1、,Better For Business Better For The Environment,CEPREI,中國賽寶實驗室,1,中國賽寶實驗室 羅 道 軍,中國賽寶實驗室 羅道軍,無鉛焊料與無鉛工藝技術,主 要 內 容,1. 為什么要無鉛？ 2. 無鉛焊料研究狀況 3. 目前已實用的無鉛焊料介紹 4. 無鉛工藝相關技術問題 5. 典型無鉛制程工藝 6. 無鉛制程的可靠性評價,1. 為什么要無鉛 ？,1.1 鉛元素毒性對人類健康的影響。,含鉛廢物處理問題(Disposal)不當導致鉛的浸出以及循環(huán)（Lenching and Recycling），然后進入生態(tài)系統(tǒng)！

2、鉛有關的健康危害包括神經(jīng)系統(tǒng)和生育系統(tǒng)紊亂、神經(jīng)和身體發(fā)育遲緩。鉛中毒特別對兒童的神經(jīng)發(fā)育有危害。,鉛污染的機理,關鍵：Pb Pb2,鉛在各種產(chǎn)品中的使用量(1),產(chǎn)品蓄電池氧化物(用于油畫、玻璃和陶瓷、顏料和化學品) 消耗量(%)80.814.78 產(chǎn)品彈藥鉛箔紙電纜覆蓋物 鑄造金屬銅錠、銅坯 消耗量(%)4.691.791.40 1.130.72 產(chǎn)品管道、彎頭和其它擠壓成型產(chǎn)品非電子焊料 消耗量(%)0.720.70 產(chǎn)品電子焊料其它 消耗量(%)0.492.77 在電子產(chǎn)品中禁止使用鉛并不能解決全部的鉛中毒問題。,0,10,20,30,40,50,60,70,80,90,Total e

3、xemption: 93.5%,Electronic solder 0.5%,Ammunition,Other Oxide,Storage Batteries,Sheet Lead,Cable covering,Casting Metals,Brass, Bronze, Billets Senju Metals, Harima Chemicals, Alpha Metals Japan, Nihon Handa, Ishikawa, Metals, Uchibashi Estec, Speria Japan Solder Coat, Univ.of Tokyo, Osaka Univ, ICS

4、, SC Lab, Tokyo Electric Univ. Tabai Espec, Mitsui Mining,Nippon Mining & Metals, Nippaku, Ishihara Chemicals, Tanaka Electronics Ind. Furukawa Electric Ind., TDK, Murata, Rubicom, Sony, Fujitsu, NEC, Hitachi, Toshiba, Panasonic, Fuji Electric and Ornron.,Modelling of Solder Joint Reliability for El

5、ectronic Interconnects, Cambridge University - ESPRC Funded,IDEALS -Brite Euram Funded,NPL Research in lead-free solders,2.5 基本共識,(1) 無鉛焊料的基體為Sn(一般不少于90wt.%)，即新型無鉛焊料應為Sn基合金； (2) 目前為止，還沒有一種無鉛焊料可以“即時取代”(drop-in)傳統(tǒng)的Sn-Pb共晶焊料合金 根據(jù)：1997年美國國家制造科學中心(NCMS, National Center for Manufacturing Sciences)的結論；1994

6、年，作為歐洲IDEALS(Improved Design Life and Environmentally Aware Manufac-turing of Electronic Assemblies by Lead-free Soldering)計劃的一部分，研究了超過200種合金，只有不到10種合金是可行的； (3) Sn基無鉛焊料中，其它可能元素包括Ag, Cu, Sb, In, Bi, Zn等。,2. 無鉛焊料的研究狀況,2. 無鉛焊料的研究狀況,2.6 替代元素/焊料的基本要求(1),無鉛焊料不是新技術。但今天的無鉛焊料研究是要尋求年使用量為 超過6萬噸的Sn-Pb焊料的替代產(chǎn)品。 (

