Gheorghe Asachi Technical University of Iași [630496]

“Gheorghe Asachi” Technical University of Iași
Faculty of Electronics, Telecommunications and Information Technology

Bd. Carol, no. 11, 700506 , Iași, România, tel/fax: +023 2 701 603, e-mail: [anonimizat] , web: www. etti.tuiasi .ro

DIPLOMA PROJECT

Coordinator , Graduate ,
S.l.dr.ing. Constantin Barabașa Dan Cojocariu

Iași
2019

“Gheorghe Asachi” Technical University of Iași
Faculty of Electronics, Telecommunications and Information Technology

Bd. Carol, no. 11, 700506 , Iași, România, tel/fax: +023 2 701 603, e-mail: [anonimizat] , web: www. etti.tuiasi .ro

PRINTED CIRCUIT
BOARD DESIGN
TECHNIQUES AND
CONTROL SYSTEMS

SPECIALIZATION : Telecommunications Technologies and Systems

Coordinator, Graduate,
S.l.dr.ing. Constantin Barabașa Dan Cojocariu

Iași
2019

Abstract
Rezumatul, de maxim o pagină, reprezintă o redactare concisă și precisă a conținutului
proiectului /lucrării , a ideilor esențiale, urmată de o scurtă sinteză a rezultatelor, a concluziilor
și a recomandărilor. Va cuprinde scopul temei, soluțiile personale, principalele metode adoptate
pentru finalizarea acestora, concluziile la care s -a ajuns în urma studiului precum și propunerile
făcute.

CONTENT
Introduction ………………………….. ………………………….. ………………………….. ………………………….. 1
1.2 Motivation ………………………….. ………………………….. ………………………….. ………………………….. ….. 2
1.3 Objective ………………………….. ………………………….. ………………………….. ………………………….. ……. 2
Chapter 1. PCB design techniques ………………………….. ………………………….. ……………………….. 3
1.1. PCB stack -up ………………………….. ………………………….. ………………………….. ………………………….. 3
1.1.1 Multilayer boards ………………………….. ………………………….. ………………………….. ………………………….. ……… 4
1.1.2 Rigid ………………………….. ………………………….. ………………………….. ………………………….. ………………………….. … 5
1.1.3 Flex ………………………….. ………………………….. ………………………….. ………………………….. ………………………….. ….. 5
1.2 Design rules ………………………….. ………………………….. ………………………….. ………………………….. … 6
1.2.1 Component placement and clearance ………………………….. ………………………….. ………………………….. .. 6
1.2.2 Tracks and net classes ………………………….. ………………………….. ………………………….. ………………………….. 6
1.2.3 Vias ………………………….. ………………………….. ………………………….. ………………………….. ………………………….. ….. 9
1.2.4 Solder mask, silk screen and solder paste ………………………….. ………………………….. ………………….. 12
1.3 Planes / Copper pours ………………………….. ………………………….. ………………………….. …………….. 13
1.3.1 Power ………………………….. ………………………….. ………………………….. ………………………….. ………………………… 13
1.3.2 Ground ………………………….. ………………………….. ………………………….. ………………………….. ……………………… 13
1.4 Routing ………………………….. ………………………….. ………………………….. ………………………….. …….. 14
1.4.1 Manual routing vs Autorouter ………………………….. ………………………….. ………………………….. ………….. 16
1.4.2 Differential pair ………………………….. ………………………….. ………………………….. ………………………….. ………. 16
1.4.3 Tuninig ………………………….. ………………………….. ………………………….. ………………………….. ……………………… 17
1.5 Thermal ………………………….. ………………………….. ………………………….. ………………………….. ……. 18
1.5.1 Heatsinks ………………………….. ………………………….. ………………………….. ………………………….. ………………….. 18
1.5.2 Planes ………………………….. ………………………….. ………………………….. ………………………….. ……………………….. 18
1.5.3 Thermal vias ………………………….. ………………………….. ………………………….. ………………………….. ……………. 18
1.5.4 Tj Ta Rj θA Pd ………………………….. ………………………….. ………………………….. ………………………….. …………… 18
1.6 Signal and power integrity ………………………….. ………………………….. ………………………….. ………. 19
1.6.1 Signal integrity ………………………….. ………………………….. ………………………….. ………………………….. ………… 19
1.6.2 EMC / EMI ………………………….. ………………………….. ………………………….. ………………………….. ………………… 19
1.6.3 Decoupling capacitors ………………………….. ………………………….. ………………………….. ……………………….. 19
1.6.4 Controlled impedance ………………………….. ………………………….. ………………………….. ……………………….. 19
1.6.5 Shielding ………………………….. ………………………….. ………………………….. ………………………….. …………………… 19
1.7 Fabrication outputs ………………………….. ………………………….. ………………………….. …………………. 19
1.7.1 Test points ………………………….. ………………………….. ………………………….. ………………………….. ……………….. 19
1.7.2 Fiducials ………………………….. ………………………….. ………………………….. ………………………….. …………………… 19

