A printed circuit board (pcb) mechanically supports and electrically connects electronic components using conductive tracks, pads and other features etched from copper sheets laminated onto a non-conductive substrate. pcb's can be single sided (one copper layer), double sided (two copper layers) or multi-layer. Conductor on different layers are connected with plated-through holes called vias. Advanced PCB's may contain components - capacitors, resistors or active devices - embedded in the substrate.
Single layer
Specifications for circuits
Max size 8’’X 8’’
Min. line width6 mils
Min. gap between lines 6 mils
Connectorspacing0.5’’
Drawing file: Gerber RS-274X , precision2.4
Units are inches
Each layer has to contain text with a minimum height 80 mils and track width 8 mils
Cutting marks: 200x200x20 mils
Origin at the lowest left corner of the layout
Single layer with vias
Same as single layer
Riveted vias
-Used only if circuit contains less than 15 holes
-Hole 31 mils diameter
-Pad 60 mils diameter
-Center of pad uncovered
Plated vias
-Used for large quantity of holes on circuits or if size of hole is critical
-Min. aspect ratio of 2:1
-Center of pad covered in the layout
-.dxffile for holes (precision 2.4),
-Max. circuit size 6"x6"
Circuits with riveted vias
Layout files: Gerber RS-274X, precision 2.4
No drill file required
Only one hole size:31 mil
Plated Vias
•Layout file: Gerber RS-274x, 2.4
•Hole file dxf, 2.4, single layer
•Holes are filled on the layout file
•Three alignment holes of 66/120 mils diawith donuts outside of layout
•Aspect ratio for plated hole max 2:1
•Clearance of 10 mils
•Max PCB size 6” X 6”
•Laser cutting area is limited to 3.75 X 3.75
Laser drilling
For laser drilling use poly-line
Holes need to be circles, not line segments
Minimum space 10 mil between 2 holes
For soft substrates maximum thickness: 60 mils
For ceramic: 20 mils
Minimum hole diameter 5 mils
Maximum circuit size 3.75” X 3.75”
Oversize of cutting 2 mils
Plated Vias–Gerber and dxffiles
Plated Vias–dxffiles
Clearance
•Spacing of 10 mils min. between hole edges
•Spacing of 10 mils min. between hole edge and copper
Component assembly
Component spacing
0402 Gap 20 mil Pad width 25 mils length 55 mils
0603 Gap 30 mil Pad width 35 mils length 75 mils
0805 Gap 40 mil Pad width 55 mils length 95 mils
1206 Gap 40 mil Pad width 65 mils length140 mils
For integrated circuits refer to the specification of manufacturer
Consider that you will have to solder the components, leave enough space
Assembly box
Drawing of a 2D box dxffile
Position of hole on drawing should be accurate and at scale
Unit is inch
Origin in the lowest-left corner
Provide all the information needed (thickness, material, etc)
Assembly Base
SIW
Holes or slots are cut by laser
Consider an oversize of 2 mils for laser cutting
Laser cuts only through-hole
Aspect ratio of minimum 2:1 should be maintained for plating
dxffile precision 2.4, single layer
Partly machined substrate
The channel is cut by milling, only standard sizes are available.
Patterning required: Gerber file.
Minimum remaining thickness of substrate 10 mils
Multilayer
Required files
Need a 3 D drawing to represent the entire circuit
Plated hole is possible and inner connection is possible too.