7、1) 其全球儲量足夠滿足市場需求。某些元素，如銦和鉍，儲量較小，因此只能作為無鉛焊料的添加成分； (2) 無毒性。某些在考慮范圍內的替代元素，如鎘、碲，是有毒的。而某些元素，如銻，如果改變毒性標準的話，也可以認為是有毒的； (3) 能被加工成需要的所有形式，包括用于修補的wire；用于焊料膏的powder；用于波峰焊的bar等。不是所有的合金能夠被加工成所有形式，如鉍的含量增加將導致合金變脆而不能拉拔成絲狀； (4) 替代合金也可以再循環(huán)利用。如果無鉛焊料中包含3到4種金屬元素將使再循環(huán)工藝復雜化并增加成本。,2.6 替代元素/焊料的基本要求(2),(5) 相變溫度(固/液相線溫度)與Sn-P

8、b焊料相近； (6) 合適的物理性能，特別是電導率、熱導率、熱膨脹系數(shù)； (7) 與現(xiàn)有元件基板/引線及PCB材料在金屬學性能上兼容； (8) 足夠的力學性能：剪切強度、蠕變抗力、等溫疲勞抗力、熱機疲勞抗力、金屬學組織的穩(wěn)定性； (9) 良好的潤濕性； (10) 可接受的成本價格。,2. 無鉛焊料的研究狀況,2.7 替代元素的價格,鉛的市場價格約為0.4美元/磅（2000）,2.8 替代元素的供需情況（1998）,單位：萬噸,2.9 合金成本情況（2000）,2. 無鉛焊料的研究狀況,2.10 關于熔點(固相線/液相線),替代元素應該使新型合金的熔點低于Sn的熔點(232oC) 。,2. 無鉛

9、焊料的研究狀況,2.11 關于金屬學組織,合金的性能，特別是力學性能取決于其金屬學組織。 Se(硒)和Te(碲)將導致Sn基合金脆化。 Sb(銻)的含量不適當將惡化Sn基合金的潤濕性能。 In(銦)原子在Sn晶格中的分布顯著影響其疲勞性能。 如果存在Bi(鉍)的第二相沉淀將顯著脆化Sn基合金。 Sn與Cu、Ag、Sb等之間金屬間化合物的形成將顯著影響其強度和疲勞壽命。 可以斷定，新型無鉛焊料中各組分含量必須是特定的，或者只能在一個很窄的范圍內變動。,2. 無鉛焊料的研究狀況,2.13 無鉛焊料的定義,RoHS 0.1wt%Pb JEIDA 0.1wt%Pb EUELVD 0.1wt%Pb,EU

10、ELVD - EU End of Life Vehicles Directive JEIDA - Japanese Electronic Industry Development Association JEDEC - Joint Electronic Device Engineering Council,Note: Solders with 85wt%Pb are exempted!,At present, there is no common world （or GB） standardfor the stipulation of the lead content as impuritie

11、s to lead-free solders (i.e., maximum concentration values). However,3 實用化的無鉛焊料,3.1無鉛焊料簡介與分類,目前已經(jīng)有超過100（？）個無鉛焊料的專利，由于性能與價格方面的原因，只有其中一小部分可以實用化。,實用化焊料通常按熔點范圍作如下分類：,1.Low melting temperature (below 180OC), 2.Melting temperature equivalent to the tin-lead eutectic (180-200OC), 3.Mid-range melting temper

12、ature (200-230OC), 4. High temperature alloys (230-350OC).,3.2 低溫無鉛焊料Low Temperature Alloys,Table1 Examples of lead-free solder alloys melting below 180OC,3.3 Sn-Pb Equivalents無鉛焊料,Table2 : Example of lead-free solder alloys melting 180-200OC,3.4 Mid-range Melting Temperature Alloys,Table 3: Example

13、s of lead-free solder alloys melting 200-230OC,3.5 可能替代錫鉛焊料的合金熔點系列,3.6 高溫無鉛焊料,Table 4: Examples of lead-free solder alloys melting above 230 oC,Dieattach （Sn10Pb90），F(xiàn)or this particular high power, high temperature application it is not yet possible to propose a suitable lead-free alternative.（RoHS ,

