An embodiment composite material for semiconductor package mount applications may include a first component including a tin-silver-copper alloy and a second component including a tin-bismuth alloy or a tin-indium alloy. The composite material may form a reflowed bonding material having a room temperature tensile strength in a range from 80 MPa to 100 MPa when subjected to a reflow process. The reflowed bonding material may include a weight fraction of bismuth that is in a range from approximately 4% to approximately 15%. The reflowed bonding material may an alloy that is solid solution strengthened by a presence of bismuth or indium that is dissolved within the reflowed bonding material or a solid solution phase that includes a minor component of bismuth dissolved within a major component of tin. In some embodiments, the reflowed bonding material may include intermetallic compounds formed as precipitates such as Ag.sub.3Sn and/or Cu.sub.6Sn.sub.5.

An electronic device includes a substrate including first and second metal regions, a first passive device that includes a metal joining surface and is arranged on the substrate with the metal joining surface of the first passive device facing first metal region, a semiconductor die that includes a metal joining surface and is arranged on the substrate with the metal joining surface of the semiconductor die facing the second metal region, a first soldered joint between the metal joining surface of the first passive device and the first metal region; and a second soldered joint between the metal joining surface of the semiconductor die and the second metal region, wherein a minimum thickness of the first soldered joint is greater than a maximum thickness of the second soldered joint.

Ball grid assembly (BGA) bumping solder is formed on the back side of a laminate panel within a patterned temporary resist. Processes such as singulation and flip chip module assembly are conducted following BGA bumping with the temporary resist in place. The resist is removed from the back side of the singulated laminate panel prior to card assembly. Stand-off elements having relatively high melting points can be incorporated on the BGA side of the laminate panel to ensure a minimum assembly solder collapse height. Alignment assemblies are formed on the socket-facing side of an LGA module using elements having relatively high melting points and injected solder.

A method for soldering a surface-mount component onto a circuit board. The melting of die-bonding solder material is prevented by using a mounting solder material when soldering a surface-mount component formed using the die-bonding solder material onto a printed circuit board. The surface-mount component, formed using (SnSb)-based solder material having high melting point, the (SnSb)-based solder material containing Cu but not more than a predetermined quantity of Cu constituent and a main ingredient thereof being Sn, is soldered on a board terminal portion of a circuit board using (SnAgCuBi)-based solder material or (SnAgCuBiIn)-based solder material as the mounting solder material and with the solder material being applied on the terminal portion. Since solidus temperature of the die-bonding solder material is 243 degrees C. and liquidus temperature of the mounting solder material is about 215 through 220 degrees C., the melting of die-bonding solder material is prevented even at the heating temperature (240 degrees C. or less) of a reflow furnace.

The melting of die-bonding solder material is prevented even when soldering a surface-mount component formed using the die-bonding solder material on a printed circuit board using a mounting solder material. The surface-mount component formed using (SnSb)-based solder material having high melting point as the solder material for die pad, the (SnSb)-based solder material containing Cu not more than a predetermined quantity of Cu constituent and a main ingredient thereof being Sn, is soldered on a board terminal portion of a circuit board using (SnAgCuBi)-based solder material as the mounting solder material with the solder material being applied on the terminal portion. The melting of die-bonding solder material is prevented even at the heating temperature (240 degrees C. or less) of a reflow furnace.

Ball grid assembly (BGA) bumping solder is formed on the back side of a laminate panel within a patterned temporary resist. Processes such as singulation and flip chip module assembly are conducted following BGA bumping with the temporary resist in place. The resist is removed from the back side of the singulated laminate panel prior to card assembly. Stand-off elements having relatively high melting points can be incorporated on the BGA side of the laminate panel to ensure a minimum assembly solder collapse height. Alignment assemblies are formed on the socket-facing side of an LGA module using elements having relatively high melting points and injected solder.

A method and a system for stacking printed circuit boards includes providing a lower baseboard, a pinboard, and an upper baseboard; printing a first solder paste on the lower baseboard; placing a placement component on the lower baseboard; placing the pinboard on the lower baseboard; reflow soldering the lower baseboard with the placement component and the pinboard and forming a first assembly; printing the first solder paste and a second solder paste on the upper baseboard; placing the placement component on the upper baseboard and the first assembly on the upper baseboard; and reflow soldering the upper baseboard with the placement component and the first assembly and forming a printed circuit board; a melting point of the first solder paste is higher than a melting point of the second solder paste.

A dual solder layer for fluidic self assembly, an electrical component substrate, and method employing same is described. The dual solder layer comprises a layer of a self-assembly solder disposed on a layer of a base solder which is disposed on the solder pad of an electrical component substrate. The self-assembly solder has a liquidus temperature less than a first temperature and the base solder has a solidus temperature greater than the first temperature. The self-assembly solder liquefies at the first temperature during a fluidic self assembly method to cause electrical components to adhere to the substrate. After attachment, the substrate is removed from the bath and heated so that the base solder and self-assembly solder combine to form a composite alloy which forms the final electrical solder connection between the component and the solder pad on the substrate.

An electrical device for soldering to a circuit board with a solder includes a capacitor, a lead frame including a solder dam, and a solder joint electrically coupling the capacitor to the lead frame. The solder dam includes one of a physical barrier to flow or an area of reduced wettability to the solder. The solder dam is between the solder joint and the circuit board. The solder dam is on one or both of a lead portion and main portion of the lead frame. In one embodiment, the first solder dam extends substantially the full width of the first lead portion. The solder dam may be a barrier and/or include a metal oxide. A method of manufacturing the device includes soldering a lead frame to a capacitor with a solder and modifying a surface on the lead frame to include a physical barrier and/or an area of reduced wettability.

An embodiment composite material for semiconductor package mount applications may include a first component including a tin-silver-copper alloy and a second component including a tin-bismuth alloy or a tin-indium alloy. The composite material may form a reflowed bonding material having a room temperature tensile strength in a range from 80 MPa to 100 MPa when subjected to a reflow process. The reflowed bonding material may include a weight fraction of bismuth that is in a range from approximately 4% to approximately 15%. The reflowed bonding material may an alloy that is solid solution strengthened by a presence of bismuth or indium that is dissolved within the reflowed bonding material or a solid solution phase that includes a minor component of bismuth dissolved within a major component of tin. In some embodiments, the reflowed bonding material may include intermetallic compounds formed as precipitates such as Ag.sub.3Sn and/or Cu.sub.6Sn.sub.5.