Abstract: Some implementations of the disclosure are directed to a method, comprising: receiving a sheet of graphite comprising a first surface and a second surface opposite the first surface; and perforating the sheet in a first plurality of locations from the first surface through the second surface to form a first plurality of perforations through the sheet and a first plurality of protrusions of the graphite oriented outward from the second surface, the first plurality of protrusions configured to conduct heat away from a plane of the sheet. Further implementations comprise perforating the sheet in a second plurality of locations from the second surface through the first surface to form a second plurality of perforations through the sheet and a second plurality of protrusions of graphite material oriented outward from the first surface, wherein the second plurality of protrusions are configured to conduct heat away from the plane of the sheet.

Abstract: Implementations of the disclosure are directed to thermally decomposable build plates that enable the facile release of 3D metal printed parts created by additive manufacturing. In some implementations, an additive manufacturing build plate comprises: a top surface, a bottom surface, and sidewalls comprised of a material, wherein the top surface, bottom surface, and sidewalls are dimensioned such that the build plate is useable in a 3D printing device; and a recessed section formed through the top surface, wherein the recessed section is configured to be filled with a solid metal or metal alloy to provide a surface for forming a 3D printed object in the 3D printing device.

Abstract: High reliability leadfree solder alloys for harsh service conditions are disclosed. In some embodiments, a solder alloy comprises 2.5-4.0 wt % Ag; 0.4-0.8 wt % Cu; 5.0-9.0 wt % Sb; 1.5-3.5 wt % Bi; 0.05-0.35 wt % Ni; and a remainder of Sn. In some embodiments, an apparatus comprises: a component comprising: a main ceramic body, and a side surface having disposed thereon an electrode and a thermal pad; a copper substrate; and a solder alloy electrically coupling the component and the copper substrate, wherein the solder alloy comprises: 2.5-4.0 wt % Ag; 0.4-0.8 wt % Cu; 5.0-9.0 wt % Sb; 1.5-3.5 wt % Bi; 0.05-0.35 wt % Ni; and a remainder of Sn. In some embodiments, an apparatus comprises: a light-emitting diode (LED) component; a Metal Core Printed Circuit Board (MCPCB); and a solder alloy electrically coupling the LED component and the MCPCB, wherein the solder alloy comprises: 2.5-4.0 wt % Ag; 0.4-0.8 wt % Cu; 5.0-9.0 wt % Sb; 1.5-3.5 wt % Bi; 0.05-0.35 wt % Ni; and a remainder of Sn.

Abstract: Some implementations of the disclosure relate to a lead-free solder paste with mixed solder powders that is particularly suitable for high temperature soldering applications involving multiple board-level reflow operations. In one implementation, the solder paste consists of 10 wt % to 90 wt % of a first solder alloy powder, the first solder alloy powder consisting of an SnSbCuAg solder alloy that has a wt % ratio of Sn:Sb of 0.75 to 1.1; 10 wt % to 90 wt % of a second solder alloy powder, the second solder alloy powder consisting of an Sn solder alloy including at least 80 wt % of Sn; and a remainder of flux.

Abstract: Implementations of the disclosure are directed to a lead-free mixed solder powder paste suitable for low temperature to middle temperature soldering applications. The lead-free solder paste may consist of: an amount of a first solder alloy powder between 44 wt % and 83 wt %, the first solder alloy powder comprising Sn; an amount of a second solder alloy powder between 5 wt % to 44 wt %, the second alloy powder comprising Sn, where the first solder alloy powder has a liquidus temperature lower than a solidus temperature of the second solder alloy powder; and a remainder of flux. The solder paste may be used for reflow at a peak temperature below the solidus temperature of the higher solidus temperature solder powder but above the melting temperature of the lower solidus temperature one.

Abstract: Some implementations of the disclosure are directed to a solder preform, comprising: a solder alloy body, the solder alloy body comprising at least one opening; and a flux core embedded in the solder alloy body, the flux core comprising a thermochromic indicator, wherein during reflow soldering, the flux core comprising the thermochromic indicator is configured to flow out of the at least one opening of the solder alloy.

