AU2021104459A4 - A tin silver-platingbathusing methane sulfonate for low alpha solder bumping - Google Patents
A tin silver-platingbathusing methane sulfonate for low alpha solder bumping Download PDFInfo
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- AU2021104459A4 AU2021104459A4 AU2021104459A AU2021104459A AU2021104459A4 AU 2021104459 A4 AU2021104459 A4 AU 2021104459A4 AU 2021104459 A AU2021104459 A AU 2021104459A AU 2021104459 A AU2021104459 A AU 2021104459A AU 2021104459 A4 AU2021104459 A4 AU 2021104459A4
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- tin
- silver
- bath
- methane sulfonate
- methane
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- AFVFQIVMOAPDHO-UHFFFAOYSA-N Methanesulfonic acid Chemical compound CS(O)(=O)=O AFVFQIVMOAPDHO-UHFFFAOYSA-N 0.000 title claims abstract description 45
- 229910000679 solder Inorganic materials 0.000 title claims abstract description 41
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 title claims abstract description 32
- 238000007747 plating Methods 0.000 claims abstract description 67
- 238000000034 method Methods 0.000 claims abstract description 44
- YCIMNLLNPGFGHC-UHFFFAOYSA-N catechol Chemical compound OC1=CC=CC=C1O YCIMNLLNPGFGHC-UHFFFAOYSA-N 0.000 claims abstract description 36
- 238000009713 electroplating Methods 0.000 claims abstract description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229920001223 polyethylene glycol Polymers 0.000 claims abstract description 19
- SXRSQZLOMIGNAQ-UHFFFAOYSA-N Glutaraldehyde Chemical compound O=CCCCC=O SXRSQZLOMIGNAQ-UHFFFAOYSA-N 0.000 claims abstract description 17
- 239000002202 Polyethylene glycol Substances 0.000 claims abstract description 16
- 229920004890 Triton X-100 Polymers 0.000 claims abstract description 14
- 239000013504 Triton X-100 Substances 0.000 claims abstract description 14
- 239000012153 distilled water Substances 0.000 claims abstract description 14
- 229940098779 methanesulfonic acid Drugs 0.000 claims abstract description 14
- RYKLZUPYJFFNRR-UHFFFAOYSA-N 3-hydroxypiperidin-2-one Chemical compound OC1CCCNC1=O RYKLZUPYJFFNRR-UHFFFAOYSA-N 0.000 claims abstract description 13
- YWYZEGXAUVWDED-UHFFFAOYSA-N triammonium citrate Chemical compound [NH4+].[NH4+].[NH4+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O YWYZEGXAUVWDED-UHFFFAOYSA-N 0.000 claims abstract description 11
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims abstract description 8
- 239000002253 acid Substances 0.000 claims abstract description 7
- JALQQBGHJJURDQ-UHFFFAOYSA-L bis(methylsulfonyloxy)tin Chemical compound [Sn+2].CS([O-])(=O)=O.CS([O-])(=O)=O JALQQBGHJJURDQ-UHFFFAOYSA-L 0.000 claims abstract description 7
- 238000000576 coating method Methods 0.000 claims abstract description 6
- 239000004519 grease Substances 0.000 claims abstract description 6
- 230000000007 visual effect Effects 0.000 claims abstract description 6
- 238000009826 distribution Methods 0.000 claims abstract description 5
- 238000004626 scanning electron microscopy Methods 0.000 claims abstract description 5
- 238000005406 washing Methods 0.000 claims abstract description 4
- QCEUXSAXTBNJGO-UHFFFAOYSA-N [Ag].[Sn] Chemical compound [Ag].[Sn] QCEUXSAXTBNJGO-UHFFFAOYSA-N 0.000 claims description 23
- 239000000243 solution Substances 0.000 claims description 19
- 229910001316 Ag alloy Inorganic materials 0.000 claims description 18
- 229960000587 glutaral Drugs 0.000 claims description 13
- 239000010935 stainless steel Substances 0.000 claims description 10
- 229910001220 stainless steel Inorganic materials 0.000 claims description 10
- 229910021626 Tin(II) chloride Inorganic materials 0.000 claims description 9
- 239000003795 chemical substances by application Substances 0.000 claims description 9
- 238000000151 deposition Methods 0.000 claims description 8
- 238000004070 electrodeposition Methods 0.000 claims description 8
- 230000008021 deposition Effects 0.000 claims description 7
- AICMYQIGFPHNCY-UHFFFAOYSA-J methanesulfonate;tin(4+) Chemical compound [Sn+4].CS([O-])(=O)=O.CS([O-])(=O)=O.CS([O-])(=O)=O.CS([O-])(=O)=O AICMYQIGFPHNCY-UHFFFAOYSA-J 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- QIGBRXMKCJKVMJ-UHFFFAOYSA-N Hydroquinone Chemical compound OC1=CC=C(O)C=C1 QIGBRXMKCJKVMJ-UHFFFAOYSA-N 0.000 claims description 6
- 239000000470 constituent Substances 0.000 claims description 6
- 230000003647 oxidation Effects 0.000 claims description 6
- 238000007254 oxidation reaction Methods 0.000 claims description 6
- 229910001128 Sn alloy Inorganic materials 0.000 claims description 5
- 238000002360 preparation method Methods 0.000 claims description 5
