Dual printing mask for screen printing
A dual printing mask is used for coating a die adhering paste of a predetermined pattern on a substrate uniformly during a semiconductor packaging process. This dual printing mask includes a metal mask layer having a predetermined pattern of openings so as to receive a paste for adhering a semiconductor die onto a substrate, and a mesh layer integrally attached on the metal mask layer.
1 . A printing mask for coating a paste layer of a predetermined pattern into a uniform thickness in order to adhere a semiconductor die onto a substrate, the printing mask comprising:
a metal mask layer having a predetermined pattern of openings so as to receive a paste for adhering a semiconductor die onto a substrate; and
a mesh layer integrally attached on the metal mask layer.
2 . The printing mask according to claim 1 ,
wherein the mesh layer has meshes whose size is smaller than that of the openings.
3 . The printing mask according to claim 1 ,
wherein the mesh layer is made of one material selected from the group consisting of nylon, polyester and stainless steel.
4 . The printing mask according to claim 1 ,
wherein the metal mask layer is made of stainless steel.
5 . The printing mask according to claim 2 ,
wherein the meshes of the mesh layer have lateral and vertical lengths of 25 to 2000 μm.