pcb-lab2

PCB Manufacturing steps

Exposing
After properly aligning films on the photoresist laminated board, the board is
exposed by a UV light on both sides in the UV exposure unit.

Spray developing
The exposed board is developed in a spray developer unit. The developer solution is sprayed on both sides of the board by a spray rotating system. Afterwards the rest of the non‐exposed laminate is removed by a rinsing process, whereas the exposed laminate is etch resistant and thus protects the circuit pattern against etching

Etching process
In that process the UV nonexposed copper is etched. Afterwards the etch resistant
material over the tracks, pads of PCB is rinsed by means of a solvent attack.

Solder resist masking/Legend printing (optional)
In our lab this is done manually by screenprinting process.

A. OVERALL GUIDELINES (SUMMARY )

Maximum PCB size which can be fabricated: 10 inches x 12 inches                    
Minimum PCB size which can be fabricated: 3 inches x 2 inches                        
Maximum track width possible: 100 mil                                                                           
Minimum track width possible: 8 mil                                                                                    
Minimum clearance required for perfect plot: 8 mil
legend-printing

B. DETAILED GUIDELINES FOR PCB JOB ORDER

B.1 Pad dimension requirements

Inner diameter is 33 mil minimum. Higher values will automatically be mapped  to nearest hole drill bit available. Must be at least 4 mil greater than component lead
diameter to allow considerations for minimum copper plating thickness in the hole.

Outer diameter is 55 mil minimum and an integer values thereafter.

Differencebetween inner diameter and outer diameter must be 20 mil minimum to ensure good copper area for soldering. This also applies to those footprints which
have been specially created for the purpose by the designer. For SMDs, the standard pad size specified by the component manufacturer may be used.

B.2 Via requirements

Inner diameter is 24 mil minimum to ensure correct feedthrough. Outer diameter is 40 mil minimum.

B.3 Fill requirements

Copper fills for power planes need to be created with basic blocks of squares of thefollowing dimensions: blocks of sizes 10 mil to 100 mil in steps of 5 mil; blocks of
sizes 100 mil to 200 mil in steps of 10 mil. Considerable overlapping between these building blocks is necessary to ensure no visible gaps in the photo plot.

B.4 Maximum primitive dimension
The photoplotter at PCB fab facility, IIT Kanpur can accept and plot aperture sizes up
to 100 mil. So the designer might take this into consideration before designing the
PCB. If any dimension higher than this is needed, he/she might have to use some
basic primitives. For example, if a track of 150 mil is required, a 100 mil track and a
55 mil track can be placed side by side with a 5 mil overlap to get a 150
mil track.
masking

B.5 Hole drill bits available at the facility

Manual Drill
78.70 mil (2.0 mm), 62.99 mil (1.6 mm), 51.18 mil (1.3 mm), 39.37 mil (1.0 mm), 35.43 mil
(0.9 mm), 31.49 mil (0.8 mm), 27.56 mil (0.7 mm), 23.62 mil (0.6 mm), 19.69 mil (0.5 mm)
CNC Mill/Drill
118.11 mil (3.0 mm), 59.06 mil (1.5 mm), 51.18 mil (1.3 mm), 43.31 mil (1.1 mm), 39.37 mil
(1.0 mm), 35.43 mil (0.9 mm), 31.49 mil (0.8 mm), 27.56 mil (0.7 mm), 23.62 mil (0.6 mm)
RF Cutters
78.70 mil (2.0 mm), 39.37 mil (1.0 mm), 15.75 mil (0.4 mm),7.87 mil (0.2 mm), 5.91 mil
(0.15 mm)

B.6 Solder Masking/Legend Printing Facility: Available on request

B.7 Copper thickness on board

Single layer: Options of 1.38 mil (35 microns) with a board thickness of 62.99 mil (1.6
mm) and 2.76 mil (70 microns) with a board thickness of 94.49 mil (2.4 mm) are
available. Board material is Glass Epoxy or Paper Phenolic.
Double layer: Options of 1.38 mil (35 microns) and 0.67 mil (17 microns) both with a
board thickness of 62.99 mil (1.6 mm) are available. Board material is Glass Epoxy
(FR4).
multilayered-pcb