If connection is required between two substrates, a plated via is required
Max size is 2” X 5”
First substrate is on the bottom
Text needs to be printed on each layer
Indicate on the drawing the top or bottom layer
Ex: S1B ( substrate 1 bottom)
Gerber file scale 1 for each layer
Drill file is in .dxf
Limited to 3.75’’ X 3.75’’
The alignment between substrates is made using 0.125” diameter pins at 2.5” center to center distance
Adhesive specification
•Adhesive is epoxy
•ER = 3.5
•Td= 0.03
•Thickness 5 μm
•Solvent resistant
•Hole can be plated through adhesive
Capacitor test
Without epoxy
-C= 1.33 pF
With epoxy
-C= 1.325 pF
Res. Freq
Without epoxy 5.194935420 GHz
With epoxy 5.193403890 GHz
-Variation of .2%
Q without epoxy 182
Q with epoxy 167
-Variation of 8%
Capacitortest
Adhesive pull-test
Copper to copper surface pull force is 300 PSI
Dielectric to dielectric surface pull force is 400 PSI
MHMIC Fabrication process
MHMIC
Without Via
With Via
MHMIC without Via
Circuit is made with photoresistmaterial, resolution is better
Max size 0.950” x 0.950”
Ceramic Al2O3 10 mil thick
Min line width 1 mil
Min line to line gap 1mil
Resistor 100 Ω/S
Conductor is Au 1 μm
MHMIC with via
Max size 0.950” x 0.950”
Ceramic Al2O3 10 mils thick
Min line width1.5mil
Min line to line gap 1.5 mil
Min hole dia. 5 mils
Overdevelopment of 0.2 mil
Minimum hole covering is 3 mils
Hole covering
File
Without Via
Mask for conductor: Gerber file scale 5X
Mask for resistor: Gerber file scale 5X
Conductor mask has to cover the resistor mask
With Via
Mask for conductor: Gerber file scale 5X
Mask for resistor: Gerber file scale 5X
Via DXF file 1X
Slot or rectangle can be cut in the ceramic with laser
Mask is covering vias
Resistor
Resistive coating is a layer of 20 nm of Ti under the gold
First step: conductor is etched including Ti
Resistor
Resistive coating is a layer of 20 nm of Ti under the gold
First step: conductor is etched including Ti
Second step: resistor is open trough the conductor
Conductor Gerber file
The conductor layer is positive mask
Indicate your name and professor on circuit
Always print text on circuit
Indicate cutting mark
Layout on Gerber scale 5X
Need at least 2 test resistors
Resistor mask
Negative mask
Open only the resistor area
Mask is Gerber scale 5X
The opening is larger than the line by 5 mils
Alignment is corner to corner of circuit in the cutting mark
Resistor mask
Die assembly
Mounted on substrate
-No power dissipation
Mounted on base
-Better grounding
-Power dissipation
-For higher frequency
If you use the S parameter of device manufacturer use the same mounting parameters.
Die mounted on substrate
Die is bonded onto alumina with conductive epoxy
A gap of 2 mils is required between die and line
Die mounted on base
•The step is 1 mil larger than Die
•The cutting hole on ceramic is 2 mil larger than Die
•DXF file for mechanical work
Wire Bonding parameters
Wirediameter: 0.7 mil or 18 μm
Ribbon: 3 mils X 0.5 mil
For die mounted on substrate bond length is 2 times the height of die
For die mounted on base the bond length is the spacing between pad and line
Always provide a wire bonding layout
DC connection
It is impossible to solder wire to thin film gold
Small PCB line is added to make interconnection
Machined waveguide
Machined waveguide
For 2D
-Drawing needs to be a DXF file
-Drawing is scaled 1:1
-Unit is inch
-Indicate material Al or Brass
-Side view of piece with indication of height
For 3D
-Drawing needs to be .SAT or VDA, not DWG
-Drawing is at scale 1:1
-Unit is inch
-Indicate material Al or Brass
Circuit test
Never forget, you need to test your circuit
Anritsu Test fixture
-Microstrip
-Coplanar
-40 GHz 4”
-65 GHz 2”
Connector SMA, K, V
-Circuit needs to be mounted on a base
-To be provided by your professor
-Take care of spacing between connectors 0.5”
SIW requires waveguide
Probing station
Probe size 150 μm and 250 μm
Frequency range up to 110 GHz
Coplanar or microstrip
Antenna
Compact Range
Frequencyband
-4 to 40 GHz
-75 to 110 GHz
Quiet zone
-75 cm x 75 cm x 75 cm
Useful softwares
Gerber viewer
-ViewMatePentalogix(on the 97 and 100 servers)
Dxfeditor and viewer
-Autosketch(on the 097 and 100 servers)
Unit converter
-Convert.exe ( K:\convert\convert.exe )
AutoCAD to Gerber translator
-LinkCAD4 (Free demo at //www.linkcad.com/)
Please take note that the layout will look exactly as in Viewmate, so, before sending any Gerber file, double-check it, including the size (D-key in the software)!
How to name the file
To simplify the comprehension please include in file name the following information
Name-circuit-layer-substrate-thickness.ext
Example:
Gratton-converter-S1T-5880-20.gbr
Gratton-converter-S1T.dxf
Substrate
Rogers Laminates
5870, 5880, 6002, 6006, 6010, 4000, 3000
Order: rolled copper, 0.5 ounce thick (5R/5R)
Sample is available on the web site, limited to 2 samples
Warning!5870 and 5880 substrates cannot be drilled using a laser beam.
Usefulhints
Alignment donut and origin position
Nothing has to be found at the left and under the x and y axis
How to makean alignment donutin ADS: maketwo, proper sized circles, align them and –Edit-Merge-Union minus Intersection
Proper units in ADS: adjust the proper units before starting to workin the layout window (Options-Preferences-Layout Units-in)
Gerber file export
Multilayer drawing explanation
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