Chapter 34

Question 1

Define: Surface Mount vs. Through-hole Technology

Answer 1

Surface Mount: (SMT) is more widely used in industry; uses an assembly method in which component leads are soldered to lands on the surface of the board rather than into holes running through the board. By eliminating the need for leads inserted into through holes in the board, several advantages are gained (smaller components available, densities can be increased, and components an be mounted on both sides of the board)

Through-Hole: in circuit board assembly, lead pins are inserted into through-holes in the circuit board. Once inserted, the leads are soldered into place in the holes on the board.

Question 2

Define: Etching

Answer 2

Process in which copper cladding is removed from unprotected regions from the board surface, ususally by means of a chemical etchant. Etching is the transforms the solid copper film into the interconnections for an electrical circuit

Question 3

Define: Plating

Answer 3

Plating is needed onto the hole surface to provide conductive paths form one side to the other in double sided boards or between layers in multilayer boards.

Question 4

Define: Circuitization

Answer 4

The processing sequence involved in transforming a copper-clad board of reinforced polymer into a printed circuit board.

Question 5

Define: Solder Paste

Answer 5

A suspension of solder powders in a flux binder. Has three functions: it is the solder, it is the flux, and it is the adhesive that temporarily secures the components to the surface of the board.

Question 6

Define: Wave Soldering

Answer 6

After adhesion to the plate, the board is put through wave soldering, which places molten solder on mold joints.

Question 7

Define: Crimping

Answer 7

Mechanical deformation of the terminal barrel to form a permanent connection with the stripped end of a wire inserted into it. The crimping operation squeezes and closes the barrel around the bare wire. Done with hand tools or crimping machines.