Manufactered by : CRC Industries Europe NV Touwslagerstraat 1 – 9240 Zele – Belgium
Tel  (32) (0) 52/45.60.11  Fax  (32) (0) 52/45.00.34                  Technical Data Sheet
KONTAKT CHEMIE Positiv 20 Page 1/5 Photo-positive resist KONTAKT CHEMIE Positiv 20 Description: Liquid photo-resist with 0-Naphtho-chinon-diazide / Novolack base General properties and applications: KONTAKT    CHEMIE    Positiv    20    is    a    classic    liquid    photo-resist   for   a   wide   variety   of
applications.   The   product   can   be   applied   anywhere   where   patterns   must   be   transferred
directly   onto   working   materials   for   processing   by   etching,   electroplating,   etc.      Typical
applications   are   the   production  of  printed  circuit  boards,    a  range  of  photo-lithographical
processes on metals, glass and suitable synthetic materials.
The   lacquer   is   at   its   most   photo-sensitive  at  close  ultra-violet  range  (UVA).  The  lacquer
should therefore be applied in yellow light.  Windows can be darkened with yellow Plexiglass
(e.g.  Röhm  Darmstadt,  Type  Yellow  303).    KONTAKT  CHEMIE  Positiv  20  is  resistant  to
oxidizing agents, ammoniacal to strongly acidic solutions. Coats of Positiv 20 which are no
longer  required  can  be  easily removed (stripped) by solvents (Ester, Ketone) or 10 to 30 %
sodium or potasium hydroxide aqueous solution. Technical data As delivered Colour                                                     blue, transparent Aerosol Flash point <0°C Density at 20°C FEA 605 0.780 g/cm³ coverage Filmthickness 8 µm calculated 1 m² / 200 ml spray Bulk Flash point ASTM D 56 <0°C Density ASTM D 891 (C) 0.871 g/cm³ Coverage at 8 µm calculated 8.4 m²/l

Manufactered by : CRC Industries Europe NV Touwslagerstraat 1 – 9240 Zele – Belgium
Tel  (32) (0) 52/45.60.11  Fax  (32) (0) 52/45.00.34 KONTAKT CHEMIE Positiv 20 Page 2/5 Properties of the lacquer coating Maximum spectral photo-sensitivity UVA, 340 nm to 420 nm Typical thickness recommended 6 µm to 8µm 20°C 24 h Drying time 70°C Recommended, IR or
circulating air dryer, special
care must be taken! 15 min Developer With correct lighting and
film thickness of the
coating.
Developing time approx. 1
min. at room temperature. Sodium Hydroxide
7g / l in water Recommended etching agents Copper, brass Etching temperature 40°C
Bath agitation e.g. by air Fe(III)Cl(35-40%)
400 g/l in water Aluminium Room temperature Fe(III)Cl (35-40%)
200 g/l in water Steel, zinc Follow safety regulations!
Only to be applied by
specialists. HCl (10%) Silver Etching temperature 60°C.  
Follow safety regulations!  
Only to be applied by
specialists! Cure Positiv 20 :
20 mins, 160°C to 190°C HNO3 (65%) Glass Room temperature, Follow
safety regulations! Only to
be applied by specialists! Hydrofluoric acid 40% Plating Processes   Check resistance of the
Positiv 20 lacquer.  If
insufficient adhesiveness,
cure the lacquer (20 min
120°C to 190 °C) Ammoniacal to strongly
acidic solutions Room temperature Solvent :
Acetone,
Methyl-ethyl-ketone
Butyl acetate Stripper 20°C to 50°C.  
Pay particular attention to
safety notices with highly
concentrated alkaline
solutions! Aqueous alkaline:
Sodium hydroxide,
50 g/l to 300 g/l in water Storage of coated materials Heat and light proof 4 weeks at 25°C Maximum storage time of
KONTAKT CHEMIE Positiv 20 Store at ±10 °C in light
proof containers (brown
glass bottles) 1,5 year from filling date
at max. 25°C

Manufactered by : CRC Industries Europe NV Touwslagerstraat 1 – 9240 Zele – Belgium
Tel  (32) (0) 52/45.60.11  Fax  (32) (0) 52/45.00.34 KONTAKT CHEMIE Positiv 20 Page 3/5 Surface preparation: Surfaces  must  be  free  of  grease  and  oxide.  Solvents  are  only  used  when  dirty,  oily  stains
have to be removed.  Otherwise a water-based cleaning process has proved to be the best.  
