MIL- STD-883F 2004 TEST METHOD STANDARD MICROCIRCUITS.pdf - 第375页

MIL-STD-883F METHOD 2023.5 19 August 1994 3 Also, RF/mic rowave hybri ds that contai n tuning wir es (des ignated wi res t hat w ill alter RF p erforman ce w hen moved) or wires that c annot be acc essed wi th a pull hoo…

MIL-STD-883F

METHOD 2023.5

19 August 1994

3. PROCEDURE. The test shall be conducted as specified in the applicable acquisition document, as a sample or as a

screen, and shall be consistent with the particular bond materials and construction. All bond wires in each device shall be

pulled and counted, and the specified sampling, acceptance, and added sample provisions shall be observed, as applicable.

Where there is any adhesive, encapsulant or other material under, on, or surrounding the wire such as to increase the

apparent bond strength, the test shall be performed prior to the application of the material.

a. Set the rate of force application.

b. Mount the specimen to be tested and set the lifting mechanism to apply the specified force for the appropriate wire

size and material.

c. The device shall be rotated and positioned such that the hook contacts the wire between midspan and loop apex

(for forward wedge and ball bonding, this would be between midspan and die edge; for reverse bonding, this would

be between midspan and package edge) and the pulling force is applied in a direction approximately normal to the

die or substrate, or approximately normal to a straight line between the bonds. The manufacturer should pull as

close to midspan as possible without causing adverse wire deformation.

d. The lifting mechanism shall be actuated to stress the wire bond such that the specified stress is applied with

minimum impact loading and with no overshoot greater than specified accuracy of the indicator at any time during

the bond pull. The dwell time of maximum force application shall be a maximum of one second.

e. Observe whether the bond breaks.

f. If the bond breaks, reject the device and proceed to the next device, unless rework is acceptable. If so, record the

identification of the broken bond and the device containing the bond. If rework is permitted, all bonds shall be

tested prior to any bond rework and reworked bonds shall be tested.

g. If no bonds on the device break, accept the device as satisfactory.

h. Repeat a through g for all bonds to be tested.

i. Record the total number of wires or wire bonds that fail when subjected to the predetermined stress.

j. Record the number of devices that failed the test.

3.1 Failure criteria

. Any bond pull which results in separation (of bonds at the bond interface or breakage of the wire or

interconnect anywhere along the entire span including bond heels) at an applied stress less than the specified stress for the

applicable material and construction shall constitute a failure. Unless otherwise specified, the applied nondestructive pull

stress shall be 80 percent of the preseal minimum bond strengths for the applicable material, size and construction given in

table I of method 2011 or figure 2011-1 of method 2011. Table I herein lists pull force values for commonly used wire sizes.

NOTE: RF/microwave hybrids that require extremely flat loops which may cause erroneous wire pull data may use the

following formula to determine the proper wire pull value.

= V

Sin Θ

Where: V

= New value to pull test.

= Table I value for size wire tested.

Θ = Greatest calculated wire loop angle (figure 2023-1).

MIL-STD-883F

METHOD 2023.5

19 August 1994

Also, RF/microwave hybrids that contain tuning wires (designated wires that will alter RF performance when moved) or

wires that cannot be accessed with a pull hook must be simulated on a test coupon in such a way to allow hook access for

purposes of pull testing. These wires are to be bonded at the same time the production hybrids are bonded using the same

setup, operator, schedule, and elements (electrical rejects may be used). The test coupon wires are to be pull tested in lieu

of the tuning or inaccessible wires on the production hybrid. Failures on the test coupon shall be considered as failures to

production units and appropriate action is to be taken in accordance with the applicable specification (figure 2023-2).

TABLE I. Nondestructive pull forces

AL and AU wire

diameter

(inches)

Pull force

(gf)

Pull force

(gf)

0.0007

0.0010

0.00125

0.0013

0.0015

0.0030

1.2

2.0

2.5

3.0

9.5

1.6

2.4

3.2

4.0

12.0

NOTES:

1. Nondestructive pull force values for wire sizes not specified

shall be 80 percent of the preseal pull forces for aluminum or

gold wire given in method 2011.

2. Tolerances shall be ±0.3 gf for pull forces up to 6 gf and ±5

percent for pull forces above 6 gf.

3. Any bond subjected to a nondestructive pull force exceeding

the specified pull force and the positive tolerance shall be

eliminated and not counted toward the PDA failures.

3.2 Alternative procedure

. This alternate procedure may be used where 100 percent non-destructive bond pull cannot be

performed because of high pin count (greater than or equal to 84 terminals) and small bonding wire pitch at the package

post (less than or equal to 12 mils).

