Electricity circuit soldering

In fabrication of printed circuit boards (Goh 1994), a resin formula is prepared and impregnated with fibreglass and other particles. This is baked to form a panel or a board. Lamination involves metallic copper being bonded to the board in (sandwiched) layers. Each side of the laminate is cleaned, photoprinted and etched to form the electrical circuits. Solder plating is done, and the boards are drilled and cut to the required sizes. Finally, the boards are marked and tested. 

Solder (alloy of tin and lead) used for joining metals, e.g. in electrical circuits. 

Steel is an alloy containing chromium, manganese, molybdenum, nickel, vanadium and boron. Copper-nickel alloy, bronze and aluminium alloys are used in making coins. Fusible alloys having low melting points are used as solder and fuses in electrical circuits. 

I have used the well-known photo-electric cell to examine the lines. The lines are horizontal. Just below them is a horizontal black line in the figure at the center of which lies a very narrow horizontal slit in the side of the small metal box. The metal box contains the photo-electric cell just behind the slit. The positive anode of the photo-electric cell is joined to earth through the metal box, all connections being soldered. The inner negative surface of the cell, from which the electrons proceed, is connected to the negative pole of a battery contained in the larger metal box d. To complete the electrical circuit of the photo-electric cell, the positive pole of the battery is joined through a heavily insulated,... 

Liquid solutions usually freeze at lower temperatures than the pure liquids, with the freezing point depression (for aqueous solutions) being directly related to the amount of solute dissolved. Certain proportions of two metals often freeze at a temperature much lower than for other proportions. The proportions of these two metals that freeze at the minimum temperature is called the eutectic mixture. One useful eutectic mixture is tin/lead in a 60/40 mixture. Pure lead melts at 327°C pure tin melts at 232°C. The 60/40 mixture, called solder, melts at 190°C, lower than for either metal alone. For this reason, 60/40 solder is often used for constructing electric circuits. 

Seebeck effect A current circulates in the loop formed with two different materials under the effect of a temperature difference between the two soldered joints. The electric circuit is closed (electrically isolated) and the global potential difference is zero. The thermal circuit is powered by a heat source (providing an entropy flow fs). Thermocouple A potential difference appears at the terminals of an open circuit made up of two different materials having their soldered joints brought to two different temperatures. The electric circuit is open and the electric current is zero. (The temperature is the same for each terminal BO, B3 of the circuit.)... 

This shows that he does not appreciate the difference between a drawing of some physical components soldered together (= mechanical connection) which does not lead to a device that has any electrical meaning as no current can flow and an electrical circuit diagram in which connections may coincide with physical connections (soldering points), but may as well be conceptual. 

Many metallic elements are contained in electronic assemblies either as terminations or coatings for component devices or as the electrical circuit, terminations, or coatings on PWBs. The elimination of lead in electronic products requires substitution by other metals that can provide the performance and reliable properties characteristic of traditionally used lead-bearing alloys. There are a number of metal resources that can be selected as substitutes for lead in solders and as coatings for lead-free electronic assemblies. These metals include tin (Sn), silver (Ag), copper (Cu), bismuth (Bi), antimony (Sb), gold (Au), indium (In), nickel (Ni), palladium (Pd), platinum. 

Because of the ease with which they can be soldered, electroplated tin—lead coatings of near eutectic composition (62 wt % tin) are extensively used in the electronics industry for coating printed circuit boards and electrical coimectors, lead wires, capacitor and condenser cases, and chassis. 

The generally very good electrical insulation properties coupled with heat resistance and non-burning behaviour indicate usage in coil bobbins, printed circuit boards (which resist heat of soldering), lamp bulb bases and TV... 

Films have been used for insulating electric motors, in capacitors requiring a heat resistance not met by conventional polyester and polycarbonate dielectrics and as a soldering-resistant base for flexible printed circuits. 

These qualities have also lead to its use on printed circuit boards and on electrical connectors, although the persistent oxide film obstructs easy solderability and produces too high a contact resistance for satisfactory switching at low voltages. 

---