evaluation of press-fit connector for space-flight

TÜV NORD GROUP

EVALUATION OF PRESS-FIT CONNECTOR FOR SPACE-FLIGHT APPLICATIONS,

FEEDBACK AND DESIGN IMPROVEMENTS

2

Trends show an increasing demand for the incorporation of new fabricationconcepts and components into the space industry. This requires for fast andreliable evaluation processes adapted to the specific system design and thecharacteristics.

Press-fit technology is already consolidated in different industrial sectors andcurrently is emerging for space applications.

Solder-less alternative for PCB assembly.

Cost and time effective.

Mature commercial technologies

Space qualification

Spaceimplementation

This communication reports on thequalification process to asses the reliability ofselected press-fit connector for theimplementation in space applications.

INTRODUCTION

3

Standard and high density connectors comply with the

space regulation

profile(f)

high-abort(f)

low-abort(f)

high-alarm(f)

low-alarm(f)

control(f)

2000.0020.00 100.00 1000.00

8.3176

0.0013

0.0100

0.1000

1.0000

Frequency (Hz)

(gn)²/Hz

-80

-60

-40

-20

0

20

40

60

80

100

120

0:0

00:1

50:3

00:4

51:0

01:1

51:3

01:4

52:0

02:1

62:3

12:4

63:0

13:1

63:3

13:4

64:0

14:1

74:3

24:4

75:0

25:1

75:3

25:4

76:0

26:1

86:3

36:4

87:0

37:1

87:3

37:4

88:0

38:1

8

TEM

PER

AT

UR

E

(ºC

)

TIME (minutes)

Vibrationand temperature cycling

Control visual inspections Control electrical

measurements

Microsectioning Microinspection

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

PCB 1 Conect. 1 PCB 2 Conect. 1 PCB 3 Conect. 1

Aver

age

Cont

act R

esita

nce

(mΩ

)

Initial Vibration 200 Temp Cycles 300 Temp Cycles

Thorough and accurate tests are conducted to determine thesuitability for space applications

Environmental test

4

1. Compliant-Press-Fit concept

2. Test vehicles and test flow

3. Vibration test

4. Temperature cycling

5. Visual inspection and electrical verification control test

6. Micro section inspection

7. 2nd Generation

8. Summary

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

PCB 1 Conect. 1 PCB 2 Conect. 1 PCB 3 Conect. 1

Aver

age

Cont

act R

esita

nce

(mΩ

)


-80

-60

-40

-20

0

20

40

60

80

100

120

0:0

00:1

50:3

00:4

51:0

01:1

51:3

01:4

52:0

02:1

62:3

12:4

63:0

13:1

63:3

13:4

64:0

14:1

74:3

24:4

75:0

25:1

75:3

25:4

76:0

26:1

86:3

36:4

87:0

37:1

87:3

37:4

88:0

38:1

8

TEM

PER

AT

UR

E

(ºC

)

TIME (minutes)

OUTLINE

5

Deformable tail is inserted into a plate

through hole (PTH).

PTH slightly narrower than theinsertion pin.

Eye-of-the-needle design: The tail isadapted to the PTH at the same timethat the spring-force ensurespermanent low-resistivity electricalcontact.

Semiautomatic mounting tool to regulatethe insertion force.

COMPLIANT-PRESS-FIT CONCEPT

6

Denomination Pin size Number of pins Intended aplication Quantuty

High density 22 75 Singal comunication 3 PCBs with 2 connectors

Standard density 20 50 Low power supply 3 PCBs with 2 connectors

Combo-D 8 5 High power supply 3 PCBs with 2 connectors

General PCB characteristics

- 4 Cu layers of 2.4 mm of thickness - Electroless Nickel Immersion Gold (ENIG) - PTHs gold coating of 5 µm of thickness

3 types of press fit connectors conceived for different applications:

Signal communication. Low power supply. High power supply.

High density75 pins Standar density

50 pinsCombo-D

8 pins

TEST VEHICLES

Inspections

Environmental tests

Connector mountingon PCB

Visual inspection+

Electrical verification

Connector unmounting

from PCBx1

Visual inspection+


VibrationTests (sin + random)

Visual inspection+


Temperature cycling200 cycles

Visual inspection+


Cross-sectionInternal µ-inspection


Visual inspection+


7

Qualification program adapted from ECSS-Q-ST-70-38C for surface mounting technology but including harder requirements

Test / inspection Specification

Visual inspection ESCC 20500

Electrical characterization DENG-008-1 Rev. B § 7 (customer procedure)

VibrationECSS Q ST 70 08C § 13 (sine + random)