1.7.3 Gerber and drill files ………………………….. ………………………….. ………………………….. ………………………….. . 19
1.7.4 Bill of materials(BOM) ………………………….. ………………………….. ………………………….. ……………………….. 19
Chapter 2. Mechanical implementation and part selection ………………………….. …………………. 20
2.1 Building the chassis ………………………….. ………………………….. ………………………….. ……………….. 20
2.1.1 Schematic ………………………….. ………………………….. ………………………….. ………………………….. …………………. 20
2.1.2 Layout ………………………….. ………………………….. ………………………….. ………………………….. ……………………….. 20
2.1.3 Generating fab rication outputs ………………………….. ………………………….. ………………………….. ………… 20
2.2 Components ………………………….. ………………………….. ………………………….. ………………………….. 20
2.2.1 Microcontroller – MSP4302553 ………………………….. ………………………….. ………………………….. ………. 20
2.2.2 DC and motor driver 8833 ………………………….. ………………………….. ………………………….. ………………… 20
2.2.3 Servos ………………………….. ………………………….. ………………………….. ………………………….. ……………………….. 20
2.2.4 Ultrasonic senso r ………………………….. ………………………….. ………………………….. ………………………….. ……. 20
2.2.5 Bluetooth module ………………………….. ………………………….. ………………………….. ………………………….. …… 20
2.2.6 Buck converter ………………………….. ………………………….. ………………………….. ………………………….. ……….. 20
2.2.7 Camera PAL standard ………………………….. ………………………….. ………………………….. ………………………… 20
2.2.8 VTX RTX ………………………….. ………………………….. ………………………….. ………………………….. ……………………. 20
2.2.9 Others ………………………….. ………………………….. ………………………….. ………………………….. ……………………….. 20
Chapter 3. Hardware and software developing ………………………….. ………………………….. …….. 22
3.1 Design ………………………….. ………………………….. ………………………….. ………………………….. ……… 22
3.1.1 Schematic ………………………….. ………………………….. ………………………….. ………………………….. …………………. 22
3.1.2 Layout ………………………….. ………………………….. ………………………….. ………………………….. ……………………….. 22
3.1.3 Waveforms ………………………….. ………………………….. ………………………….. ………………………….. ………………. 22
3.2 Software ………………………….. ………………………….. ………………………….. ………………………….. …… 22
3.2.1 Energia IDE ………………………….. ………………………….. ………………………….. ………………………….. ……………… 22
3.2.2 Programming ………………………….. ………………………….. ………………………….. ………………………….. ………….. 22
3.3 Mobile application ………………………….. ………………………….. ………………………….. …………………. 22
3.3.1 Mit app inventor platform ………………………….. ………………………….. ………………………….. ………………… 22
3.3.2 Components ………………………….. ………………………….. ………………………….. ………………………….. …………….. 22
3.3.3 Blocks ………………………….. ………………………….. ………………………….. ………………………….. ……………………….. 22
Conclusion ………………………….. ………………………….. ………………………….. ………………………….. 25
Bibliography ………………………….. ………………………….. ………………………….. ……………………….. 26
Annex 1 ………………………….. ………………………….. ………………………….. ………………………….. …. 27