- 230000002285 radioactive effect Effects 0.000 claims description 5
- 239000004094 surface-active agent Substances 0.000 claims description 5
- 239000005028 tinplate Substances 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 4
- 238000012360 testing method Methods 0.000 claims description 4
- 239000007864 aqueous solution Substances 0.000 claims description 3
- 239000008367 deionised water Substances 0.000 claims description 3
- 229910021641 deionized water Inorganic materials 0.000 claims description 3
- 230000002401 inhibitory effect Effects 0.000 claims description 3
- 229920002114 octoxynol-9 Polymers 0.000 claims description 3
- GGCZERPQGJTIQP-UHFFFAOYSA-N sodium;9,10-dioxoanthracene-2-sulfonic acid Chemical compound [Na+].C1=CC=C2C(=O)C3=CC(S(=O)(=O)O)=CC=C3C(=O)C2=C1 GGCZERPQGJTIQP-UHFFFAOYSA-N 0.000 claims description 3
- 238000003756 stirring Methods 0.000 claims description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 abstract description 6
- 150000003839 salts Chemical class 0.000 abstract description 5
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 abstract description 4
- -1 tin (II) ethane Chemical compound 0.000 abstract description 3
- LEHOTFFKMJEONL-UHFFFAOYSA-N Uric Acid Chemical compound N1C(=O)NC(=O)C2=C1NC(=O)N2 LEHOTFFKMJEONL-UHFFFAOYSA-N 0.000 abstract description 2
- DBYWIUFNYFZUHJ-UHFFFAOYSA-N methane;silver Chemical compound C.[Ag] DBYWIUFNYFZUHJ-UHFFFAOYSA-N 0.000 abstract description 2
- GPRLSGONYQIRFK-MNYXATJNSA-N triton Chemical compound [3H+] GPRLSGONYQIRFK-MNYXATJNSA-N 0.000 abstract description 2
- 229910052718 tin Inorganic materials 0.000 description 21
- 230000008901 benefit Effects 0.000 description 11
- 210000004027 cell Anatomy 0.000 description 11
- 230000008569 process Effects 0.000 description 8
- 229910045601 alloy Inorganic materials 0.000 description 7
- 239000000956 alloy Substances 0.000 description 7
- 239000003792 electrolyte Substances 0.000 description 7
- 238000004377 microelectronic Methods 0.000 description 7
- 229910052709 silver Inorganic materials 0.000 description 7
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000004332 silver Substances 0.000 description 6
- 229910020836 Sn-Ag Inorganic materials 0.000 description 5
- 229910020988 Sn—Ag Inorganic materials 0.000 description 5
- 239000008139 complexing agent Substances 0.000 description 5
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 4
- LQBJWKCYZGMFEV-UHFFFAOYSA-N lead tin Chemical compound [Sn].[Pb] LQBJWKCYZGMFEV-UHFFFAOYSA-N 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 238000004806 packaging method and process Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 3
- 230000018109 developmental process Effects 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 229910020816 Sn Pb Inorganic materials 0.000 description 2
- 229910020922 Sn-Pb Inorganic materials 0.000 description 2
- 229910008783 Sn—Pb Inorganic materials 0.000 description 2
- 238000005282 brightening Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000009462 micro packaging Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 230000001105 regulatory effect Effects 0.000 description 2
- 150000003378 silver Chemical class 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000003860 storage Methods 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 1
- 229910020830 Sn-Bi Inorganic materials 0.000 description 1
- 229910020888 Sn-Cu Inorganic materials 0.000 description 1
- 229910018728 Sn—Bi Inorganic materials 0.000 description 1
- 229910019204 Sn—Cu Inorganic materials 0.000 description 1
- 230000005260 alpha ray Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 229910052787 antimony Inorganic materials 0.000 description 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 description 1
- VQLYBLABXAHUDN-UHFFFAOYSA-N bis(4-fluorophenyl)-methyl-(1,2,4-triazol-1-ylmethyl)silane;methyl n-(1h-benzimidazol-2-yl)carbamate Chemical compound C1=CC=C2NC(NC(=O)OC)=NC2=C1.C=1C=C(F)C=CC=1[Si](C=1C=CC(F)=CC=1)(C)CN1C=NC=N1 VQLYBLABXAHUDN-UHFFFAOYSA-N 0.000 description 1
- 229910052797 bismuth Inorganic materials 0.000 description 1
- JCXGWMGPZLAOME-UHFFFAOYSA-N bismuth atom Chemical compound [Bi] JCXGWMGPZLAOME-UHFFFAOYSA-N 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 210000001787 dendrite Anatomy 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002848 electrochemical method Methods 0.000 description 1
- 239000010793 electronic waste Substances 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000006870 function Effects 0.000 description 1
- 238000009499 grossing Methods 0.000 description 1
