MIL- STD-883F 2004 TEST METHOD STANDARD MICROCIRCUITS.pdf - 第188页

MIL-STD-883F METHOD 2004.5 29 November 1985 2 3. PROCEDURE . Each l ead or ter minal t o be test ed shall be subjec ted to for ce s uffi cient to bend the lead as spec ifi ed in 3.1 thr ough 3.5, as applic able. Any numb…

MIL-STD-883F

METHOD 2004.5

29 November 1985

METHOD 2004.5

LEAD INTEGRITY

1. PURPOSE

. This method provides various tests for determining the integrity of microelectronic device leads

(terminals), welds, and seals. Test condition A provides for straight tensile loading. Test condition B

provides for

application of bending stresses to determine integrity of leads, seals, and lead plating while B

employs multiple application

of bending stresses primarily to determine the resistance of the leads to metal fatigue under repeated bending. Test

conditions C

and C

provide for application of torque or twisting stresses to device leads or studs, respectively, to

determine integrity of leads and seals. Test condition D provides for application of peel and tensile stresses to determine

integrity of terminal adhesion and plating of leadless packages. It is recommended that this test be followed by a seal test in

accordance with method 1014 to determine any effect of the stresses applied on the seal as well as on the leads (terminals).

2. APPARATUS

. See applicable test condition.

3. GENERAL PROCEDURE APPLICABLE TO ALL TEST CONDITIONS

. The device shall be subjected to the stresses

described in the specified test condition and the specified end-point measurements and inspections shall be made except for

initial conditioning or unless otherwise specified. Unless otherwise specified, the Sample Size Series sampling shall apply

to the leads, terminals, studs or pads chosen from a minimum of 3 devices.

4. SUMMARY

. The following details and those required by the specific test condition shall be specified in the applicable

acquisition document:

a. Test condition letter.

b. Number and selection of leads (terminals), if different from above.

TEST CONDITION A - TENSION

1. PURPOSE

. This test is designed to check the capabilities of the device leads, welds, and seals to withstand a straight

pull.

2. APPARATUS

. The tension test requires suitable clamps and fixtures for securing the device and attaching the

specified weight without lead restriction. Equivalent linear pull test equipment may be used.

3. PROCEDURE

. A tension of 0.227 kg (8 ounces), unless otherwise specified, shall be applied, without shock, to each

lead or terminal to be tested in a direction parallel to the axis of the lead or terminal and maintained for 30 seconds

minimum. The tension shall be applied as close to the end of the lead (terminal) as practicable.

3.1 Failure criteria

. When examined using 10X magnification after removal of the stress, any evidence of breakage,

loosening, or relative motion between the lead (terminal) and the device body shall be considered a failure. When a seal

test in accordance with method 1014 is conducted as a post test measurement following the lead integrity test(s), meniscus

cracks shall not be cause for rejection of devices which pass the seal test.

4. SUMMARY

. The following details shall be specified in the applicable acquisition document:

a. Weight to be attached to lead, if other than .227 kg (8 ounces) (see 3).

b. Length of time weight is to be attached, if other than 30 seconds (see 3).

TEST CONDITION B

- BENDING STRESS

1. PURPOSE

. This test is designed to check the capability of the leads, lead finish, lead welds, and seals of the devices

to withstand stresses to the leads and seals which might reasonably be expected to occur from actual handling and

assembly of the devices in application, or to precondition the leads with a moderate bending stress prior to environmental

testing.

2. APPARATUS

. Attaching devices, clamps, supports, or other suitable hardware necessary to apply the bending stress

through the specified bend angle.

MIL-STD-883F

METHOD 2004.5

29 November 1985

3. PROCEDURE

. Each lead or terminal to be tested shall be subjected to force sufficient to bend the lead as specified in

3.1 through 3.5, as applicable. Any number or all of the leads of the test device may be bent simultaneously. Rows of leads

may be bent one row at a time. Each lead shall be bent through one cycle as follows: Bend through the specified arc in one

direction and return to the original position. All arcs shall be made in the same plane without lead restriction.

3.1 Direction of bends

. Test leads shall be bent in the least rigid direction. If there is no least rigid direction, they may be

bent in any direction. No lead shall be bent so as to interfere with another lead. If interference is unavoidable, the test lead

shall be bent in the opposite direction to the angle specified and returned to its normal position.

3.2 Procedure for initial conditioning of formed leads

. When normally straight leads are supplied in a formed condition

(including the staggered lead dual-in- line configuration), the lead forming operation shall be considered acceptable initial

conditioning in place of that specified, provided the lead forming has been done after lead plating and the forming is at least

as severe in permanent lead deformation as the specified bending.

3.3 Procedure for flexible and semi-flexible leads (e.g., flat packs and axial-lead metal-can devices)

3.3.1 Flexible leads

. A lead shall be considered flexible if its section modulus (in the least rigid direction) is less than or

equal to that of a rectangular lead with a cross section of 0.15 x 0.51 mm (.006 x .020 inch). Round leads less than or equal

to 0.51 mm (.020 inch) in diameter shall be considered flexible. Flexible leads shall be bent through an arc of at least 45°

measured at a distance 3.05 ±.76 mm (0.120 ±0.03 inch) along the lead from the seal unless otherwise specified.