1 INTRODUC TION
Introducerea va fi limitată la maxim um 2 pagini.
Se vor arăta clar și concis obiectivele și scopul proiectului /lucrării , problemele care au
trebuit să fie analizate și rezolvate în proiect/ lucrare și modul general de soluționare a acestora.
Se vor face scurte referiri la măsura în care proiectul /lucrarea contribuie la rezolvarea sau
îmbunătățirea problemelor, respectiv soluțiilor studiate.

Introduction

1.2 Motivation
1.3 Objective

3 CHAPTER 1. PCB DESIGN TECHNIQUES
ABOUT EDA AND PCB HISTORY BRIEFLY

Se recomandă ca fiecare capitol să înceapă pe o pagină nouă, păstrând constantă distanța
de la marginea de sus a foii la titlul capitolului.
Conținutul propriu -zis al proiectului /lucrării care se va redacta sistematic, clar și concis,
evitând scrierea repetată a unor formule, ex plicații simple etc. Redactarea textului se va face la
persoana a 3 -a.
Atât în text, cât și în partea grafică se vor utiliza simbolurile și terminologiile conform
standardelor în vigoare, chiar dacă în documentațiile utilizate apar alte notații. De asemene a,
este necesar ca simbolurile și notațiile utilizate să fie uniforme în toată lucrarea.

Maybe ipc 2221

1.1. PCB stack -up
PCBs structure consists of two major parts: the substrate and the printed wires.
Substrate is represented by the physical structure that holds the circuit components and the
copper traces(printed wires) together and assures the electrical insulation between the
conductive parts . FR4 is a highly used substrate which is a fiber -glass -epoxy laminate, it is
flame resistant. Other material from which substrates are built are Teflon, ceramics, and special
polymers .

Chapter 1. Pcb Design Techniques
4

1.1.1 Multilayer boards
When more than two layers are encountered we can refer to a multilayer PCB. Despite
the fact that single sided PCB has one conductive material and double -sided PCB two
conductive material layers, the multilayer boards must have at least three layers of conductive
material, one of them being buried in the center of the structure.
Fabrication process o f multilayer PCBs
Prepreg and core are essentially the same material, but prep reg is not fully cured, making
it more malleable than the core. Alternating layers of prep reg and core materials are laminated
together under high temperature and pressure to pro duce Multilayer PCBs. This process ensures
that air isn't trapped between layers, conductors are completely encapsulated by resin, and the
adhesive that holds the layers together are properly melted and cured.

Advantages of using multilayer PCBs
• reduced weight (less wiring needed for interconnection)
• higher assembly density
• flexibility increased

Chapter 1. Pcb Design Techniques
5 • easier incorporation controlled impedance features
• EMI shielding
• smaller size
The goal of any PCB stack -up design is to select the material and specify th e layer ordering
such that it adequately delivers the required signal performance and power integrity at the
lowest PCB cost. After the appropriate PCB material is selected, consider the following issues
to design the layer stack -up: layer count, signal la yers, high speed signal planning, power and
ground planes, capacitor placement.
1.1.2 Rigid
IPC-2222 is the sectional desig n standard for rigid organic printed board s. The standard
establishes the specific requirements for the design of rigid organic prin ted boards and other
forms of component mounting and interconnecting structures. The organic materials may be
homogeneous, reinforced, or used in combination with inorganic materials; the
interconnections may be single, double, or multilayered.
The requir ements shall be in conjunction with IPC -2221 to produce designs intended to
mount and attach passive and active components.
Types of components : through -hole, surface mount, fine pitch, ultra -fine pitch, array mounting
or unpackaged bare die. The materials may be any combination able to perform the physical,
thermal, environmental, and electronic function.
1.1.3 Flex
IPC-2223 is the sectional design standard for flexible printed boards . This standard
establishes the specific requirements for the design of flexible printed circuit applications and
its forms of component mounting and interconnecting structures. The flexible materials used in
the structures are comprised of insulating films, reinforced and/or non -reinforced, dielectric in
combination with meta llic materials. These interconnecting boards may contain single, double,
multilayer, or multiple conductive layers and can be comprised wholly of flex or a combination
of both flex and rigid.
Like previous, the requirements shall be in conjunction with IPC -2221 and also IPC –
2222 for the sections where rigid -flex sections are involved .

