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.

      

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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 ManufacturingPackage Outlines

 

   

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