WO2000047800A1 - Solution of electrolytes and method for producing lead-tin layers - Google Patents
Solution of electrolytes and method for producing lead-tin layers Download PDFInfo
- Publication number
- WO2000047800A1 WO2000047800A1 PCT/EP2000/001146 EP0001146W WO0047800A1 WO 2000047800 A1 WO2000047800 A1 WO 2000047800A1 EP 0001146 W EP0001146 W EP 0001146W WO 0047800 A1 WO0047800 A1 WO 0047800A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- lead
- tin
- solution according
- electrolytic solution
- electrolyte solution
- Prior art date
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Classifications
-
- 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
- C25D3/56—Electroplating: Baths therefor from solutions of alloys
- C25D3/60—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of tin
Definitions
- Electronic components e.g. System carriers for integrated circuits or connectors must be provided with solderable coatings to maintain good soft solderability.
- the general state of the art is to provide such components electrolytically with a coating of tin or lead tin. Because of the risk of whisker formation in pure tin layers, coating with tin-lead alloys is particularly preferred. Any tin / lead alloy ratio can be used to maintain soft solderability.
- solder connection is made by wave soldering or reflow soldering with the eutectic lead tin alloy with 63% tin and 37% lead or also with silver alloy solders with the composition 62% Sn 36% Pb 2% Ag, it was common in the past, also for the electrolytic coating to choose this eutectic composition.
- the advantage of the eutectic alloy is that the system has the lowest melting point, so the solder connection can be made at a lower temperature than that of solder alloys with a non-eutectic composition.
- Lead tin layers can be mechanically processed. Such mechanical processing steps are, for example, punching out the components from the system carrier strip and a mechanical reshaping of the connection legs of the circuits.
- This processing leads to mechanical wear of the lead tin surface. Deposits of this lead tin surface are deposited on the forming tool. This process is known to the person skilled in the art under the term “solder peeling”. This leads to operational interruptions in order to clean the forming tools again. If this cleaning is not carried out at regular intervals, lead tin alloy particles can be transferred back to the components from the forming tool. With the small distance between the connecting pins in a grid dimension of 0.5 mm, this deposit can lead to an electrical short circuit between the individual connecting pins and thus to the failure of high-quality components.
- Fig. 1 Cross section of a material coated with a lead tin coating
- Fig. 2 Electronic component with bent
- Connection leg Fig. 3 Electronic component with curved
- FIG. 1 The ideal arrangement of the tin crystallites in the lead tin coating according to JP 100 72 694 is shown in FIG. 1.
- the tin crystallites are aligned in the lead tin coating (2) along the normal to the base material surface (1).
- FIG. 2 When bending the connections (4) of a component (3) into the so-called "J-shape" (FIG. 2) or the connections (6) of a component (5) into the so-called "gull-wing shape” (Fig. 3), due to the orientation of the tin crystallites according to FIG. 1, crack formation occurs along the grain boundaries. This allows the base material of the components to be exposed. The function of the electrodeposited lead tin coating to maintain solderability is no longer guaranteed. Furthermore, this patent application does not describe what the orientation of the lead crystallites must be in order to achieve the lowest possible lead-tin abrasion during mechanical processing.
- an acidic electrolytic solution the alkyl sulfonic acids Tin salts, soluble lead salts and, as inhibitors, a mixture of one or more nonionic surface-active substances and one or more anionic surface-active substances, and dissolved by a process of electrolytic deposition of lead tin layers from such an acidic electrolyte solution.
- Lead tin layers which are obtained from the electrolytic solution according to the invention are characterized by a texture which for the tin crystallites the reflections for the Millers indices ⁇ 220 ⁇ , ⁇ 321 ⁇ and ⁇ 501 ⁇ and for the lead crystallites the reflections for the Millers index ⁇ 200 ⁇ shows .
- the ⁇ 220 ⁇ , ⁇ 321 ⁇ and ⁇ 50l ⁇ bands have the three highest intensities for the tin crystallites.
- the band of the highest intensity for the lead crystallites is assigned to the ⁇ 200 ⁇ reflex.
- Lead tin layers of the described texture are characterized by little or no lead-tin abrasion during mechanical processing.
- Alkyl sulfonic acids according to the present invention preferably have 1-3 carbon atoms and can be substituted with one or more hydroxyl groups.