Chapter 1. Pcb Design Techniques
6 1.2 Design rules
In PCB design it is important to know from the beginning what you are allowed to do
and what you are not allowed. For this it is required a plan, a set of rules well defined that can
be implemented in any EDA tools.
1.2.1 Component placement and clearance
Component placement is the combination of electronics and art. Here will be ilustrated
the artistic side of the designer, but also a lot of measurement must be taken into consideration.
This rule component spacing specifies the minimum distance that components can be
placed from each other. Component clearance includes clearance between 3D models used to
define component bodies (extruded (simple) types). In the absence of 3D bodies, the primitives
on the silk is used to define the object shape and size along with the height value specified in
the component properties.
In the below picture with cy an color it is expressed the courtyard or place outline. This
setting prevent component overlapping and DRC (design rule check) will alert the designer in
case of misplaced components.

1.2.2 Tracks and net classes
A trace is a continuous path of coppe r on a circuit board. They are optained by
selectively removing the copper cladding and foil. To remove the unwanted copper there are a
few metho d used such as: chemical etching, mechanical milling (CNC -computer numerical
control) , laser and plasma etching.

Chapter 1. Pcb Design Techniques
7 Chemical etching
To remove the unwanted copper from the board it is necessary to use a photoresist, a
polymer coating, to protect from etchant the desired form of tracks and pads . The process of
getting the desired circuit on the sur face of the pcb cladding is called photolithography. There
exists two types of photoresist: negative and positive. In case of negative photo resist the
material covered from UV light is removed and in case of positive photoresist the one exposed
breaks down . Before being exposed to UV a mask is placed in front of the light allowing or
blocking it .

After the image is optained on the PCB, the board is introduced in ferric chloride( FeCl 3) bath.
When the process is completed it can be observed that the copper traces are not perfect because
the resist film can only protect the covered copper and leaving the board for a long time in the
acid can affect the track width and thickness , also the entire functionality .

Chapter 1. Pcb Design Techniques
8
Mechanical Milling
Consists in programming a computer numerical control (CNC) machine with the digital
map of the circuit which grind away the unwanted copper. The unwanted copper can be
completely removed or just enough copper may be removed to isolate the pads and traces from
the area of copper. The remained copper areas can affect the impedance of the traces.

Net clas ses represent a set of settings to easily manage and organize routing.

Chapter 1. Pcb Design Techniques
9 1.2.3 Vias
Vias are used to electrically and thermally join traces, pads, and polygons on different
layers of a PCB. Vias are copper cylinders that are placed or formed in holes that have been
drilled in a PCB.
Vias require a minimum amount of copper on a layer for a proper connection so, in most
instances, a via pad (circle of copper called an annular ring) is attached to the end of narrow
traces to increase the material available for a connection.
Surrounding the via pad is an area without copper known as the “antipad”, which
insulates the pad from surrounding copper.

Type of vias

Through -hole
The main characteristic of this type of holes is that, during the manufacturing process,
after drilling the boards a thin copper layer is plated onto the walls of the holes, providing them
with electrical conductivity. This way, after the PCB assembly is f inished, the link between the
component's leads and the copper tracks has a lower resistance and better mechanical stability.

Chapter 1. Pcb Design Techniques
10 Today most PCBs are double sided, or multi -layered, and most of the through holes are plated,
this way the components can connect to the required layers in the board.