3.2.1 In-process controls

. In order for a manufacturer to use the alternate procedure, a SPC program shall be

implemented for the wire bond operation in accordance with EIA-557-A, Statistical Process Control Systems. Any change in

the various effects shown to be significant by the characterization with respect to wire bond strength shall require a re-

characterization of the wire bonding process for the changed effect(s) on wire bond integrity. For QML, the SPC program

and the requirements listed herein shall be approved by the qualifying activity and may be subject to an audit at any time by

the government qualification activity. For Non-Jan devices, the SPC program and the requirements listed herein are subject

to review by the government agency responsible for the acquisition or their designee. All statistical evaluation,

characterizations, and designed experiments shall be available for review.

3.2.1.1 Applicable incoming materials

. Applicable incoming materials including wafer pad metallization targets, package

bonding post, and bonding wire shall have their critical characteristics determined and made requirements for acceptance

using either incoming inspection or vendor SPC data. Critical characteristics shall include possible sources of material

contamination (e.g. excessive carbon content in aluminum wire). Also, the applicable incoming inspection requirements of

MIL-PRF-38535 or MIL-PRF-38534 shall apply.

MIL-STD-883F

METHOD 2023.5

19 August 1994

3.2.1.2 Applicable manufacturing processes. Applicable manufacturing processes including bond pad metal disposition,

glassivation etch, and worst case package seal excursion shall have their critical characteristics determined and placed

under SPC control. Also, the process control requirements of the applicable general specification shall apply for these

operations including contamination controls, preventative maintenance procedures and schedules, and complete removal of

glassivation from the bonding pad.

3.2.1.3 For packages with gold plated posts

. For packages with gold plated posts, the device manufacturer shall perform

a bake test on one device from each incoming package lot. This test shall evaluate for basic plating or contamination

anomalies of the package post. The package shall be wire bonded post-to-post. The wire bonded package shall be baked

at 300 degrees celsius for 1 hour in either air or inert atmosphere. Bond strength shall then be tested in accordance with

MIL-STD-883, method 2011, using a sample size number = 45, C = 0 on the number of wires pulled. If any bond strength

failure is determined to be package plating or contamination related then the package lot shall not be used for this

alternative unless the defect can be effectively screened and the package lot resampled to a tightened sample size number

= 76, C = 0 for the number of wires pulled.

3.2.1.4 An active foreign material control program

. An active foreign material control program shall be in accordance with

MIL-STD-883, method 2010 or method 2017. A procedure and system for storing and handling wafers, packages, related

piece parts, and unsealed devices that will prevent contamination through package seal including face masks, lint free

gloves, restrictions on particle generating make-up, hair covers, and cleanroom gowns.

3.2.1.5 A 100 percent pre-bond visual inspection procedure

. A 100 percent pre-bond visual inspection procedure of the

die pads and package post shall be documented. The visual inspection shall be performed at 100-200X in a class 100

environment. Cleaning to remove rejectable contamination is allowed. No device shall exhibit evidence of the following

criteria:

a. Glassivation on the designed open contact area of the bond pads.

b. Chemical, film, photoresist or liquid contamination on the pads or posts.

c. Particulate and /or foreign material contamination on the pads or the critical bond area of the posts greater than

0.25 mils in diameter.

d. Die pads and package posts that do not meet all applicable requirements of MIL-STD-883, method 2010, condition

A or method 2017.

NOTE: 100 percent pre-bond visual inspection may be waived by the qualifying activity provided a 100 percent pre-

clean of pads and posts is performed, and all pads and posts for five (5) randomly selected devices pass the

inspection criteria. Precleaning may also be waived by the qualifying activity if historical data demonstrates the

cleaning is unnecessary. No cleaning is allowed during sample inspection. A 100 percent pre-clean and sample

inspection of 5(0) may be repeated a maximum of two times. Rejection of the sample after the second pre-clean

shall result in a 100 percent pre-bond inspection of the lot in accordance with 3.2.1.5. An investigation of the

rejects in the lot and sample shall be required and corrective action, as necessary shall be instituted. Until then,

100 percent pre-bond inspection is required. Once the effectiveness of any corrective action has been

determined, the 100 percent pre-bond inspection may be eliminated.

3.2.1.6 Bonding machine parameters

. Bonding machine parameters (e.g., temperatures, pressure, timing, fixtures, wire

size, wire material, height settings, etc.) must be defined for each die/package combination. The bonding equipment

parameters ranges shall be optimized by designed experiments. The experiments shall consider variations in bonding wire

geometry (e.g., loop height, wire length, shelf height, etc.). The experiments shall establish the predicted strength and

tolerance of the bonding operation. The allowable performance ranges of the bonding parameters determined by controlled

experiments shall be documented. Equipment parameter changes outside the allowable limits must be evaluated and

documented as to still meeting the predicted wire pull strength and tolerance.

Note: ASTM Standards F 458 and F 459 may be used as guideline documents.