- 231100001261 hazardous Toxicity 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 231100000053 low toxicity Toxicity 0.000 description 1
- 239000002932 luster Substances 0.000 description 1
- 238000003760 magnetic stirring Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 238000001465 metallisation Methods 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 150000002825 nitriles Chemical class 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000005985 organic acids Nutrition 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- NNFCIKHAZHQZJG-UHFFFAOYSA-N potassium cyanide Chemical compound [K+].N#[C-] NNFCIKHAZHQZJG-UHFFFAOYSA-N 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 239000001393 triammonium citrate Substances 0.000 description 1
- 235000011046 triammonium citrate Nutrition 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D21/00—Processes for servicing or operating cells for electrolytic coating
- C25D21/12—Process control or regulation
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/30—Electroplating: Baths therefor from solutions of tin
- C25D3/32—Electroplating: Baths therefor from solutions of tin characterised by the organic bath constituents used
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/46—Electroplating: Baths therefor from solutions of silver
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Automation & Control Theory (AREA)
- Electroplating And Plating Baths Therefor (AREA)
Abstract
The present disclosure relates to a tin silver-plating method using
methane sulfonate bath low alpha solder bumping comprises preparing
plating bath consisting of tin (II) methane sulfonate, silver methane
sulfonate, methane sulfonic acid, citric acid tri-ammonium salt,
polyethylene glycol, triton X-100, glutaraldehyde, catechol, and distilled
water; washing electrodes with distilled water thereby subjecting to
microetching with dilute 10% sulfuric acid to remove any grease or dirt
before treating the electrodes by employing electroplating cell; and
keeping plating bath under examination to check stability for a period of
three months, wherein developed coatings are examined for visual
appearances and scanning electron microscopy images are observed to
examine morphology and porosity distribution, and compositional purity
for low alpha solder bumping.
19
10(L
''
Preparing plating bath consistirg of tin (II) ethane s ulfornate, silver methane s ulfornate, methane
s ulfonic acid, citric acid tri-arn riurn salt, polyethylene glycol, triton X-10), glutaradehyde, rV
catechol,anddistilledwater
Washingelectrodeswithdistilledwalertherebysubjectingto Tj fl w ithdilite10%stUlf Uric 104
acid to remove a ny grease or dirt before treati rig the electrodes by ern ploying electroplating cell
Keeping platirg bath rider examination to check sta ability for a period of three months, w herein
developedcoatirigsareexamirkedforvisualappearancesandscanringelectrorimicroscopyimages 106
areobservedtoexaminemorphology,porositydistributiori,andcompositiorialpurityforlowalpha
solderbumping
Figure
zt t Ot 6 9 1
nulatngTape Stel4 Cathode
CopperTape
Figure
Figure3
Description
Preparing plating bath consistirg of tin(II) ethane s ulfornate, silver methane s ulfornate, methane s ulfonic acid, citric acid tri-arn riurn salt, polyethylene glycol, triton X-10), glutaradehyde, rV catechol,anddistilledwater
Washingelectrodeswithdistilledwalertherebysubjectingto Tj fl w ithdilite10%stUlf Uric 104 acid to remove a ny grease or dirt before treatirig the electrodes byern ployingelectroplating cell
Keeping platirg bath rider examination to check sta ability for a period of three months, w herein developedcoatirigsareexamirkedforvisualappearancesandscanringelectrorimicroscopyimages 106 areobservedtoexaminemorphology,porositydistributiori,andcompositiorialpurityforlowalpha solderbumping
Figure
zt t Ot 6 9 1
nulatngTape Stel4 Cathode CopperTape Figure
Figure3
FIELD OF THE INVENTION The present disclosure relates to a tin silver-plating method using methane sulfonate bath low alpha solder bumping. In more details, electroplating bath composition for co-depositing Sn-Ag alloy solder for low alpha wafer bumping in the manufacture of microelectronic devices at chip scale.
BACKGROUND OF THE INVENTION Electroplating is a technique that involves using a direct electric current to reduce the cations of a metal to form a metal coating on a solid substrate. The cathode of an electrolytic cell is the component to be coated; the electrolyte is a solution of a salt of the metal to be coated; and the anode is often a block of that metal or another inert conductive substance.
