Control of under-fill with a packaging substrate having an integrated trench for a dual-sided ball grid array package
Described herein are methods of manufacturing dual-sided packaged electronic modules to control the distribution of an under-fill material between one or more components and a packaging substrate. The disclosed technologies include forming a trench in a packaging substrate that is configured to prevent or limit the flow of a capillary under-fill material. This can prevent or limit the capillary under-fill material from flowing onto or contacting other components or elements on the packaging substrate, such as solder balls of a ball-grid array. Accordingly, the disclosed technologies control under-fill for dual-sided ball grid array packages using a trench in a packaging substrate.
1. A method of fabricating a packaged radio-frequency (RF) device, the method comprising:
forming a trench in insulating material of a packaging substrate so that the trench does not penetrate to a conductive layer of the packaging substrate, the trench formed on an underside of the packaging substrate;
mounting electrical components to an upper side of the packaging substrate;
forming an over-mold over the electrical components mounted to the upper side of the packaging substrate;
mounting a lower electrical component to the underside of the packaging substrate;
mounting solder balls to the underside of the packaging substrate; and
under-filling the lower electrical component mounted on the second side of the packaging substrate with an under-fill material such that the under-fill material at least partially fills the trench formed in the insulating material of the packaging substrate, the void in the packaging substrate forming the trench not including conductive material.
2. The method of claim 1 wherein the trench is configured to limit the distribution of the under-fill material to maintain the under-fill material a targeted distance from the solder balls while providing targeted coverage under and around the lower electrical component.
3. The method of claim 1 further comprising singulating individual units from the packaging substrate to yield a plurality of dual-sided packages.
4. The method of claim 1 wherein the under-fill material includes a sealing resin or an epoxy.
5. The method of claim 1 further comprising curing the under-fill material.
6. The method of claim 1 wherein forming the trench includes using a solder mask process.
7. The method of claim 1 wherein the trench includes continuous trench structures.
8. The method of claim 1 wherein the trench includes a plurality of disconnected elongated trenches.
9. The method of claim 1 wherein the trench includes a plurality of voids in the substrate.
10. The method of claim 1 wherein the trench defines a keep out region that includes contact points for the lower electrical component and excludes contact points for the solder balls.