14、exempt for Pb85）,3.7 Lead-free alloys: A comparison,Diagram Illustrating Fillet Lifting,3.7.1 無鉛工藝（含Bi或鉛污染）易產(chǎn)生的問題,3.7.2典型無鉛焊料的物理性能比較,3.8 Suppliers And Patents,非專利產(chǎn)品：Sn-Cu與Sn-Ag共晶合金，Sn-4Ag-0.5Cu,3.8.1 Overview of SnAgCu Patent Coverage,US Patent no. 5,527,628 (Iowa State & Ames) 3.5-7.7Ag1-4Cu0-10Bi0

15、-1Zn JP Patent no. 5,050,286 (Senju) 3-5Ag0.5-3Cu0-5Bi0-5Sb,3.9 Solders Used by Area of Industry Served,3.10 部分機構推薦使用的無鉛焊料,Specific Alloy Compositions Reviewed and/or Recommended by Other Organizations,3.11 典型的無鉛焊料商品舉例,3.12 美國NEMI推薦選用的無鉛焊料,NEMI (Nat. Elec. Manuf. Initiative) 95.5Sn-3.9Ag-0.6Cu for r

16、eflow soldering (217oC) 99.3Sn-0.7Cu for wave soldering (227oC) (Note, dont use this solder, otherwise youll have 2 different kinds of solders on your PCBA),3.13 歐洲BRITE-EURAM & IDEALS推薦的無鉛焊料,The European Consortium - BRITE-EURAM (IDEALS) 95.5Sn-3.8Ag-0.7Cu - an all purpose alloy. Other alloys with

17、potential are 99.3Sn-0.7Cu, 96.5Sn-3.5Ag and SnAgBi UK, Department of Trade and Industry (DTI) 1)High professional group (automotive, military) - SnAgCu(Sb) 2)Medium professional group (industrial, telecommunications) -SnAgCu, SnAg 3)General consumer & low professional group (TV, audio-video, office

18、 equipment) - SnAgCu(Sb), SnAg, SnCu, SnAgBi,3.14 日本JIEDA &JIETA推薦的無鉛焊料,3.14 IPC 組織對所推薦焊料的研究評估,IPC Solder Products Value Council (SPVC) Aim *Kester Northrup Grumman Alpha Metals & Fry *Koki Company, Ltd. Advanced Metals *Nihon Superior Amtech, Inc. *P. Kay Metals EFD, Inc. *Qualitek Henkel Loctite *

19、Thai Solder Heraeus *Senju Metal Industry Indium *Cookson Electronics,（一階段）,IPC SPVC (First Phase) for Process Parameters The solders being investigated are: (1) Sn-3wt%Ag-.5wt%Cu (2) Sn-3.8wt%Ag-.7wt%Cu (3) Sn-4wt%Ag-.5wt%Cu Tested by multiple vendor (1) DSC (Differential Scanning Calorimetry) for

20、melting point (2) IPC-TM-650, 2.4.14.2, for wetting balance (3) IPC-TM-650, 2.4.46 for solder spreading,The IPC SPVC will standardize on a single solder, to reduce costs and benefit the supply chain.,Tw = Time to cross the zero,Fmax = Max wetting force,3.14.1 評價不同組成SAC焊料的潤濕性方法,Wetting Balance Curve,

21、潤濕性評估 結果,3.14.2 三種不同組成SAC之間的評價結果,*Results: No significant difference among these solders！,Board Processing Solder Paste SnAg4%Cu0.5% Board Surface Finish ImAg OSP (within limitations) Rework SnAg3.5-4%Cu0.5%,Intel preferred* Pb-free materials,3.15 合金選擇公司案例,4 實施無鉛工藝的相關問題,Sn-Pb共晶焊料只需要30-50秒的再流時間來保證充分鋪

