1 / 15

Technische Information / Application Recommendation Solder Paste Series F 640 V_10_05 1. Specification of Heraeus solder paste series F 640 • Alloy: Composition (%): (1) Sn95.5Ag4Cu0.5

(2) Sn96.5Ag3Cu0.5 (3) SnAg4

Other SAC on request

Melting Point (°C) (1) 217°C (2) 217°C (3) 221°C

Shape: Spherical Particle size (µm): 25-45

20-38 Type 3

Type 4 (on request) Density (g/cc): 7,4 Oxidation level (ppm): < 150 • Solder paste: Metal content (%): 88 ± 1 By weight Viscosity (Pas): 130 ± 40 Physica CSS 10 s-1 Copper plate corrosion: Pass J-STD-004 Silver Chromate Test: Pass J-STD-004 Copper Mirror Test: Pass J-STD-004 Shelf life (per month): Cartridges Minimum of 3

Jars Minimum of 6 2-10 °C

2 / 15

2. Solder paste properties Item Typical Property Test Method

Alloy (Standard:) SnAg4Cu0,5 ---

Flux Content (Standard) : 11% Weight percent

Powder size (Standard): Type 3 ---

Shape: Sphere ---

Solidus-Liquidus: 217°C ---

Chlorine Content: < 20 ppm IPC-TM-650

Bromide Content: < 20 ppm IPC-TM-650

Copper Plate Corrosion Test: Pass J-STD-004

Silver Chromate Test: Pass J-STD-004 / Bellcore 2E+10 Ohm

Copper Mirror Test: Pass J-STD-004 / Bellcore 2E+10 Ohm

Electric Insulation Resistence Test (SIR)

40C/93%/168H: 1,5E+09 ohm 2E+10ohm

Siemens SN 59650 Bellcore

Voltage applied Moisture Resistance, SIR (Bias DC50V):

85C/85%/500H: 6,5E+09 ohm Acc. DIN IEC 61189 See Diagramm

Solder ball Test (air):

Good

Heraeus Benchmarker 2

Tackiness Time of keeping 100g minimum: 24 hours JIS_Z-3284

Hot Slump:

Benchmarker 2

Viscosity : See specifications Physica CSS D= 10 s-1

• Test results:

Copper Plate Corrosion Test Silver Chromate Test Copper Mirror Test

3 / 15

3. Viscosity curve • Test method: CSS

0 Pa to 2000 Pa within 2 min

• Equipment: Physica MCR 300 Plate/Plate r=50 mm

• Test result:

Temperature (°C)

Yieldpoint (Pa)

Viscosity@ 10s-1 (Pas)

Viscosity@ 2000 Pa (Pas)

15 653 200 201 20 523 153 108 25 452 125 62 30 402 104 43 35 362 89 25

4. Slump Observe the minimum spacing across which the paste has not merged after reflowing the substrate with the temperature condition of 5 min 150°C.

Yieldpoint vs Temperature

0

100

200

300

400

500

600

700

15 20 25 30 35

T [°C]

Visc

osity

[Pa]

Viscosity@2000Pa vs Temperature

0

50

100

150

200

250

15 20 25 30 35

T [°C]

Visc

osity

[Pas

]

4 / 15

5. Solder balling • Test method: Prepare two test pieces by printing the paste on each alumina plate (50 x 50 x 0.8tmm) with a 0.2mm thick stencil provided with three 6.5 diameter apertures with a distance between centers of 15mm.

Reflow one if them in 1 hour after printing and the other after storing it at 25±2°C 60±20%RH for 24 hours.

Inspect the degree of reflowing referring to ‘Solder balling evaluation standard’ using the x 10 magnifying glass.

Category: Status of coalescence of solder: Illustration:

1 The molten solder from paste has melted into one solder ball.

2 The molten solder from the paste has melted into one large solder ball with no more than three isolated small solder balls with diameter less than 75 µm.

3 The molten solder from the paste has melted into on large solder ball surrounded by more than three solder balls with diameters less than 75 µm which do not form a semi-continuous halo.

4 The molten solder from paste has melted into one ball accompanied by a large number of smaller solder balls which may form a semi-continuous halo, or has melted to form a number of similarly sized balls.

• Test results:

Test substrate – before reflow

5 / 15

6. Solder wettability Test method: Test result: Use as test plate a copper plate, 0.3x30x30mm in size polished by #1500 abrasive paper an washed by alcohol. Print the solder paste with a 0.2mm thick stencil provided with three 6.5mm diameter apertures and reflow one if them in 1 hour after printing (storing it at 25±2°C 60±20%RH ).

