Method of overmolding circuit
A method is provided for the punching of a bridge break and thereafter sealing the bridge break during the injection molding process of the lead frame. The bridge breaking tool is placed over the bridge that is to be broken. The collar presses down on the circuit and the punch presses down on the bridge with enough force to form the bridge break. Once the bridge break is formed the punch is retracted from the cavity of the template and molten polymer is injected to flow around the ends of the bridge break. The bridge breaking tool's hold down collars and retracted punch form a molding area for molten polymer to flow over the bridge break and the exposed circuit area. The bridge breaking tool is retracted after the bridge break is encased in the cured molten polymer and the cured molten polymer forms a lead frame structure.
1. A method of creating a sealed bridge break between circuits;
providing a template for forming a lead frame thereon;
providing a one piece circuit frame having one or more circuits connected by one or more bridges;
providing one or more bridge break tools each having a collar and a punch;
providing a polymer material;
placing said one piece frame on the surface of said molding tool; placing said collar of each of said one or more bridge break tools against said one piece frame;
punching one or more bridge breaks between said one or more bridges using said one or more bridge break tools;
lifting said punch of each of said one or more bridge break tools away from said bridge break and keeping said collar of each of said one or more bridge break tools against said one piece frame;
flowing said molten polymer material through said collar around said one piece frame and said one or more bridge breaks;
retracting said one or more bridge break tools; and
curing said molten polymer material to form a solid lead frame structure having bridge breaks that are sealed by said polymer material.
2. The method of creating a sealed bridge break between circuits of claim 1 wherein said collar of said one or more bridge tools forms the exterior side of said bridge break tool wherein said collar presses and holds said one piece frame onto said template.
3. The method of creating a sealed bridge break between circuits of claim 2 , wherein said punch moves through said collar and presses on said bridge forming said bridge break.
4. The method of creating a sealed bridge break between circuits of claim 1 further comprising:
providing a first backing connected to each said punch of said one or more bridge break tools and a second backing connected to each collar of said one or more bridge break tools, wherein said first backing and said second backing contact during said step of punching and said first backing moves away from said second backing during said step of lifting.
5. The method of creating a sealed bridge break between circuits of claim 1 further comprising the step of providing at least one window on said collar that extends from the base of said collar, wherein said window allows said polymer to flow across the radius of said collar after said punch is retracted.