The integration density of modern electronic modules increases constantly. Apart from
the components (µBGA, CSP, FC), the printed circuit board is particularly affected by this.
Apart from the general reduction in trac k widths and spacing, blind vias are a necessary and
tried & tested aspect for new design and layout options of printed circuit boards.
Blind & Buried Via technology has played a pivotal role in squeezing more capability
into a smaller space. By shortenin g vias to only pass through necessary layers, more surface
area become available for components.
Blind
Blind vias are used to connect one outer layer with at least one inner layer. The holes for each
connection level must be defined as a separate drill fi le. The ratio of hole depth to drill diameter
(aspect ratio) must be ≤ 1. The smallest hole determines the depth and thus the max. distance
between the outer layer and the corresponding inner layers.
Blind Via is a copper plated hole that connects only one outer layer to one or more inner layers.
A blind via never goes all the way through a circuit board. In terms of design, blind vias are
defined in a separate drill file.
Additional Benefit of Blind Vias:
Ability to widen BGA breakout channel (layer count reduction)

Buried
Buried vias are used to create connections of the inner layers, which have no contact with the
outer layers. The holes for each connection level must be defined as a separate drill file. The
ratio of hole depth to drill diameter (aspect ratio) must be ≤ 12. The smallest hole determines
the depth and thus the max. distance between the respective inner layers.

Chapter 1. Pcb Design Techniques
11 Buried Via is a copper plated hole that connects two or more inner layers, with no contact with
the outer layer. It is impossible t o detect a buried via as it is "buried" underneath the outer layer
surfaces of a PCB. Buried vias also require a separate drill file.
Additional Benefits of Buried Vias
No impact to any trace or surface mount component on the top or bottom layers of the bo ard.
Trace or an SMD pad placement on the outer layers directly over the buried via (added space
on outer layers)
Blind and buried vias are particularly advantageous in HDI PCBs because they optimize the
density of the boards without increasing board size or the number of board layers you require.
FILLED VIAS !!!
Mounting holes
The role of the mounting holes is to help attaching the PCB to a stand, case or attaching
hardware parts to PCB such as heatsinks, support pins of components and plastic/metal holders
for a good mechanical fix ing. Mounting holes are of two types, plated and non -plated. Plated
holes are often confused with through -hole vias but the difference between vias and holes is the
electric connection made by vias between la yers. The hole is seen as a component footprint but
not a s a part from schematic. Non -plated through holes (NPTH) don’t have a metal plating on
the inside.
In the design was considered a circular plated through hole with 3 mm drill size, 5.8 mm pad
diamete r, and 0.5 mm keepout are a for any electrical part.

Chapter 1. Pcb Design Techniques
12 1.2.4 Solder mask , silk screen and solder paste
Solder mask is a protective laquer layer applied and developed to expose only those
parts of the board that will have solder coating , on top and bottom layers . There are a number
of types of solder mask and solder mask processes. Solder mask prevent oxidation, creating
short during soldering, ex ternal conductive influence, between nets when operating with high
voltages and residues deposits that might create a short -circuit in time. When big chips with a
high density of pins and a small pitch are encountered solder mask plays a vital role in
preventing solder bridges between pins. The minimum solder mask exposure of pads is
considered to be 0.05mm.
Example:
Good solder mask opening according to
standard: 0.05mm (pin 1 and 2)
Potential risk of solder bridges between pin s
(pin 4 and 5)

Silkscreen , also known as component overlay or component layey is a layer of ink used
to identify components, test points, parts reference, value, body, logo, text and additional
markings. Its standard colour is white but other colors are available. It is a good practice to
mark polarised components, such as capacitors, diode’s cathode, first pin of microcontroller
capsule for proper placement. No silkscreen must overlap a bare pad.

Chapter 1. Pcb Design Techniques
13 1.3 Planes / Copper pours
In designing tools there is available a function called „polygon” that automatically fills
or floods a desired area with copper, which spreads around traces and pads. The designer has
the posibility to choose a solid plane or a hatched regarding the applicati on. It is recommended
to place a polygon after all component, tracks and pads have been place d.

