JLCPCB Blog

Flexible PCBs

The Ultimate Guide to Flexible PCB: Types, Design, and Applications

Key Takeaways JLCPCB 1–4 Layer Flex PCB: Supports 1 to 4-layer FPCs with polyimide (PI) substrates and trace/space down to 3/3 mil. Stiffener Selection: Use PI (0.1–0.25mm) for ZIF connectors, FR4 (0.1–1.6mm) for SMT support, and Stainless Steel (0.1–0.3mm) for high rigidity. Layout Optimization: Use cross-hatched copper ground planes and stagger 2-layer traces to eliminate the "I-Beam effect." Surface & Protection: Combine Immersion Gold (ENIG 1u"/2u") for SMT planarity with flex coverlay to protect ......

Aug 17, 2026

SMT Stencil Design

DFN Package Guide: Footprint, Soldering & Stencil Tips

Key Takeaways What a DFN is: A DFN (Dual Flat No-Lead) package is a leadless chip-scale IC package with connection pads on two opposing sides of its underside, usually plus a central exposed thermal pad. Assembly requirements: DFN joints sit hidden under the body, so it needs reflow soldering with a stencil and X-ray or AOI inspection, not hand soldering. Design essentials: Follow IPC-7351 land patterns and IPC-7525 aperture rules, use a thinner stencil foil around 0.1-0.12 mm, and segment the thermal......

Aug 17, 2026

Hand Soldering & Stencils

How to Solder QFN Components: A Step-by-Step Guide

Key Takeaways A solder paste stencil is the most reliable way to achieve consistent QFN solder joints. Always use a window-pane paste pattern on the center thermal pad instead of one large paste deposit. Control solder paste volume to prevent floating, bridging, and excessive voiding. Reflow needs a proper soak-then-reflow-then-cool profile Hand soldering is practical only for certain QFN packages and usually cannot solder the center thermal pad effectively. Because QFN solder joints are hidden beneat......

Aug 17, 2026

Heating Hub

Graphene Heat Spreader Design: Layers and Interfaces

Key Takeaways Conductivity alone is not enough: A record thermal-conductivity value does not guarantee a cooler chip. Effective thickness, interface resistance, hot-spot geometry, and heat-sink connections all belong to the same thermal path. Few-layer graphene can outperform a single layer in practice: A few-layer sheet provides a larger heat-flow cross section and better tolerates transfer, embedding, and defects, even though its intrinsic conductivity is lower. Interface resistance is the bottlenec......

Aug 14, 2026

Design Tools & Best Practices

Multilayer PCB Design: A Comprehensive Guide

Key Takeaways Higher Density & Efficiency: Multilayer PCBs pack complex routing and superior thermal management into compact layouts beyond 2-layer limits. Superior Integrity: Dedicated ground and power planes minimize EMI, cross-talk, and noise for clean high-speed signal execution. Controlled Impedance: Precise stackup engineering ensures accurate signal matching (±10%) with High-Tg FR-4 materials. DFM-Ready Design: Symmetric stackups and Via-in-Pad (POFV) technology prevent board warpage and ensure......

Aug 14, 2026

Components & Sourcing

Complete Guide to Resistor Types: Fixed, Variable, and Non-Linear Resistors

The decision becomes difficult even for designers when a circuit board involves different types of resistors. Knowing which one your circuit actually needs solves half of the design problem. In this guide, you will go through: The full resistor types chart — fixed, variable, and non-linear families. How to choose between carbon film, metal film, wirewound, and foil resistors. When to use a potentiometer, thermistor, LDR, or varistor in design. SMD/through-hole resistor types and what each costs you. H......

Aug 13, 2026