QFN封装设计.pdf

Footprint Design and Surface Mount Application for QFN/ DFN Package App Note QA200501-A 1. Introduction 立理, QFN/ DFN Package (Quad Flat No-lead, Dual Flat No-lead) (SMD). QFN Package ()/ DFN Package ()良量, (Figure 1) QFN CSP(Chip Scale Package), QFN , PCB(Print Circuit Board) QFN (Pad)PCB (Footprint or Land Pattern)IR , SMT(Surface Mount Technology) PCB Footprint , IPC-SM-782, QFN PCB , QFN Footprint , Application Note QFN General Guideline 數, Guideline , 理, Figure 1: QFN Section View 2. QFN/ DFN Outline Drawings RichTek QFN/ DFN Package Outline RichTek Data Sheet Outline Dimension, RichTek Web-site 4.1.2 Outline Dimension Package Outline Dimension. 3. SMT Process SMT 數良率, 數SMT 參 Factors Control Point Solder Paste Shippment and Storeage Tempture, Paste Expiration Date, Viscosity and Texture, Dry out, Stencil Design PCB Quality Clean, Flat, Residue, Wrapage… Reflow Profile Profile Depended PCB Design, PCB Thickness, Compontent… Placement SMT Machine, Orientation, Speed, Alignment Mark… 1 Footprint Design and Surface Mount Application for QFN/ DFN Package App Note QA200501-A 4. Stencil Design Guideline 4.1 度Stencil Thickness Design , 列: 雷, 金 . 度, 略Footprint , 1:1 Footprint. IPC-7525 . 130um~150um(5~6mils), 150um 易連度(更不), 參數 4.2 Stencil Design for Thermal Pad 了Package QFN PCB Thermal Pad, Thermal Pad , Thermal Pad 易洞Void, Splatter, Solder Balling,…, 易(Fig2), Thermal Pad 率50%~80%, 連40% Non-wetting to Terminal Molding Compound