When preparing metal surfaces manually, household scouring powders are ideal.  To ensure
this,   clean   with   a   good   detergent   (Vim,   ATA   or   other   powdered   cleanser).   Rub   in   the
detergent with a moist rag so that it brightens the copper surface, removes any oxides and
makes  the  copper  layer  completely  wettable.  This  can  be  checked  by  running  the  surface
under a tap to make sure that there are no water-repellent areas left.  After rinsing the plate
thoroughly with water, dry it between sheets of absorbent paper taking extreme care to avoid
any  fingerprints  on  the  board  surface.  For  large  areas  use  rollers  fitted  with  abrasive  pads
(e.g.   3M   Scotch   Brite)   and   rinse   with   purified   water.   Glass   should   be   prepared   using
commercial glass cleaning agents or chromic acid and rinsed with purified water. Applying the coat: Spray-coating: Spray-coating with the aerosol can is the easiest for small production runs.  That way there is
no risk of the lacquer stocks being contaminated with dust.
Larger areas can be coated with the bulk product using normal spray guns.  The diameter of
the spray nozzle, the spraying distance and the spray pressure must be determined in trials.  
The  lacquer  is  applied  as  delivered.    The  compressed  air  must  be  free  from  oil  and  dust.   
Close the canister lid immediately after removing the Positiv 20. Dip-coating: This kind of coating can only be recommended in exceptional cases, as the Positiv 20 stocks
can only be kept sufficiently clean in the bath with considerable cost of time and effort (clean
atmosphere).    A  guideline  for  the  copying  speed  is  approx.  1cm/s  to  3  cm/s.    For  double-
sided   circuit   boards   or   other   highly   3-dimensional  structured  surfaces,  dip-coating  is  not
suitable.  Positiv  20  is  applied  as  delivered.    The  viscosity  must  be  checked  constantly,  a
viscosity cup with a 3 mm opening in accordance with ISO 2431 is suitable.  If the flow-out
time is greater than (over 10%) the time taken with new Positiv 20, thinners should be added
in small quantities. KONTAKT CHEMIE thinner for Urethan 71 is ideal or Acetone.  In bigger
baths Positiv 20 must be filtered regularly, e.g. through a 10µm candle filter.
Glass,   high-grade  steel  or  polytetrafluoroethylene  are  suitable  materials  for  the  container.  
Washers made of butyl rubber  are suitable, however their resistance must be tested.  Viton
and EPDM are not suitable! Spin Coating: Commercial spin coating equipment is used. The desired film thickness is obtained by adjust-
ment of the rotation speed and spinning is to be continued until the coating is sufficiently dried. Drying: After  application  of  the  sprayed-on coating, boards must be dried immediately in the dark. If
necessary, the coating can be dried at room temperature which will take at least 24 hours.
This  gives  only  a  sufficient  quality  for  very  simple  work.  If  the  temperature  is  too  low  the
adhesive strength of the Positiv 20 coating is reduced and the risk of dust contamination is
very   high.   It   is   safer   to   accelerate   drying,   infra-red  drying  or  drying  in  a  thermostatically
controlled  oven.  Always  make  sure  that  all  opening  are  covered  and  any  source  of  light  is
shut  off.  Raise  the  temperature  slowly  to  70°C  maximum  and  dry  at  this  temperature  for
about 20 minutes.  Caution: Any drying temperature exceeding 70°C is liable to damage the
electrical components on the board!  If there are problems with developing, it is a good idea
to measure the oven temperature.

Manufactered by : CRC Industries Europe NV Touwslagerstraat 1 – 9240 Zele – Belgium
Tel  (32) (0) 52/45.60.11  Fax  (32) (0) 52/45.00.34 KONTAKT CHEMIE Positiv 20 Page 4/5 Exposure: Time required for exposure depends on both the thickness of the film and the intensity of the
light source. The spectral sensitivity for the Positiv 20 lies within the wavelength range 360
and 410 nm.  Vapour lamps using iron or pure mercury are ideal.  For small areas (up to 30 x
30  cm²)                         lamps  of  the  OSRAM  Vitalux  type  are  suitable.    If  the  correct  thickness  of  coat  is
chosen (6µm to 8µm) the developing time will be approx. 60 seconds.  Large areas can be
exposed   by,   for   example,   impure   5kW   iron   burners   type   MO   61   Fa.      Sylviana.      If   the
exposure  strength  is  100  mJ/cm²    the  exposure  time  will  be  approx.  10  seconds  for  a  film
which is 8µm thick. Developing: Developing   may   not   be   performed   in   direct   light,   dark   conditions   are   preferred.      For
developing,  7  g/l  sodium  hydroxide  in  water  is  used.    The  developer  is  applied  at  room
temperature.  After a maximum of 2 minutes the image should be fully developed. If not the
board   is   under   exposed.      Normally   the   exposed   sections   of   the   Positiv   20   coating   are
removed in the developer, the original copper is clearly visible. The circuits are now outlined
in a different colour compared to the copper. Do not leave the plate in the developer for an
overlong time, otherwise it will attack the unexposed parts of the Positiv 20 coating. In cases
of over-exposure and if the ink drawings are not completely opaque, the image of the circuits
will appear for a short time but will eventually be removed by the developer.
