3 Difference between PCB Layout and bread board connection
4 Bread board ADVANTAGES: DISADVANTAGES: 1. A QUICK CHECK FOR EASY AND COMPLEX CIRCUITS BOTH AND VERIFIES CIRCUITS AT INITIAL STAGE.2.REUSABLE.3.NO SOLDERING REQUIRED.4.CAN BE DEBUGGED EASILY.5.CHEAP AND CONNECTIONS CAN BE CHANGED.DISADVANTAGES:1. UNRELIABLE.2. DELICATE.3.TEMPORARY.4.HEAVIER.
5 PCB There are subdivided into, A printed circuit board, or PCB, is used to mechanically support and electrically connect electronic components using conductive pathways, tracks or signal traces etched from copper sheets laminated onto a nonconductive substrate. It is also referred to as printed wiring board(PWB) or etched wiring board. Printed circuit boards are used in virtually all but the simplest commercially produced electronic devices.Components used for PCBCopper cladded sheetsThere are subdivided into,paper phinallyglass epoxy
6 Advantages of PCB Inexpensive/cheaper High volume production Automated soldering is possibleHighly reliableHold the component easily
7 Thickness Of Copper0.8mm(used for low power component( e.g.: slim phone,smd,multimeter)1.6mm(used in commercial purpose)3.2mm(power electronics sideExamples: MOSFET, Diode.
9 Manual printing Get the required size copper board. Draw the layout on the board using permanent marker or nail police.Etching process.Fix the component on the boardCheck the output
10 Photo-resist methodThe main properties characterizing the photo resist types are:Photo resists are classified into two groups: positive resists and negative resistspositive resist methodnegative resist method
11 Positive resist method A positive resist is a type of photo resist in which the portion of the photo resist that is exposed to light becomes soluble to the photo resist developer. The portion of the photo resist that is unexposed remains insoluble to the photo resist developer.Negative resist methodA negative resist is a type of photo resist in which the portion of the photo resist that is exposed to light becomes insoluble to the photo resist developer. The unexposed portion of the photo resist is dissolved by the photo resist developer.
12 Characteristic Positive Negative Adhesion to Silicon Fair Excellent Relative Cost Less Expensive Developer Base Aqueous Organic Minimum Feature μm and below ± 2 μ step Coverage Better LowerWet Chemical Resistance Fair Excellent
14 Screen printingScreen printing printed circuit boards is typically performed in a clean, dust free room using semi-automatic or fully-automatic screen printing presses. The most common PCB panel size is 53 x 72 cm, with the printing area around 50 x 70 cm. The printed panel may contain many PCB panels that are printed at once, and will eventually be separated.
15 1.4 Soldering MethodsHand soldering: It is the oldest method of soldering, it is still popular method in certain kinds of applications: Development of prototype boardsLow volume productionSoldering of extremely temperature sensitive componentsSolder reflow of fine pitch components using hot barRework or repair of machine soldered boardsThe main disadvantages are operator training, speed, and consistent quality.
16 1.4.2 Machine Soldering: Two prominently used machine soldering types are: A. Wave Soldering Primarily used for soldering through-hole components on to PCBs.B. Reflow Soldering.Used for soldering SMD components on to PCBs. Reflow soldering of SM components have the following advantages over manual soldering:Mass solderingConsistency in manufacture through precise control of process parameters.flexible for small production runs as well.
17 Etching process Fecl3+cu->cucl3+fe The following are used for etchingHCLCupric chlorideFerric chlorideAmmonium chloride.Fecl3+cu->cucl3+fe
18 Method of etchingHand drought methodSplash methodSpray method
19 Solder mask Solder mask is used to prevent oxidization solder able solder maskUn solder able solder mask
20 Why masking?a. Protect tracks from environmental effects suc as corrosionb. avoid between two electrical components during soldering, testing.c. Protects PCB material from environmental effects.
21 Plating To avoid corrosion brightness easy solder able deposit harder than ordinary platingcorrosion resistancenon-stainingnon-toxic
22 SoftwareEagle version (Easily Applicable Graphically Layout Editor)PCB WizardPad2padSpark PCB