Navy Electricity and Electronics Training Series - Historic Naval ...

More documents

Recommendations

Info

Figure 3-21.—Flat pack in protective holder.LEAD-BENDING TECHNIQUES.—The 2M technician learns several methods of lead formingthat will provide proper contact for soldering and circuit operations. The techniques used to bend leadsinclude the use of specialized tools and such common items as flat toothpicks, bobby pins, and excesscomponent leads. Care is taken not to stress the seal of the component during any step of the leadforming. Figure 3-22 illustrates two views, view (A) and view (B), of properly formed flat-pack leads.Figure 3-22A.—Properly formed flat pack leads.Figure 3-22B.—Properly formed flat pack leads.3-30
Because most replacement flat packs come with leads that are longer than required, they must betrimmed before they are soldered. The removed part is used as a guide in determining lead length.Surgical scissors or scalpels are recommended for use in cutting flat-pack leads. Surgical scissors permitall leads to be cut to the required lead length in a smooth operation with no physical shock transmitted tothe IC.LAP-SOLDERING CONNECTIONS.—Before a connection is lap-soldered, the solder pads arecleaned and pretinned and the component leads are tinned. This is particularly important if they are goldplated. The IC is properly positioned on the pad areas, and the soldering process is a matter of "sweating"the two conductors together. When multilead components, such as ICs, are soldered, a skipping pattern isused to prevent excessive heat buildup in a single area of the board or component. When soldering iscompleted, all solder connections are thoroughly cleaned. All joints should be inspected and tested. Thestandards of workmanship are more specific for flat-pack installation.Q24. When removing the component, under what circumstances may component leads be clipped?Q25. How are imbedded TOs removed once the leads are free?Q26. How is a flat pack removed from a pcb?Q27. How do you prevent excessive heat buildup on an area of a board when soldering multileadcomponents?Q28. What are the two final steps of any repair?REPAIR OF PRINTED CIRCUIT BOARDS AND CARDSRemoval and replacement of components on boards and circuit cards are, by far, the most commontypes of repair. Equally important is the repair of damaged or broken cards. Proper repair of damagedboards not only maintains reliability of the board but also maintains reliability of the system.Cards and boards may be damaged in any of several ways and by a number of causes. Untrainedpersonnel making improper repairs and technicians using improper tools are two major causes ofdamage. Improper shipping, packaging, storage, and use are also common sources of damage. The sourceof damage most familiar to technicians is operational failure. Operational failures include cracking causedby heat, warping, component overheating, and faulty wiring.Before attempting board repairs, the technician should thoroughly inspect the damage. The decisionto repair or discard the piece depends on the extent of damage, the level of maintenance authorized,operational requirements, and the availability of repair parts and materials. The following procedures willhelp you become familiar with the steps necessary to repair particular types of damage. Remember, onlyqualified personnel are authorized to attempt these repairs.Repair of Conductor and Termination PadsConductor (run) and pad damage is very common. The technician must examine the board for nicks,tears, or scratches that have not broken the circuit, as well as for complete breaks, as shown in figure 3-23. Crack damage may exist as nicks or scratches in the conductor. These nicks or scratches must berepaired if over one-tenth of the cross-sectional area of the conductor is affected as current-carryingcapability is reduced. Cracks may also penetrate the conductor.3-31
Page 1 and 2:
NONRESIDENTTRAININGCOURSESEPTEMBER
Page 3 and 4:
PREFACEBy enrolling in this self-st
Page 5:
TABLE OF CONTENTSCHAPTERPAGE1. Micr
Page 8 and 9:
Module 11, Microwave Principles, ex
Page 10 and 11:
INSTRUCTIONS FOR TAKING THE COURSEA
