Method for reducing warpage occurred to substrate strip after molding process
A method for reducing warpage occurred to a substrate strip after a molding process is provided. First, several dies are mounted on a top surface of a substrate strip. Then, a base having a top surface with a surface curvature is provided, and the top surface of the base is contacted against a bottom surface of the substrate strip to bend the substrate strip. Next, under the status that the top surface of the base is contacted against the bottom surface of the substrate strip, a molding compound is wrapped around each die. Finally, the molding compound is cooled to a room temperature. Accordingly, the molding process is performed on the substrate strip reversely bent in a direction opposite to a warpage direction. Therefore, the warpage originally caused by the molding process is offset by the reverse bending.
1. A method for reducing warpage occurred to a substrate strip after a molding process, comprising:
mounting a plurality of dies on a top surface of a first substrate strip;
heating a first molding compound to a molding temperature, and wrapping the first molding compound around each of the dies on the top surface of the first substrate strip;
cooling the first molding compound to a room temperature, and measuring a surface curvature of the first substrate strip;
providing a base, wherein a top surface of the base has the surface curvature;
mounting a plurality of dies on a top surface of a second substrate strip;
enabling the top surface of the base to contact against a bottom surface of the second substrate strip, so that the bottom surface of the second substrate strip is bent and has the surface curvature;
under a state that the top surface of the base is contacted against the bottom surface of the second substrate strip, heating a second molding compound to the molding temperature, and wrapping each of the dies on the top surface of the second substrate strip with the second molding compound; and
cooling the second molding compound to the room temperature.
2. The method according to claim 1 , wherein the second molding compound is cooled to the room temperature under the state that the top surface of the base is contacted against the bottom surface of the second substrate strip.
3. The method according to claim 1 , wherein the second molding compound is cooled to an intermediate temperature under the state that the top surface of the base is contacted against the bottom surface of the second substrate strip, and then the second molding compound is cooled to the room temperature after removal of the second substrate strip from a press molding device.
4. The method according to claim 3 , wherein the intermediate temperature is not lower than 50° C.
5. The method according to claim 1 , wherein the first substrate strip and the second substrate strip are rectangular, lengths of the first and second substrate strips are in a range of 165 mm to 180 mm, and widths of the first and second substrate strips are in a range of 50 mm to 60 mm.
6. The method according to claim 1 , wherein the molding temperature is in a range of 170° C. to 180° C.