Currently, there are multiple of electroplating techniques are available. Traditional plating baths are unconcerned with the development of soft errors in electronic equipment. Solder bumps have moved extremely near to active Si devices as a result of the usage of flip-chip joints and advancements toward 3D packaging, where even a low-energy alpha ray with a limited range can produce soft error. Soft errors in microelectronic devices have necessitated the development of a plating electrolyte that can give a deposit with the fewest possible soft errors in current times.
Because traditional Sn-Pb solders include lead, which is hazardous to our environment, items containing lead are strictly regulated, and tin lead solder is gradually being phased out in favour of lead-free solder. As a result, tin-lead solder plating layers should be replaced with lead-free solder. As a result of using tin-silver alloy instead of tin-lead solder alloy, a technique of plating a tin-silver solder layer is now necessary.
However, during plating work, the traditional tin-silver alloy plating bath tends to produce acicular, dendrite, whisker-like, granular, or powdery deposits in the order of several m to several mm, as well as burnt deposits, resulting in failures in terms of external appearance of the plated surface, film, thickness, alloy composition, and short-circuit between adjacent leads. As a result, a plating bath that is extremely stable, produces smooth deposits with maximum brightness, and has minimal precipitate on storage for a longer period of time is required.
As a typical oxidation-reduction potential, the difference in electro deposition potential between silver and tin is 900 mV or more. When creating the tin-silver alloy layer, cyanide, such as potassium cyanide, is added to the plating solution to co-deposit tin and silver. As complexing agents, cyanides, ammonia, organic acids, and other chemicals are commonly employed. However, there are only a few complexing agents that are efficient for metal deposition, and treating waste water with these organic agents, which are reasonably successful among these agents, is challenging owing to their detrimental effect on humans. As a result, a complexing agent that can effectively complex a wide range of metals without endangering human health is required.
However, the existing technologies have various problems in microelectronic packaging is the introduction of soft errors in solder bumping. Additionally, pollution of underground water by disposal of electronic wastes containing lead and other radioactive components. Furthermore, conventional electroplating baths usually provide a limited current densities range and thus a low output of the Sn-AG solder bump manufacture, due to the decomposition of solution over time.
In the view of the forgoing discussion, it is clearly portrayed that there is a need to have a tin silver-plating method using methane sulfonate bath low alpha solder bumping.
The present disclosure seeks to provide a tin silver-plating method using methane sulfonate bath low alpha solder bumping for methyl sulfonic acid plating baths for plating tin silver alloys.
In an embodiment, a tin silver-plating method using methane sulfonate bath low alpha solder bumpingis disclosed. The method includes preparing plating bath consisting of tin (II) methane sulfonate, silver methane sulfonate, methane sulfonic acid, citric acid tri-ammonium salt, polyethylene glycol, triton X-100, glutaraldehyde, catechol, and distilled water. The method further includes washing electrodes with distilled water thereby subjecting to microetching with dilute 10% sulfuric acid to remove any grease or dirt before treating the electrodes by employing electroplating cell. The method further includes keeping plating bath under examination to check stability for a period of three months, wherein developed coatings are examined for visual appearances and scanning electron microscopy images are observed to examine morphology and porosity distribution, wherein the radioactive tests are performed to check characteristic for low alpha solder bumping.
In an embodiment, preparation of plating bath comprises dissolving tin methane sulfonate and silver methane sulfonate in deionized water followed by gradual addition of methane sulfonic acid; stirring solution until the tin and silver salts are dissolved completely; and adding other constituents for preparing planting bath there by maintaining plating bath at room temperature during the electro deposition.
In an embodiment, other constituents are citric acid tri-ammonium salt, polyethylene glycol, triton X-100, glutaraldehyde, catechol, and distilled water.
In an embodiment, the material used for preparing planting bath includes.065 M Tin (II) Methane sulfonate (50 0/ Solution in water, ((CH 3SO 3) 2Sn), 0.0002 M Silver Methane sulfonate (AgSO 3CH 3), 2M Methane sulfonic Acid (CH 3SO 3H), 0.016 M Citric acid tri-ammonium salt (C 6 H 1 7 N 3 0 7 ), 0.00025 M Polyethylene glycol (PEG, H(CH 2 CH 2 0)nOH, n=8000)), 0.00016 M Triton X-100 (t-octylphenoxy polyethoxyethanol, C 8 H1 7C 6H 4 (OCH 2CH 2)nOH, n=9-10), 0.001 M Glutaraldehyde (25% Aqueous Solution, 1, 5-Pentanedial, C 5H 2 ), 80 0.004 M Catechol (1, 2 Dihydroxybenzene, C 6 H 6 0 2 ), and Distilled water.
In an embodiment, the bath temperature is maintained in between 250 Cto 350 C and the cathode current density is maintained about 5 to mA/cm 2 .
