A method for producing a joined structure according to the present invention includes: a reflow step of heating a first member and a solder material while keeping them in contact with each other in a reflow chamber to melt a solder alloy constituting the solder material, the reflow step including: a first reflow step of melting the solder alloy with an atmosphere in the reflow chamber reduced to a first pressure P.sub.1 lower than the atmospheric pressure; and a second reflow step of, after the first reflow step, melting the solder alloy with the atmosphere in the reflow chamber reduced to a second pressure P.sub.2 lower than the first pressure P.sub.1.

Embodiments relate to using flux or underfill as a trapping layer for temporarily attaching light emitting diodes (LEDs) to a substrate and heating to simultaneously bond multiple LEDs onto the substrate. The flux or underfill may be selectively coated at the ends of electrodes of the LEDs prior to placing the LEDs on the substrate. Due to adhesive properties of the flux or underfill, multiple LEDs can be placed on and attached to the substrate prior to performing the bonding process. Once LEDs are placed on the substrate, the flux or underfill facilitates formation of metallic contacts between electrodes of the LED and contacts of the substrate during the bonding process. By using the flux or underfill, the formation of metallic contacts can be performed even without applying pressure.

Embodiments relate to using flux or underfill as a trapping layer for temporarily attaching light emitting diodes (LEDs) to a substrate and heating to simultaneously bond multiple LEDs onto the substrate. The flux or underfill may be selectively coated at the ends of electrodes of the LEDs prior to placing the LEDs on the substrate. Due to adhesive properties of the flux or underfill, multiple LEDs can be placed on and attached to the substrate prior to performing the bonding process. Once LEDs are placed on the substrate, the flux or underfill facilitates formation of metallic contacts between electrodes of the LED and contacts of the substrate during the bonding process. By using the flux or underfill, the formation of metallic contacts can be performed even without applying pressure.

According to an embodiment, a temperature of an inside of a furnace is set to fall within a range of a reduction temperature or more of a carboxylic acid and less than a melting temperature of a solder bump, and the inside is concurrently set to have a first carboxylic acid gas concentration. Thereafter, the temperature of the inside is raised up to the melting temperature, and the inside is concurrently set to have a second carboxylic acid gas concentration. The second carboxylic acid gas concentration is lower than the first carboxylic acid gas concentration, and is a concentration containing a minimum amount of carboxylic acid gas defined to achieve reduction on an oxide film of the solder bump. The inside has the second carboxylic acid gas concentration at least at a time when the temperature of the inside reaches the melting temperature.

Provided is a method for setting the conditions for heating a semiconductor chip during bonding of the semiconductor chip using an NCF, wherein a heating start temperature and a rate of temperature increase are set on the basis of a viscosity characteristic map that indicates changes in viscosity with respect to temperature of the NCF at various rates of temperature increase and a heating start temperature characteristic map that indicates changes in viscosity with respect to temperature of the NCF when the heating start temperature is changed at the same rate of temperature increase.

A stack type power module includes: a power semiconductor having a gate and an emitter, each of which has a pad shape, adjacent to each other on one surface of the power semiconductor, and a collector having a pad shape on another surface of the power semiconductor; an upper substrate layer stacked on an upper portion of the power semiconductor, and electrically connected to a metal layer that has a lower surface with which the collector is in contact; and a lower substrate layer stacked on a lower portion of the power semiconductor, and electrically connected to the metal layer that has an upper surface with which each of the gate and the emitter is in contact.

Embodiments relate to using flux or underfill as a trapping layer for temporarily attaching light emitting diodes (LEDs) to a substrate and heating to simultaneously bond multiple LEDs onto the substrate. The flux or underfill may be selectively coated at the ends of electrodes of the LEDs prior to placing the LEDs on the substrate. Due to adhesive properties of the flux or underfill, multiple LEDs can be placed on and attached to the substrate prior to performing the bonding process. Once LEDs are placed on the substrate, the flux or underfill facilitates formation of metallic contacts between electrodes of the LED and contacts of the substrate during the bonding process. By using the flux or underfill, the formation of metallic contacts can be performed even without applying pressure.

A stack type power module includes: a power semiconductor having a gate and an emitter, each of which has a pad shape, adjacent to each other on one surface of the power semiconductor, and a collector having a pad shape on another surface of the power semiconductor; an upper substrate layer stacked on an upper portion of the power semiconductor, and electrically connected to a metal layer that has a lower surface with which the collector is in contact; and a lower substrate layer stacked on a lower portion of the power semiconductor, and electrically connected to the metal layer that has an upper surface with which each of the gate and the emitter is in contact.

A method includes picking up a first package component, removing an oxide layer on an electrical connector of the first package component, placing the first package component on a second package component after the oxide layer is removed, and bonding the first package component to the second package component.

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.