Low-Cost Vacuum Molding Process for BGA Using a Large Area Substrate

We have developed a new ball grid array vacuum molding process using a large area substrate, called vacuum dip compression molding (VDCM), with the aim of reducing the substrate molding cost. The VDCM method imposes less of a burden on the environment because it enables efficient use of the substrate area for packaging, increasing the proportion of the effective area on the substrate. In contrast to the transfer molding method, VDCM does not generate cull or runner waste. VDCM also has the advantage of reducing the thickness of the mold resin. It can mold packages with various thicknesses using a single mold. Using VDCM equipment, we conducted a basic evaluation of molding performance. It was confirmed that no significant wire sweep occurred even when the wire length exceeded 3 mm, indicating that VDCM is less prone to wire sweep compared to transfer molding. The prototyped fine pitch ball grid arrays had a satisfactory level of moisture sensitivity.