22、展。,無鉛焊料需要50-70秒的再流時間來保證充分鋪展。,4.0 無鉛工藝的特點01-高熱容,Pb-free Reflow Profile (Example),4.0 無鉛工藝特點02工藝窗口明顯縮小,工藝窗口的大幅縮??！,如采用SnAgCu焊料(熔點為217oC)，再加上5oC的控制限制，實際的工藝窗口只有8oC。如此之窄，對于電子組裝絕對是一個挑戰(zhàn)。同時，工藝過程的溫度實時監(jiān)控更為重要。,應對策略：增加窗口上限? 提高焊接的最高溫度?,元器件的安全溫度235245,SAC熔點217,SnPb熔點183,4.0 無鉛工藝特點03無鉛焊料潤濕性下降,SnCu(260): 1.82.3s SnP

23、b(235): 0.8s同樣條件下：助焊劑、(溫度)被焊面,tw,焊接設備的改進01氮氣保護,增加溫度區(qū)數(shù)目，同時減小每個溫度區(qū)的尺寸，以便在高溫時更好控制。如上圖中oven總長度為150英寸，而傳統(tǒng)oven總長度為183英寸。,4.1 無鉛制造設備,針對無鉛焊料/焊料膏，再流焊設備的改進,溫度超過150oC時，PCB會發(fā)生玻璃態(tài)相變，引起其中間部分下塌。再流焊溫度越高，下塌越顯著，回復平整的可能性越小。特別是對于雙面PCB，這一問題更為重要。,傳統(tǒng)的支撐條貫穿整個加熱區(qū)，會阻礙空氣向PCB流動，增加PCB上的溫差。同時由于設置支撐結構會降低PCB的整體溫度水平，因此有/無支撐結構需要不同的再

24、流溫度規(guī)范。 改進：只在再流區(qū)和冷卻區(qū)設置支撐結構，而去除預熱區(qū)的支撐結構(因為其溫度小于150oC)。,焊接設備的改進02印刷電路板中間的支撐問題,4.1 無鉛制造設備,再流焊設備的改進03環(huán)保的考慮,閉環(huán)焊劑分離/收集系統(tǒng)可去除再流焊設備內部95%的焊劑殘渣，同時保證氮氣的再循環(huán)利用。,4.1 無鉛制造設備,以下設備分別在介紹工藝流程時介紹： 波峰焊設備的改進 手工焊設備的改進 返修設備的改進,4.1 無鉛制造設備,4.2 無鉛元器件,無鉛元器件的定義與標識 無鉛元器件面臨的挑戰(zhàn) 無鉛元器件的工藝適用性要求,4.2.1 無鉛元器件的定義,RoHS 0.1wt%Pb JEIDA 0.1wt%

25、Pb EUELVD 0.1wt%Pb,Note: Solders with 85wt%Pb are exempted!,物理性能滿足無鉛工藝的要求； 材料組成符合如下要求：,4.2.2 無鉛元器件的標識（1）,IPC1066,4.2.2 無鉛元器件的標識（2）,Note: Items that contain Pb shall not use this label even if exempted by RoHS.,Pb-Free label be a minimum of 75 mm by 50 mm.,e1,e2,e3,e4,e5,e6,e7,4.2.2.1 無鉛可焊性涂層材料分類標識,I

26、dentification of Interconnect Material Differences 2nd Level Connection for packages and boards,4.2.3 無鉛PCB與PCBA的標識,BOARD/ASSEMBLY MARKING,4.2.4 無鉛元器件面臨的挑戰(zhàn),熱損傷,Cross-section of 144LQFP package after level2a/260C indicating crack in mold compound.,元器件熱損傷失效的例子1,Cross-section of the 2-layer PBGA packag

27、e afterlevel 2a/260C stressing indicating delamination within thedie attach layer and internal substrate layers,元器件熱損傷失效的例子2,4.2.5無鉛元器件工藝適應性要求,Solderability可焊性 Resistance to Solder Heat 耐焊接熱（Reflow，flow ，Hand soldering） Resistance to Dissolution of Metallization金屬化涂層（或端子）耐熔解(260-30s) Whisker Risk 錫須

