TW200303938A - Electroplating solution containing organic acid complexing agent - Google Patents

Abstract

A solution for use in connection with the deposition of one or more metals on electroplatable substrates. This solution includes water; a metal ion; and a complexing agent. The complexing agent is advantageously an organic compound having between 4 and 18 carbon atoms which includes at least two hydroxyl groups and a five or six membered ring that contains at least one oxygen atom. The compound is present in an amount sufficient to complex the metal in the solution and inhibit oxidation of the metal. If necessary, a suitable pH adjusting agent can be included in the solution to maintain the pH of the solution in the range of between 2 and 10 and preferably to a pH of about 3.5 to 5.5. At the preferred pH range, the solution is particularly useful for electroplating composite articles that have electroplatable portions and non-electroplatable portions without deleteriously affecting the non- electroplatable portions.

Description

200303938

Software and description of invention Deposition of tin or tin-lead alloys on electroplatable substrates, such as metals, or articles or articles composed of composite articles with plateable and non-platable parts. The present invention also describes a method that inhibits the melting of most of these composite parts during electrodeposition, which is related to the plating of small electrical components that have a large surface area per unit mass and are sensitive to melting. Of particular interest in this article are electrical components such as capacitors and resistors with metal and ceramic, glass, or plastic parts on the surface. Previously, the size of electrical components has been significantly reduced in recent years, and this reduction in size has made it significantly more difficult to plate these components. In addition, 'many surface mount technology (SMT) components have sensitive ceramic parts' which can be destroyed by strong acids or strong test solutions. To avoid this problem, a neutral or near neutral pH plating solution is preferred. -Tin and tin / lead alloy electrolytes specially formulated to be compatible with sensitive ceramic SMTs at neutral or near neutral pH are described in U.S. Patent Nos. 4,163,700, 4,329,207, 4,640,746, 4,673,470, and No. 4,681,670. The formulations described in these patents include component complexing agents such as citrate, gluconate or pyrophosphate, which are used to mix with tin and / or solder to sub-complex the complex at the desired high pHs Dissolve in solution. The use of prior art solutions has a persistent problem that components can couple or condense in electrical / electrical accumulation. When tin or tin alloy plating is applied to a small component with a flat surface 200303938 _ Gate, I Invention Description Continued, it is quite common that the component has a tendency to cluster during the plating process. When the barrel is electroplated with SMT components, it is not unusual for up to 10% of the feed to become coupled (ie stick together). In some cases, the entire feed will fuse together to form large pieces. The extent of this problem depends on the composition of the plating solution and the plating method and the geometry of the component. This problem is particularly noticeable in tin-lead alloy plating. Specially formulated tin and tin / lead alloy plating baths that are compatible with sensitive ceramic 兖 SMTs to be neutral or near neutral pΗ have some benefits, but they are not aimed at the problem of component melting. In addition, it was found that the erosion of ceramics was strongly affected by the composition of the electrolyte and ρ Η. Electrolytes of the prior art have been found to harm new low-fire ceramics even at near neutral ρ ρ; and there are still questions about tin whisker growth on thin plated parts, so a whisker-resistant tin coating Is expected. The present invention now provides a solution and method which can overcome this problem and provide the desired coating. The present invention relates to a solution for the deposition of one or more metals on an electroplatable substrate. This solution contains water, metal ions in an amount sufficient to provide a metal plating layer on a plateable substrate, and a complexing agent. The complexing agent is preferably an organic compound having between 4 and 18 carbon atoms, which includes at least two vials and five or six rings containing at least one oxygen atom. The complexing agent is present in an amount sufficient to complex metals and dissolve them in the solution. In addition, the complexing agent can suppress the oxidation of metal ions in the solution. When the metal ion has the ability to exist in solution in at least two different valence states, the complexing agent can prevent the metal from oxidizing from a lower valence state to a higher valence state. If necessary, in 200303938 _ η, I Invention Description Continued The solution may contain a suitable pH adjuster to maintain the pH of the solution in the range of 2 and 10. In the optimal pH range, this solution is particularly useful for electroplating of composite objects having electroplatable portions and non-platable portions, and does not adversely affect non-platable portions. The complexing agent preferably has one of the following structures:

RC

I (T-CR) m cr2or where each R is the same or different and is hydrogen or a lower alkyl group of 1 to 3 carbon atoms; T is R, OR or 0 = P (OR) 2-; Z Is 0 = or RO-; η is 2-4 and each occurrence of Z in the structure can be the same or non-bank; and m is 1-3, or the complexing agent is a soluble salt of this structure. The most preferred compounds include ascorbic acid, erythorbic acid, dehydroascorbic acid, glucose-type ascorbic acid, galactobismuth acid, glucuronic acid and glucose 6-phosphate, or salts thereof. Typical salts include alkali metals or alkaline earth metals. These complexing agents are usually present in an amount of about 25 to 200 grams / liter. The invention also relates to a method for electroplating a metal plating layer on a composite object, the composite object including a plateable and non-platable portion. The method includes contacting a large portion of the article with a solution described herein, and then applying a current to the solution to provide a metal plating layer on the electroplatable portion of the article without adversely affecting the non-platable portion of the article. influences. Better metal plating 200303938 _ ⑷ I Description of the invention Continuation sheet The layer is tin metal or tin-lead alloy, and the preferred object is an electronic component. Embodiments It has now been found that the melting of electronic components of composite objects can be largely eliminated by providing an electrolyte including one or more complexing agents disclosed herein, and ascorbic acid and related compounds are particularly preferred as such complexing agents. Although the complexing agent can also be used in the plating of other metals, especially those having multiple valence metals, it is more useful in the plating of tin or tin-lead plating solutions. These complexing agents help maintain the metal in the solution in one of its lower valence states, thereby facilitating the plating step and avoiding the oxidation of the metal, which can affect the proper operation of the solution. Tetravalent tin is also mismatched in these systems. Any of the above complexing agents can be used in the present invention. The more advantageous complexing agents are organic acids. The preferred agents include ascorbic acid, erythorbic acid, dehydroascorbic acid, glucose-type ascorbic acid, sequential lacturonic acid, and glucose Alkyd. Salts of these acids can also be used. Preferred salts are alkali metal or alkaline earth metal salts. Ketone gluconate can be used because these compounds are converted to ascorbic acid in the plating bath; heptyl gluconate is also suitable due to conversion to similar acidic species in solution. Either of these agents can be used in a typical amount of about 25 to 200 g / L. The best blending agents are ascorbic acid or an ascorbate salt because these compounds are less expensive and readily available. Ascorbic acid is pure ascorbic acid, an ascorbic acid salt such as sodium or potassium ascorbate, and / or ascorbic acid-metal complexes, such as ascorbic acid 200303938 _I Description of the Invention Continued Tin is contained in the solution. The latter is preferred when it is desired to use other acidic components such as organic acids or organic acid salts to maintain the desired solution pΗ. Ascorbic acid should be present in an amount at least sufficient to dissolve the metal present in the solution in a solution of a specific pH, so the amount of ascorbic acid required is proportional to the metal concentration. At a tin concentration of 15 grams / liter, the preferred ascorbic acid concentration is about 45 to 200 grams / liter. Any electroplatable substrate can be electroplated with the solution of the present invention. Typically, these substrates are made of a metal such as copper, nickel, steel, or stainless steel. In today's commercial products, parts that need to be plated are made in ever smaller sizes, especially electronic components are a typical example of such parts; moreover, these parts are composite objects with plateable and non-platable parts. When the metal part is metallic or metallic, the non-platable part is usually ceramic, glass or plastic. This solution is particularly suitable for plating such composite objects. The plating solution can have any pH between 2-10, but in order to make the solution compatible with the electronic components being plated, the pH is preferably in the range of 3 and 7.5, and more preferably about 4 to 5.5. . When the component has metallic and inorganic parts, the preferred range of ρ 可使 allows the metal to be plated on the metallic part without adversely affecting the inorganic part. Generally, very high or very low pH solutions will destroy the ceramic portion of the plated composite article. Although essentially any acid or base can be used for the pH adjustment, these solutions preferably do not contain a sensible amount of free acid or free base. Since the solution is usually acidic, use a base or alkaline component to convert the free acid to a comparable salt. Preferred bases for this purpose include sodium or potassium hydroxide and many others. 200303938 _ ⑹ I Description of Invention Continued

