
- Prevention: Keep components at least 2-3mm away from V-score lines. Use router depaneling instead of "pizza cutter" blades.
Incorrect Impedance (RFID/NFC):
- Root Cause: If the strike includes a reader, poor stackup control affects antenna tuning.
- Detection: Reduced read range; failure to read cards.
- Prevention: Specify controlled impedance for antenna traces. Request TDR (Time Domain Reflectometry) reports.

Strike Lock PCB validation and acceptance (tests and pass criteria)

To mitigate the risks identified above, a robust validation plan is required before mass production.

Endurance Cycling Test:
- Objective: Simulate the product lifespan.
- Method: Actuate the lock/PCB 250,000 to 1,000,000 times (depending on Grade 1 vs Grade 2 standards).
- Acceptance Criteria: No component failure, no solder joint cracking, no degradation in response time.
Vibration and Shock Test:
- Objective: Replicate door slamming.
- Method: Random vibration testing (e.g., 10-500Hz) and mechanical shock pulses (e.g., 50G for 11ms).
- Acceptance Criteria: Physical integrity maintained; no intermittent electrical discontinuities >1µs.
Thermal Shock Test:
- Objective: Stress test vias and solder joints against rapid temp changes.
- Method: Cycle between -40°C and +85°C for 100 cycles with 30-minute dwell times.
- Acceptance Criteria: Resistance change <10%; no delamination.
Humidity/Salt Fog Test:
- Objective: Validate corrosion resistance.
- Method: Exposure to 95% RH or salt mist for 48-96 hours.
- Acceptance Criteria: No corrosion bridging traces; conformal coating intact.
ESD Immunity Test:
- Objective: Verify protection against static shock.
- Method: Apply ±8kV contact / ±15kV air discharge to user-accessible points.
- Acceptance Criteria: Device must self-recover without user intervention (Class B) or continue operating normally (Class A).
Dielectric Withstand Voltage (Hi-Pot):
- Objective: Ensure isolation between logic and power (if applicable) or chassis.
- Method: Apply 500V DC or 1000V AC between isolated circuits.
- Acceptance Criteria: Leakage current <1mA; no breakdown.
In-Circuit Test (ICT) / Flying Probe:
- Objective: Verify assembly quality.
- Method: Check all passive values and diode drops.
- Acceptance Criteria: 100% pass on netlist verification.
Functional Test (FCT):
- Objective: Verify logic and power handling.
- Method: Simulate inputs (trigger) and measure outputs (solenoid drive current, status relay closure).
- Acceptance Criteria: All functions operate within specified voltage ranges (e.g., 12V ±10%).

Strike Lock PCB supplier qualification checklist (RFQ, audit, traceability)

Use this checklist to vet potential manufacturing partners. A supplier unable to meet these points introduces unnecessary risk to your security product.

RFQ Inputs (What you must provide)

Gerber Files (RS-274X): Including all copper layers, solder mask, silk, and drill files.
Fabrication Drawing: Specifying material (Tg), thickness, copper weight, and tolerance class (IPC Class 2 or 3).
Stackup Diagram: Explicitly defining layer order and dielectric thickness if impedance is controlled.
BOM (Bill of Materials): With approved vendor list (AVL) for critical components like relays and connectors.
Pick & Place File (Centroid): For automated assembly.
Conformal Coating Spec: Area to be coated and area to be masked (connectors, sensor windows).
Test Requirements: Specific instructions for ICT or FCT fixtures.
Volume & EAU: Estimated Annual Usage to determine pricing tiers.

Capability Proof (What they must demonstrate)

Experience with Thick Copper: Ability to etch and plate 2oz+ copper without undercutting.
Rigid-Flex Capability: If your design requires bending into the strike housing.
Conformal Coating Line: Automated spray or dip coating capability in-house.
Box Build Experience: Ability to integrate the PCB into the metal strike housing if needed.
Small Form Factor Assembly: Precision placement for 0402 or 0201 components if space is tight.
High-Mix Low-Volume Support: Willingness to prototype and scale.

Quality System & Traceability

ISO 9001 Certification: Mandatory baseline.
UL Certification: The PCB factory must have an active UL file (ZPMV2) for the laminate and process.
AOI (Automated Optical Inspection): 100% AOI required for all layers and assembly.
X-Ray Inspection: Available for checking QFNs or BGAs if used.
Date Code/Lot Tracing: Every PCB should be marked with a date code or serial number for recall management.
IPC Standards: Adherence to IPC-A-600 (PCB) and IPC-A-610 (Assembly) Class 2 or 3.

Change Control & Delivery

PCN (Product Change Notification): Agreement to notify 3 months in advance of any material or process change.
Safe Packaging: Vacuum sealed with desiccant and humidity indicator cards (HIC).
DFM Feedback: Process to provide Design for Manufacturing feedback before production starts.
Lead Time Stability: Clear communication on standard vs. expedited lead times.

How to choose Strike Lock PCB (trade-offs and decision rules)

Selecting the right architecture involves balancing cost, size, and reliability. Here are the key trade-offs to consider.

