Evaluation of the effects of residual stress occurred and hydrogen co-deposited during tin electroplating on the suppression and growth of tin whisker

研究了镀液温度对酸性硫酸锡电镀锡薄膜中锡须生长的影响。由于黄铜比其他金属更容易促进锡须的生长，因此采用黄铜作为镀液基体。在0℃、5℃、10℃、15℃、20℃、25℃和50℃ 7种镀液温度下进行了镀锡试验。随着电镀锡的进行，内应力总是由电解初期的拉伸变为压缩。随着镀液温度的升高，TiN薄膜中的压应力减小。在50℃下沉积的TiN薄膜中残余应力几乎为零。镀液温度越高，沉积锡的粒度越大，沉积锡的电流效率越高。锡晶须生长的温度顺序为0 ℃>5℃>10℃>15℃>20℃>25℃>50℃，并研究了锡锌合金的形成对锡晶须生长的影响 关于我们 还研究了电镀锡。试样的基体为铝板，其一面化学镀锌，另一面用塑料树脂绝缘，锌膜上电镀锡。将镀有锡镀层的铝板放入恒温控制在50℃的恒温箱中，以加速锡晶须的生长。当锡须生长后，在含锡须的试样上覆盖一层氨基磺酸镍电铸层。剥离塑料树脂，露出另一面铝，在25℃ 1.0moldm^NaOH溶液中浸泡腐蚀<-3>，测定腐蚀电位，在锡晶须出现之前，试样只测到锌和锡电极的腐蚀电位。另一方面，含有锡晶须的试样，除了锡和锌的腐蚀电位外，其余的腐蚀电位都与锡锌合金的腐蚀电位相同。这表明锌扩散到镀锡层中形成锡锌合金，导致锡晶须生长。少

Effects of the electroplating bath temperature on the growth of whisker from tin film electroplated from an acid tin sulfate bath were investigated. Brass was used as the plating substrate, since brass always accelerated the growth of tin-whisker compared with the other metals. Tin electroplating was performed at seven kinds of bath temperature such as 0℃, 5℃, 10℃, 15℃ 20℃, 25℃ and 50℃. The internal stress always changed from tension at the beginning of electrolysis to compression with successive electroplating of tin. The compressive stress in as-deposited tin film decreased with increasing in bath temperature. The residual stress in tin film deposited at 50℃ was almost zero. The higher the bath temperature was, the larger the granular size of deposited tin became and the current efficiency for tin deposition increased. The growth of tin-whisker was enhanced in temperature orders of O℃>5℃>10℃>15℃>20℃>25℃>50℃.The Influences of tin-zinc alloy formation on tin whisker growth out of the e … More lectroplated tin was also investigated. The substrate of specimen was aluminum sheet with one-side chemically plated zinc and the reverse side insulated electrically by a plastic resin on it. Tin was electroplated on the zinc film. The aluminum sheet with the plated tin deposits was put in the incubator controlled thermostatically at 50℃ for the purpose of accelerating tin whisker growth. After some tin whisker grew, the specimen with tin whisker was covered by nickel electroformed from a nickel sulfamate bath. The plastic resin was stripped off for exposing the other-side aluminum, which was immersed and corroded in 1.0 moldm^<-3> NaOH solution at 25℃ and the corrosion potential was measured.Only the corrosion potentials concerning the zinc and tin electrode were detected for the specimen before tin whisker occurred. On the other hand, the specimen with some tin whisker always showed the corrosion potentials concerning tin-zinc alloy except the corrosion potential of tin and zinc, respectively. Such results suggested that zinc diffused into the plated tin to form tin-zinc alloy, which resulted in tin whisker growth. Less