The solution is formulated to be compatible with the substrate to be plated, and preferably has no adverse effect on the substrate. When plating composite parts with plateable and non-platable parts, the solution should be formulated so as not to erode or crack the non-platable parts of the substrate. A simple test can be used to measure substrate / solution compatibility. The plated object is completely immersed in the solution for a period of time equal to or greater than the time used in the plating process. The temperature of the solution can be close to the temperature of the solution during the plating process, or the high temperature used in the accelerated test. After the part has been immersed in the solution for the required time, it is then removed and weighed to measure the weight loss caused by the solution invading the object during the immersion. For example, today's composite articles for capacitor products are made of low-fire ceramics. These ceramics contain a larger proportion of glass than conventional ceramics and tend to be more susceptible to erosion during the power ore process. A simple comparison test was used to measure the compatibility of different commercially available solutions with the solution according to the invention: a capacitor was placed in a beaker containing an equivalent amount of these solutions, and the weight loss of the part was measured after 5 hours of immersion. The results are shown in the following table:: Loss (%) of the solution after soaking in the solution for 5 hours: Competitor A (mainly gluconate, pH 1.0% 3.5 bath) Competitor A (based on glucose Acid salt-based, pH 4 0.5% bath)-Competitor B (mainly citrate, pH 4.2 5.0% bath) The present invention (ascorbic acid bath, pH 5) 0.0% -10- 200303938 (7) Description of the invention Continuation sheet This table shows that the present invention has basically no effect on capacitors' and that plating of such components is a substantial improvement over conventional plating baths. A particularly useful design for electrical components of this type is disclosed in U.S. Patent No. 6,193,858 and need not be described further herein. To the extent required, the full text of this patent is expressly disclosed herein by reference. Improvements to the previous patent system have been disclosed in Published International Application No. WO 02/053809, the entire text of which is expressly incorporated herein by reference. As disclosed in this application, the immersion of the electrical room into the electrolyte represents a significant improvement, and externally dissolvable electrodes are now available. It was found that the electrolyte containing the complexing agent of the present invention is capable of electrodepositing tin or tin without lead alloys while minimizing the melting or coupling of plated parts, which may adversely affect the non-plated parts of the object. Regarding the @ _, ^ ~ points, some-electrolyte is superior to the previous artist, especially the main bath with citric acid. The complexing agent is used to maintain the tin and / or lead in the solution to maintain the pH of the solution. Some complexing agents, especially ascorbic acid, are also used as 々, J-π avoidance, ， ~ Stabilizers that oxidize tin into tetravalent tin. L-ascorbic acid (AA) can be easily converted to L-dehydroanti-scratching-" Only gray acid (DAA, bream-based conversion