Additional provision µ-cuts ≥ 1 µs are not allowed

Temperature Cycling

DENG-008-1 Rev. B Par. 14

-55 ºC to +100 ºC abrupt thermal shock

Cross-section µ-inspection DENG-008-1 Rev. B

TEST FLOW

8

Vibration

Inspections

Environmental tests


Visual inspection+



from PCBx1

Visual inspection+



Visual inspection+



Visual inspection+




Visual inspection+


9

Sine sweep vibration test Random vibration test

High level vibration


XAxis

YAxis

ZAxis

Sine Sweep

(X)

Sine survey

(X)

Sine survey

(X)

Sine Sweep

(X)

Sine survey

(X)

Sine survey

(Y)

Sine Sweep

(Y)

Sine survey

(Y)

Sine survey

(Z)

Sine Sweep

(Z)

Sine survey

(Z)

Sine Sweep

(X)

Sine survey

(X)

Sine survey

(X)

Random(X)

Sine survey

(X)

Sine survey

(Y)

Random(Y)

Sine survey

(Y)

Sine survey

(Z)

Random(Z)

Sine survey

(Z)

VIBRATION TEST: TEST SEQUENCE

10

DUT natural frequencies identification


DUT natural frequencies

shift

In situ electrical

monitoring

Electrical

Electrical discontinuities

(in-situ)

Resistance drift (ex-situ)

Mechanical

Natural frequencies

(in-situ)

Visible damages (ex-situ)

Inspected parameters

In-situ inspection

Sine sweep and random vibration tests

Sine Sweep

(X)

Sine survey

(X)

Sine survey

(X)

Sine orrandom

(X)

Sine survey

(X)

Sine survey

(Y)

Sine orrandom

(Y)

Sine survey

(Y)

Sine survey

(Z)

Sine orrandom

(Z)

Sine survey

(Z)

VIBRATION TEST: INSPECTED PARAMETERS

11

Y-axis vibration

Vibr

atio

n

Z-axis vibration

X-axis vibration

Elec

trica

l m

onito

ring

Daysi chain electrical monitoring

VIBRATION TEST: SET-UP

No discontinuities longer than 1 µs were observed

12


Sine Sweep conditions

Range Amplitude(0 to peak) Sweep rate

25 to 100 Hz 20 g 1 oct/min

100 to 200 Hz 15 g 1 oct/min

Vibration level follows the required profile neither resonances nor other deviations were observed

In situ electrical

monitoring

Sine Sweep

(X)

Sine survey

(X)

Sine survey

(X)

Sine Sweep

(X)

Sine survey

(X)

Sine survey

(Y)

Sine Sweep

(Y)

Sine survey

(Y)

Sine survey

(Z)

Sine Sweep

(Z)

Sine survey

(Z)

VIBRATION TEST: SINE SWEEP

13

Sine sweep vibration test Random vibration test


XAxis

YAxis

ZAxis

Sine Sweep

(X)

Sine survey

(X)

Sine survey

(X)

Sine Sweep

(X)

Sine survey

(X)

Sine survey

(Y)

Sine Sweep

(Y)

Sine survey

(Y)

Sine survey

(Z)

Sine Sweep

(Z)

Sine survey

(Z)

Sine Sweep

(X)

Sine survey

(X)

Sine survey

(X)

Random(X)

Sine survey

(X)

Sine survey

(Y)

Random(Y)

Sine survey

(Y)

Sine survey

(Z)

Random(Z)

Sine survey

(Z)

VIBRATION TEST: RANDOM

14

profile(f)

high-abort(f)

low-abort(f)

high-alarm(f)

low-alarm(f)

control(f)

2000.0020.00 100.00 1000.00

8.3176

0.0013

0.0100

0.1000

1.0000

Frequency (Hz)

(gn)²/Hz

profile(f)

high-abort(f)

low-abort(f)

high-alarm(f)

low-alarm(f)

control(f)

2000.0020.00 100.00 1000.00

3.1623

0.0126

0.1000

1.0000

Frequency (Hz)

(gn)²/Hz Parallel to PCB

Range (Hz) PSD level

20 to 100 +3 dB/oct (ramp)

100 to 800 0.5 g2/Hz (plateu)

800 to 2000 -3 dB/oct (ramp)

Global RMS 27.1

Vibration level confined within the required range. Neither resonances nor other deviations were observed

Perpendicular to PCB

Range (Hz) PSD level

20 to 100 +6 dB/oct (ramp)

100 to 500 1 g2/Hz (plateau)

500 to 2000 -6 dB/oct (ramp)

Global RMS 28.5

No discontinuities longer than 1 µs were observed

VIBRATION TEST: RANDOM

Sine survey

(X)

High level

vibration(X)

Sine survey

(X)

Sine survey

(X)