C. Basic PCB Design Issues
IIT Kanpur PCB Design Guide Sheet Page 23 of 26 
The designer can use auto‐route tools of the PCB design software he/she is using.
But care must be taken that all dimensions are of integer values. Usually the designer
can restrict the auto‐route tool to use only integer dimensions by setting design rules
for the PCB. It must also be ensured to keep outer most layer, a little larger in
dimension than the actual board. A mechanical layer called ‘Mechanical Layer 4’
showing the actual dimensions of the board must be incorporated. This helps the
fabricator to correctly use the CNC machine for drilling holes into the PCB. The origin
of the PCB dimensions must also be set a little far, diagonally from the left bottom
corner of the board. Please refer to the documentation of the PCB design software
used for further information.
The PCB design name must also be mentioned either on the top layer or the bottom
layer for a dual layered PCB. The text placement tool of the concerned PCB design
software can be used. It is a good practice to make sure that the name of the file
which contains the PCB design represents the PCB design very closely
oven

D. Recommended CAD Software
Altium Protel DXP Suite 2004
Note: If DXP 2004 is being used, please ensure that the .PCBDOC file is exported to
PCB Version 4 Binary format (.PCB file) before ordering the PCB. The file which
results due to the export must be directly sent to PCB fab for processing. Opening
this file in DXP again could result in problems with the existing procedure .
Note: Please send only the final PCB file while ordering .
pcb-lab

E. Ordering, Fabrication and Delivery

The final file required for fabrication must be submitted in the PCB Lab after filling up
the PCB job order form The process might result in delivery periods of 2‐3 weeks for
normal PCBs and 3‐4 weeks for PCBs with green masking and legend printing. 
These times may vary a bit depending on the queue pending at the facility and
the process conditions of the PCB. Single layer PCBs will be delivered in less than 2
weeks time. PCB fabrication is a time and resource consuming process and hence is
done with utmost care. Any complaints regarding the PCB fabrication and quality
may directly be addressed to the PCB fabrication facility in charge

pcb-lab2

F. Glossary of terms
Footprint : The pattern and space on a board taken up by a component.
Clearance : The spacing required between two entities on a PCB to ensure safe
operation.
Photoplotter: ( also “vector plotter”, or “Gerber photoplotter” after Gerber Scientific
Co., which built the first vector photoplotters for commercial use). It plots images
from a CAD database on photographic film in a darkroom by drawing each line with a
continuous lamp shined through an annular‐ring aperture, and creating each shape
(or pad) by flashing the lamp through a specially sized and shaped aperture. 
Gerber File : Data file used to control a photoplotter. Named after Gerber Scientific
Co., who made the original vector photoplotter .
Aperture: An indexed shape with a specified x and y dimension, or line‐type with a
specified width, used as a basic element or object by a photoplotter in plotting
geometric patterns on film. The “apertures” are thin trapezoidal pieces of plastic
which are mostly opaque, but with a transparent portion that controls the size and
shape of the light pattern passing through it.
Track : Besides its usual definition of a strand of conductor, wire on a printed board
also means a route or track .

facility-of-inspection

facility

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pcb-lab2

Setting the Schematic Options

The first thing to do before you start drawing your circuit is to set up the appropriate document options. Complete the following steps.

1. From the menus, choose Design » Document Options and the Document Options dialog will open.
For this tutorial, the only change we need to make here is to set the sheet size to standard A4 format.
In the Sheet Options tab, find the Standard Styles field.
Click the arrow next to the entry to see a list of sheet styles.

2. Select the A4 style and click OK to close the dialog and update the sheet size.

3. To make the document fill the viewing area again, select View » Fit Document.
In Altium Designer, you can activate any menu by pressing the menu hotkey (the underlined letter in the
menu name). Any subsequent menu items will also have hot keys that you can use to activate the item.
For example, the shortcut for selecting the View » Fit Document menu item is to press the V key followed by the D key. Many submenus, such as the Edit » DeSelect menu, can be called directly.
To activate the Edit » DeSelect » All on Current
Document menu item, you need only press the X key (to call up the DeSelect menu directly) followed by the S key.