1.3.1 Power
Power planes are often required for low noise requirements and consist of complete
layers of copper (excluding th rough holes) and are normally on internal layers. Using power
planes can drastically reduce the power wiring inductance and impedance to your components.
This can be vital for high speed digital design for instance. A power plane is basically one solid
copper layer of board dedicated to either ground or power rails, or both. Power planes go in the
middle layers of the board, usually on the layers closest to the outer surfaces. Using power
planes is always a good choice whenever possible. They can even be us ed on double sided
boards, if most of the signal tracks are on the top layer. For delimitation of the power planes
traces can be placed completely around the outer edge of the PCB . This will ensure that the
power planes do not extend right to the edge of t he board. Power planes placed right on the
edges of the board can short to not only one another, but also to any guide rails or mounting
hardware. Delimitation was taken into consideration in the design.
1.3.2 Ground
In electrical engineering, a ground pl ane is an electrically conductive surface, usually
connected to electrical ground. The term has two different meanings in separate areas of
electrical engineering. In printed circuit boards, a ground plane is a large area of copper foil on
the board which is connected to the power supply ground terminal and serves as a return path
for current from different components on the board. Ground rail is usually signal reference line,
so a ground plane is first preference before a power plane is considered.

Chapter 1. Pcb Design Techniques
14
Insurance of a good grounding:
▪ Use of copper as a lot of ground plane because impedance is inverse proportional with
the rise of copper area
▪ Separating ground zones for critical parts from the circuit prevent current and noise
affecting the functionality o f other components.
▪ Stitching plane with vias keeping length of tracks shorter.
▪ Ground close to signal layer will be a good reference.
▪ Vias decrease trace impedance if routed to ground

1.4 Routing
Wire routing is the process is which components already placed are connected according
design rules implemented by designer . Over the years engineers have used different methods to
improve wire routing and as final result to increase PCB functiona lity.
Right -angled track turns should be avoided because it can produce a field concentration
at the inner edge. This field can cause noise that can be coupled to nearby tracks. Therefore, all
orthogonal tracking should be 45 degrees when making turns. Other benefits using 45 degrees
track are shortening the electrical path between components, in high speed digital signals where
there are present a lot of fast transitions or in high frequency analog the signals can be reflected
causing interferences when using 90 degrees traces , because in case of a turn the trace width

Chapter 1. Pcb Design Techniques
15 increases by a factor of 1.41 and causes a change in characteristic impedance due to increase in
capacitance . When 3 traces are intersecting, 45 degrees ending called chamfer, is good to be
taken into consideration because it not only reduces the signal reflections but also strengthens
the trace’s joint.

Due to increase of PCB complexity and manufacturing requirements, on flexible areas,
the routing will be done with rounded traces. Also, if layer transitions are needed (via usage is
mandatory) it i s absolutely a must to use teardrops in order to prevent trace -to-via detachments.
Teardrops, a nice smooth exit, are often used to create mechanically stronger connections
between pads or vias and tracks to prevent drill breakout during manufacturing. A r eplacement
for teardrops is a hatched zone in bendable area with no net assigned.

Traces must be snap on the grid and to start from the center of the pad . The software
may consider that there doesn’t exist a connection. A proper exist from the pad is m andatory
because this leads to etch traps due to acute angles of traces.

Chapter 1. Pcb Design Techniques
16 Routing ICs is complex task for routers because of high number of pins and small pitch
between them. Nowadays most of the ICs are that are provided by the supplier are in BGA (ball
grid array) capsule. The method for routing BGAs is called fanout. One small trace can be
routed between two solder pads of a 0.5mm pitch on the same side where the component is
placed, top or bottom. Therefore, each solder pad will need a via to connect to another routing
layer. The designer should start routing from the inner pads to the outer pads of the component.
Below is presented a typical pad exit of a BGA component on top layer.

