In some embodiments, the present disclosure relates to a package assembly having a bump on a first substrate. A molding compound is on the first substrate and contacts sidewalls of the bump. A no-flow underfill layer is on a conductive region of a second substrate. The no-flow underfill layer and the conductive region contact the bump. A mask layer is arranged on the second substrate and laterally surrounds the no-flow underfill layer. The no-flow underfill layer contacts the substrate between the conductive region and the mask layer.

In some embodiments, the present disclosure relates to a package assembly having a bump on a first substrate. A molding compound is on the first substrate and contacts sidewalls of the bump. A no-flow underfill layer is on a conductive region of a second substrate. The no-flow underfill layer and the conductive region contact the bump. A mask layer is arranged on the second substrate and laterally surrounds the no-flow underfill layer. The no-flow underfill layer contacts the substrate between the conductive region and the mask layer.

A PoP semiconductor device has a top semiconductor package disposed over a bottom semiconductor package. The top semiconductor package has a substrate and a first semiconductor die disposed over the substrate. First and second encapsulants are deposited over the first semiconductor die and substrate. A first build-up interconnect structure is formed over the substrate after depositing the second encapsulant. The top package is disposed over the bottom package. The bottom package has a second semiconductor die and modular interconnect units disposed around the second semiconductor die. A second build-up interconnect structure is formed over the second semiconductor die and modular interconnect unit. The modular interconnect units include a plurality of conductive vias and a plurality of contact pads electrically connected to the conductive vias. The I/O pattern of the build-up interconnect structure on the top semiconductor package is designed to coincide with the I/O pattern of the modular interconnect units.

A PoP semiconductor device has a top semiconductor package disposed over a bottom semiconductor package. The top semiconductor package has a substrate and a first semiconductor die disposed over the substrate. First and second encapsulants are deposited over the first semiconductor die and substrate. A first build-up interconnect structure is formed over the substrate after depositing the second encapsulant. The top package is disposed over the bottom package. The bottom package has a second semiconductor die and modular interconnect units disposed around the second semiconductor die. A second build-up interconnect structure is formed over the second semiconductor die and modular interconnect unit. The modular interconnect units include a plurality of conductive vias and a plurality of contact pads electrically connected to the conductive vias. The I/O pattern of the build-up interconnect structure on the top semiconductor package is designed to coincide with the I/O pattern of the modular interconnect units.

A method for attaching a semiconductor die to a substrate includes providing a substrate that includes an attachment layer at a surface of the substrate. The attachment layer is covered by a protective flash plating layer. The protective flash plating layer has a reflow temperature less than or equal to a reflow temperature of the attachment layer. The method further includes preheating the substrate to a temperature greater than or equal to a reflow temperature of the attachment layer, attaching a semiconductor die to the attachment layer, and cooling the substrate and semiconductor die.

A solder pad includes a surface. A tin layer is arranged on the surface. At least one out of a bismuth layer, an antimony layer and a nickel layer is arranged on the tin layer.

A method of making an assembly can include juxtaposing a top surface of a first electrically conductive element at a first surface of a first substrate with a top surface of a second electrically conductive element at a major surface of a second substrate. One of: the top surface of the first conductive element can be recessed below the first surface, or the top surface of the second conductive element can be recessed below the major surface. Electrically conductive nanoparticles can be disposed between the top surfaces of the first and second conductive elements. The conductive nanoparticles can have long dimensions smaller than 100 nanometers. The method can also include elevating a temperature at least at interfaces of the juxtaposed first and second conductive elements to a joining temperature at which the conductive nanoparticles can cause metallurgical joints to form between the juxtaposed first and second conductive elements.

A method of making an assembly can include juxtaposing a top surface of a first electrically conductive element at a first surface of a first substrate with a top surface of a second electrically conductive element at a major surface of a second substrate. One of: the top surface of the first conductive element can be recessed below the first surface, or the top surface of the second conductive element can be recessed below the major surface. Electrically conductive nanoparticles can be disposed between the top surfaces of the first and second conductive elements. The conductive nanoparticles can have long dimensions smaller than 100 nanometers. The method can also include elevating a temperature at least at interfaces of the juxtaposed first and second conductive elements to a joining temperature at which the conductive nanoparticles can cause metallurgical joints to form between the juxtaposed first and second conductive elements.

A semiconductor structure includes: a first base having a first face, a second base having a second face and a welded structure. The first base is provided with an electrical connection column protruding from the first face. A conductive column is provided in the second base, and a first groove and a second groove are further provided at the second face. The first groove is located above the conductive column, and the second groove exposes at least part of a side surface of the conductive column. The protruding portion of the electrical connection column is located in the second groove, and part of a side surface of the electrical connection column and part of the side surface of the conductive column overlap in staggered way in a direction perpendicular to the first face or the second surface. At least part of the welded structure is filled in the first groove.

A method of forming a semiconductor package is provided. The method includes forming a metallization stack over a semiconductor die. Polymer particles are mounted over the metallization stack. Each of the polymer particles is coated with a first bonding layer. A heat spreader lid is bonded with the semiconductor die by reflowing the first bonding layer. A composite thermal interface material (TIM) structure is formed between the heat spreader lid and the semiconductor die during the bonding. The composite TIM structure includes the first bonding layer and the polymer particles embedded in the first bonding layer.