Printed Circuit Board Designing

1. Printed Ckt Board
Types of PCB
(I) Single Side (II) Double Side (III) Multi Layer
(V) Flexible PCB
* Single Side ( 1 layer ) :- The insulating substrate contains ckt pattern on
only one side. Which is called as solder side. The other side is called component side.
* Double Side (2 layer) :- Double side means the ckt pattern is present on
the either side of the insulating material ckt pattern both on component side & solder side.
* Flexible Cards :- Flexible boards are similar to rigid boards except
the board are made from a flexible substrate material. The base materials are very thin and
the common thickness is 0.1mm.

2. * Multi layer Board (MLB, 4L,6L,8L,12L,16L ) :-
The ckt density is high compare to D/S for inner layer
made of special laminate is used for bonding purpose ( Prepreg). The inner layer
is etched “CU” and outer layer is Non- etched ckt. After lamination or pressing
the boards are drilled and plated like PTH D/S.

3. Process Flow chart for Single Side P.C.B.
Sheet Cutting Film master preparation Screen Preparation
Drying Screen Printing Board cleaning
Retouching Etching Drilling Ink Stripping
Legend Printing Roller Tinning or HAL Masking
Final Cutting Q.C.

4. Process Flow Chart of Double Side P.C.B.
Sheet Cutting Film Master Preparation CNC Drilling
Photo Printing PTH or Electroplating Board Cleaning
Pattern Plating or Electro Plating Dry film Stripping Etching
H.A.L. Green Masking Tin Stripping
Legend Printing Final Cutting Q.C.

5. Mechanical Operation
* Sheet Cutting :- Measure the size of PCB from film or
Artwork.
W
L
* Board Area
Panel Sz.
PCB Sz.
Boarder Area
* Laminates or Copper Sheet :-
1. Glass Epoxy 2. Paper fenolic 3.Teflon 4. Ceramick (CEM)

6. * Glass Epoxy :- Thickness S/S 1.6 35/0 Cu Thickness
Insulating Material
thickness
D/S 0.8-18/18
1.6-18/18
2.4-18/18
3.2-18/18
Base material is reinforced with glass fiber or paper fiber as filler and epoxy resin and the cu
foil is pressured over it to get cu clad laminates.
* Paper Phenolic :- Phenolic laminates are reinforced with paper fillers and the cu foil
is pressed to the base material.
Thickness :- Fr-2, C-8000, 1.6- 35/0------ S/S, 0.8-18/18--- D/S
1.6- 18/18-----D/S

7. * Teflon Laminates :- Teflon is reinforced with glass fiber to get
aminates of low dielectric constant and it is used in Radio frequency.
* SHEARING MACHINE :- Used for laminate cutting for PCB
production.
* Manual Shearing * Motor drive Shearing.
* Final Cutting i.e. cutting in finish size.
* Shearing Blades :-Two Blades :- (I) Fixed Blades
(ii) Movable Blades.
* Punching :-Making Big hole, slot of different shape Die &Punch.
1 to 1.50

8. * Blanking :- Clean Cutting operation is done with a punching tool.
* Routing :- Final Cutting by CNC machine or Pin router
* Drilling :- (I) Manual Drilling
(ii) CNC Drilling ( Computer numeric Control)
* Manual Drilling :- * Used H.S.S. Drill Bit
* Speed of M/C is 6,000-16,000 RPM
* Stack Drilling
* Jig Drilling.

9. CNC Programming & Drilling
(I) Do path making
(II) Focus the Hole with help of camera and monitor.
(III) For time saving and maintained the accuracy.
(IV) After programming Drill one Panel for checking the
program.
(V) Checked Missing Hole, Extra Hole,Shifting, Inter changed Hole, Drill Dia (
Drill dia checked by Hole Gauge. )
T3 T2
T1 Path Making

10. * Drill Bit :- Tungsten Carbide drill bit used in CNC machine.
Shank dia
* In double side PCB drill dia is always 0.1mm extra from finish size.
3.175
*. Ink Stripping/ Dry film :-
To remove the ink by using Naoh or Koh solution.
Ink remove and the cu appears on track and pads only.

11. Masking
(I) Thermal Masking (II) PISM ( Photo Imagable solder Mask)
# Thermal Masking :-
*. Using Screen Printing.
*. -ve Masking film used in thermal masking.
*. Ink in paste form added Hardener and
masking reducer for making liquid form.
# P.I.S.M.:-
* Using Photo Printing Method.
* + ve Masking film used in PISM.
* Panel coated with PISM ink.
* Dry in oven or UV Light.
* Panel develop in Na2co3 solution.
# Peel off Test
#. To cover the panel with insulating ink.
#. To protect the cu for oxidation
# To avoid the short ckt.

12. Brushing (Surface Preparation)
To remove the dust particles and oxide layer from the surface of panel.
.
*. Chemical cleaning *. Mechanical cleaning
* Chemical Cleaning :- Using Alkali chemical to remove oil, grease & soil particle
on the surface of laminates.
* Mechanical Cleaning :-
Laminate Drilling Deburing (320 grid brush)
Water rinse Buffing (wet condition ) Water rinse
Drying (with hot blow air )

13. FILM MASTER PREPARATION
* High efficiency Compact camera used for reduction and inlargement
purpose.
Material Used :- (I) Lith film
(ii) Lith film Developer
(iii) Sodium Thosulphate
(iv) Developing Trays
(v) Retouching Ink
(vi) Retouching Brush
(vii) Butter Paper
* Art Work :- (I) Manual Artwork (ii) Take Design Print out
* Lith film Developer :- PART- “A”(P-Methyl amino phenol sulphats
PART- “B” ( Sodium Carbonate )
Temp.- 200
+--
30
c
* Fixer :- Sodium Thosulphate
* Retouching :- Using Opaque ink for cover the pin holes.