High level

vibration(X)

Sine survey

(X)

Sine survey

(X)

High level

vibration(X)

Sine survey

(X)

Sine surveyNatural frequencies analysis

Test conditionsAmplitude 0.5 g (0 to peak)Frequency 10 to 2000 HzSweep rate 2 oct/min

Direction X, Y & Z



profile(f)

high-abort(f)

low-abort(f)

high-alarm(f)

low-alarm(f)

control(f)

2000.0010.00 100.00 1000.00

1.1749

0.1778

1.0000

Frequency (Hz)

gn

VIBRATION TEST: NATURAL FREQUENCIES

profile(f)

high-abort(f)

low-abort(f)

high-alarm(f)

low-alarm(f)

control(f)

2000.0010.00 100.00 1000.00

1.1749

0.1778

1.0000

Frequency (Hz)

gn

profile(f)

high-abort(f)

low-abort(f)

high-alarm(f)

low-alarm(f)

control(f)

2000.0010.00 100.00 1000.00

1.1749

0.1778

1.0000

Frequency (Hz)

gn

profile(f)

high-abort(f)

low-abort(f)

high-alarm(f)

low-alarm(f)

control(f)

2000.0010.00 100.00 1000.00

1.1749

0.1778

1.0000

Frequency (Hz)

gn

profile(f)

high-abort(f)

low-abort(f)

high-alarm(f)

low-alarm(f)

control(f)

2000.0010.00 100.00 1000.00

1.1749

0.1778

1.0000

Frequency (Hz)

gn

X-Ax

isY-

Axis

Z-Ax

is

Initial After high level vibrationAfter high level

vibration

(sine sweep and random)

The DUT preserves its mechanical impedance.

profile(f)

high-abort(f)

low-abort(f)

high-alarm(f)

low-alarm(f)

control(f)

2000.0010.00 100.00 1000.00

1.1749

0.1778

1.0000

Frequency (Hz)

gn

profile(f)

high-abort(f)

low-abort(f)

high-alarm(f)

low-alarm(f)

control(f)

2000.0010.00 100.00 1000.00

1.1749

0.1778

1.0000

Frequency (Hz)

gn

No changes on the DUT

natural frequencies are observed

VIBRATION TEST: NATURAL FREQUENCIES


Visual inspection+



from PCBx1

Visual inspection+



Visual inspection+



Visual inspection+




Visual inspection+


17

Inspections

Environmental tests

Temperature cycling

High temperature 100 ºC

Low temperature - 55 ºC

Soak time 15 min

ESA speciation for soldered connections imposes temperature ramps < 10 ºC/min

According to the customer specifications harder conditions were applied.

-80

-60

-40

-20

0

20

40

60

80

100

120

00:0

0

00:0

2

00:0

5

00:0

8

00:1

1

00:1

4

00:1

7

00:2

0

00:2

3

00:2

5

00:2

8

00:3

1

00:3

4

00:3

7

00:4

0

00:4

3

TEM

PER

ATU

RE

(ºC

)

Stabilization time < 10 min

DU

TH

ot b

ath

Col

d ba

th

Thermal shock between two air baths.

TEMPERATURE CYCLING: SET-UP AND CONDITIONS

-80

-60

-40

-20

0

20

40

60

80

100

120

00:0

000

:15

00:3

000

:45

01:0

001

:15

01:3

001

:45

02:0

002

:16

02:3

102

:46

03:0

103

:16

03:3

103

:46

04:0

104

:17

04:3

204

:47

05:0

205

:17

05:3

205

:47

06:0

206

:18

06:3

306

:48

07:0

307

:18

07:3

307

:48

08:0

308

:18

TEM

PER

ATU

RE

(ºC

)

TIME (minutes)

PCB ComboDS/N 0

ComboDS/N 1

ComboDS/N 2

Standard S/N 0

Standard S/N 1

Standard S/N 2

High S/N 0

High S/N 1

High S/N 2

Min -57.0 -56.6 -56.7 -57.0 -57.0 -56.8 -57.0 -57.0 -57.0

Max 101.2 102.4 100.6 102.1 101.9 103.0 102.7 102.3 102.8

Temperature register of 10 representative

cycles

To ensure the test reliability the temperature is continually monitored withISO17025-calibrated thermocouples attached to the DUT surface.

Max and min temperatures are within the tolerances stated by MIL-STD-202 TM107

TEMPERATURE CYCLING: SET-UP AND CONDITIONS

20

Inspections

Environmental tests

Visual inspection


Visual inspection+



from PCBx1

Visual inspection+



Visual inspection+



Visual inspection+




Visual inspection+


21

In one case small marks were observed near the PTH after mounting and unmounting test.

