composed  of  carbon  particles,  impregnated  in  the plastic, that provide volume conductivity throughout the  material. Antistatic ESD-Protective Materials Antistatic  materials  are  normally  plastic-type materials  (such  as  polyethylene,  polyolefin, polyurethane,  and  nylon)  that  are  impregnated  with  an antistatic substance. This antistatic migrates to the surface and combines with the humidity in the air to form  a  conductive  sweat  layer  on  the  surface.  This layer is invisible, and although highly resistive, it is amply   conductive   to   prevent   the   buildup   of electrostatic   charges   by   triboelectric   methods   in normal handling. Simply stated, the primary asset of an antistatic material is that it will not generate a charge on its surface.   However, this material won’t protect  an  enclosed  ESD  device  if  it  comes  into contact with a charged surface. This  material  is  of  a  pink  tint—a  symbol  of  its being  antistatic. Antistatic materials are for inner- wrap  packaging. However,  antistatic  trays,  vials, carriers, boxes, etc., are not used unless components and/or  assemblies  are  wrapped  in  conductive packaging. Hybrid ESD-Protective Bags Lamination of different ESD-protective material is  available.  This  combination  of  conductive  and antistatic  material  provides  the  advantage  of  both types in a single bag. ESDS DEVICE HANDLING The following are general guidelines applicable to  the  handling  of  ESDS  devices: l  Make  sure  that  all  containers,  tools,  test equipment,  and  fixtures  used  in  ESD-protected  areas are  grounded  before  and  during  use.  This  may  be done  either  directly  or  by  contact  with  a  grounded surface. l  Personnel  handling  ESDS  items  must  avoid physical activities that are friction-producing in the vicinity of ESDS items. Some examples are putting on  or  removing  smocks,  wiping  feet,  and  sliding objects  over  surfaces. .  Personnel  handling  ESDS  items  must  wear cotton  smocks  and/or  other  antistatically  treated clothing. . Avoid the use or presence of plastics, synthetic textiles,  rubber,  finished  wood,  vinyls,  and  other static-generating materials (table 10-1) where ESDS items  are  handled  out  of  their  ESD-protective packaging. l Place the ESD-protective material containing the ESDS item on a grounded work bench surface to remove  any  charge  before  opening  the  packaging material. .  Personnel  must  attach  personnel  grounding straps to ground themselves before removing ESDS items  from  their  protective  packaging. .  Remove  ESDS  items  from  ESD-protective packaging  with  fingers  or  metal  grasping  tool  only after  grounding,  and  place  on  the  ESD-grounded work  bench  surface. .  Make  periodic  electrostatic  measurements  at all ESD-protected areas. This   assures   the ESD-protective  properties  of  the  work  station  and  all equipment  contained  have  not  degraded. .   Perform   periodic   continuity   checks   of personnel  ground  straps,  ESD-grounded  work  station surfaces,  conductive  floor  mats,  and  other  con- nections   to   ground. Perform  this  check  with  a megohmmeter  to  make  sure  grounding  resistivity requirements  are  met. ESDS DEVICE PACKAGING Before an ESDS item leaves an ESD-protected area, package the item in one of the following ESD protective  materials: l  Ensure  shorting  bars,  clips,  or  noncorrective conductive materials are correctly inserted in or on all terminals  or  connectors. l Package ESDS items in an inner wrap, of type II  material  conforming  to  MIL-B-81705,  and  an  outer wrap  of  type  I  material  conforming  to  MIL-B-81  705. You may use a laminated bag instead of the above provided it meets the requirements of MIL-B-81705. Cushion-wrap   the   item   with   electrostatic-free material  conforming  to  PPP-C-1842,  type  III,  style  A. Place the cushioned item into a barrier bag fabricated from MIL-C-131 and heat-seal closed, method 1A-8. Place  the  wrapped,  cushioned,  or  pouched  ESDS  item in  bags  conforming  to  MIL-B-117,  type  I,  class  F, style I. Mark the packaged unit with the ESD symbol and caution as shown in figure 10-15. 10-18