Converted to hydroxyl to AA. In addition, DAA can be easily converted into a double bond by converting two radicals on adjacent carbons, and a single bond connecting those atoms into a double bond. The ease of transforming 1988 into 008 makes it a strong ^^ etchant. In the electroplating solution of the present invention, AA can help tin ions to be mixed in the tetravalent state, which avoids or at least reduces the formation of deposits, and the solution -11-200303938 (8 ) DESCRIPTION OF THE INVENTION The formation of tin oxides which adversely affect the performance of the continuation sheet. A preferred solution according to the present invention contains water, a divalent tin salt and ascorbic acid as a complexing agent, and optionally a divalent lead salt, a salt for increasing electrical conductivity, and a surfactant Or an agent that promotes cation dissolution. Divalent tin salts useful in the present invention include stannous sulfate, stannous chloride, stannous oxide, stannous methanesulfonate, stannous ascorbate or any other suitable source of divalent tin. The concentration of divalent tin in the solution may be from 5 to 100 g / L, and most preferably from 10 to 50 g / L. As described above, since the complexing agent of the present invention is also complexed with a tetravalent tin salt ', it is possible to add the tetravalent tin salt to the solution without any doubt to replace or use the divalent tin salt together. The lead salts that may be added as needed to provide a tin-lead coating include any solution-soluble divalent bisalts, including, for example, methanesulfonic acid, diacetate, or lead ascorbate.

If desired, the conductivity of the solution can be increased by the addition of a salt. If a pure tin solution is desired, a simple salt such as potassium sulfate can be used; if a tin alloy is desired, potassium methanesulfonate or potassium acetate is more appropriate. If necessary, metal sulfide salts can also be used. Any of these salts can be used to promote anodic dissolution and aid electrodeposition. Surfactants commonly used in tin or tin alloy electrolytes may be included in the solution to improve the crystal structure of the coating and improve the quality of the coating at high current densities. Preferred surfactants include solution-soluble alkylene oxide condensation compounds, solution-soluble quaternary ammonium-fatty acid compounds, solution-soluble amine oxide compounds, solution-soluble tertiary amine compounds, or mixtures thereof. A -12-200303938 (9) Description of the Invention Continued The preferred surfactant is an alkylene oxide condensation compound, which is present in an amount of about 0.001 to 20 g / liter. Although some added bullets 1 can perform better than other additives in the handle of the electroforged object, because there are no critical conditions for this component in the appearance of the coating, other conventional surfactants can also be used. Those skilled in the art can perform routine tests to determine the most appropriate surfactant for any particular plating solution.

When a bright coating is required, the aromatic aldehyde can be added in an amount sufficient as a brightener. If necessary, other conventional brighteners may be used instead. The substrates to be plated are preferably those having a composite of conductive and non-conductive portions. When the metal part is metallic or metallic, the non-conductive part is usually ceramic, glass or plastic. This solution is particularly useful for electroplating such composite objects, does not adversely affect the non-metallic parts of the object, and does not cause the part to melt. When electroplating is required on a composite substrate electronic component, the pH of the plating solution is preferably kept in the range of about 4 to 5.5. pH can use bases, such as hydrogen

Increase by adding potassium oxide, ammonium hydroxide, sodium hydroxide, or the like; or decrease by acid, such as sulfuric acid or methamidite. Because sulfuric acid produces lead-insoluble sulfate (which has a tendency to precipitate), alkane or alkanol sulfonic acids, such as thorium sulphuric acid, are preferred for tin-boat alloy solutions. As mentioned above, p Η of about 4 to 5.5 will have the strongest inhibitory effect on the cohesion of such metals; moreover, in order to suppress and minimize the cohesion, the amount of ascorbic acid should not exceed the amount required for complex tin . Typical antioxidants for tin and tin-hydroxide solutions can be included in the solution of the present invention (e.g., o-phthalenedi-13 as disclosed in U.S. Patent No. 4,871,429-200303938 Description of the Invention Continued (ίο) phenol or p-benzenediene Phenol); however, ascorbic acid has been found to be effective in avoiding the oxidation of divalent tin to tetravalent tin in electrolytic solutions at neutral or near neutral pH. Therefore, ascorbic acid has a dual function as a complexing agent and an antioxidant in this solution. _ At the same time, it has been found that by formulating the plating solution of the present invention to have a low electroplating ability, the plating of the non-conductive portion of the composite article and the melting of the composite article can be minimized or largely eliminated. These solutions are specially formulated to not deposit metals at low current densities, as opposed to conventional applications where electrolytes are adjusted to deposit metals at as wide a range of current densities as possible. In fact, most conventional tin plating solutions extend the current density range of electrodeposition in a wide range by adding various additives. It was found that the melting of parts can be reduced by limiting the range of electrodeposition current density to higher current densities. Xianxin Melting occurs because the metal is deposited on the electrolyte film between two parts in close contact or between the part and the feeder. Because the deposition occurs on the thin film between the two conductive surfaces, it must be initiated at a low current density.