No evolution was observed after each environmental test

For most of inspected connectors and PCB no noticeable deviations were observed

VISUAL INSPECTION

22

Inspections

Environmental tests



Visual inspection+



from PCBx1

Visual inspection+



Visual inspection+



Visual inspection+




Visual inspection+


0

0.2

0.4

0.6

0.8

1

1.2

PCB 1Conect. 1

PCB 1Conect. 2

PCB 2Conect. 1

PCB 2Conect. 2

PCB 3Conect. 1

PCB 3Conect. 2

Aver

age

Con

tact

Res

itanc

e (m

Ω)


0

0.2

0.4

0.6

0.8

1

1.2

PCB 1 0º PCB 1 90 º PCB 2 0º PCB 2 90 º PCB 3 0º PCB 3 90 º

Combo D

Standard

0

0.2

0.4

0.6

0.8

1

1.2

PCB 1 0º PCB 1 90 º PCB 2 0º PCB 2 90 º PCB 3 0º PCB 3 90 º

Aver

age

Con

tact

Res

itanc

e (m

Ω) High

In all the cases R < 1 mΩ no variations of statistical

significance were observed

VISUAL INSPECTION

24

Inspections

Environmental tests

Microsectioning


Visual inspection+



from PCBx1

Visual inspection+



Visual inspection+



Visual inspection+




Visual inspection+


25

µ-se

ctio

ning

Visu

al &

fluo

resc

ent

µ-in

spec

tion

Selected parts are separated from PCB & cut using a precision diamond wire saw.

Each sample placed in a mounting mold & embedded into epoxy resin (low exothermic).

Luminescent marker added to the resin to analyse defects using its fluorescence.

Automatic Grinding/polishing machine.

Normal and/or fluorescent micro-inspection

MICROSECTIONING & MICROINSPECTIONAccurate wire cutting

Cold Mounting suitable for sensitive parts Multi-step delicate

gridding & polishing

26

Control the removalrate depending onPressure, Time &Rotational Speed.

Damages reductionproduced by the grindingprocess.

Gridding and Polishing optimization by DOE methodology.

Results presented at the Electronic Materials and Processes for Space 9th Workshop, YVERDON-LES-BAINS

Optimization

Certifications

Certified inspectors:

Inspection of crimping connections (ECSS-Q-ST-70-26)Inspection of solder joints for SM & mixed technology (ECSS-Q-ST-70-38).

To be announced:

ESA Recommended company for PCB assembly verifications (ECSS-Q-ST-70-38).

In progress: ISO17025 certification to conduct PCB verification programmes (ECSS-Q-ST-70-38)

Original

27

Through and an detailed inspection in different inspection planes

Transversal cut right connector

Transversal cut vertical connector

Longitudinal cut vertical connector

Stan

dard

and

hig

h de

nsity

con

nect

ors

Com

bo-D

co

nnec

tors

Transversal cut vertical connector

Longitudinal cut vertical connector

MICROSECTIONING & MICROINSPECTION

28

Cracks: • Base of the pin insert • PCB resin

No other anomalies are observed

Combo-D connectors


29

Standard and high density connectorsNo anomalies observed


30

Standard and high density Environmental µ-inspection

Visual +

Electrical

Detailed µ-inspection enables Positronic to identify the trouble and develop new design to overcome the observed issues

Combo-D

Standard and high density connectors successfully pass all the tests

1ST GENERATION SUMMARY


Visual inspection+



from PCBx1

Visual inspection+



Visual inspection+



Visual inspection+




Visual inspection+


31

Environmental test

Inspection

In some cases initial external visual inspection revealed anomalies (crazing) at the PCB.

Environmental testAll the inspected specimens

successfully pass the environmental tests and the

electrical verifications.

Microsection inspectionDissimilar results. Further developments in progress.

2ND GENERATION SUMMARY

SUMMARY.

• Different types of press-fit connectors conceivedfor different applications has been assesses fortheir implementational in space environments.

• The verification program included:

o Hard environmental (vibration andtemperature cycling) tests.

o Control electrical and visual inspections.o Detailed microsection inspections.

• Standard and high density connectorssuccessfully passed all the tests andinspections , demonstrating high reliability andassembly consistency.

• Combo-D presented internal cracks as revealedby µ-inspection.

• New Combo-D are under developed indenting toovercome such shortcoming.

Mature commercial technologies

Space qualification

Spaceimplementation

TÜV NORD GROUP

THANK YOU FOR YOUR KIND ATTENTION!

https://www.altertechnology-group.com/en/home/

Contact info : [email protected]

[email protected]

mailto:[email protected]

mailto:[email protected]

evaluation of press-fit connector for space-flight

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