gate

**Gate** is the **final narrow flow entry that meters molding compound from runner channels into each cavity** - it strongly influences shear rate, fill front behavior, and package defect formation. **What Is Gate?** - **Definition**: Gate dimensions define local flow restriction and cavity entry dynamics. - **Shear Profile**: Small gates raise shear and velocity, while larger gates lower shear but alter fill timing. - **Location Effect**: Gate placement influences flow direction, wire sweep, and air-trap locations. - **Separation**: Gate geometry also affects runner break-off and post-mold finishing effort. **Why Gate Matters** - **Fill Quality**: Gate design is critical for complete fill without void entrapment. - **Wire Integrity**: Improper gate orientation can induce wire deformation or sweep. - **Dimensional Control**: Gate freeze timing affects cavity pressure and package consistency. - **Throughput**: Balanced gate flow reduces cycle variation across cavities. - **Rework**: Poor gate break characteristics increase deflash and cleanup burden. **How It Is Used in Practice** - **Geometry Tuning**: Use DOE to optimize gate width, thickness, and land length. - **Placement Review**: Align gate direction with robust flow paths around sensitive structures. - **Inspection**: Track gate wear and burr formation as part of preventive maintenance. Gate is **a precision flow-control feature at the cavity entrance** - gate optimization must balance shear control, fill timing, and downstream finishing requirements.