Abstract: Some implementations of the disclosure are directed to a thermal interface material. In some implementations, a method comprises: applying a solder paste between a surface of a heat generating device and a surface of a heat transferring device to form an assembly; and reflow soldering the assembly to form a solder composite, wherein the solder composite provides a thermal interface between the heat generating device and the heat transferring device, wherein the solder paste comprises: a solder powder; particles having a higher melting temperature than a soldering temperature of the solder paste, wherein the solder paste has a volume ratio of solder powder to high melting temperature particles between 5:1 and 1:1.5; and flux.

Abstract: A SnAgCuSb-based Pb-free solder alloy is disclosed. The disclosed solder alloy is particularly suitable for, but not limited to, producing solder joints, in the form of solder preforms, solder balls, solder powder, or solder paste (a mixture of solder powder and flux), for harsh environment electronics.

Abstract: Implementations of the disclosure are directed to a lead-free mixed solder powder paste suitable for low temperature to middle temperature soldering applications. The lead-free solder paste may consist of: an amount of a first solder alloy powder between 44 wt % and 83 wt %, the first solder alloy powder comprising Sn; an amount of a second solder alloy powder between 5 wt % to 44 wt %, the second alloy powder comprising Sn, where the first solder alloy powder has a liquidus temperature lower than a solidus temperature of the second solder alloy powder; and a remainder of flux. The solder paste may be used for reflow at a peak temperature below the solidus temperature of the higher solidus temperature solder powder but above the melting temperature of the lower solidus temperature one.

Abstract: A SnAgCuSb-based Pb-free solder alloy is disclosed. The disclosed solder alloy is particularly suitable for, but not limited to, producing solder joints, in the form of solder preforms, solder balls, solder powder, or solder paste (a mixture of solder powder and flux), for harsh environment electronics. An additive selected from 0.1-2.5 wt. % of Bi and/or 0.1-4.5 wt. % of In may be included in the solder alloy.

Abstract: A method of joining a semiconductor die to a passive heat exchanger can include applying a bond enhancing agent to a semiconductor device; creating an assembly that includes a thermal interface disposed on the semiconductor device such that a first major surface of the thermal interface material is in touching relation with the bond enhancing agent on the semiconductor device, and a heat exchanger disposed in touching relation with a second major surface of the thermal interface material; and reflowing the assembly such that the thermal interface bonds the heat exchanger to the semiconductor device. Embodiments can use the ability of indium to bond to a non-metallic surface to form the thermal interface, which may be enhanced by a secondary coating on either or both joining surfaces.

Abstract: A semiconductor device assembly includes: a semiconductor device; a heat exchanger; and a thermal interface material. In embodiments, the thermal interface material may contact a facing surface of the heat exchanger, the thermal interface material includes alloys that react with a bond enhancing agent to form an indium alloy layer in a portion of the thermal interface. In embodiments, a solid, solder preformed thermal interface material includes an indium metal and may be disposed on the first surface of the semiconductor device; and a liquid metal bond enhancing agent may be disposed on a first surface of the semiconductor device; and contacting a facing surface of the heat exchanger.

Abstract: A lead-free solder preform includes a core layer and adhesion layer coated over surfaces of the core layer, where the preform delivers the combined merits from constituent solder alloys of the core and adhesion layers to provide both high temperature performance and improved wetting in high-temperature solder applications such as die attach. The core layer may be formed of a Bi Alloy having a solidus temperature above 260° C., and the adhesion layer may be formed of Sn, a Sn alloy, a Bi alloy, In, or an In alloy having a solidus temperature below 245° C. The solder preform may be formed using techniques such as: (1) electroplating a core ribbon with an adhesion material, (2) cladding an adhesion material foil onto a core ribbon, and/or (3) dipping a core ribbon in a molten adhesion alloy bath to allow thin layers of adhesion material to adhere to a core ribbon.