- the alkylsulfonic acids are preferably present in a concentration of 20-500 g / 1 electrolyte solution, particularly preferably in the concentration range 50-300 g / 1 electrolyte solution.
- Soluble tin and lead salts in the electrolyte solution according to the invention are preferably the corresponding alkyl sulfonates and hydroxyalkyl sulfonates, particularly preferably the methanesulfonates, ethanesulfonates, n-propanesulfonates, iso-propanesulfonates, methanedisulfonates, ethanedisulfonates, 2-hydroxyethanesulfonates, 2-hydroxy-n-2 -Hydroxy-n-propane sulfonates, 3-hydroxy-2-propane sulfonates, 2, 3-dihydroxy-n-propane sulfonates and 1,3-dihydroxy-2-propane sulfonates are present.
- the concentration of the soluble tin salts is preferably 10-200 g / 1 electrolyte solution, particularly preferably 30-70 g / 1 electrolyte solution, in each case based on the pure metals.
- the preferred concentration is in the range of 1 - 200 g / 1 electrolyte solution, particularly preferred are 1 - 20 g / 1 electrolyte solution, based in each case on the pure metals.
- Preferred nonionic surface-active substances are one or more compounds of the following general formulas (I) to (VI):
- n 1-100, preferably 6-15,
- n 1-100, preferably 6-15,
- the preferred concentration of the nonionic surfactants is 0.1-20 g / 1 electrolyte solution. Concentrations in the range from 0.5 to 5 g / l of electrolyte solution are particularly preferred.
- Preferred anionic surface-active substances are one or more aromatic sulfonated compounds of the following general formulas (VII) to (VIII):
- X is an alkali metal or NH 4 , preferably Na, K or NH 4
- the preferred concentration of the anionic surfactants is 0.1 - 4 g / 1 electrolyte solution. Concentrations of 0.4-0.6 g / l electrolyte solution are particularly preferred.
- a particularly preferred electrolyte solution comprises one or more compounds of the general formulas as nonionic surface-active substances
- the electrolyte solution comprises a combination of compounds of the formulas (IV) and (VII), (IV) and (VIII) or (VIb) and (VII) as an inhibitor mixture.
- ⁇ -naphthol ethoxylate-12-EO is used as the nonionic surface-active substance and the sodium salt of 1,8-naphtholsulfonic acid and the sodium salt of the naphthalenesulfonic acid-formaldehyde condensation product, which have an average degree of condensation of 2 to, as anionic surface-active substances 3 has before.
- the pH of the electrolyte solution is preferably between 0 and 2.
- the lead tin electrolyte further comprises 0.1-10 g / 1 electrolyte solution, particularly preferably 0.5-2 g / 1 electrolyte solution, oxidation stabilizers to prevent the oxidation of the tin salts.
- Catechol, hydroquinone, resorcinol, pyrogallol and / or ascorbic acid are particularly preferably used as oxidation stabilizers.
- the electrolytic solution defoamer e.g. include octyl alcohol.
- lead tin layers which are characterized by little or no lead-tin abrasion during mechanical processing
- a method is used according to the invention in which the lead tin layers are electrolytically extracted from the acidic electrolytic solution, the alkyl sulfonic acids, soluble tin salts, soluble lead salts and as inhibitors comprising a mixture of one or more nonionic surfactants and one or more anionic surfactants.
- the process of electrolytic lead tin deposition is preferably carried out at current densities of greater than or equal to 5 A / dm 2 .
- the current density is 15-25 A / dm 2 .
- Current densities of 80-100 A / dm 2 are particularly preferably used in the jet plating process.
- the working temperature during the electrolytic lead tin deposition is preferably in the range from 25 to 70 ° C., particularly preferably between 40 ° C. and 50 ° C.
- the deposited layers are preferably characterized by a layer thickness of 5-20 ⁇ m.
- a coating obtained by the process according to the invention preferably has a proportion of 60 to 98% by weight of tin and 2 to 40% by weight of lead, particularly preferably 80 to 90% by weight of tin and 10 to 20% by weight of lead.
- the components to be coated can be pretreated according to methods known in the art, for example by alkaline degreasing and anodic activation.
- the method according to the invention can advantageously be used to form lead tin coatings on electronic components.
- the present invention is illustrated by the following example.
