A connection method for a chip and a circuit board includes: placing the circuit board on the chip, the circuit board having a first surface in contact with the chip having a plurality of contacts, and the circuit board having a plurality of through holes aligned with the plurality of contacts respectively; placing a mask on a second surface of the circuit board, the mask having a plurality of openings aligned with the plurality of through holes respectively; covering a surface of the mask with a conductive adhesive to fill the plurality of through holes with the conductive adhesive; and keeping portions of the conductive adhesive that are respectively in the plurality of through holes to be spaced apart from each other. The portions of the conductive adhesive that fill the plurality of through holes remain to provide an electrical connection between the circuit board and the chip.

A printed circuit board has an in-pad via. In a first step, a component is mounted on a first surface of a printed circuit board. A screen to be used in a second step has openings at positions corresponding to those of a plurality of pads on a second surface and has a recess positioned to overlap an in-pad via. Solder cream is applied from above the screen, and the screen is removed. Then, a component is mounted on the second surface.

Electrical input devices, conductive traces, and microcontroller interface devices can be created in a single print using a multi-material 3D printing process. The devices can include a non-conductive material portion and a conductive material portion. The non-conductive and conductive material portions are integrally formed during a single 3D printing process. For example, a fully functional QWERTY keyboard, ready to receive a microcontroller, can be multi-material 3D printed using the techniques described herein.

In a printed circuit board (1), thermal vias (19) are formed between the lower surface (A) and an upper surface (B) of the substrate plate (10) of the printed circuit board through the steps of: applying a respective solder resist mask (21, 31) to the lower surface (A) and the upper surface (B); applying solder to the lower surface (A) and reflow soldering the solder, wherein the solder penetrates into the boreholes (20) and forms convex menisci (26) protruding beyond the edge (22) of the respective boreholes on the lower surface (A); and creating regions (35) on the upper surface (B), which are freed from solder resist material, and which are intended for contacting at least one electronic component (17) on the upper surface and each of which comprise at least one of the thermal vias. Subsequently, the upper surface (B) can be provided with electrical components (17) on these regions (35). The first solder resist mask (21) has a respective region (23) that is free of solder resist on the lower surface around the edge of every borehole (20).

A printed circuit board has an in-pad via. In a first step, a component is mounted on a first surface of a printed circuit board. A screen to be used in a second step has openings at positions corresponding to those of a plurality of pads on a second surface and has a recess positioned to overlap an in-pad via. Solder cream is applied from above the screen, and the screen is removed. Then, a component is mounted on the second surface.

An electrical connection between the backplane and the light-transmissive front electrode of an electrowetting device is provided by forming an aperture through the top front electrode coupled and a substrate coupled thereto and subsequently introducing a flowable, electrically-conductive material into the aperture. The flowable, electrically-conductive material provides an electrical contact between the light-transmissive electrically-conductive layer and the backplane.

An electrical connection between the backplane and the light-transmissive front electrode of an electro-optic display is provided by forming an aperture through the top front electrode coupled and a substrate coupled thereto and subsequently introducing a flowable, electrically-conductive material into the aperture. The flowable, electrically-conductive material provides an electrical contact between the light-transmissive electrically-conductive layer and the backplane.

Fabrication of a reliable circuit board assembly with soldered, plated through-hole structures is facilitated by characterizing plating of a plated through-hole of the circuit board using time-domain reflectance to obtain a base reflectance measurement, and applying solder to the plated through-hole. Based on applying the solder, the plating of the plated through-hole of the circuit board is re-characterized using time-domain reflectance to obtain a new reflectance value. Based on a deviation between the new reflectance measurement and the base reflectance measurement exceeding a threshold, dissolution, at least in part, of the plating of the plated through-hole due to applying the solder is identified.

In a printed circuit board (1), thermal vias (19) are formed between the lower surface (A) and an upper surface (B) of the substrate plate (10) of the printed circuit board through the steps of: applying a respective solder resist mask (21, 31) to the lower surface (A) and the upper surface (B); applying solder to the lower surface (A) and reflow soldering the solder, wherein the solder penetrates into the boreholes (20) and forms convex menisci (26) protruding beyond the edge (22) of the respective boreholes on the lower surface (A); and creating regions (35) on the upper surface (B), which are freed from solder resist material, and which are intended for contacting at least one electronic component (17) on the upper surface and each of which comprise at least one of the thermal vias. Subsequently, the upper surface (B) can be provided with electrical components (17) on these regions (35). The first solder resist mask (21) has a respective region (23) that is free of solder resist on the lower surface around the edge of every borehole (20).

Fabrication of a reliable circuit board assembly with soldered, plated through-hole structures is facilitated by characterizing plating of a plated through-hole of the circuit board using time-domain reflectance to obtain a base reflectance measurement, and applying solder to the plated through-hole. Based on applying the solder, the plating of the plated through-hole of the circuit board is re-characterized using time-domain reflectance to obtain a new reflectance value. Based on a deviation between the new reflectance measurement and the base reflectance measurement exceeding a threshold, dissolution, at least in part, of the plating of the plated through-hole due to applying the solder is identified.