The electrolyte is formulated so that it will not be electroplated at low current densities, and melting can be minimized. It was found that the melting of the part is closely related to the composition of the electrolytic bath, and the selection of an appropriate grain refiner or surfactant is important to minimize melting. In this regard, a simple electrolyte containing only a metal salt and a complexing agent has been found to plate electroplated surface adhesion technology (SMT) components without melting. The resulting tin plating is a dark gray matte, which is not commercially useful. Accepted. When a typical surfactant or grain refiner is added to the electrolyte to improve the quality of the coating, a very strong melt is observed in almost all cases. -14-200303938 Invention Description Continued (11) It is shown that cathodic surface polarization from surfactants and grain refiners strongly affects part melting. Moreover, it has been found that electrolytes containing additives that provide limited coverage at low current densities have less tendency to melt than those containing additives that provide high coverage at low current densities.

It is generally believed that the formulation solution for plating individual components in a barrel or other suitable equipment must have Nanning Power ' s capability so the current will pass through the feed and deposit metal in most of the feed. It is also clear that the plating speed at low current densities is negligible because no solid metal is deposited in this case; correctly, most metals are near the plating barrel at high current densities. Everywhere deposited. Therefore, it has been found that as long as the part itself does not have low current density areas such as recesses or blind holes, it is not necessary to provide a solution with a high plating ability to plate individual components in a bucket or other suitable device.

Furthermore, plating solutions that do not deposit metals at low current densities will minimize metal deposition on non-conductive portions of the composite. The phenomenon of metal deposition extending from the conductive end of an object to a non-conductive part is commonly referred to as creep or bridging. The extent of this phenomenon depends mainly on the composition of non-conductive materials. For example, ceramic materials with some electrical conductivity tend to have more metal creep than ceramic materials / materials that are good insulators. Xianxin latent is caused by the current leakage from the conductive part of the object to the π non-conductive π composite part during electrodeposition. By limiting metal deposition to high current density conditions, metal deposition on non-conductive portions can be minimized or eliminated. The plating solution of the present invention can also help reduce or eliminate the presence of whiskers in the coating, which are caused by the growth of the filaments in the coating after plating under certain thermal conditions. This whisker was found to be a cause of short circuit in low voltage equipment. And -15- 200303938 Invention Description Continued (12), the whiskers can be detached from the coating and accumulated in other areas to further cause short circuit problems or interfere with mechanical operation. By using the plating solution disclosed herein, the degree of whisker formation is significantly reduced and completely eliminated. The plating solution of the present invention can be formulated to preferably have the following characteristics and advantages: 1. It will deposit a white matte to translucent plating layer. 2. It will not damage the coated components.

3. It does not deposit metal at low current densities. 4. When the coating is subsequently exposed to thermal conditions, it can reduce or even eliminate whisker formation.

When the plated part is a composite object containing ceramic or lead-containing glass parts, the acid or alkali solution will destroy the ceramic or glass parts during plating. Components such as SMT resistors, induction coils and capacitors are all this type. In order to minimize damage to the ceramic or glass part of the article, the pH of the plating solution used for SMT components must be between about 2.5 and 9. For: T to reach this pH, tin must be a mismatched plastic form. Prior art complexing agents generally include citrate, gluconate, and pyrophosphate; however, for translucent plating / one or more organic additives are generally used. Most of the well-known additives greatly increase the low current density coverage of the solution, resulting in melting of the plated parts and overcoating of the non-conductive parts of the parts. The low current density coverage of the electrolyte can be reduced by operating at a low metal concentration, operating at high temperatures, choosing not to increase the low current density coverage (LCDC), or reducing the LCDC and / or any combination of additives to reduce it . For example, when tin is electroplated metal, high metal ions of at least about 25 g / l -16 ** 200303938 Description of the Invention Continued (13) content is preferred. Since it has been found that high temperatures usually increase part melting, high plating bath temperatures are the least desirable method of reducing LCDC.