1.4.1 Manual routing vs Autorouter
Once the critical traces, power rails and ground connection have been routed the
autorouter can be used to route de rest of the board to earn time. Some softwares have the option
to use the autorouter to route the entire board or only defined zones. Automa tically router
requires a entire set of rules and if it is not configured properly it will produce an entire mess.
Usually autorouter is efficient when big and repetative designs are involved . Even with a full
automated process, the autorouter can’t replac e the human designer.
1.4.2 Differential pair
A differential signaling system is one where a signal is transmitted down a pair of tightly
coupled carriers, one of these carrying the signal, the other carrying an equal but opposite image
of the signal. Di fferential signaling was developed to cater for situations where the logic
reference ground of the signal source could not be well connected to the logic reference ground
of the load. Differential signaling is inherently immune to common mode electrical no ise, the
most common interference artifact present in an electronic product. Another major advantage
of differential signaling is that it minimizes electromagnetic interference (EMI) generated from
the signal pair. Differential pair PCB routing is a design technique employed to create a

Chapter 1. Pcb Design Techniques
17 balanced transmission system able to carry differential (equal and opposite) signals across a
printed circuit board. Typically this differential routing will interface to an external differential
transmission system, such as a connector and cable. It is important to note that while the
coupling ratio achieved in a twisted pair differential cable may be better than 99%, the coupling
achieved in differential pair routing will typically be less than 50%. Current expert opinion i s
that the PCB routing task is not to try and ensure a specific differential impedance is achieved,
rather the objective is to maintain the properties required to ensure the differential signal arrives
in good condition at the target component as it travel s from the external cabling.
1.4.3 Tuninig
Length
Routing of differential pairs inevitably results in length mismatches between the signals
within a differential pair that must be compensated. As signals are routed, bends add positively
or negatively to the accumulating skew. In all cases, the outside signal in the bend has a longer
length than the inside signal, creating a length mismatch. Corners routed at 90 degrees are
generally held as the least favored routing type for signal integrity as they add t he most routing
length mismatch and theoretically the greatest capacitance. It is advised to add mitering to the
bends to reduce the capacitance in the bend
Skew/Phase
The primary reason to maintain skew in differential pairs is to maintain low EMI, one
of the favorable advantages of differential signaling . When electric fields no longer cancel from
equal and opposite currents, common -mode EMI will become a serious problem.

Chapter 1. Pcb Design Techniques
18 1.5 Thermal
Controlling the heat loss of electronic and microelectronic systems is a more and more
challenging task as miniaturization is increasing, and the growth in functionality is driving the
components to their limits, which means that they are generating more heat loss. Printed circuit
boards are the carrier of the components and are therefore also highly involved in the matter of
controlling the heat. The PCB by its nature is not a good thermal conductor.
The thermal conductivity of a typical substrate material is about λ ~ 0.2 W/mK.
However, copper, the material of the condu ctive traces of a PCB, has a high thermal
conductivity of λ ~ 390 W/mK.
A power or ground plane has a bigger influence on the heat flux. The heat flux and
direction is mainly dominated by the thermal conductivity of the materials and the ΔT in a
given area . The conductive traces of a PCB in practi ce cannot be used as a good and efficient
thermal conductor. Their cross sectional area is simply much too low. Many microelectronic
components are designed with a predetermined thermal pathway inside their package s while
other have a big solder pad underneath called EPAD. An inexpensive way to improve thermal
transfer for PCBs is to add thermal plated through hole vias between conductive layers. Thermal
vias are created in the same way as normal vias, by drilling a nd then plated with copper.

1.5.1 Heatsinks
Saturn
1.5.2 Planes
Spoke , thermal relief
1.5.3 Thermal vias
Epad
1.5.4 Tj Ta RjθA Pd
Tj document, formula etc

Chapter 1. Pcb Design Techniques
19 1.6 Signal and power integrity
1.6.1 Signal integrity
Trace separation is used to minimize the crosstalk and noise coupling (by magnetic flux
coupling)
between adjacent traces on the same PCB layer.
The 3W rule states that all signals (clocks, video, audio, reset, etc.) must be separated
between traces,
edge -to-edge as shown Figure 20 . To further mi nimize magnetic coupling, place reference
grounds near critical signals to isolate other noise being coupled onto the signal lines.
1.6.2 EMC / EMI
1.6.3 Decoupling capacitors
1.6.4 Controlled impedance
1.6.5 Shielding
1.7 Fabrication outputs
1.7.1 Test po ints
1.7.2 Fiducials
Global
Local
1.7.3 Gerber and d rill files
1.7.4 Bill of materials(BOM)

