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

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REPAIRING DELAMINATED CONDUCTORS.—DELAMINATED CONDUCTORS (figure 3-26) are classified as conductors no longer bonded to the board surface. Separation of the laminations mayoccur only on a part of the conductor. Proper epoxying techniques ensure complete bonding of theconductor to the circuit board laminate. The following procedures are used to obtain a proper bond:Figure 3-26.—Delaminated conductors.1. A small amount of epoxy is mixed and applied to the conductor and the conductor path; no areasare left uncoated.2. The conductor is clamped firmly against the board surface until the epoxy has completely cured.REPLACING EYELETS.—Eyelets have been referred to in several places in this topic. Not onlyare they used for through-the-board terminations, but also to reinforce some types of board repairs. Aswith any kind of material, eyelets are subject to damage. Eyelets may break, they may be installedimproperly, or they may be missing from the equipment. When an eyelet is missing or damaged,regardless of the kind of damage, it should be replaced. The guidelines for the selection and installation ofnew eyelets are far too complex to explain here. However, they do comprise a large part of the 2Mtechnician's training.Repair of Cracked BoardsWhen boards are cracked, the length and depth of the cracks must be determined. Also, thedisruption to conductors and components caused by cracks must be determined by visual inspection. Toavoid causing additional damage, the technician must exercise care when examining cracked boards and3-34
must not flex the board. Rebuilding techniques must be used to repair damage, such as cracks, breaks, andholes that extend through the board. The following steps are used to repair cracks:1. Abrasive methods are used to remove all chips and fractured material.2. The edges of the removed area are beveled and undercut to provide bond strength.3. A smoothly surfaced, nonporous object is fastened tightly against one side of the removed area.4. The cutaway area is filled with a compound of epoxy and powdered fiberglass (figure 3-27).Extreme care is exercised to prevent the formation of voids or air bubbles in the mixture.Figure 3-27.—Repair of cracked pcbs.5. The surface of the filled area is smoothed to make it level with the surface of the original board.6. The board is cured, smoothed, redrilled, and cleaned.Broken Board RepairBroken boards should be examined to determine if all parts of the board are present and if circuitconductors or components are affected by the break. They are also examined to determine if the brokenpieces may be rejoined reliably or if new pieces must be manufactured.Breaks and holes are repaired in the same manner as cracks unless broken pieces are missing or thehole exceeds 1/2 inch in diameter. In such cases, the following repair steps are used:1. The same technique used in repairing cracks is used to prepare the damaged edge.2. A piece as close in size to the missing area as possible is cut from a scrap board of the same typeand thickness. The edges of this piece are prepared in the same manner as the edges of the hole.3. A smooth-surfaced object is tightly fastened over one side of the repair area, and the board isfirmly clamped in an immovable position with the uncovered area facing up.4. The replacement piece is positioned as nearly as possible to the original board configuration andfirmly clamped into place.3-35
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NONRESIDENTTRAININGCOURSESEPTEMBER
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PREFACEBy enrolling in this self-st
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TABLE OF CONTENTSCHAPTERPAGE1. Micr
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Module 11, Microwave Principles, ex
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INSTRUCTIONS FOR TAKING THE COURSEA
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THIS PAGE LEFT BLANK INTENTIONALLY.
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CHAPTER 1MICROELECTRONICSLEARNING O
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VACUUM-TUBE EQUIPMENTVacuum tubes w
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SOLID-STATE DEVICESNow would be a g
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FILM INTEGRATED CIRCUITS are broken
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Development of a microelectronic de
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Figure 1-9.—Crystal furnace.The c
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Figure 1-12.—Planar-diffused tran
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Figure 1-14.—Vacuum evaporation o
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Figure 1-17.—Cathode-sputtering m
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Q23. How do the two types of monoli
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Figure 1-21A.—TO-5 mounting PLUG-
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Dual Inline PackageThe dual inline
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wafer, as shown in figure 1-27. Thi
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Figure 1-29.—J-K flip-flop discre
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Figure 1-31.—Lead numbering for a
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Figure 1-34.—Manufacturer's Data
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comparison to the distance between
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LEVEL III.—Drawers or pull-out ch
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Conductors located several layers b
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Figure 1-43A.—Evolution of modula
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ENVIRONMENTAL CONSIDERATIONSThe env
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SUMMARYThis topic has presented inf
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Rapid development has resulted in i
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Large DIPs are being used to packag
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MINIATURE ELECTRONICS are card asse
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Three methods of interconnecting ci
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ANSWERS TO QUESTIONS Q1. THROUGH Q5
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A43. Conventional printed circuit b
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Upon satisfactory completion of a 2
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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 122 and 123: Figure 3-21.—Flat pack in protect
Page 124 and 125: Figure 3-23.—Pcb conductor damage
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
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