Test substrate – before reflow

7. Voltage applied sir • Test method: Print the solder past to each comb type electrode JIS type-II (stencil thickness: 0.15mm)

Put the test piece in a climate chamber under the conditions of 85 ± 2 °C and 85 ± 2% RH (DC50 V)

Measure the insulation resistance at every hour, DC50V for the measurement.

Substrate before test Example for a soldered Example for migration Substrate

• Test result: F640

SIR 85°C / 85% r.F. / 50 V

1,00E+07

1,00E+08

1,00E+09

1,00E+10

1,00E+11

1,00E+12

1,00E+13

0 25 50 75 100 125 150 175 200 225 250 275 300 325 350 375 400 425 450 475 500

Hours

Ohm

6 / 15

8. Printability • Print parameters: Stencil: Benchmarker II150µm Printer: EKRA X5 Squeegee: 200mm / steel 60° Print speed: 50 mm/s Stencil separation speed: 10mm/s Atmosphere: 25°C ± 1°C • Test patterns:

Aperture Test 10 groups of fine pitch apertures with same width ranging from 120µm to 300µm in 20µm steps, vertical, horizontal and 45° angle.

300µm 280µm 260µm 240µm

120µm 140µm 160µm 180µm 200µm 220µm

7 / 15

a) Print - Result of 15 prints

b) Print - Result of 15 prints after storage 7d@30°C

c) Print-Result 5th print

Vertical 200 µm Horizontal 200 µm 45 ° 200 µm

8 / 15

Spread Test 5 rows of 25*50 mil pads with different gap between the pad in each row, ranging from 4mils to 12mils (100µm to 300µm).

Result:

Initial 5 min. 150°C Hot Slump Test Inspect 5th board spread and aperture, place board in a box oven at 150°C and 180°C for 5min within 10min of printing and re-inspect spread and aperture. Result: Pitch 0,4mm

Initial 5 min./150°C Pitch 0,4mm

Initial 5 min./180°C

9 / 15

Print After Wait The test determines the time which can elapse between two prints without having to clean the stencil. Print 5 boards; clean the stencil; print 6th board = initial; wait eg. 30/45/60 minutes ; print 7th board = PAW; inspect the narrow pad (horizontal and vertical) of a 25mil 100P BQFP.

Generally a 15% or more reduction is considered a failure. Re-start the test with shorter time Note: For specific customer applications any other aperture may be used (eg. µBGA, CSP, BGA)

horizontal vertical

Results:

10 / 15

9. Wetting Print at least 2 boards each combination (board surface, atmosphere, profile); reflow & inspect wetting area* “A”, “B”, “C” and “D” area “A”:

area “B”:

area “C”:

area “D”:

*the pictures show printed paste • Wetting results:

11 / 15

• Screen Life Test:

Stencil: Benchmarker II150µm for SLT Printer: EKRA X5 Squeegee: 200mm / steel 60° Print speed: 50 mm/s Stencil separation speed: 10mm/s

Test method: Print (knead) solder paste on the sealed-up stencil continuously up to 8 hours to observe viscosity variation.

Atmosphere: 25°C ± 1°C Result of 8 hours:

Yield Point

0

300

600

900

1200

0 1 2 3 4 5 6 7 8

Time / h

Tau

0 [

Pa]

12 / 15

10. Use of Heraeus Solder Paste In order to make the paste use of HERAEUS SOLDER PASTE, please refer to the following guideline carefully before use.

1. Preparation for printing 1.1 Temperature

After taking the solder paste out of the fridge, in which the temperature is controlled to be below 10°C, wait ca. 2 hours that the paste temperature comes back to room temperature. Caution: • Do not open the jar while it is cold, or it causes condensation of

moisture on the paste, and could be a case of poor performance, such as increase of viscosity, solder balling and etc.

• Do not heat the paste.

1.2 Stirring By using a stainless steel chemically resistive plastic spatula, stir up the paste before use. It is recommended to stir it for at least 1- 2 min. to obtain uniform and stable viscosity. Caution: • When an automatic stirring equipment is used, do not stir the paste longer than 4 min.