28、風險 MSL塑料封裝器件潮濕回流敏感度評價 可焊性涂層與焊料的兼容性,4.2.5.1 無鉛元器件可焊性要求,由有鉛工藝向無鉛工藝轉換過程中各要素的變化,有鉛,良好焊點形成要素100,無鉛,無鉛,無鉛,無鉛,端子可焊性S,焊接溫度T,助焊劑活性A,焊料潤濕性w,4.2.5.1.1 無鉛元器件可焊性測試評價01,Wetting Balance 潤濕天平法 測試方法與依據(jù)：ANSI/J-STD-002B, IEC 60068-2-58,MIL-STD-202G,4.2.5.1 無鉛元器件可焊性測試評價02,Dip and Look,4.2.5.2 Resistance to Soldering He

29、at 耐焊接熱,Reflow，flow ，Hand soldering,Hand soldering,wave soldering,Reflow235(30S)，F(xiàn)low 260(10S) ，Hand soldering 350(5S),Soldering Heat 造成的元件損傷,4.2.5.3 Resistance to Dissolution of Metallization,金屬化涂層（或端子）耐熔解(260-30s)-SMD,Moisture/Reflow Senstive問題由來,4.2.5.4 MSL？ 塑封器件的回流敏感度,Wire-Bonded Plastic Ball Gr

30、id Array (PBGA) Package,Plastic Quad Flat Pack (PQFP) Package,Molding Compound,塑封器件的典型封裝形式介紹,4.2.5.4塑料封裝器件潮濕回流敏感度評價（1）,4.2.5.4塑料封裝器件潮濕回流敏感度等級評價（2）,回流工藝條件Reflow profile,4.2.5.4塑料封裝器件潮濕回流敏感度評價（3）,4.2.5.4塑料封裝器件潮濕回流敏感度等級評價（4）,4.2.5.5 錫須風險,Leading Component Finishes主要的無鉛可焊性涂層 PTH Leaded Components: (e.g.

31、, PGA) Sn (either plate or dip) SMT Leaded Components: (e.g., PQFP) Matte-Sn (for short life cycle applications) Matte-Sn with Ni barrier underlayer* Solder Balled Components: (e.g., PBGA) Sn4wt%AgCu Discrete Components: (e.g., chip resistor) Matte-Sn,錫須的由來,4.2.5.5.1 純錫鍍層的主要問題,純錫單晶，最長可達10mm 典型大?。?3微

32、米300微米 錫須的主要形狀：Filament/Nodule/Column/Hillock 危險：可導致將來短路的可靠性問題,錫須的產(chǎn)生與錫須特征,4.2.5.5.2 Various Kinds of Tin Whiskers,For Fine Pitch Leaded Components Tin Whiskers May Short Circuits!,4.2.5.5.2 錫須的結構,4.2.5.5.3Tin Whisker Mechanisms,(1) The diffusion of Cu into Sn and the formation of Cu6Sn5 can generate

33、 compressive stress in the Sn layer. (2) The thermal loads. (3) The mechanical loads. (4) The shock and vibration loads. (5) The self-diffusion of Sn along Sn grain boundaries to the root of a whisker will supply more Sn atoms to push the Sn whisker upward (dislocation loop climbing effect on the gr

34、ain boundaries). (6) SnOx layer with weak spots,4.2.5.5.4 錫須生長過程,Nodule Pictures Taken Periodically (x1700),4.2.5.5.5如何降低錫須造成的可靠性風險？,鍍大結晶顆粒的matte-錫以減低錫須生長速率 鍍厚錫，最好10um,最少8um 回流或再熔化一次錫鍍層，以釋放鍍層中的壓縮應力 使用鎳阻擋層，阻止銅擴散入錫層形成錫銅IMC 使用合金鍍層（如SnCu/Bi） 采用退火工藝（1503h） 錫表面形成較厚的SnO，但不能太厚以免潤濕不良,For High-End (Long Life