The choice of organic additives in the plating bath is particularly important in maintaining the plating ability at a low level. The optimal additive can be determined by routine testing of the particular plating solution of interest. These additives include conventional surfactants and grain refiners, such as condensation compounds of mono- or polyaromatic organic compounds and other organic condensates or reaction products that have dye-like properties but are not surfactants. These compounds are well known in the art, so only tests to ensure that they do not provide the high plating ability of the plating solution.

Other additives can also be used with surfactants and grain refiners to reduce the plating ability of the electrolyte. When used with various surfactants and grain refiners, ammonium chloride, ascorbic acid, and m-nitrophenol have been found to reduce plating ability. Obviously, many other additives also have this function, and the use of these other additives is a subject of the present invention. Those skilled in the art can perform routine tests to determine whether or not to use the best combination of additives in any particular plating solution. When plating composite articles, this solution can be used in the equipment disclosed in U.S. Patent No. 6,193,858 and published International Application No. WO 02/053809. The electroplating solution of the present invention can also be used in the rotary electroplating devices described in US Pat. Nos. 5,487,824 and 5,565,079, and improved results are obtained. Since the deposition of tin in the feed coil is substantially reduced, the feed line needs to be replaced and removed Maintenance is significantly reduced. Therefore, the use of an electrolytic solution with reduced LCDC in a rotary electroplating apparatus is also a subject of the present invention. When using electroplating barrels, the use of the present invention is also advantageous because less gold is deposited on the stilt, and metal creep and part melting are reduced because of less gold. Therefore, the use of LCDC electrolyte in barrel plating is also a subject of the present invention. Although the present invention is particularly useful in plating non-conductor composite objects, the use of the present invention in reducing the plating of feeders and reducing or eliminating metal on non-conductive parts of composite objects is useful in plating individual objects mixed with conductors. Clear advantages of deposition.

A useful method for testing the LCDC of an electrolyte is to use a standard 265 milliliter hull cell test. Standard procedures are used to run any type of tank. Typical conditions are 5 minutes at 1 A, 5 minutes at 0.5 A, or 5 minutes at 0.25 A, each using paddle agitation. If the back of the Hoch plate is mostly unplated except for the portion extending from the edge of the panel that is less than 1 cm, the Hoch groove prepared at 1 A has LCDC; in addition, the electrolyte is best at the front with low current density There are unplated parts on the edges. This unplated part can be from 1/8 "to 3/4" inches wide. The electrolyte exhibiting the results of this type of grooved plate generally has less tendency to melt than an electrolyte that produces a significant plating on the back of the plate. Limiting current density that prevents metal from being deposited can be measured by preparing a Hood plate at 0.25 A and measuring the current density at the edge of the metal plating using an appropriate Hood plate scale. In addition, when the electrolyte with LCDC is used in the latest SMTs without conductors in the SBE device, it is usually found that the feeders are not mostly tin-plated at the end of the plating cycle and the plated parts are not melted to the feeders. In contrast, when a commercially available neutral tin plating solution is used to electroplate SMTs on SBE non-conductor, the parts are stuck within three minutes of the start of plating, and it is found that the feeder is completely coated with tin-18-200303938 Continued (15). Therefore, the use of tin or tin alloy electrolytes with LCDC is necessary for successful plating of non-conductor SMTs in SBE devices. Examples The following examples illustrate useful specific embodiments of the present invention. Example 1: A pure tin plating layer was obtained from the following solution and the following plating conditions. Ascorbic acid 100 g / l

Tin (methanesulfonate form) 15 g / l Surfactant 0.5 ml / l Adjust pH with KOH to: 4.05 The above solution will deposit translucent tin at a current density of up to 20 ASF. Example 2: 1.5 g / l of lead methanesulfonate was added to the solution of Example 1 and electroplated under the same conditions to obtain a translucent tin-lead coating. Ascorbic acid 100 g / l '.