2. Printing 2.1 Recommended printing parameters 2.1.1 Squeegee

• Kind: Flat • Material: Rubber or metal blade • Angle: 60 – 80° (rubber) or metal blade • Pressure: Lowest pressure to get a clean wipe on the upper side of the stencil • Squeegee speed: 10 – 75mm/sec.

2.1.2 Stencil

• Stickiness 200 ~ 120µm for 0,65 – 0,4mm pitch pattern • Snap-off distance 0 ~ 0,5mm

*Although on-contact (0 snapp-off) is normally for fine pitch printing, if a printing equipment is not provided to ensure smooth and gradual separation of the stencil from the substrate for good solder paste deposits.

• Fixing method of substrate: It is recommended to have fixture or vacuum system to hold the substrate in position during printing to prevent movement of PC board and to have good separation from the stencil.

2.1.3 Ambiance

• Temperature: 20-32°C • Humidity: 30-85%RH • Wind: Wind badly affects stencil lie and tack performance of solder pastes. * Caution: When local air conditioner is equipped, make sure it is not enhancing drying out of solder paste.

13 / 15

2.1.4 Printing

• initial quantity of solder paste to put on the stencil shall decided according to the size of the stencil (PC board). EX. Size of PC board A5 – approx. 200gs B5 – approx. 300gs A4 – approx. 400gs *In order to ensure good rolling of the paste across the stencil and easy separation from squeegees, a certain amount of solder paste must be required through out the printing process.

• Add the paste to replenish only the consumed amount. • Every after certain times of continuous printing, thoroughly clean the bottom side or both the

top and bottom side of the stencil. • Clean both the top and bottom side of the stencil before every break. • Do not return the used paste into the original jar to prevent mixture and contamination of the

fresh paste, but put it in a separate container for reuse, if necessary. 3. Reflowing

Remarks: - The profile should have a length of approx. 250 sec. before going into peak. - The profile window was specified to consider the different thermal masses that may appear on a PCB surface. - An optimization of the profile is complex because of the different PCB- and component-finishes. If you have any question regarding the optimization of the profile (e.g. for wetting, voids, etc.), we are willingly to support you.

14 / 15

0

50

100

150

200

250

300

0 50 100 150 200 250 300 350 400 450

time [s]

tem

pera

ture

[°C

]Reflow window

Profiles: Max. profile: Min. profile: Peak: 250°C 230°C T>217°C: 100s 30s 100°C-217°C: 260s 130s 11. Further technical information you will find in the appendix

Appendix 1 Siemens – Qualification – Results Status : available Appendix 2 Flux– Qualification– Analysis– Bellcore GR-78-

Core Status : available

Appendix 2a Flux– Qualification– Analysis– J-STD-004 Status : available Appendix 3 Halide – Analysis Status : available Appendix 4 Self – Alignements – Results Status : available Appendix 5 Cleaning – Flux – Residues Status : in process Appendix 6 DOE (Design of experiment) Soldering Status : in process Appendix 7 DOE Printing Status : in process

The descriptions and engineering data shown here have been compiled by Heraeus using commonly-accepted procedures, in conjunction with modern testing equipment, and have been compiled as according to the latest factual knowledge in our possession. The information was up-to date on the date this document was printed (latest versions can always be supplied upon request). Although the data is considered accurate, we cannot guarantee accuracy, the results obtained from its use, or any patent infringement resulting from its use (unless this is contractually and explicitly agreed in writing, in advance). The data is supplied on the condition that the user shall conduct tests to determine materials suitability for a particular application.

Production Locations Europe

Americas

Asia

W. C. Heraeus GmbH Circuit Materials Division Hanau / Germany Phone: +49 6181 35-5265 E-Mail: cmdinfo@heraeus.com

Heraeus Incorporated Circuit Materials Division West Conshohocken, PA, USA Phone: +1 610 825-6050 E-Mail: techservice@4cmd.com

Heraeus Ltd. Circuit Materials Division On Lok Tsuen, Fanling, Hong Kong Phone: +852 2675 1200 E-Mail: cmdinfo@heraeus.com.hk

15 / 15

W. C. Heraeus GmbH, Facility Potsdam Welco Finest Solder Powders Potsdam / Germany Phone: +49 331 74616-00 E-mail: juergen.schulze@heraeus.com

Web: www.4cmd.com

Heraeus Materials Technology Shanghai Circuit Materials Division Shanghai, P.R.C. Phone: +86 21 6489 0380 e-mail: sm@heraeus-hmts.com