Editing Transistor (section)

===Packaging===
{{See also|Semiconductor package|Chip carrier}}
[[File:Transbauformen.jpg|thumb|Assorted discrete transistors]]
[[File:Kt315b.jpg|thumb|[[Soviet Union|Soviet]]-manufactured [[KT315]]b transistors]]
Discrete transistors can be individually packaged transistors or unpackaged transistor chips.

Transistors come in many different [[semiconductor package]]s (see image). The two main categories are ''[[through-hole technology|through-hole]]'' (or ''leaded''), and ''surface-mount'', also known as ''surface-mount device'' ([[surface-mount technology|SMD]]). The ''ball grid array'' ([[Ball grid array|BGA]]) is the latest surface-mount package. It has solder balls on the underside in place of leads. Because they are smaller and have shorter interconnections, SMDs have better high-frequency characteristics but lower power ratings.

Transistor packages are made of glass, metal, ceramic, or plastic. The package often dictates the power rating and frequency characteristics. Power transistors have larger packages that can be clamped to [[heat sink]]s for enhanced cooling. Additionally, most power transistors have the collector or drain physically connected to the metal enclosure. At the other extreme, some surface-mount ''microwave'' transistors are as small as grains of sand.

Often a given transistor type is available in several packages. Transistor packages are mainly standardized, but the assignment of a transistor's functions to the terminals is not: other transistor types can assign other functions to the package's terminals. Even for the same transistor type the terminal assignment can vary (normally indicated by a suffix letter to the part number, q.e. BC212L and BC212K).

Nowadays most transistors come in a wide range of SMT packages. In comparison, the list of available through-hole packages is relatively small. Here is a short list of the most common through-hole transistors packages in alphabetical order:
ATV, E-line, MRT, HRT, SC-43, SC-72, TO-3, TO-18, TO-39, TO-92, TO-126, TO220, TO247, TO251, TO262, ZTX851.

Unpackaged transistor chips (die) may be assembled into hybrid devices.<ref name="Greig">{{cite book
 |last=Greig |first=William
 |date=April 24, 2007
|title=Integrated Circuit Packaging, Assembly and Interconnections
 |url=https://books.google.com/books?id=g29xoTAyAMgC&q=hybrid+&pg=PA63 
 |page=63 
 |publisher=Springer
 |quote=A hybrid circuit is defined as an assembly containing both active semiconductor devices (packaged and unpackaged)|isbn=9780387339139
 }}</ref>  The [[IBM SLT]] module of the 1960s is one example of such a hybrid circuit module using glass passivated transistor (and diode) die.  Other packaging techniques for discrete transistors as chips include ''direct chip attach'' (DCA) and ''chip-on-board'' (COB).<ref name="Greig"/>

====Flexible transistors====
Researchers have made several kinds of flexible transistors, including [[organic field-effect transistor]]s.<ref>{{cite journal|title=Can We Build a Truly High Performance Computer Which is Flexible and Transparent? |journal=Scientific Reports |volume=3 |pages=2609 |doi=10.1038/srep02609 |year=2013 |last1=Rojas |first1=Jhonathan P. |last2=Torres Sevilla |first2=Galo A. |last3=Hussain |first3=Muhammad M. |bibcode = 2013NatSR...3.2609R |pmid=24018904 |pmc=3767948}}</ref><ref>{{cite journal|doi=10.1088/0022-3727/45/14/143001|title=Fast flexible electronics using {{sic|transferrable|nolink=y}} silicon nanomembranes|journal=Journal of Physics D: Applied Physics|volume=45|issue=14|pages=143001|year=2012|last1=Zhang|first1=Kan|last2=Seo|first2=Jung-Hun|last3=Zhou|first3=Weidong|last4=Ma|first4=Zhenqiang|bibcode = 2012JPhD...45n3001Z |s2cid=109292175}}
</ref><ref>{{cite journal|doi=10.1038/NNANO.2011.1 |pmid=21297625 |title=Flexible high-performance carbon nanotube integrated circuits |journal=Nature Nanotechnology |volume=6 |issue=3 |pages=156–61 |year=2011 |last1=Sun |first1=Dong-Ming |last2=Timmermans |first2=Marina Y. |last3=Tian |first3=Ying |last4=Nasibulin |first4=Albert G. |last5=Kauppinen |first5=Esko I. |last6=Kishimoto |first6=Shigeru |last7=Mizutani |first7=Takashi |last8=Ohno |first8=Yutaka |bibcode = 2011NatNa...6..156S |s2cid=205446925 }}</ref> Flexible transistors are useful in some kinds of [[flexible display]]s and other [[flexible electronics]].