Electrical Engineering Stack Exchange is a question and answer site for electrical and electronics engineering professionals, students, and enthusiasts. Horizontal setup of through-hole components with 2 axial leads (for example, resistors, capacitors, and diodes) is done by bending the leads 90 degrees in precisely the same way, including the part in the board (frequently bending leads positioned on the back of the board in opposite directions to enhance the part’s mechanical strength), soldering the leads, and trimming off the ends.
Prior to the advent of integrated circuits , this procedure allowed the highest possible component packing density; as of the, it was utilized by a number of computer vendors including Control Data Corporation The cordwood method of construction was used only rarely once semiconductor electronic equipment and PCBs became prevalent.
This led to very short design times (no more complex algorithms to work with even for high density designs) and decreased crosstalk (that is worse when cables run parallel to each other–which http://www.mspecllc.com almost never occurs in Multiwire), although the price tag is too high to compete with more affordable PCB technologies when large quantities are needed.
Chemical etching is typically done using ammonium persulfate or ferric chloride For PTH (plated-through holes), further steps of electroless deposition are done after the holes are drilled, then copper is electroplated to build up the depth, the boards are screened, and garnished with tin/lead.
In surface-mount technologies (SMT), the component is placed on the PCB so that the pins line up with the conductive components or pads on the surfaces of their PCB; solder paste, that was previously applied to the pads, holds the parts in place; if surface-mount parts are applied to both sides of the plank, the bottom-side components are glued to the board.
Surface mount components can be approximately one-quarter to one-tenth of the dimensions and weight of through-hole parts, and passive elements much cheaper; prices of semiconductor surface mount devices (SMDs) have been determined more by the chip itself than the bundle, with little cost advantage over bigger bundles.
A printed circuit board (PCB) mechanically supports and electrically connects electronic components using conductive tracks, pads and other features etched from aluminum sheets laminated onto a non-conductive substrate Components (e.g. capacitors , resistors or busy devices) are generally soldered on the PCB.