35、Cycle) Lead-Free SMT Leaded Components,The stress in the Sn-layer due to the formation of the Ni3Sn4 IMC (inter-Metallic Compound) is in tension,1m,10m,JEDEC STANDARD JESD22A121 Measuring Whisker Growth on Tin and Tin Alloy Surface Finishes,4.2.5.5.6 錫須評價使用方法(1),Sony Technical Standard SS-00245-8(10

36、) Tin Whisker evaluation 1)High Temperature/Humidity Test: 85oC , 85% RH for 500 hrs 2)Thermal Cycling Test: -35oC for 30min to 125oC for 30min 500 cycles Notes: No Bias Voltage and heat treatment Evaluation criteria:Whisker formation 50 um or less,4.2.5.5.6 錫須評價使用方法(2),4.2.5.5.6 錫須評價使用方法(3),Intel:

37、Whisker growth not to exceed 50 microns (2 mils) at any time during following tests Temperature Cycling (-55 to 85C): -55 +0, -10C to 85 +10, -0C air to air temperature cycle per JEDEC Temperature Cycling Standard No. 22-A104, Test condition A, soak mode 3(10 minutes), typically 3 cycles/hour Readou

38、ts every 500 cycles (1000 cycles minimum) Temperature/Humidity Storage (60C/93%RH): 60 + 5 C, 93 +2, -3 % RH Readouts at 3 weeks, 6 weeks, 13 weeks, 6 months, 1 year and annually there after (6 weeks minimum) Ambient storage (23C): Readouts at 3 weeks, 6 weeks, 13 weeks, 6 months, 1 year and annuall

39、y there after (6 weeks minimum) 20 - 25 C, 30-80% RH,Equipment Needed: An air to air temperature cycling equipment capable of cycling from 55(+0,-10)C to +85(+10 0) C A temperature humidity chamber capable of 60+5C, 93 + 2, -3 %RH Capability to store in ambient conditions (20 -25C, 30-80% RH) Scanni

40、ng Electron Microscope (SEM) Whisker Inspection: 3 leads per device,Sample Size:,Sample Size, Equipment Needed,SEM檢查錫須時注意與枝晶的區(qū)別（1）,SEM檢查錫須時注意與枝晶的區(qū)別（2）,4.2.5.6 材料及其兼容性問題,Another important technological issue is the compatibility of fluxes, board finishes and component finishes with lead-free solders.

41、,(i) Components finishes,(ii) Board finishes,(iii) Fluxes,The SnAgCu alloy is not compatible with Ag/Pd which exhibits very poor solderability.,SnCu is compatible with OSP and Sn/Pb HASL finishes. SnAgCu alloy is compatible with Sn, Ag, Au and (OSP) finishes.,Warpage Delamination(T288,IPC-TM-650 2.2

42、.4.1) CAF Via Integrity (Barrel /Foil Crack/ Interconnect separation) PCBFR4？ 材料參數(shù)：Tg/Td(ASTM D3850)/ CTE/ IST(1cycle/5min)/SIR?,4.3 無鉛PCB,4.3.1 PCB Materials stability/reliability.,PCB熱應力失效案例,4.3.2 無鉛PCB 焊盤Pad的主要可焊性涂層,OSP Benzotriazole Imidazole Benzimidazole (substituted) Preflux (rosin/resin) Ni/

43、Au Electrolytic Ni/Au, or EG Electroless Ni/Electroless (immersion) Au, or ENIG Electroless Ni/Electroless (autocatalytic) Au Electroless Ni/Electroless (substrate-catalyzed) Au Ag Electroless (immersion, or galvanic) Ag,Bi Electroless (immersion) Bi Pd Electrolytic Pd or Pd-alloys Electroless (auto

44、catalytic) Pd Electroless (autocatalytic) Pd/Electroless (immersion) Au Ni/Pd Electroless Ni/Electroless (immersion) Pd Electroless Ni/Electroless (autocatalytic) Pd Electroless Ni/Electroless (autocatalytic) Pd/Electroless (immersion) Au,現(xiàn)有的Finishes1,現(xiàn)有PCB PadFinishes2,Ni/Pd(X) Electrolytic Ni/PdCo

