Electroless Gold Beam Lead Plating

Sard, R.; Okinaka, Y.; Waggener, H.A.

doi:10.1149/1.2396831

Cited by 21 publications

(17 citation statements)

References 5 publications

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“…Electroless metal deposition in ionic metal (silver) HF solution is based on micro-electrochemical redox reaction in which both anodic and cathodic processes occur simultaneously at the silicon surface [20]. This is a simple and inexpensive fabrication technique and has been widely used in microelectronics and the metal-coating industry [21][22][23]. Moreover, we also analyze the growth mechanisms of the obtained materials in detail on the basis of self-assembled localized microscopic electrochemical cell model.…”

Section: Introductionmentioning

confidence: 99%

From Si nanotubes to nanowires: Synthesis, characterization, and self-assembly

Qiu

Mei

et al. 2005

Journal of Crystal Growth

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Section: Introductionmentioning

confidence: 99%

From Si nanotubes to nanowires: Synthesis, characterization, and self-assembly

Qiu

Mei

et al. 2005

Journal of Crystal Growth

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“…The original baths did not contain stabilizing additives, and they were sensitive to minute amounts of impurities, which tended to lead to spontaneous decomposition. Nevertheless, those baths were employed successfully with sufficient stability under carefully controlled conditions [2][3][4][5], yielding highly pure, soft gold useful for the purpose of bonding semiconductor devices [6]. Other successful applications documented in the open literature include (1) metallization of GaAs microwave field-effect transistors [7], (2) formation of ohmic contacts consisting of Pd/Sn/Au films on n-GaAs [8], (3) metallization of polyvinylidene fluoride (PVDF) films used for making piezoelectric devices [9], (4) deposition of a conducting layer on the interior surface of waveguide tubes made of an aluminum alloy [10], and (5) deposition of a gold layer on tungsten-metallized ceramics for packaging semiconductor devices [11].…”

Section: Yutaka Okinaka and Masaru Katomentioning

confidence: 99%

“…However, the bath stability was still insuficient, and effects of other additives were examined. They reported that K 4 Fe(CN) 6 , K 2 Ni(CN) 4 , 2,2 0 -bipyridyl, and cupferron were effective in the concentration range of 0.1-100 ppm. It was found that the bond strength between gold wire and the deposit was much greater when the bath with K 2 Ni(CN) 4 or cupferron was used than that with 2,2 0 -bipyridyl.…”

Section: Baths Containing Both Sulfite and Thiosulfatementioning

confidence: 99%

Electroless Deposition of Gold

Okinaka

Kato

2010

Modern Electroplating

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The term electroless plating was originally used by Brenner and Riddell [1], inventors of the well-known autocatalytic nickel and cobalt plating processes using hypophosphite as the reducing agent. A literature survey indicates, however, that this term is currently being used to describe three mechanistically different, nonelectrolytic processes for depositing metals and alloys: (1) galvanic displacement plating (also called immersion plating or cementation), (2) substrate-catalyzed plating, and (3) autocatalytic plating. In this chapter only autocatalytic gold plating processes are reviewed.The first autocatalytic, electroless gold plating bath was developed in 1970 at Bell Laboratories [1a] to plate thick, pure soft gold on semiconductors and circuit boards without employing an external source of electric current. The bath contained potassium cyanoaurate (I), KAu(CN) 2 , as the source of gold, potassium borohydride, KBH 4 , or dimethylamine borane, (CH 3 ) 2 NHÁBH 3 , as the reducing agent, potassium cyanide, and potassium hydroxide. Typical bath compositions are given in Table 21.1. The original baths did not contain stabilizing additives, and they were sensitive to minute amounts of impurities, which tended to lead to spontaneous decomposition. Nevertheless, those baths were employed successfully with sufficient stability under carefully controlled conditions [2-5], yielding highly pure, soft gold useful for the purpose of bonding semiconductor devices [6]. Other successful applications documented in the open literature include (1) metallization of GaAs microwave field-effect transistors [7], (2) formation of ohmic contacts consisting of Pd/Sn/Au films on n-GaAs [8], (3) metallization of polyvinylidene fluoride (PVDF) films used for making piezoelectric devices [9], (4) deposition of a conducting layer on the interior surface of waveguide tubes made of an aluminum alloy [10], and (5) deposition of a gold layer on tungsten-metallized ceramics for packaging semiconductor devices [11].More recently the accelerating trend of miniaturization and the need for greater reliability of electronic components have resulted in the development of new technologies for mounting devices on circuit boards, which in turn created new requirements for compatibility of the plating process with substrate materials and also for properties of gold films to be deposited on semiconductors and circuit boards. Quite generally, the method of electroplating has inherent advantages over that of electroless plating in terms of the ease of maintaining the bath and controlling the film thickness and properties. On the other hand, electroless plating has, in principle, a distinct advantage over electroplating in its capability of minimizing the number of processing steps when gold is needed in areas which are electrically isolated from each other. Under these circumstances, efforts have been made to improve the original borohydride and dimethylamine borane (DMAB) baths, especially in their stability and plating rate, and such improved baths are...