In an embodiment, tin silver alloy plating baths containing tin salt, such as silver-tin alloy baths, oxidation of tin salt can be effectively suppressed by adding oxidation inhibiting agents such as catechol or hydroquinone in amount of 0.4 g/l.
In an embodiment, operating conditions comprises maintaining preferred range of the solution pH is 1.12 while deposition, making simple and easier handling of bath solution; maintaining current density ranges from 5 to 60 mA/cm 2 ; maintaining time of the deposition time of 30 minutes; wherein the tin-silver alloys is deposited at a temperature in the range of 25-35 °C, more specifically at 250 C; and wherein composition is agitated by any magnetic stirrer for increased plating speed at 200 rpm.
In an embodiment, treating the electrodes by employing electroplating cell includes electrochemical deposition, wherein high purity tin-silver alloy electroplating bath for low alpha solder bumping containing tin methane sulfonate as tin salt, silver methane sulfonate as silver salt, methane sulfonic acid as acid, triton X-100 as no ionic surface-active agent, and polyethylene glycol and glutaraldehyde as a brightener.
In an embodiment, the electroplating cell consists of a system of two electrodes, pure tin plate ( 9 9 .9 9 9 % ultra-high pure) with an area of 1 cm2 as the anode and stainless steel with an area of 1 cm 2 as the cathode, wherein the stainless steel is polished metallographically and mounted in a predetermined fashion.
In an embodiment, electroplating cell further consists SCE electrode and a magnetic stirrer, wherein the anode, SCE electrode, and cathode are connected to a pulse plater.
An object of the present disclosure is to provide micro packaging at chip level packaging.
Another object of the present disclosure is to plate Sn-Ag alloy solder wafer bumps on Cu UBM in the manufacture of microelectronic devices.
Another object of the present disclosure is to provide plating bath with low alpha solders plated from an electrolyte with higher bath stability which provide bright deposits in addition for various microelectronic applications.
Yet another object of the present invention is to deliver an expeditious and cost-effective tin silver-plating method using methane sulfonate bath low alpha solder bumping.
To further clarify advantages and features of the present disclosure, a more particular description of the invention will be rendered by reference to specific embodiments thereof, which is illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail with the accompanying drawings. BRIEF DESCRIPTION OF FIGURES
These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Figure 1 illustrates a flow chart of a tin silver-plating method using methane sulfonate bath low alpha solder bumping in accordance with an embodiment of the present disclosure; Figure 2 illustrates specimen preparation before plating in accordance with an embodiment of the present disclosure; Figure 3 illustrates experimental parameters used in EPP-4909 pulse plater in accordance with an embodiment of the present disclosure; Figure 4 illustrates process flow of tin silver-plating method using methane sulfonate bath low alpha solder bumping in accordance with an embodiment of the present disclosure; and Figure 5 illustrates electroplating setup in accordance with an embodiment of the present disclosure.1. Cathode, 2. Plating bath, 3. Reference electrode, 4. Anode, 5. Stirrer, 6. Connection to negative terminal of plating machine, 7 and 8. Connection to negative and reference terminal of plating machine.
Further, skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and may not have necessarily been drawn to scale. For example, the flow charts illustrate the method in terms of the most prominent steps involved to help to improve understanding of aspects of the present disclosure. Furthermore, in terms of the construction of the device, one or more components of the device may have been represented in the drawings by conventional symbols, and the drawings may show only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the drawings with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
For the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated system, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.
It will be understood by those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not intended to be restrictive thereof.
Reference throughout this specification to "an aspect", "another aspect" or similar language means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present disclosure. Thus, appearances of the phrase "in an embodiment", "in another embodiment" and similar language throughout this specification may, but do not necessarily, all refer to the same embodiment.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process or method that comprises a list of steps does not include only those steps but may include other steps not expressly listed or inherent to such process or method. Similarly, one or more devices or sub-systems or elements or structures or components proceeded by "comprises...a" does not, without more constraints, preclude the existence of other devices or other sub-systems or other elements or other structures or other components or additional devices or additional sub-systems or additional elements or additional structures or additional components.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The system, methods, and examples provided herein are illustrative only and not intended to be limiting.
Embodiments of the present disclosure will be described below in detail with reference to the accompanying drawings.
Referring to Figure 1, illustrates a flow chart of a tin silver-plating method using methane sulfonate bath low alpha solder bumpingis illustrated in accordance with an embodiment of the present disclosure. The method facilitates methyl sulfonic acid plating baths for plating tin silver alloys. At step 102, the method 100 includes preparing plating bath consisting of tin (II) methane sulfonate, silver methane sulfonate, methane sulfonic acid, citric acid tri-ammonium salt, polyethylene glycol, triton X-100, glutaraldehyde, catechol, and distilled water.
At step 104, the method 100 includes washing electrodes with distilled water thereby subjecting to microetching with dilute 10% sulfuric acid to remove any grease or dirt before treating the electrodes by employing electroplating cell.