45、/Au flash (Electroless) Ni/(Electroless) PdNi/Electroless (immersion) Au Sn Electrolytic Sn Electroless (immersion) Sn Electroless (Modified immersion + autocatalytic) Sn,Ni/Sn Electrolytic Ni/Electrolytic Sn SnAg Electrolytic SnAg SnBi Electrolytic SnBi Electroless (immersion) SnBi SnCu Electrolyti

46、c SnCu SnNi Electrolytic SnNi,4.3.2 .1 無鉛PCB主流的PadFinishes,Leading PCB Cu-Pad Finishes OSP (Organic Solder Preservative), Entek ENIG (Electroless Nickel-Immersion Au) ImAg (Immersion Silver) HASL (Hot-Air Solder Leveling), SnCu/SAC Sn（Plated/Immersion）,4.3.3 無鉛焊盤finishes的典型問題,Black Pads in ENIG,4.3.

47、3.1無鉛焊盤典型問題Black Pads 產(chǎn)生機理,4.4 其它無鉛工藝材料,無鉛助焊劑（Flux Requalification） 活性增強 、高溫穩(wěn)定性改善 （更加注意：殘留物增加、SIR 、離子殘留、電遷移） 無鉛焊錫絲 焊錫芯助焊劑增加，典型：2 3 無鉛焊錫膏 潤濕性提升、存儲穩(wěn)定性改善,4.4.1 無鉛助焊劑,需要關注的關鍵性能與可靠性指標： 助焊性（擴展率，最好90） 腐蝕性（銅鏡腐蝕、銅板腐蝕） 表面絕緣電阻（SIR，1012歐姆） 鹵素含量（Cl） 殘留物 固體含量 參考標準：ANSI/J-STD-004,GB9491,JIS Z3197,PCBA腐蝕的案例,應該關注的性能

48、與可靠性指標： 本身項目（粘度、坍塌性能、潤濕性、錫珠試驗、金屬含量、工藝性可印刷性、干燥時間） 助焊劑部分（SIR、腐蝕性、鹵素） 合金部分（化學成分、粒度形狀以及分布） 參考的技術標準：ANSI/J-STD-005,4.4.2 無鉛焊錫膏,焊錫膏的坍塌性能測試,應該關注的關鍵性能與可靠性指標： 合金部分（合金比例/雜質） 助焊劑（SIR、腐蝕性、鹵素、殘留物） 本身項目（助焊劑含量、線徑、連續(xù)性、噴濺量） 參考的標準：ANSI/J-STD004/006,JIS Z3283,4.4.3 無鉛焊錫絲,焊錫絲噴濺試驗,噴濺量,焊錫絲,電烙鐵,注意：無鉛焊錫絲 助焊劑含量增大； 腐蝕性增加； 噴濺

49、量增加！,4.5 Logistical 生產(chǎn)實施的后勤物流問題,The lack of a single drop-in replacement has several implications as far as the logistics of actually implementing lead-free soldering are concerned. It should be noted that the overall trend of the electronics industry is towards contract manufacture rather than in h

50、ouse assembly. The consequence of this is that the contract manufacturers will have to address most of these logistical issues.,A particular concern is that, in the event of large customers specifying more than one alloy for their assemblies the contract manufacturer may be faced with having to have

51、 different assembly lines for each alloy.,4.6 Transition 生產(chǎn)實施中的過度問題,案例分析。,4.7 Inspection 檢驗檢查,IPC-A-610C IPCA610D ！,An important part of the electronics assembly process is the visual inspection of boards to pick up possible or potential defects and faults.,無鉛焊點與有鉛焊點之間有非常大的差異，因此組件可接受外觀標準需要及時修訂，但要基于新

52、的標準（IPC-A-610D/J-STD-001D）以及時間的可靠性測試數(shù)據(jù),4.8 Reliability 可靠性問題,If it does exist, is not freely available for lead-free solders and indeed even with accelerated testing will still take many years to establish. While this may not be so critical for consumer electronics such as mobile telephones, with pr