Next we will set the general schematic preferences.
1. Select Tools » Schematic Preferences [shortcut: T, P] to open the schematic Preferences dialog.
This dialog allows you to set global preferences that will apply to all schematic sheets you work on.

2. Click on Schematic – Default Primitives in the selection tree (left side of the dialog) to make it the
active page and enable the Permanent option. Click OK to close the dialog.

3. Before you start capturing your schematic, save this schematic sheet, so select File » Save [shortcut:F, S].

http://www.saltlakecityhotelstoday.com/wp-content/uploads/2016/10/Schematic-Options.jpg

pcb-lab2

Creating a New Schematic Sheet

Create a new schematic sheet by completing the following steps:

1. Select File » New » Schematic, or click on Schematic Sheet in the New section of the Files panel. A blank schematic
sheet named Sheet1.SchDoc displays in the design window and the schematic document is automatically added (linked)
to the project. The schematic sheet is now listed under Source Documents beneath the project name in the Projects tab.
http://www.saltlakecityhotelstoday.com/wp-content/uploads/2016/10/Schematic-Sheet.jpg

2. Rename the new schematic file (with a .SchDoc extension) by selecting File » Save As. Navigate to a location where you would like to store the schematic on your hard disk, type the name Multivibrator.
SchDoc in the File Name field and click on Save.

When the blank schematic sheet opens you will notice that the workspace changes.
The main toolbar includes a range of new buttons, new toolbars are visible, the menu bar includes new items and the Sheet panel is displayed.
You are now in the Schematic Editor.

You can customize many aspects of the workspace. For example, you can reposition the panels and toolbars or customize the menu and toolbar commands.
Now we can add our blank schematic to the project before proceeding with the design capture.

Adding Schematic Sheets to a Project

If the schematic sheets you want to add to a project file have been opened as Free Documents, right-click on the project name in the Projects panel and select Add Existing to Project.
Select the free documents name(s) and click Open. Alternatively, you could drag-and-drop the free document into the project documents list in the Projects panel.
The schematic sheet is now listed under Source Documents beneath the project name in the Projects tab
and is linked to the project file.

pcb-lab2

Getting Started with PCB Design

Summary

This introductory tutorial is designed to give you an overview of how to create a
schematic, update the design information to a PCB document, route the PCB and
generate manufacturing output files. It also investigates the concept of projects and
integrated libraries and provides a summary of the 3D PCB environment.

Creating a New PCB Project

A project in Altium Designer consists of links to all documents and setups related to a design. A project file, eg. xxx.PrjPCB, is an ASCII text file that lists which documents are in the project and related output setups, eg.
for printing and CAM. Documents
that are not associated with a project are called ‘free documents’. Links to schematic sheets and a target output, eg. PCB,FPGA, embedded (VHDL) or library package, are added to a project.
Once the project is compiled, design verification, synchronization and comparison can take place.
Any changes to the original schematics or PCB, for example, are updated in the project when compiled.

The process of creating a new project is the same for all project types. We will use the PCB project as an example. We will
create the project file first and then create the blank schematic sheet to add the new empty project. Later in this tutorial we will
create a blank PCB and add it to the project as well.
To start the tutorial, create a new PCB project:
1. Select File » New » Project » PCB Project from the menus, or click on Blank
Project (PCB) in the New section of the Files panel. If this panel is not displayed,
select Files from the System button at the bottom right of the main design window.
Alternatively, you could select Printed Circuit Board Design in the Pick a Task
section of the Altium Designer Home Page (View » Home) and then click on New
Blank PCB Project.
http://www.saltlakecityhotelstoday.com/wp-content/uploads/2016/10/pcb-project.jpg

2. The Projects panel displays. The new project file, PCB_Project1.PrjPCB, is
listed here with no documents added.

3. Rename the new project file (with a .PrjPCB extension) by selecting File » Save Project As. Navigate to a location where you would like to store the project on your hard disk, type the name Multivibrator.
PrjPCB in the File Name field and click on Save.

Next we will create a schematic to add to the empty project file. This schematic will be for an astable multivibrator circuit.