Rigid vs. Rigid-Flex:
- Decision Rule: If the strike housing is extremely compact or requires the PCB to wrap around the solenoid, choose Rigid-Flex. It eliminates connectors and improves reliability but costs 2-3x more. If space permits, choose Rigid for cost efficiency.
Integrated vs. Separate Controller:
- Decision Rule: If you are building a standalone "smart" strike, choose an Integrated PCB with onboard MCU. If the strike is part of a larger networked system with a central panel, choose a Simple Driver PCB (passive) to reduce per-door cost and complexity.
Fail-Safe vs. Fail-Secure Logic:
- Decision Rule: If the application is for fire safety (must unlock on power loss), prioritize Fail-Safe logic designs that default to open. For high-security areas (must stay locked on power loss), prioritize Fail-Secure. The PCB design must support the specific solenoid configuration for the chosen mode.
Thick Copper vs. Standard Copper:
- Decision Rule: If the solenoid inrush current >2A or the duty cycle is high (continuous hold), choose 2 oz Copper. For standard intermittent duty strikes (<500mA), 1 oz Copper is sufficient.
Conformal Coating vs. No Coating:
- Decision Rule: If the lock is installed on an exterior door or in a humid environment, Conformal Coating is mandatory. For strictly interior, climate-controlled office doors, you may skip it to save cost, though it is still recommended for longevity.
Class 2 vs. Class 3 (IPC):
- Decision Rule: For standard commercial security, IPC Class 2 is the industry standard. For critical infrastructure, prisons, or military applications, specify IPC Class 3 for higher reliability requirements.

Strike Lock PCB FAQ (cost, lead time, Design for Manufacturability (DFM) files, materials, testing)

Q: What is the primary cost driver for a Strike Lock PCB? A: Aside from volume, the primary cost drivers are the layer count (if HDI is needed for small size), copper weight (2oz costs more than 1oz), and rigid-flex construction. Adding conformal coating also adds a process step that impacts cost.

Q: How does Strike Lock PCB testing differ from standard PCB testing? A: Standard testing focuses on electrical continuity (Open/Short). Strike Lock PCB testing must include functional load testing (simulating the solenoid firing) and often requires vibration validation during the NPI phase to ensure solder joints can withstand door impacts.

Q: What materials are best for Strike Lock PCBs in fire-rated doors? A: You must use High-Tg FR4 (Tg 170°C+) to withstand higher operating temperatures. The material must be UL 94V-0 rated. For extreme heat resistance, ceramic or metal-core PCBs are rarely used due to cost/size, so high-grade FR4 is the standard.

Q: What is the typical lead time for Strike Lock PCB manufacturing? A: For standard rigid boards, prototypes take 3-5 days, and mass production takes 10-15 days. If you require Rigid-Flex or special heavy copper, expect 15-20 days for production.

Q: Can APTPCB assist with DFM for Strike Lock PCBs? A: Yes. We review your Gerber files for trace width sufficiency (for power), component spacing (for assembly), and mechanical constraints. We specifically look for risks related to vibration and thermal management in small enclosures.

Q: What files are required for a Strike Lock PCB quote? A: We need Gerber files, a BOM (if assembly is required), and a fabrication drawing specifying the stackup and materials. If you need functional testing, a test procedure document is also required.

Q: How do I ensure my Strike Lock PCB meets acceptance criteria for security? A: Define your acceptance criteria clearly in the RFQ: "Must pass 100% ICT," "Must be UL recognized," and "Must pass 50G shock test." Requesting a First Article Inspection (FAI) report is the best way to verify these criteria before full production.

Q: Why is my Strike Lock PCB failing due to "Flyback"? A: This occurs when the solenoid (an inductor) is de-energized, creating a high-voltage spike. If your PCB lacks a flyback diode (or if the diode is too far from the source/too slow), this spike destroys the driver transistor. Ensure the design includes proper protection.

Security Equipment PCB Solutions: Explore our specific capabilities and case studies in the security and access control sector.
Rigid-Flex PCB Technology: Learn how rigid-flex designs can solve space constraints in compact electric strike housings.
PCB Conformal Coating Services: Understand the options for protecting your lock electronics from moisture and environmental corrosion.
DFM Guidelines: Use our design-for-manufacturing rules to optimize your board layout for cost and reliability.
Box Build Assembly: See how we can handle the full assembly of your strike lock, including enclosure integration.

Request a quote for Strike Lock PCB (Design for Manufacturability (DFM) review + pricing)

Ready to move your design to production? APTPCB provides a comprehensive DFM review alongside your quote to identify potential reliability risks before you pay.

To get an accurate quote and DFM analysis, please prepare:

Gerber Files: RS-274X format preferred.
Fabrication Drawing: Specify Tg, copper weight, and surface finish.
BOM: If you need PCBA services.
Volume: Prototype quantity vs. Mass production EAU.

Click here to Request a Quote & DFM Review – Our engineering team typically responds within 24 hours with a detailed cost breakdown and technical feedback.

Conclusion (next steps)

A Strike Lock PCB is a critical component where failure means a security breach or a locked-out user. By prioritizing high-Tg materials, robust vibration protection, and rigorous validation testing, you can ensure your product withstands the harsh reality of daily door operation. Whether you need a simple driver board or a complex rigid-flex assembly with encrypted logic, APTPCB is ready to support your engineering and procurement teams with reliable manufacturing and expert guidance.