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“…1 Silicon undergoes a displacement reaction in the bath, which deposits loosely adherent gold with simultaneous dissolution of silicon. Consequently, in plating on silicon wafers, the backs and edges must be effectively protected from exposure to solution (8).…”

Section: Electroless Gold Plating 5~mentioning

confidence: 99%

Some Practical Aspects of Electroless Gold Plating

Okinaka¹,

Sard²,

Wolowodiuk³

et al. 1974

J. Electrochem. Soc.

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The electroless gold plating process using potassium borohydride as the reducing agent has been investigated for impurity effects, material compatibility, bath agitation effects, and thickness uniformity and line resolution in selective plating of patterned substrates. Impurities may cause a decrease in plating rate [Ni(II) ], bath instability [Ni(II), Co(II), Fe(II) ], thickness nonuniformity (polyethylene, organics in deionized water), and nodule formation (some surfactants). Bath agitation is beneficial: it increases plating rate, minimizes porosity of thin deposits, and eliminates nodule formation. Edge build-up generally occurs in selective pattern plating but, with proper selection of bath compositions and agitation conditions, it can be maintained below 10% in the thickness range of 1-12 ~m. The rate of lateral growth of electroless gold deposits is about 60% of that of perpendicular growth under optimum plating conditions. Also considered in this paper are certain aspects of the scale-up and waste disposal problems associated with electroless gold plating.Electroless gold plating has been found to be useful in a variety of applications, especially for selective plating on patterned substrates for electronics applications. Such applications generally require pure soft gold with a thickness in the range of 1-15 ~m. A bath developed in this laboratory (1) has been found to be quite suitable for forming such deposits. Previous papers described the general bath characteristics (1), physical properties of deposits (2), bath operation with replenishment (3), reaction mechanism (4), and the nucleation and growth of deposits (5). The purpose of this paper is to describe several other aspects of the process which are important from the practical viewpoint and which have hitherto not been discussed. The topics covered include impurity effects, material compatibility, bath agitation effects, deposit thickness uniformity, and line resolution in selective plating of fine line patterned substrates. General recommendations are made as a guide for users of this process. Specific applications will be described in separate communications. Solution Preparation and Plating ProcedureCompositions of three electroless gold plating baths used are listed in Table I. Bath A was used often in our earlier studies (1-3) including those of impurity effects and porosity described in this paper. More recently, baths B and C have been used exclusively. These two baths contain less KCN and KBH4 and, therefore, are more preferable than bath A for practical reasons. Bath B gives the highest deposition rate (5-7 ~m/hr at 70~176 with vigorous agitation), but deposits with acceptable physical properties can be obtained only when plated with agitation. Bath C is slower plating (2 ~m/hr at 70~ with agitation) but gives better thickness uniformity on thin deposits in fine line plating. Details will be described in subsequent sections. It is convenient to prepare the baths by dilution of 5• concentrated stock solutions. These solutions can...

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Electroless Gold Beam Lead Plating

Cited by 21 publications

References 5 publications

From Si nanotubes to nanowires: Synthesis, characterization, and self-assembly

From Si nanotubes to nanowires: Synthesis, characterization, and self-assembly

Electroless Deposition of Gold

Some Practical Aspects of Electroless Gold Plating

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