14. SCREEN PRINTING
It is done with the help of a wooden/ Aluminum frame having a
polyester cloth tightened over it. Polyester is available in different meshes. Which
are indicated by “T” that indicate the number of thread gapping.
Wooden frame
Three methods for Screen Printing :-
(I) Direct Method :- Ammonium dichromate or Potassium dichromate is
mixed with super coat solution in 1:3 ratio.

15. (II) Indirect Method :- Using Five Star film.
* Film Develop in H202 (Hydrogen Peroxide Solution )
(III) Direct-Indirect Method :- Chromaline film is used.
* Printing Ink :- Acid Resist Blue ink for Printing of
Single Side PCB.
* Squeegees :- The sharpness of the squeegees is very
important for printing. Line sharpness. Uniform ink
coating thickness and the edge definition depends on
the squeegees sharpness.

16. ETCHING
(1)Immersion (2) Bubble (3) Splash (4) spray Etching
* Ferric Chloride Etching Solution
Fecl3 350-500 g/ltr
HCL 60 to 65 ml/ltr
Temp 200
c to 300
c
Cu +Fecl3 Fecl2 +Cucl (Green Color )
* Chromic Sulfuric Acid Etchant
Chromic Acid
H2so4
Temp
200 to 240 g/ltr
60 to 65 ml/ltr
20 to 300
c

17. * Ammonium Chloride Etchant
Ammonium Bicarbonate
Ammonium Nitrate
Cupric Chloride
Ammonium Chloride
Temp
75g/ltr
80g/ltr
200g/ltr
100 to 110g/ltr
45 to 55o
C
* Etching Problems
1- Under Cut
2- Over Hang
Over Hang :- Excess metal growth on the side of the lone is
called over hang.
* ( Used in Spray Etching )

18. Electrolyses/ P.T.H (Plated Through Hole):-
The Copper will be deposited on hole wall without electricity.
* With the help of chemical reaction
* 2 to 5microne Cu ( Deposit on hole wall)
Most important process in double Side PCBs
Process of Electrolyses
1- Debarring
Drilled panel are cleaned using debarring machine
which uses a 320 grade silicon carbide brush.

19. 2 - Alkaline Soda Cleaning:-
Ginplate CC-50 5% by volume
D. I. Water 50%
Temp. 26 to 70o
C
W. R. 1- 2 Min.
3 - Micro Etch:- Ginplate Ad-481 120-150gm/l
D. I. Water To make one ltr.
H2SO4 5cc /ltr.
Time 2-5Min.
W.R. 1Min.

20. 4 - Pre-Activator
The function of this bath is to initiate the reaction of catalyst.
HCL 30%
Remain Water D. I. Water
Time 1min.
5- Activator
Gin plate -additive 443 5ml/l
Ginplate activator 76ml/l
Time 5-6 Min.
The function is to activate the entire surface including
metal and base.
6- Post Activator Gin Plate PA-491
Remaining
17%
D.I. Water
Its function is to remove stannic layer and to increases
the bonding of electrolyses cu and ensure uniform bonding.

21. *. Gin Plate Cu 406A
*. Gin Plate Cu 406B
*. Gin Plate Cu 406C
Water
Time
100ml/ltr
100ml/ltr
10ml/ltr
D.I. Remaining
10-12 Min.
PHOTO PRINTING
# Lamination :- Laminted the D/S Panel with P.P.D.F.R. Film
(Phto Polymer Dry Film Resist ) (1.0,1.5,2.0 mils)
Release Sheet of 1.0mil, Polthin 1.0mils
#. Normalizing
#. Expose in U.V. Light,
used +ve Pattern (ckt) film in D/S

22. #. Develop in Na2Co3 Solution ,
Take -ve image on Panal
#. In S/S PCB -ve ckt film is used
for mfg. Of S/S PCB
#. Temp- 110-115 0
c
Electro Plating
(1) Cu Plating (2) Tin Plating
* To increase the cu thickness of hole wall.
H2So4
CuSo4
Cupper acid
Current
Time
Anode
Anode Bag
10%
80g/l
7cc/l
2-3 Amp/Sq.dm
15min
Cu. Min-0.04-0.08%
Polypropylene
Anode Hook
Titanium or
Stainless Steel
Bath Tank P.v.c.

23. *. Tin Plating
Stannous Sulphate
H2So4
Stannous Carrer Additive
Stannolume Brighter
Time
Anode Current
Anode
30g/l
100ml/l
30ml/l
2ml/l
5min
1-2 Amp/dm2
60% Tin &40% Lead

24. *. Legend Printing or Back Marking
Used for identification of holes for which
component can be placed .Screen Printing method for Back marking
process.
*. Roller Tinning Or Hot Air Levelling ( H.A.L.)
To avoid the oxidation layer on Pads
# Flux ( Liquid)
# Sn+Pb ( Tin+ Lead) 60+40#. Temp- 2300
c to 2500
c

25. *. Final Cutting ( Routing)
To Cut the PCB in exact Size ad required by
the customer.
Quality Control
(I) Checking for short ckts.
(II) Checking for shifting
(III) Checking for required hole dia.
(IV) Checking for the proper masking.
(v) Checking for final cut and above all whether the PCB is
delivered in the same material as desired or not