Electronic component and method for its production
View Patent ↗The invention relates to an electronic component and to a method for its production. The electronic component has a semiconductor chip and a wiring board, and a plastic package. The plastic package is divided into two plastic package molding compounds arranged one on top of the other. Of the plastic package molding compounds a first layeroof plastic package molding compound forms a relatively uneven surface, which is smoothed by a second layer of plastic package molding compound so that the electronic component has smooth outer sides of the plastic package.
1. A method for coating a a plurality of semiconductor chips mounted on a lead frame with a plastic package molding compound, the method comprising:
printing a first layer of viscous plastic package molding compound on the lead frame to fill intermediate spaces between the semiconductor chips and to coat surfaces of the semiconductor chips with the plastic package molding compound;
placing the lead frame with the first layer of plastic package molding compound in a vacuum chamber with reduced air pressure; and
printing a second layer of viscous plastic package molding compound onto the first layer of plastic package molding compound.
2. The method as claimed in claim 1 , wherein the printing of the first and second layers of viscous plastic package molding compound takes place by screen printing.
3. The method as claimed in claim 1 , wherein, when printing the first and second layers of viscous plastic package molding compound a spatula is pressed under pressure onto a printing screen.
4. The method as claimed in claim 1 , wherein the air pressure is repeatedly decreased and increased in the vacuum chamber to degas the first layer prior to applying the second layer of plastic package molding compound.
5. The method as claimed in claim 1 , wherein the second layer of plastic package molding compound is applied with the same printing screen as the first layer of plastic package molding compound.
6. The method as claimed in claim 1 , wherein the printing of the first layer of plastic package molding compound is performed under normal cleanroom conditions.
7. The method as claimed in claim 6 , wherein the printing of the second layer of plastic package molding compound is performed under normal cleanroom conditions.
8. The method as claimed in claim 1 , wherein the lead frame is stacked in the vacuum chamber.
9. The method as claimed in claim 1 , wherein the printing of the first layer of plastic package molding compound is performed without use of a vacuum chamber.
10. The method as claimed in claim 1 , wherein the printing of the second layer of plastic package molding compound is performed without use of a vacuum chamber.
11. The method as claimed in claim 1 , wherein, upon printing the first layer of plastic package molding compound, air bubbles are present in the first layer of plastic package molding compound.
12. The method as claimed in claim 11 , wherein placing the lead frame in the vacuum chamber with reduced air pressure degasses the first layer of plastic package molding compound.
13. The method as claimed in claim 1 , wherein, subsequent to printing the second layer, the first and second layers are cured to form crosslinks between the first and second layers.
14. The method as claimed in claim 1 , further comprising:
connecting electronic circuits of the semiconductor chips to wiring interposers of the lead frame via bonding connections.