At step 106, the method 100 includes keeping plating bath under examination to check stability for a period of three months, wherein developed coatings are examined for visual appearances and scanning electron microscopy images are observed to examine morphology and porosity distribution, wherein the radioactive tests are performed to check characteristic for low alpha solder bumping.
In an embodiment, preparation of plating bath includes dissolving tin methane sulfonate and silver methane sulfonate in deionized water followed by gradual addition of methane sulfonic acid, Then, stirring solution until the tin and silver salts are dissolved completely. Thereafter, adding other constituents for preparing planting bath there by maintaining plating bath at room temperature during the electro deposition.
In an embodiment, other constituents are citric acid tri-ammonium salt, polyethylene glycol, triton X-100, glutaraldehyde, catechol, and distilled water.
In an embodiment, the material used for preparing planting bath includes.065 M Tin (II) methane sulfonate (50 % Solution in water, ((CH 3SO 3) 2Sn), 0.0002 M Silver methane sulfonate (AgSO 3CH 3 ), 2M Methane sulfonic Acid (CH 3SO 3H), 0.016 M Citric acid tri-ammonium salt (C 6 H 1 7 N 3 0 7 ), 0.00025 M Polyethylene glycol (PEG, H(CH 2 CH 2 0)nOH, n=8000)), 0.00016 M Triton X-100 (t-octylphenoxypolyethoxyethanol, CsH 1 7C6H 4 (OCH 2CH 2)nOH, n=9-10), 0.001 M Glutaraldehyde (25%
Aqueous Solution, 1, 5-Pentanedial, C 5H 2 ), 80 0.004 M Catechol (1, 2 Dihydroxybenzene, C 6 H 6 02 ), and Distilled water.
In an embodiment, the bath temperature is maintained in between 250 Cto 350 C and the cathode current density is maintained about 5 to mA/cm 2 .
In an embodiment, tin silver alloy plating baths containing tin salt, such as silver-tin alloy baths, oxidation of tin salt can be effectively suppressed by adding oxidation inhibiting agents such as catechol or hydroquinone in amount of 0.4 g/l.
In an embodiment, operating conditions includes maintaining preferred range of the solution pH is 1.12 while deposition, making simple and easier handling of bath solution. Then, maintaining current density ranges from 5 to 60 mA/cm 2 . Then, maintaining time of the deposition time of 30 minutes. The tin-silver alloys is deposited at a temperature in the range of 25-35 °C, more specifically at 250 C. Composition is agitated by any magnetic stirrer for increased plating speed at 200 rpm.
In an embodiment, treating the electrodes by employing electroplating cell includes electrochemical deposition, wherein high purity tin-silver alloy electroplating bath for low alpha solder bumping containing tin methane sulfonate as tin salt, silver methane sulfonate as silver salt, methane sulfonic acid as acid, triton X-100 as no ionic surface-active agent, and polyethylene glycol and glutaraldehyde as a brightener.
In an embodiment, the electroplating cell consists of a system of two electrodes, pure tin plate ( 9 9 .9 9 9 % ultra-high pure) with an area of 1 cm2 as the anode and stainless steel with an area of 1 cm 2 as the cathode, wherein the stainless steel is polished metallographically and mounted in a predetermined fashion.
In an embodiment, electroplating cell further consists SCE electrode and a magnetic stirrer, wherein the anode, SCE electrode, and cathode are connected to a pulse plater.
Figure 2 illustrates specimen preparation before plating in accordance with an embodiment of the present disclosure. The stainless steel is polished metallographically and mounted in a fashion as shown in Fig. 2.The electroplating cell consists two electrodes, pure tin plate ( 9 9 .9 9 9 % ultra-high pure) with an area of 1 cm 2 as anode and stainless steel with an area of 1 cm 2 as cathode.
The electrochemical measurements have been conducted using EC LAB instrument at room temperature. The potential values are referred to SCE standard electrode. The electro deposition parameters are.5 to 60 mA/cm2current density range, 25-35 °C temperature, 30 minutes time, 1.12 pH, 200 rpm magnetic stirring, 9 9 .9 9 9 % Tin plate Of area 1cm 2 anode, 9 9 . 9 9 9 % pure stainless steel of area 1cm 2 cathode and 3cm distance between Anode to cathode.
Figure 3 illustrates experimental parameters used in EPP-4000 pulse plater in accordance with an embodiment of the present disclosure. The plating bath is kept under examination to check their stability for a period of three months. The developed coatings are examined for their visual appearances, i.e. physical lustre, their scanning electron microscopy images are also observed to examine their morphology and porosity distribution. Finally, the radioactive tests are performed to check their characteristic for low alpha solder bumping.