Abstract: Some implementations are directed to a burn-in solder preform including: a barrier layer to prevent thermally conductive material from adhering to a semiconductor component during burn-in testing; and a thermally conductive cladding layer attached to a portion of the barrier layer such that at least one dimension of the barrier layer extends past the thermally conductive cladding layer, where the thermally conductive cladding layer is attached over the barrier layer through continuous attachment or spot attachment. In some implementations, a method includes: placing the aforementioned burn-in solder preform between a test fixture and a semiconductor component; attaching a portion of the barrier layer of the burn-in solder preform to a head of the text fixture; and after attaching a portion of the barrier layer of the burn-in solder preform to the head of the test fixture, performing burn-in testing of the semiconductor component.

Abstract: Implementations of the disclosure describe techniques for eliminating or reducing hot tearing in via-in-pad plated over (VIPPO) solder joints by incorporating an adhesive into a printed circuit board assembly (PCBA). In an embodiment, the adhesive is an adhesive containing fluxing agent that prevents tearing by reducing a differential in thermal expansion caused by a coefficient of thermal expansion (CTE) mismatch between a plated metal of the VIPPO pads and the PCB substrate.

Abstract: The disclosure describes techniques for eliminating or reducing non-wet open (NWO) defect formation by using a low activity flux to prevent a solder paste from sticking to ball grid array (BGA) solder balls during reflow soldering. The low activity flux may be configured such that: i) it creates a barrier that prevents the solder paste from sticking to the solder balls of the BGA; and ii) it does not impede the formation of solder joints during reflow. In implementations, a solid coating of the low activity flux may be formed over balls of the BGA, and the BGA may then be bonded to a PCB during reflow. In implementations, the balls of a BGA may be dipped in a low-activity creamy or liquid flux prior to reflow. In some implementations, the flux may applied on a solder paste printed on pads of the PCB, followed by placement of a BGA.

Abstract: A method of joining a semiconductor die to a passive heat exchanger can include applying a bond enhancing agent to a semiconductor device; creating an assembly that includes a thermal interface disposed on the semiconductor device such that a first major surface of the thermal interface material is in touching relation with the bond enhancing agent on the semiconductor device, and a heat exchanger disposed in touching relation with a second major surface of the thermal interface material; and reflowing the assembly such that the thermal interface bonds the heat exchanger to the semiconductor device. Embodiments can use the ability of indium to bond to a non-metallic surface to form the thermal interface, which may be enhanced by a secondary coating on either or both joining surfaces.

Abstract: Methods are provided for controlling voiding caused by gasses in solder joints of electronic assemblies. In various embodiments, a preform can be embedded into the solder paste prior to the component placement. The solder preform can be configured with a geometry such that it creates a standoff, or gap, between the components to be mounted in the solder paste. The method includes receiving a printed circuit board comprising a plurality of contact pads; depositing a volume of solder paste onto each of the plurality of contact pads; depositing a solder preform into each volume of solder paste; placing electronic components onto the printed circuit board such that contacts of the electronic components are aligned with corresponding contact pads of the printed circuit board; and reflow soldering the electronic components to the printed circuit board.

Abstract: A braided solder wire rope includes a first alloy including Bi—Ag, Bi—Cu, Bi—Ag—Cu, or Bi—Sb; and the second alloy including Sn, In Sn—Ag, Sn—Cu, Sn—Ag—Cu, Sn—Zn, Bi—Sn, Sn—In, Sn—Sb or Bi—In, such that the second alloy controls an interface reaction chemistry with various metallization surface finish materials without interfering with a high temperature performance of the first alloy. The first alloy may have a solidus temperature around 258° C. and at least the first alloy of the first wire and the second alloy of the second wire may be braided together.

Abstract: A solder paste consists of an amount of a first solder alloy powder between 60 wt % to 92 wt %; an amount of a second solder alloy powder greater than 0 wt % and less than 12 wt %; and a flux; wherein the first solder alloy powder comprises a first solder alloy that has a solidus temperature above 260° C.; and wherein the second solder alloy powder comprises a second solder alloy that has a solidus temperature that is less than 250° C.