Lead Frames
The
lead frame, or
leadframe, is the 'skeleton' of the IC package, providing mechanical support to the
die during its assembly into a finished product. It consists of a die paddle, to which
the die is attached, and leads, which serve as the
means for external electrical connection to the outside world. The die is connected to the leads by wires through wirebonding or by tape automated bonds.
Plastic
package lead frames are made of
alloys that meet the following
critical
properties: good adherence to the molding compound, a coefficient of
thermal expansion as close as possible to those of the die and the
molding compound, high strength, good formability, and high electrical
and thermal conductivities.
Alloy42
is an example of such an alloy.
 |
|
Fig. 1.
Examples of Leadframes |
Lead frames
are constructed from flat sheet metal either by stamping or etching.
Stamping is a highly-automated mechanical process that employs
die and punch sets to progressively achieve the intended lead frame
structure through a series of stamping/punching steps.
Etching
consists of
selectively covering the sheet metal with photoresist in
accordance with the pattern of the lead frame.
The sheet metal is then exposed to chemical etchants that remove
areas not covered by photoresist. After
the etching process, the 'etched' frames are singulated into strips.
After
stamping or etching, the lead frame is then
finished
with cleaning,
silver-plating, taping and downsetting steps.
Silver-plating is done on the bonding fingers and die pad to
improve wirebond and die attach quality.
Taping consists of putting a lead lock tape over the leads to
prevent lead deformation, while
downsetting consists of pushing the die
paddle down relative to the bonding fingers in compliance with standard
industry requirements.
The
lead frames are then inspected before being packed for shipment to the
customer.
Examples
of vendors of lead frames are QPL, DCI, and Olin Brass.
Table 1. QPL Etched Leadframe Open Tool Partial List
|
LEADCOUNT |
DESCRIPTION |
DRAWING NO. |
|
28L |
300X300
PDIP (.600") |
QPL-28-PDIP-0016 |
|
48L |
350X350
PDIP (.600") |
QPL-48-PDIP-0006 |
|
84L |
360X360
PLCC |
QPL-84-PLCC-0018 |
|
100L |
290X290 QFP
(14X20) |
QPL-100-QFP-0016 |
|
100L |
410X410 QFP
(14X20) |
QPL-100-QFP-0024 |
|
18L |
160X200
SOIC DUAL (.300") |
QPL-18-SOIC-0005 |
|
18L |
140X170
SOIC DUAL (.300") |
QPL-18-SOIC-0006 |
|
20L |
180X220
SOIC DUAL (.300") |
QPL-20-SOIC-0010 |
|
20L |
180X260
SOIC DUAL (.300") |
QPL-20-SOIC-0012 |
|
28L |
170X170
SOIC DUAL (.300") |
QPL-28-SOIC-0017 |
|
28L |
195X330
SOIC DUAL (.300") |
QPL-28-SOIC-0056 |
|
20L |
96X140 SSOP
DUAL (.150") |
QPL-20-SSOP-0002 |
|
24L |
96X140 SSOP
DUAL (.150") |
QPL-24-SSOP-0002 |
Table
2. QPL Stamped Leadframe Open Tool Partial List
|
LEADCOUNT |