Figure 4 illustrates process flow of tin silver-plating method using methane sulfonate bath low alpha solder bumping in accordance with an embodiment of the present disclosure. There is no decomposition of the tin silver alloy plating baths of up to 72 days. There is silver deposition on the walls of the container housing the bath at around 76 days, however there are no precipitate on the bottom of the beaker. No precipitation in open air after more than one month and still under observation
The plated films thus obtained are subjected to visual observation. As a result, the plated film obtained exhibited maximum brightness and is colored in grayish white.
Smooth and shiny finish, as a result, the plated film obtained in exhibited excellent brightness at a wide current density range and is colored in milky white.
Figure 5 illustrates electroplating setup in accordance with an embodiment of the present disclosure. The operation of electroplating setup includes Tin Anode ( 9 9 .9 9 9 % Pure), 1cm2 area, Electrolytic bath, SCE electrode, Cathode Substrate (Stainless steel, 9 9 .9 9 9 % pure), Magnetic stirrer, Anode Connection to Pulse plater, SCE connection to Pulse plater, Cathode connection to pulse plater, Waveform generated during the experiment, E versus time,
In an embodiment, a high purity plating bath with high purity Sn and Ag salts is employed, and a soluble tin anode of ultra-high purity 9 9 .9 9 9 % of tin is used. Ultra-high purity tin anode and electrolyte is used to minimize the sources of alpha emissions, like trace amounts of lead, antimony or bismuth in the electrolyte and tin anode.
In an embodiment, plating baths is provided and a plating process which will yield right tin silver plates of high luster over a wide range of current densities. The composition of the invention is able to run at high speed current densities of 5-60 mA/cm2 . It can be employed in high speed electroplating processes in the electronics industry and in the connector industry, which has previously not been possible.
The tin-silver alloy plating bath of the present invention has an advantage that it has only a low toxicity and a high safety because it is of a non-cyanide type unlike an ordinary alkaline cyanide bath. The present invention provides a bath with excellent stability over an extended time. With regard to silver alloy plating baths, the present invention provides a safe, non-cyanide bath, which can reliably co-deposit silver and another metal.
An object of the present invention is to provide the tin-silver plating solution having fewer solid precipitations and better storage stability over a long time. The electrolytic plating method also makes it possible that a plating process can be carried out with a wide range of current density.
In addition, although silver easily forms insoluble salts with various substances, the tin-silver alloy plating bath of the present invention can be kept stable for a long period of time without changing the plating function thereof. Another advantage of this plating bath is that since it does not necessitate any special treatment of the waste water, the waste water treatment cost is low.
Methane sulfonic acid has proven to be especially suitable since the use of silver and tin-methane sulfonate in a methane sulfonate-based electrolyte permits the application of high current densities.
A complexing agent is useful - citric acid triammonium salt in composition. In MSA bath if triammonium citrate is greater than 10 g/L, stability degraded and precipitates are formed. The complexing agent may be added in a concentration of at least about 1 g/L, such as between about 1 g/L and about 10 g/L.
Polyethylene glycol is used as a suitable brightener. Polyethylene glycolin conjunction with glutaraldehyde may be employed to have a brighter finish. Triton X-100 is used as a non-ionic surface-active agent.
With the above brightening agents, semi-brightening agents, or smoothing agents, by using them together with the aforementioned various surface-active agents, the desired effect is further improved by their synergistic effect. As a result, the plating operation becomes easier, and the productivity is improved. Moreover, the bath lifespan is extended, resulting in a more economically advantageous plating bath.
Another specific object of the present invention is to provide an electroplating bath for tin and tin-alloys, which can be employed in a wide range of current density and more particularly is excellent in working efficiency at a higher current density.
The fields of technology are applied to micro packaging industries at chip level packaging. The solder wafer bumps conventionally comprise solders of the conventional tin lead solders. Recent regulatory and environmental developments have increased interest in Pb-free solders. Accordingly, various lead-free solders are developed and studied such as pure Sn, Sn-Cu, Sn-Bi, Sn-Ag, and ternary Sn alloys have been explored as potential alternatives to Sn-Pb alloys. The Sn-Ag alloys are attractive because of their low resistivity, stability, the ability to achieve a wide range of melting points, and the elimination of alpha particle emissions by using pure Sn sources.
The electroplating baths of the present invention are preferably employed to plate Sn-Ag alloy solder wafer bumps on Cu UBM in the manufacture of microelectronic devices. However, the plating baths may be used in any application requiring any Sn based solder.
Electrochemical industries are always in a search for a plating bath with low alpha solders plated from an electrolyte with higher bath stability which provide bright deposits in addition for various microelectronic applications.