Page 12 and 13:
THIS PAGE LEFT BLANK INTENTIONALLY.
Page 15 and 16:
CHAPTER 1MICROELECTRONICSLEARNING O
Page 17 and 18:
VACUUM-TUBE EQUIPMENTVacuum tubes w
Page 19 and 20:
SOLID-STATE DEVICESNow would be a g
Page 21 and 22:
FILM INTEGRATED CIRCUITS are broken
Page 23 and 24:
Development of a microelectronic de
Page 25 and 26:
Figure 1-9.—Crystal furnace.The c
Page 27 and 28:
Figure 1-12.—Planar-diffused tran
Page 29 and 30:
Figure 1-14.—Vacuum evaporation o
Page 31 and 32:
Figure 1-17.—Cathode-sputtering m
Page 33 and 34:
Q23. How do the two types of monoli
Page 35 and 36:
Figure 1-21A.—TO-5 mounting PLUG-
Page 37 and 38:
Dual Inline PackageThe dual inline
Page 39 and 40:
wafer, as shown in figure 1-27. Thi
Page 41 and 42:
Figure 1-29.—J-K flip-flop discre
Page 43 and 44:
Figure 1-31.—Lead numbering for a
Page 45 and 46:
Figure 1-34.—Manufacturer's Data
Page 47:
comparison to the distance between
Page 50 and 51:
LEVEL III.—Drawers or pull-out ch
Page 52 and 53:
Conductors located several layers b
Page 54 and 55:
Figure 1-43A.—Evolution of modula
Page 56 and 57:
ENVIRONMENTAL CONSIDERATIONSThe env
Page 58 and 59:
SUMMARYThis topic has presented inf
Page 60 and 61:
Rapid development has resulted in i
Page 62 and 63:
Large DIPs are being used to packag
Page 64 and 65:
MINIATURE ELECTRONICS are card asse
Page 66 and 67:
Three methods of interconnecting ci
Page 68 and 69:
ANSWERS TO QUESTIONS Q1. THROUGH Q5
Page 70 and 71:
A43. Conventional printed circuit b
Page 72 and 73: Upon satisfactory completion of a 2
Page 74 and 75: One such improvement in system test
Page 76 and 77: those that should be observed when
Page 78 and 79: Figure 2-2.—Low voltage Handpiece
Page 80 and 81: Figure 2-6.—Rotary-drive machine
Page 82 and 83: Figure 2-9.—Pana Vise.HAND TOOLSF
Page 84 and 85: Figure 2-10a.—Pliers.TweezersView
Page 86 and 87: Even though all the items are not u
Page 88 and 89: Figure 2-14.—Stereoscopic zoom mi
Page 90 and 91: other than eutectic, go through a p
Page 92 and 93: A1. Chief of Naval Operations (CNO)
Page 94 and 95: CAUTIONTHIS SECTION IS NOT, IN ANY
Page 96 and 97: The coating material can best be id
Page 98 and 99: Figure 3-3.—Rotary tool conformal
Page 100 and 101: Figure 3-4A.—Eyelets (interfacial
Page 102 and 103: Figure 3-5B.—Clinched leads. SEMI
Page 104 and 105: Figure 3-8A.—Terminals. PIN AND T
Page 106 and 107: Figure 3-8E.—Terminals. SOLDER CU
Page 108 and 109: Figure 3-10.—Solder wicking.This
Page 110 and 111: Figure 3-12B.—Motorized vacuum/pr
Page 112 and 113: INSTALLATION AND SOLDERING OF PRINT
Page 114 and 115: Figure 3-15.—Component arrangemen
Page 116 and 117: Figure 3-16.—Thermal shunt.APPLIC
Page 118 and 119: Removal of Plug-In DIPsTo remove pl
Page 120 and 121: Figure 3-19.—TO mounting techniqu
Page 124 and 125: Figure 3-23.—Pcb conductor damage
Page 126 and 127: REPAIRING DELAMINATED CONDUCTORS.
Page 128 and 129: 5. The repair is completed using th
Page 130 and 131: SAFETYSafety is a subject of utmost
Page 132 and 133: OBJECT OR PROCESSWORK SURFACESFLOOR
Page 134 and 135: 8. When moving an ESDS device or as
Page 136 and 137: Power ToolsHazards associated with
Page 138 and 139: dispensers will prevent many accide
Page 140 and 141: A GOOD SOLDER JOINT is bright and s
Page 142 and 143: ANSWERS TO QUESTIONS Q1. THROUGH Q3
Page 145 and 146: APPENDIX IGLOSSARYALLOWANCE PARTS L
Page 147 and 148: MODULAR PACKAGING—Circuit assembl
Page 149: APPENDIX IIREFERENCE LISTCHAPTER ON
Page 152 and 153: Microelectronics—Continuedpackagi
Page 155: Assignment QuestionsInformation: Th
Page 158 and 159: 1-7. Which of the following charact
Page 160 and 161: 1-24. Vacuum evaporation and cathod
Page 162 and 163: ___________________________________
Page 164 and 165: 1-49. Ground planes and shielding a
Page 166 and 167: 1-65. Which of the following types
Page 168 and 169: ASSIGNMENT 2Textbook assignment: Ch
Page 170 and 171: 2-20. Turret, fork, and hook termin
Page 172 and 173:
2-39. Component leads may be clippe
Page 174 and 175:
2-52. To ensure a good mechanical b
show all

Navy Electricity and Electronics Training Series - Historic Naval ...

Create successful ePaper yourself

Delete template?

Save as template?