DESCRIPTION |
DRAWING NO. |
|
8L |
80X80 PDIP DUAL (.300") |
QPL-08-PDIP-0002 |
|
8L |
120X150 PDIP DUAL
(.300") |
QPL-08-PDIP-0039 |
|
14L |
80X80 PDIP (.300") |
QPL-14-PDIP-0007 |
|
14L |
150X190 PDIP (.300") |
QPL-14-PDIP-0034 |
|
16L |
80X110 PDIP (.300") |
QPL-16-PDIP-0003 |
|
16L |
150X230 PDIP (.300") |
QPL-16-PDIP-0016 |
|
18L |
80X120 PDIP (.300") |
QPL-18-PDIP-0001 |
|
18L |
160X250 PDIP (.300") |
QPL-18-PDIP-0006 |
|
20L |
90X110 PDIP (.300") |
QPL-20-PDIP-0002 |
|
20L |
160X230 PDIP (.300") |
QPL-20-PDIP-0011 |
|
22L |
140X170 PDIP (.400") |
QPL-22-PDIP-0001 |
|
22L |
160X340 PDIP (.300") |
QPL-22-PDIP-0004 |
|
24L |
120X150 PDIP (.600") |
QPL-24-PDIP-0001 |
|
24L |
300X300 PDIP (.600") |
QPL-24-PDIP-0008 |
|
28L |
260X260 PDIP (.600") |
QPL-28-PDIP-0006 |
|
28L |
196X320 PDIP (.300") |
QPL-28-PDIP-0085 |
|
40L |
180X180 PDIP (.600") |
QPL-40-PDIP-0006 |
|
40L |
300X300 PDIP (.600") |
QPL-40-PDIP-0018 |
|
28L |
200X200 PLCC |
QPL-28-PLCC-0002 |
|
28L |
300X300 PLCC |
QPL-28-PLCC-0038 |
|
32L |
200X200 PLCC |
QPL-32-PLCC-0063 |
|
32L |
240X290 PLCC |
QPL-32-PLCC-0066 |
|
44L |
200X200 PLCC |
QPL-44-PLCC-0006 |
|
44L |
300X300 PLCC |
QPL-44-PLCC-0032 |
|
52L |
360X360 PLCC |
QPL-52-PLCC-0015 |
|
68L |
300X300 PLCC |
QPL-68-PLCC-0004 |
|
68L |
410X410 PLCC |
QPL-68-PLCC-0034 |
|
84L |
425X425 PLCC |
QPL-84-PLCC-0004 |
|
44L |
200X200 QFP (10X10) |
QPL-44-QFP-0026 |
|
44L |
300X300 QFP (10X10) |
QPL-44-QFP-0032 |
|
52L |
210X210 QFP (10X10) |
QPL-52-QFP-0019 |
|
52L |
280X280 QFP (10X10) |
QPL-52-QFP-0022 |
|
64L |
280X280 QFP (10X10) |
QPL-64-QFP-0031 |
|
80L |
315X315 QFP (14X20) |
QPL-80-QFP-0021 |
|
100L |
315X315 QFP (14X20) |
QPL-100-QFP-0086 |
|
128L |
370X370 QFP (28X28) |
QPL-128-QFP-0029 |
|
160L |
370X370 QFP (28X28) |
QPL-160-QFP-0060 |
|
32L |
200X200 TQFP DUAL (7X7) |
QPL-32-TQFP-0019 |
|
44L |
200X200 TQFP (10X10) |
QPL-44-TQFP-0011 |
|
44L |
300X300 TQFP (10X10) |
QPL-44-TQFP-0013 |
|
48L |
200X200 TQFP DUAL (7X7) |
QPL-48-TQFP-0014 |
|
52L |
210X210 TQFP (10X10) |
QPL-52-TQFP-0008 |
|
52L |
280X280 TQFP (10X10) |
QPL-52-TQFP-0009 |
|
64L |
280X280 TQFP (10X10) |
QPL-64-TQFP-0020 |
|
80L |
320X320 TQFP (14Xl4) |
QPL-80-TQFP-0009 |
|
80L |
410X410 TQFP (14Xl4) |
QPL-80-TQFP-0014 |
|
100L |
360X360 TQFP (14Xl4) |
QPL-100-TQFP-0013 |
|
100L |
236X236 TQFP (14X20) |
QPL-100-TQPF-0073 |
|
8L |
90X100 SOIC DUAL (.150") |
QPL-08-SOIC-0013 |
|
14L |
90X150 SOIC DUAL (.150") |
QPL-14-SOIC-0014 |
|
16L |
90X110 SOIC DUAL (.150") |
QPL-16-SOIC-0001 |
|
16L |
150X200 SOIC DUAL
(.300") |
QPL-16-SOIC-0043 |
|
20L |
110X140 SOIC DUAL
(.300") |
QPL-20-SOIC-0043 |
|
20L |
180X220
SOIC DUAL (.300") |
QPL-24-SOIC-0049 |
See Also:
Semiconductor
Matls;
IC Manufacturing; Package
Outlines
HOME
Copyright
©
2005-2007
www.EESemi.com.
All Rights Reserved.
