The requested file:
https://pdf.datasheetcatalog.com/datasheet/siemens/BC639.pdf
is the data sheet for the following electronic components:

Siemens

#	Part Name	Description
1	BC635	NPN Silicon AF Transistors (High current gain High collector current)
2	BC637	NPN Silicon AF Transistors (High current gain High collector current)
3	BC639	NPN Silicon AF Transistors (High current gain High collector current)

Select the part name and then you can download the datasheet in PDF format.