- a lead tin electrolyte of the following composition was prepared:
- Tin methanesulfonate (as Sn (II)) 40.0 g / 1
- Methanesulfonic acid 70% 200.0 g / 1 ß-naphthol ethoxylate-12-EO 1.0 g / 1
- a continuous high-speed system e.g. Meco-EPL, manufactured by Meco Equipment Engineers BV, Netherlands
- the electronic components were arranged in a band and at a relative Flow velocity of 50 to 150 m / min and a throughput speed of 1 to 5 m / min in an electrolytic bath having the composition given above, coated at a current density of 20 A / dm 2 and an electrolyte temperature of 45 ° C for 1 min.
- the three most intense bands represent the ⁇ 321 ⁇ , ⁇ 220 ⁇ and ⁇ 501 ⁇ reflections of the tin crystallites.
- the band with the fourth highest intensity is assigned to the ⁇ 200 ⁇ plane of the lead crystallites.
Abstract
Description
Claims
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU29107/00A AU2910700A (en) | 1999-02-12 | 2000-02-11 | Solution of electrolytes and method for producing lead-tin layers |
EP00907554A EP1151152A1 (en) | 1999-02-12 | 2000-02-11 | Solution of electrolytes and method for producing lead-tin layers |
JP2000598692A JP2002536554A (en) | 1999-02-12 | 2000-02-11 | Method for producing electrolyte solution and lead tin layer |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19905981.0 | 1999-02-12 | ||
DE1999105981 DE19905981C1 (en) | 1999-02-12 | 1999-02-12 | Electrolyte solution and process for the production of lead tin layers and use |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2000047800A1 true WO2000047800A1 (en) | 2000-08-17 |
Family
ID=7897363
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP2000/001146 WO2000047800A1 (en) | 1999-02-12 | 2000-02-11 | Solution of electrolytes and method for producing lead-tin layers |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP1151152A1 (en) |
JP (1) | JP2002536554A (en) |
AU (1) | AU2910700A (en) |
DE (1) | DE19905981C1 (en) |
WO (1) | WO2000047800A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN109338408A (en) * | 2018-12-04 | 2019-02-15 | 中华全国供销合作总社天津再生资源研究所 | A kind of electrolyte and a kind of electrorefining method of useless electronic solder |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP4582294B2 (en) * | 2004-04-02 | 2010-11-17 | 三菱マテリアル株式会社 | Lead-tin alloy solder plating solution |
JP4812365B2 (en) * | 2005-08-19 | 2011-11-09 | ローム・アンド・ハース・エレクトロニック・マテリアルズ,エル.エル.シー. | Tin electroplating solution and tin electroplating method |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4662999A (en) * | 1985-06-26 | 1987-05-05 | Mcgean-Rohco, Inc. | Plating bath and method for electroplating tin and/or lead |
US5698087A (en) * | 1992-03-11 | 1997-12-16 | Mcgean-Rohco, Inc. | Plating bath and method for electroplating tin and/or lead |
-
1999
- 1999-02-12 DE DE1999105981 patent/DE19905981C1/en not_active Expired - Fee Related
-
2000
- 2000-02-11 EP EP00907554A patent/EP1151152A1/en not_active Withdrawn
- 2000-02-11 JP JP2000598692A patent/JP2002536554A/en active Pending
- 2000-02-11 AU AU29107/00A patent/AU2910700A/en not_active Abandoned
- 2000-02-11 WO PCT/EP2000/001146 patent/WO2000047800A1/en not_active Application Discontinuation
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4662999A (en) * | 1985-06-26 | 1987-05-05 | Mcgean-Rohco, Inc. | Plating bath and method for electroplating tin and/or lead |
US5698087A (en) * | 1992-03-11 | 1997-12-16 | Mcgean-Rohco, Inc. | Plating bath and method for electroplating tin and/or lead |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN109338408A (en) * | 2018-12-04 | 2019-02-15 | 中华全国供销合作总社天津再生资源研究所 | A kind of electrolyte and a kind of electrorefining method of useless electronic solder |
Also Published As
Publication number | Publication date |
---|---|
JP2002536554A (en) | 2002-10-29 |
DE19905981C1 (en) | 2001-05-17 |
AU2910700A (en) | 2000-08-29 |
EP1151152A1 (en) | 2001-11-07 |
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