53、oduct lifetimes as low as 6 months, for other products which require service lifetimes from a few years to decades or more, this lack of knowledge is of real concern.,A great deal of accelerated testing needs to be carried out before any conclusions can be drawn about the long term reliability of th

54、e SnCu alloy under a variety of conditions. Of prime concern is the lack of data on high lead out devices such as BGAs and flip-chips.,4.9 Rework and Repair 返修與修理,where issues with higher soldering temperatures have been thought to be of concern. These concerns are most likely to be manifest for rew

55、ork of complex components such as BGAs which require a high level of background heat to remove and reflow effectively.,返修焊料的兼容性問題，被維修點的材料確認問題。,4.10 Recycling - Solder Recovery再利用,Current solder recycling processes,無鉛焊料的循環(huán)利用由于組成難度變化很大 SnAgCu(B)-SnCu(S),Government regulations in many countries are bec

56、oming more stringent with regards to landfill and therefore companies are forced to find alternative methods for the disposal of their high-tech scrap, particularly following recycling.(WEEE),4.11 Costs 實施成本,Raw materials(Ag,In、Bar&Paste、PCB),主要構成因素,Requalification,Equipments,Energy Consumption,Retr

57、aining,Recycling,4.11.1Impact of Lead-free Solder to Product Cost,4.11.2 Energy Consumption,5 典型無鉛工藝,無鉛制程工藝準備： 無鉛元器件選用與評估 PCB選用與評估 材料（助焊劑、焊料、錫膏）等評價 設備評估 工藝優(yōu)化,5.1 典型的Lead-free solder wave Process,兩個波之間的距離要短一些，防止由于PCB降溫造成焊錫爐的沖擊，焊接時間一般控制35s；,t,雙波峰焊實時溫度曲線一例,5.1.0 典型的無鉛波峰焊過程參數(shù)(1),波峰焊錫爐溫度的選擇,5.1.0 典型的無鉛波峰

58、焊過程參數(shù)(2),5.1.1 無鉛波峰焊過程影響因素分析（1）,注意無鉛波峰焊的焊料對錫爐與焊件的影響： 使用的無鉛焊料(Sn-Cu, Sn-Cu-Ni,Sn/Ag/Cu)的錫含量均超過90%，這些高錫焊料在高溫下對鐵(Fe)有很強的溶解能力, 因此錫爐容易受到溶蝕，如果含有銀則會加速腐蝕錫爐。因此需對原有錫爐進行修改，采用鈦合金鋼錫爐、或在爐內壁鍍防護層。 對不銹鋼腐蝕率： Sn3Ag0.5Cu Sn0.7Cu Sn0.7Cu0.05Ni 對Cu 腐蝕率： Sn3Ag.5Cu Sn37Pb Sn 0.7Cu0.5 Ni,錫爐與葉輪腐蝕的典型照片,對大尺寸的PCB可能需增加中間支撐，預防高溫引

59、起 PCB變形； 為了減少焊環(huán)提升現(xiàn)象使焊點光亮和增加強度，需增加冷卻裝置以改善冷卻效率，使焊點快速降溫，但如果冷風進入錫爐表面，則會影響焊接溫度； 由于潤濕性差，除了需要改良助焊劑性能，還需要適當增加涂覆量。 由于助焊劑涂覆量多，同時由于水基助焊劑需要充分地將水分揮發(fā)掉，需要改善預熱效果，設備的預熱區(qū)的加熱效率需要進一步提高。 充N2可以減少焊渣的形成，但為了節(jié)約，大多情況下可以不充氮氣（N2）也可滿足要求，但一定要比有鉛焊接更注意每天的清理和日常維護。,5.1.1 無鉛波峰焊過程相關因素分析（2）,改善PTH填充效果的方法,1 2 3 。 9,插裝孔內上錫可能達不到75%，。改進等等可以改善填充量。,某些情況下（Fine Pitch/SnCu）,N2可能必須,