The drawings and the forgoing description give examples of embodiments. Those skilled in the art will appreciate that one or more of the described elements may well be combined into a single functional element. Alternatively, certain elements may be split into multiple functional elements. Elements from one embodiment may be added to another embodiment. For example, orders of processes described herein may be changed and are not limited to the manner described herein. Moreover, the actions of any flow diagram need not be implemented in the order shown; nor do all of the acts necessarily need to be performed. Also, those acts that are not dependent on other acts may be performed in parallel with the other acts. The scope of embodiments is by no meanslimited by these specific examples. Numerous variations, whether explicitly given in the specification or not, such as differences in structure, dimension, and use of material, are possible. The scope of embodiments is at least as broad as given by the following claims.
Benefits, other advantages, and solutions to problems have been described above with regard to specific embodiments. However, the benefits, advantages, solutions to problems, and any component(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential feature or component of any or all the claims.
Claims (10)
1. A tin silver-plating method using methane sulfonate bath low alpha solder bumping, the method comprises:
preparing plating bath consisting of tin (II) methane sulfonate, silver methane sulfonate, methane sulfonic acid, citric acid tri-ammonium salt, polyethylene glycol, triton X-100, glutaraldehyde, catechol, and distilled water; washing electrodes with distilled water thereby subjecting to microetching with dilute 10% sulfuric acid to remove any grease or dirt before treating the electrodes by employing electroplating cell; and keeping plating bath under examination to check stability for a period of three months, wherein developed coatings are examined for visual appearances and scanning electron microscopy images are observed to examine morphology and porosity distribution, wherein the radioactive tests are performed to check characteristic for low alpha solder bumping.
2. The method as claimed in claim 1, wherein preparation of plating bath comprises:
dissolving tin methane sulfonate and silver methane sulfonate in deionized water followed by gradual addition of methane sulfonic acid; stirring solution until the tin and silver salts are dissolved completely; and adding other constituents for preparing planting bath there by maintaining plating bath at room temperature during the electro deposition.
3. The method as claimed in claim 2, wherein other constituents are citric acid tri-ammonium salt, polyethylene glycol, triton X-100, glutaraldehyde, catechol, and distilled water.
4. The method as claimed in claim 1, wherein the material used for preparing planting bath includes0.065 M Tin (II) methane sulfonate (50
% Solution in water, ((CH 3SO 3) 2Sn), 0.0002 M Silver methane sulfonate (AgSO3 CH 3 ),2M Methane sulfonic Acid (CH 3SO 3 H), 0.016 M Citric acid tri ammonium salt (C 6 H 1 7 N 3 0 7 ), 0.00025 M Polyethylene glycol (PEG, H(CH 2 CH 20)nOH, n=8000)), 0.00016 M Triton X-100 (t octylphenoxypolyethoxyethanol, C 8 H1 7C 6 H 4 (OCH 2CH 2 )nOH, n=9-10), 0.001 M Glutaraldehyde ( 2 5% Aqueous Solution, 1, 5-Pentanedial, C 5 H 8 02 ), 0.004 M Catechol (1, 2 - Dihydroxybenzene, C 6 H 60 2 ), and Distilled water.
5. The method as claimed in claim 1, wherein the bath temperature is maintained in between 250 Cto 350 C and the cathode current density is maintained about 5 to 60 mA/cm 2 .
6. The method as claimed in claim 1, wherein tin silver alloy plating baths containing tin salt, such as silver-tin alloy baths, oxidation of tin salt can be effectively suppressed by adding oxidation inhibiting agents such as catechol or hydroquinone in amount of 0.4 g/l.
7. The method as claimed in claim 1, wherein operating conditions comprises:
maintaining preferred range of the solution pH is 1.12 while deposition, making simple and easier handling of bath solution; maintaining current density ranges from 5 to 60 mA/cm 2 ; maintaining time of the deposition time of 30 minutes; wherein the tin-silver alloys is deposited at a temperature in the range of 25-35 °C, more specifically at 250 C; and wherein composition is agitated by any magnetic stirrer for increased plating speed at 200 rpm.
8. The method as claimed in claim 1, wherein treating the electrodes by employing electroplating cell includes electrochemical deposition, wherein high purity tin-silver alloy electroplating bath for low alpha solder bumping containing tin methane sulfonate as tin salt, silver methane sulfonate as silver salt, methane sulfonic acid as acid, triton X-100 as no ionic surface-active agent, and polyethylene glycol and glutaraldehyde as a brightener.
9. The method as claimed in claim 8, wherein the electroplating cell consists of a system of two electrodes, pure tin plate ( 9 9 .9 9 9 % ultra-high pure) with an area of 1 cm 2 as the anode and stainless steel with an area of 1 cm 2 as the cathode, wherein the stainless steel is polished metallographically and mounted in a predetermined fashion.
10. The method as claimed in claim 8, wherein electroplating cell further consists SCE electrode and a magnetic stirrer, wherein the anode, SCE electrode, and cathode are connected to a pulse plater.
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