20 CHAPTER 2. MECHANICAL IMPLEMENTATION AND PART SELECTION

2.1 Building the chassis

2.1.1 Schematic
2.1.2 Layout
2.1.3 Generating fabrication outputs

2.2 Components

2.2.1 Microcontroller – MSP4302553
2.2.2 DC and motor driver 8833
2.2.3 Servos
2.2.4 Ultrasonic sensor
2.2.5 Bluetooth module
2.2.6 Buck converter
2.2.7 Camera PAL standard
2.2.8 VTX RTX
2.2.9 Others

Chapter 2. Mechanical implementation and part selection

21

22 CHAPTER 3. HARDWARE AND SOFTWAR E DEVELOPING

3.1 Design
3.1.1 Schematic
3.1.2 Layout
3.1.3 Waveforms
3.2 Software
3.2.1 Energia IDE
3.2.2 Programming
3.3 Mobile application
3.3.1 Mit app inventor platform
3.3.2 Components
3.3.3 Block s

Chapter 3 . Hardware and software developing

23

24

25 CONCLU SION
Vor cuprinde într -o formă cât mai concisă principale rezultatele obținute în tema tratată,
subliniindu -se contribuția adusă prin propriile cercetări. Se vor scoate în evidență elementele
de noutate ale proiectului /lucrării. Dacă rezultatele obținute pot fi aplicate în activitatea de
cercetare, producție sau în alte domenii de activitate, economică sau socială, se vor face
recomandările corespunzătoare.

Un bilanț al aspectelor pozitive și negative din activitatea d e dezvoltare a proiectului de
diplomă sau a lucrării de disertație va încheia partea scrisă a lucrării.

26 BIBLIOGRA PHY
Bibliografia cuprinde cărți, capitole din cărți, articole tipărite, articole și lucrări prezentate
la conferințe și disponibile on line, site -uri.
Redactarea se va face aplicând criteriul alfabetic numelor autorilor. Dacă același autor a
scris mai multe lucrări care apar în bibliografie, acestea se vor include în ordine cronologică,
de la cea mai veche spre cea editată recent. Vor fi menționate: numele autorului/autorilor, titlul
integral al lucrării, editura, locul publicării, anul apariției lucrării.
Pentru articolele apărute în reviste, se menționează în ordine: numele autorului/a utorilor,
titlul articolului, titlul revistei, ISBN/ISSN, anul apariției, numărul.
Paginile web se vor ordona alfabetic și vor avea menționată data accesării lor. Această
precizare va fi făcută deoarece există posibi litatea ca pagina citată de pe i nternet să fie ulterior
ștearsă.
[1] I. Voncilă, D. Călueanu, N. B adea, R. Buhosu, Cr. Munteanu, „Mașini Electrice ”, Editura
Fundației Universitare „Dunărea de Jos” din Galați , 2003 ;
[2] I. Șușnea, M. Vlase , „A software instrument for the assessment of creativity in the
educational environment ”, The Annals of the University "Dunărea de Jos" o f Galați
Romania Fascicle III Electrotechnics Electronics Automatic Control Informatics , ISSN
1221 -454X, 2016, Volum 39, Num ărul 1;
[3] https://ro.wikipedia.org/wiki/Tranzistor , 23-06-2016 .

27 ANNEX 1
Anexe le (dacă există ) – nu se numerotează ca și capitol, se numerotează crescător (Anexa
1, Anexa 2, etc).
Anexele vor conține elemente precum:
− porțiuni de cod;
− tabele de date;
− tabele de rezultate de ieșire ;
− alte elemente specifice la care s -a făcut referire în cadrul proiectului/lucrării .