It  is  important  to  assist  the  developing  process  by  agitating  the  bath  or  better  by  slightly
wiping  with  a  lint-free  cloth  or  by  spraying with the developer solution. Air movement is not
suitable  as  the  sodium  hydroxide  would  be  very  quickly  used  up  by  reaction  with  carbon
dioxide from the air.  For this reason the developer should be kept in closed containers after
use.  After developing, the workpieces are rinsed thoroughly with tap water (rinsing pressure
1.0  bar  to  1.5  bar).    If  work  is  not  going  to  continue  straight  away,  pieces  must  be  dried
immediately.    Complete,  streak-free  developing  is  the  key  to  perfect  etching.    With  copper
etching  you  can  tell  if  the  developing  is  successful  by  the  fact  that  the  light,  shiny  surface
immediately turns dark. Thermal cure: For  easily  etched  material  in  typical  acidic  or  ammoniacal  etchants  no  additional
curing  is  required.    Anyhow  for  etching  of  difficult  to  etch  materials  (steel  or  steel
alloys)  requiring  long  etching  times,  an  additional  thermal  cure  after  developing  is
recommended.    This also applies for subsequent plating processes in critical plating
baths.    Normally  a  thermal  cure  of  10   to  30  minutes  at  120°C  is  sufficient,  but  for
difficult to etch metals a thermal cure at 160 to 190 °C is suggested. Very hot cured
coats can only be removed mechanically (scourers, brushes).    Etching:   After development and if necessary curing the Positiv 20 coating is resistant to acid baths of
ferric chloride, ammonium persulphate, chromic acid and hydrofluoric acid. The latter two are
used  when  etching  glass  plates  using  the  usual  processing  methods.  For  the  etching  of
copper plates we recommend an etching bath of ferric chloride solutions (35-40%) heated to
approximately 45°C

Manufactered by : CRC Industries Europe NV Touwslagerstraat 1 – 9240 Zele – Belgium
Tel  (32) (0) 52/45.60.11  Fax  (32) (0) 52/45.00.34 KONTAKT CHEMIE Positiv 20 Page 5/5 Stripping of the lacquer When applied in small quantities the Positiv 20 coating can simply be wiped off with a cloth
soaked in acetone.  If cured above 120 °C and for large print runs a solution of 50 g/l to 300
g/l  of  sodium  hydroxide  in  water,  at  elevated  temperatures,  is  used.    A  mechanical  aid,
spraying  or  wiping  increases  the  stripping  speed.  To  keep  the  water  level  in  the  stripper
topped up, used developer can be added.
Used stripper solutions can be handled in the following way:
Acidify  with  hydrochloric  acid  to  a  pH  of  3.    The  largest  portion  of  the  organic  material  is
thereby removed.  Leave it standing overnight then decant off or draw off the clear solution.  
Add sodium hydroxide until the pH of the separated solution reaches 6.5 to 9.  In most cases
it can then be poured into the drainage system.  However, the regulations of the local water
authorities   must   be   followed.      Dispose  of  the  organic  residue  as  lacquer  sludge  (waste
classification  lacquer  and  paint  sludge  55503).    Proceed  with  care  when  neutralising  the
solutions!  Depending on their concentration levels they can become very hot, so wear safety
spectacles. Safety: Avoid skin contact with the Positiv 20 solution, developer and etching solutions.  Hydrochloric
acid should only be used as an etching agent in exceptional circumstances as its vapours
are highly corrosive. Metal equipment is attacked very quickly.  The hydrofluoric acid needed
for  glass  etching  is  very  dangerous.    It  may  only  be  used  by  fully-trained personnel.  It is
essential  to  wear  protective  clothing,  rubber  gloves  and  safety  spectacles.    Rooms  to  be
used for coating must be well ventilated.  Used air from the drier and the coating area must
be vented outside.  Drier and coating installations must be suitable for use with flammable
liquids classified as VbF B. Available Aerosol : 100 ml, 200 ml
Bulk : 1 l These values are not intended to be used as specifications.  They are based on what we believe
reliable.  However it is the user’s responsibility to determine the suitability.
Version number : 20820 03 0401 01