Tin (methanesulfonate form) 15 g / l lead (methane methanesulfonate form) 1.5 g / l 'potassium methane sulfonate 40 g / l surfactant 0.5 ml / l Adjust pH with KOH to: 4.05 This solution It will also deposit translucent 90% tin at current densities up to 20 ASF. Comparative Example: In a 2.5 "long and 4" wide bucket, a conductive ball of 140 millimeters and a radius of 2.5 millimeters is used. 19- 200303938 (16) Description of the Invention The continuation sheet is used as a conductor, and the preparation of Example 1 is used to electroplat tin to 250 pieces. 8 millimeter diameter flat gasket. Plating feed at 5 A, 6.5 V for 15 minutes. At the end of the plating cycle, no flat gaskets have melted together. The same plating cycle was performed using the electrolytes of the following formulations: tin citrate (methane sulfonate form) lead (methane sulfonate form) potassium pinane sulfonate surfactant pH adjusted with KOH to: 5 A and 9 Plating feed at V for 15 minutes. At the end of the plating cycle, the twelve pieces were not connected, and the rest of the spacers came together in as many as ten pieces and were difficult to separate. This example clearly demonstrates the solubility of the invention. Example 3: The following examples illustrate the reduction in tin whisker formation when compared to the plating solution produced by the plating solution of the present invention and the technical plating solution. As mentioned above, when the ore is exposed to heat treatment or conditions (such as those encountered when plated parts are in operation), whisker generation problems can occur. It can take a week to five years to grow, and when it grows, it can cause short circuits or other problems. To measure whether whisker formation will occur in this layer, an accelerated test has been developed: a thermal cycler that places the plated part in a chamber controlled at -55 ° C for minutes; then in 20 seconds Transfer it to another temperature chamber, and measure a half meter at 40 g / l, 10 g / l, 1.5 g / l, 40 g / l, 2.5 ml / l, 4.2, and only the previously condensate of the group condensate may be coated In the ring test, 15 let it pass another 15 minutes at a temperature of 125 -20- 200303938 description (17) ° C. Repeat this cycle 500 times and observe if whiskers are formed on the coating. The solution of Example 1 was used to plate the substrate with tin, and then subjected to the above-mentioned thermal cycle test for 500 cycles; the other substrate was tin-plated from a conventional sodium gluconate plating solution, and the plated substrate was also subjected to the same procedure. Thermal cycling test 500 cycles. The results are shown in Figures 1-4. In Figures 1 and 2, the surface of the plated part according to the present invention shows very small, very short whiskers, which are relatively harmless φ. In comparison, electroplated parts according to the prior art show much and much longer whisker formation, so that there are more plating objects that may cause short circuits or possible mechanical interference (if longer whiskers are removed). Therefore, the plating layer of the present invention is much better, especially when small parts (such as electronic components) need tin plating. Brief description of the diagrams _ Further advantages of the present invention will be illustrated by diagrams, of which:

Fig. 1 is a photomicrograph of a tin-plated substrate according to the prior art plating solution;-'Fig. 2 is a photomicrograph of the same substrate for tin electroplating according to the plating solution of the present invention; An enlarged photomicrograph of a portion of a surface of a tin-plated substrate of a plating solution; and FIG. 4 is an enlarged photomicrograph of a portion of a surface of a tin-plated substrate of a plating solution according to the present invention. -twenty one -

Claims (1)

