runner system

**Runner system** is the **network of flow channels that distributes molding compound from the pot to each mold cavity** - it governs fill balance, pressure distribution, and material waste in transfer molding. **What Is Runner system?** - **Definition**: Runner geometry controls compound path length, flow resistance, and arrival timing. - **Balance Objective**: Design aims for synchronized cavity fill under equivalent pressure conditions. - **Thermal Influence**: Runner temperature profile affects viscosity and cure progression during flow. - **Waste Link**: Runner volume contributes directly to cull and non-product material loss. **Why Runner system Matters** - **Yield**: Imbalanced runners create cavity underfill, voids, and package variation. - **Interconnect Safety**: High-shear runner design can increase wire sweep in sensitive packages. - **Cost**: Runner optimization reduces compound waste and per-unit material consumption. - **Cycle Stability**: Consistent flow paths improve lot-level process repeatability. - **Scalability**: Advanced package densities require tighter runner-flow control. **How It Is Used in Practice** - **Flow Simulation**: Validate runner pressure and fill timing before tool release. - **Dimensional Audits**: Inspect runner wear and blockage to prevent hidden flow drift. - **Design Iteration**: Refine runner cross-sections based on defect Pareto and cavity imbalance data. Runner system is **the distribution backbone of compound flow in transfer molding** - runner system design is a high-leverage control for yield, consistency, and material efficiency.