I have a BC107 transistor, and am so curious to know what those first letters means or what they indicate about the transistor and what the 3 last digits mean. What I only know is that this numbers helps us to find the datasheet of this transistor giving us all information we want to know but my curiosity is in knowing the reason behind those numbers there.
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2 Answers
Generally, the number is simply a model number, and the link between the number and any specific properties/parameters is weak at best. For example, even among transistors called BC??8, not every transistor with that name pattern is part of the same family.
However, the first few characters of the part are sometimes more useful for quickly figuring out some basic details.
For example, the actual letters BC
appear to follow the Pro Electron naming scheme identifying it as a silicon transistor for small-signal use.
You may also encounter names like 1N4148 (diode) or 2N3904 (transistor) - the prefix 1N and 2N mean diode and transistor respectively in the JEDEC naming convention which itself evolved from an old naming convention for vacuum tubes. Even then, this doesn't tell you much about the part; for example, a 2N???? part could be a JFET (e.g. 2N3819), MOSFET (e.g. 2n7000), BJT (e.g. 2n3904), or something more obscure like a unijunction transsitor, and it could be P-type or N-type.
Likewise, there is a Japanese identification scheme although I don't know part examples within it offhand.
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\$\begingroup\$ thank you so much i now understand \$\endgroup\$ Jun 26 at 18:37
In an old National Semiconductor data book, transistors are grouped in a few different ways:
- same chip encapsulated in a different package, using unique prefix (MMBTxxx versus 2Nxxx)
- same chip more (or less) rigorously measured to meet various specs. "JEDEC" versus "Consumer-grade"
- application grouping: "high-speed switch" versus "small signal amplifier".
National Semi also grouped chips by "Process number". Each process has different size, shape, and contact pad regions. For example, PROCESS #63 is a square PNP chip 0.483mm x 0.483mm. It is a PNP bipolar meant for medium-power applications. It's process is non-overlay, double-diffused silicon epitaxial. It has similar complementary specs to an NPN process #19. It lists principle device type for:
TO-5 EBC: 2N2905
TO-18 EBC: 2N2907A
TO-237 EBC: TN2905
TO-92 EBC: PN2907A, 2N4403
TO-116: MPQ2907
TO-236: MMBT2907
16-SOIC: MMPQ2907
Non-principle devices that also use this PROCESS #63 include:
2N2904, 2n2904A
2N2906, 2N2906A
2N3638, 2N3638A
2N3644
2N3645
2N3702
2N3703
2N4142
2N4143
2N4290
2N4291
2N4402
2N4971
2N4972
2N5142
2N5143
2N5221
2N5226
2N5354
2N5355
2N5365
2N5366
2N5447
2N5817
MPS3638, PN3638
MPS3638A,PN3638A
MPS3644, PN3644
MPS3645 PN3645
MPS3702
MPS3703
MPS6533
MPS6534
MPS6535
TIS91
TIS92
TIS93
TN2904A
TN2905, TN2905A