200303938 There are many kinds of gold-plated electroplating on the base material that can be deposited and applied for patents. There are many kinds of gold g-gl: Or you can include a package with it. The water-based metal that is dissolved in the liquid seed can be used to lift the base material. In the chemical compounding machine which is sufficient for the combination of its seed gold species, there are 8 carbon atoms and 4 carbon atoms; in the seed layer which is stored in the dendrite, a plated, Dissolve in a solution that is so low that it contains only two components, such as metal and metal, and that it is completely inclusive of the inclusions, such as B ring V, Gukou, or pentoxide. And, when the appropriate amount of seed is one, the chemistry of oxygen is required. If there is a chemical combination under the column, its liquid solubility is between 0 and 1. d 々 巳 ο $ 1 J 口 枪 2 ^ Specially invited to hold Shen Weiru 2 ο RC I (T-CR) m I cr2or where each R is the same or different, and is hydrogen or a lower alkyl group of 1 to 3 carbon atoms; T is R, OR, or 0 = P (OR) 2-; Z is 0 = or RO-; η is 2-4 and each occurrence of Z in the compound may be the same or different; and 200303938 _ Patent Application Park Continuation Page m is 1-3; or a complexing agent It is a soluble salt of this structure. 3. The solution according to item 2 of the scope of patent application, wherein the complexing agent is ascorbic acid, erythorbic acid, dehydroascorbic acid, glucose-type ascorbic acid, galacturonic acid, glucuronic acid, or a salt thereof; or derived from gluconic acid Ketone or heptyl gluconate, and it is present in an amount of about 25 to 200 grams / liter. 4. The solution according to item 1 of the scope of patent application, wherein the metal is tin and is based on stannous alkylsulfonate, stannous sulfate, stannous chloride, stannous ascorbate, or stannous oxide The pattern is added to the solution; again it is present in an amount between about 5 and 100 grams / liter. 5. The solution according to item 4 of the patent application, which further comprises a divalent lead salt sufficient to deposit a tin-lead alloy from the solution. 6. The solution according to item 1 of the patent application scope, which further comprises one or more conductive salts sufficient to increase the conductivity of the solution, a surfactant sufficient to enhance the quality of the coating and the grain structure, or an agent to promote anode dissociation. 7. The solution according to item 6 of the patent application, wherein the conductive salt is an alkali metal or earth metal sulfate, continuous acid salt, or acetate compound; the surfactant is an alkylene oxide condensation compound, and it is based on It is present in an amount of about 0.01 to 20 grams per liter; or the agent that promotes anodic dissociation is potassium methanesulfonate, ammonium chloride, or a metal sulfide salt. 8. The solution according to item 1 of the scope of patent application, wherein the substrate is a composite object having an electro-depositable portion and a non-platable portion; the PΗ adjusting agent is an acid or an alkali, and the pH is adjusted to about 3.5 to 5.5. The areas are plated with electroplatable parts without adversely affecting the non-platable parts. 200303938 _ Patent application continued page 9. A method for electroplating a metal coating on a substrate, comprising contacting the substrate with a solution as described in the first patent application, and passing a current through the solution to the substrate. Provide metal plating. 10. —A method for electroplating a metal plating layer on a composite object including a plateable part and a non-platable part, comprising contacting a large part of the object with a solution such as the item 1 of the patent application scope, and passing an electric current into the solution. The metal plating layer is provided on the electroplatable part of the article without adversely affecting the non-platable part. 11. A method for reducing whisker formation on a metal plating layer on a substrate, comprising contacting the substrate with a solution such as the one in the scope of patent application, and passing a current into the solution to provide a metal plating layer on the substrate At the same time, the whisker formation of the coating is reduced or eliminated. 12. A method as claimed in claim 11 wherein the substrate is a composite article containing plateable and non-platable parts; and it further includes contacting a large portion of the article with a solution to provide on the plateable part of the article No whisker or reduced whisker coating.