3.3.2 Semi-flexible leads

. Semi-flexible leads are those leads with a section modulus (in the least rigid direction) greater

than that of a rectangular lead with a cross section of 0.15 x 0.51 mm (0.006 x 0.020 inch) which are intended to be bent

during insertion or other application. Round leads greater than 0.51 mm (.020 inch) diameter shall be considered

semi-flexible except as noted in 3.5. Semi-flexible leads shall be bent through an arc of at least 30° measured at the lead

extremities unless otherwise specified.

3.4 Procedure for dual-in-line and pin grid array package leads

. Dual-in-line package leads are leads with more than one

section modulus, with leads normally aligned in parallel at a 90° angle from the bottom of the package during insertion.

Dual-in-line package leads shall be bent inward through an angle sufficient to cause the lead to retain a permanent bend

(i.e., after stress removal) of at least 15°. For configuration 1 and 2, the angle of bend shall be measured from the lead

extremities to the first bend (see figure 2004-1), For configuration 3, the angle of bend shall be measured from the lead

extremities to the seating plane (see figure 2004-1). Pin grid array packages shall have the leads required for testing from

the outside row of leads on opposite sides bent through an angle sufficient to cause the lead to retain a permanent bend

(i.e., after stress removal) of at least 15°. The angle of bend shall be 15° from normal and the bend shall be made at the

approximate seating plane. At the completion of the initial bend, the leads shall be returned to their approximate original

position.

3.5 Procedure for rigid leads or terminals

. A lead or terminal shall be considered rigid if it is not intended to be flexed in

mounting, and not covered in 3.3 or 3.4. Devices with terminals complying with this description shall be subjected to a

normal mounting operation and removal, unless otherwise specified. When the normal mounting/removal operation is

destructive to the terminals (e.g., terminal weld, wire wrap), the initial conditioning need not be performed.

3.6 Failure criteria

. When examined using magnification between 10X and 20X after removal of the stress, any evidence

of breakage, loosening, or relative motion between the terminal lead and the device body shall be considered a device

failure. When specified, post-test measurements (see 4) shall be made after visual examination. When the above

procedures are used as initial conditioning in conjunction with other tests, these measurements may be conducted at the

conclusion of that test or sequence of tests.

4. SUMMARY

. The following details shall be specified in the applicable acquisition document:

a. Bending arc, if other than that specified.

b. Procedure, if other than that specified.

c. Number and selection of leads and procedure for identification, if other than that specified.

d. Post test measurements, if applicable (see 3.6)

MIL-STD-883F

METHOD 2004.5

29 November 1985

TEST CONDITION B

- LEAD FATIGUE

1. PURPOSE

. This test is designed to check the resistance of the leads to metal fatigue.

2. APPARATUS

. Attaching devices, clamps, supports, or other suitable hardware necessary to apply a repeated bending

stress through the specified bend angle.

3. PROCEDURE

. The appropriate procedure of 3.1 or 3.2 for the device under test shall be used.

3.1 Procedure for dual-in-line packages

. The leads to be tested shall be subjected to three cycles of test condition B

and

shall be subjected to a force sufficient to bend the leads as specified in 3.4 of condition B

3.2 Procedure for flat packages and can packages

. A force of 0.229 ±0.014 kg (8 ±0.5 ounces), unless otherwise specified,

shall be applied to each lead to be tested for three 90° ±5° arcs of the case. For leads with a preplated or prefinished section

modulus equal to or less than that of a rectangular lead with a cross section of 0.16 x 0.51 mm (0.006 x 0.020 inches) or round

leads with a cross section of 0.51 mm (0.020 inch) in diameter, the force shall be 0.085 ±0.009 kg (3 ±0.3 ounces). Section

modulus is defined as bc

/6 for rectangular leads, and 0.098 (φb

)

for round leads (see MIL-STD-1835). An arc is defined as

the movement of the case, without torsion, to a position perpendicular to the pull axis and return to normal. All arcs on a single

lead shall be made in the same direction and in the same plane without lead restriction. A bending cycle shall be completed in

from 2 to 5 seconds. For devices with rectangular or ribbon leads, the plane of the arcs shall be perpendicular to the flat plane

of the lead. The test shall not be applied to end leads of packages where its application will apply primarily torsion forces at the

lead seal.

3.2.1 Optional procedure for fine pitch/small leads

. A force as determined by the following formula unless otherwise

specified, shall be applied to each lead to be tested for 90 degrees ±5 degree arcs of the device. All other conditions of section

3.2 shall apply: Weight = (area in square inches) x 2.1 % x (K psi) x 453.6 grams/lb. Where K is based on the ultimate tensile

strength (UTS) for a particular material. Typical value for kovar and alloy 42 are listed below. The UTS for other materials can

be found in vendor data sheets. The result shall be rounded to the nearest whole number.

NOTE: A lead pitch of less than or equal to 25 mils is considered fine pitch.

Material

UTS in psi

Kovar

Alloy 42

75000

71000

3.3 Failure criteria

. A broken lead on a device shall be considered a failure. When examined using magnification between

10X and 20X after removal of the stress, any device which exhibits any evidence of breakage, loosening, or relative motion

between the terminal lead and the device body shall be considered a device failure.

4. SUMMARY

. The following details shall be specified in the applicable acquisition document:

a. Force to be applied to the lead, if other than above (see 3).

b. Number of cycles, if other than above (see 3).

c. Maximum bend angle, if other than above (see 3).