PCB
Package:
This is
like a case to carry a die / IC and it is used to make connection between the
die of an IC to the PCB traces through their pins around the packages.
The die will be placed at the center of the package and it
will be connected to the package pin by golden wire, the package body will
always be plastic or resin.
Package will be of two types as like components,
•
Surface Mount Package
•
Through Hole Package
The central die will be same for example a micro controller
but it can be available in both cases or packages, surface mount package will
be more effective than through hole package because of its lesser pin length,
so it would have less pin Inductive than THT and there by reduced EMI.
Where,
A - Clearance between package body and PCB.
H - Height of package from pin tip to top of package.
T - Thickness of pin.
L - Length of package body only.
LW - Pin width.
LL - Pin length from package to pin tip.
P - Pin pitch (distance between two pins from center to center).
WB - Width of the package body only.
WL - Length from pin tip to pin tip on the opposite side.
H - Height of package from pin tip to top of package.
T - Thickness of pin.
L - Length of package body only.
LW - Pin width.
LL - Pin length from package to pin tip.
P - Pin pitch (distance between two pins from center to center).
WB - Width of the package body only.
WL - Length from pin tip to pin tip on the opposite side.
Rp – Row pitch (distance between two pins from row to row).
From these two types, it will be sub divided into different
categories likes
•
Passives
•
ICs
•
Connectors
SMD Passive packages types are
•
Flat Chip
•
Molded Tantalum
•
MELF
Flat Chip Packages:
The most commonly used passives like
Resistors, Capacitor and Inductors will be in this package type.
The name of this package type will be denoted in 4 letter
word, mostly preferred in numbers; it would specify the dimension of the
package. The first two numbers denote the length and next two numbers will
denote the width
Component Identifier mm / inch
1005 / 0402 1.0
x 0.5 / 0.040x 0.020
1608 / 0603 1.6
x 0.8 / 0.060 x 0.030
2012 / 0805 2.0
x 1.2 / 0.080 x 0.050
3216 / 1206 3.2
x 1.6 / 0.120 x 0.060
3225 / 1210 3.2
x 2.5 / 0.120 x 0.100
5025 / 2010 5.0
x 2.5 / 0.200 x 0.100
6332 / 2512 6.3
x 3.2 / 0.250 x 0.120
Molded
Tantalum packages:
Generally
all polarity capacitors are in these packages, it can either be denoted by 4
letter word or by case code.
EIA case code Metric
size mm
Case A 3216 3.2 x
1.6
Case B 3528 3.5 x
2.8
Case C 6032 6.0 x
3.2
Case D 7343 7.3 x
4.3
MELF
Packages:
These packages are in
cylindrical shape and MELF is acronym for Metal Electrode Leadless Face, as
name indicates, it does not have the leads. Resistors, Diodes and Fuses will be
in this package. As it is in cylindrical shape, it would roll off from the
board before assembly, so it is not recommended most of the time.
Capacitors & Resistors Diodes
0805 SOD 80 Mini MELF (1.6 x 3.5 mm)
1206 SM1 MELF (2.5 x 5.0 mm)
THT
Passive packages types are
•
Axial
•
Radial
Axial THT
Package:
Diodes
& Resistors will be in this type package, as their pins are axial to its
body so it is named as Axial packages, while assembling it on PCB, the leads
have to be bended and then solder has to be done on this type package.
Radial THT
Package:
Mostly
Polarity capacitors will be in this type of package like Electrolytic caps,
Tantalum & Aluminum caps and some non polarity caps also will be in this
type like Disc Ceramic caps. Their pins will be radial to its body and so it
named as Radial package.
Diodes
& Transistor Packages:
Diodes
commonly come in Small Outline Diode (SOD) Package and they are
•
SOD 123
SMD Transistors come in the
following packages (SMALL OUTLINE TRANSISTOR - SOT),
•
SOT 23
•
SOT 89
•
SOT 143
•
SOT 223
•
SOT 23-5 (Five pins)
•
SOT 23-6 (Six pins)
•
DPAK
•
D2PAK
•
TO-52
•
TO-66
•
TO-92
•
TO-220
•
TO-259
No comments:
Post a Comment