本文選題：化學(xué)鍍 + 鎳鈀磷合金��； 參考：《廣東工業(yè)大學(xué)》2016年碩士論文

【摘要】：印制線路板(PCB)的銅質(zhì)焊盤表面容易形成氧化層,使電阻變大,且易與焊料(特別是含錫的)形成金屬間互化物(IMC),這種IMC易發(fā)生脆性斷裂,嚴(yán)重影響焊接可靠性。為了限制或者消除IMC的存在,在銅與焊料的界面之間加入阻擋層。目前常常采用化學(xué)鍍鎳/浸金的表面處理工藝,但鍍鎳層具有較大的空隙率,且金沉積的顆粒較大,就需要較厚的鎳層和金層來減少空隙；同時(shí),金容易對鎳層造成過度腐蝕,存在“黑盤”的風(fēng)險(xiǎn)。本文用化學(xué)鍍的方法得到了致密的非晶態(tài)鎳鈀磷合金鍍層,對比研究了以此鍍層為阻擋層的兩種方法：(1)直接在銅表面上化學(xué)鍍鎳鈀磷合金鍍覆層,簡稱化學(xué)鍍鎳鈀合金工藝ENEP(2)在銅表面先鍍層薄鎳,再化學(xué)鍍鎳鈀磷合金鍍層,簡稱化學(xué)鍍鎳/鎳鈀合金工藝EN/ENEP。由于鈀顆粒細(xì)小,兩種工藝所得鍍層比較致密、孔隙率低,外觀呈亮白色,可直接用于焊接。同時(shí)底層Ni不易發(fā)生氧化,可避免“黑盤”問題的出現(xiàn)。通過SEM、EDS、XRD、X射線熒光測厚儀以及電化學(xué)工作站,研究了氯化鎳、氯化鈀、乙二胺、氨水、次磷酸鈉、溫度以及pH等因素對化學(xué)鍍鎳鈀磷合金鍍層成分、表面形貌、沉積速率、鍍層結(jié)構(gòu)的影響,鍍層性能通過結(jié)合力試驗(yàn)、中性鹽霧試驗(yàn)和可焊性試驗(yàn)進(jìn)行測試。經(jīng)過正交實(shí)驗(yàn)優(yōu)化得到鍍液基礎(chǔ)配方及工藝條件為：NiCl2·6H2O 12g/L, PdCl2 0.1g/L, NaH2PO2·H2O 6g/L,乙二胺(En)9mL/L,氨水7mL/L,氯化銨3g/L溫度65～70℃,pH 8.5～9.0。選取了具有代表性的典型添加劑,考擦其對鍍液穩(wěn)定性、鍍層孔隙率及沉積速率的影響,最終得到通過正交實(shí)驗(yàn)優(yōu)化的添加劑組合為：二氧化硒7mg/L、硫酸銅15mg/L、三氯化鐠7mg/L。所得鍍層表面平整,顆粒大小均勻,結(jié)晶細(xì)致,無明顯的氣孔和裂紋,鍍層中鎳鈀磷含量分別為Ni 85.19%.、Pd 6.25%、P8.56%,各元素分布均勻；通過調(diào)節(jié)pH及鍍液中鎳鹽與鈀鹽的比例,可以控制鍍層中Pd的含量,結(jié)果表明在pH為8.5的鍍液中隨著鈀鹽與鎳鹽摩爾比從10增加到100,鍍層中鈀含量可控范圍為4～50wt%；Ni-Pd-P合金鍍層的耐蝕性、可焊性優(yōu)于化學(xué)鎳層,合金中鈀含量越多,鍍層腐蝕傾向越小。采用線性電勢掃描的方法,以銅電極和鎳-磷電極為工作電極,研究了Ni-P、Pd-P以及Ni-Pd-P合金的陰極極化曲線,并探討了各添加劑對陰極沉積過程的影響。發(fā)現(xiàn)鈀離子可能是通過促進(jìn)次磷酸根氧化來催化鎳、鈀以及它們合金的沉積行為的,在Ni-Pd-P合金沉積的過程中,同時(shí)伴隨著鎳與鈀置換反應(yīng)的發(fā)生。鈀會(huì)促進(jìn)鎳的還原沉積,鎳對鈀的沉積起抑制作用。
[Abstract]:It is easy to form oxide layer on the copper pad surface of printed circuit board (PCB), which makes the resistance become larger, and forms intermetallic intermetallics with solder (especially tin). This kind of IMC is prone to brittle fracture, which seriously affects the reliability of welding.In order to limit or eliminate the existence of IMC, a barrier layer is added between the interface of copper and solder.At present, the electroless nickel plating / gold leaching surface treatment process is often used, but the nickel plating layer has a large void ratio and the gold deposit particles are larger, so the thick nickel layer and gold layer are needed to reduce the void; at the same time, the gold is easy to cause excessive corrosion to the nickel layer.There is a risk of a black disk.In this paper, a dense amorphous Ni-Pd-P alloy coating was obtained by electroless plating. Two methods of electroless Ni-Pd-P alloy plating on copper surface were studied.Electroless nickel-palladium alloy plating process ENEP2) plating on the surface of copper first thin nickel, then electroless Ni-Palladium phosphorus alloy coating, for short, electroless nickel plating / Ni-PD alloy process en / ENEP.Due to the fine palladium particles, the coating obtained by the two processes is compact, with low porosity and bright white appearance, which can be directly used in welding.At the same time, the bottom Ni is not easy to oxidize, which can avoid the problem of "black disk".The effect of nickel chloride, palladium chloride, ethylenediamine, ammonia water, sodium hypophosphite, temperature and pH on the composition, surface morphology and deposition rate of electroless Ni-Pd-P alloy plating was studied by means of SEMS-EDSX X-ray fluorescence thickness meter and electrochemical workstation.The effect of coating structure, coating properties were tested by adhesion test, neutral salt spray test and solderability test.The basic formula and process conditions of plating solution were optimized by orthogonal experiment: 1: NiCl2 6H2O 12g / L, PdCl2 0.1g / L, NaH2PO2 H2O 6g / L, ethylenediamine Enn 9 mL / L, ammonia water 7ml / L, ammonium chloride 3g/L temperature 6570 鈩，

本文編號(hào)：1768053