本书是作者从事电子制造40年来有关单板互连可靠性方面的经验总结,讨论了单板常见的失效模式、典型失效场景以及如何设计与制造高可靠性产品的广泛问题，并通过大量篇幅重点讨论了焊点的断裂失效现象及裂纹特征。 全书内容共4个部分，第一部分为焊点失效机理与裂纹特征，详细介绍焊点的失效模式、失效机理、裂纹特征及失效分析方法;第二部分为高可靠性产品的焊点设计，包括封装选型、PCBA的互连结构设计、组装热设计及焊点的寿命评估技术;第三部分为环境腐蚀与三防处理，重点介绍腐蚀失效与锡须问题，以及与之相关的清洗和三防工艺;第四部分为高可靠性产品的制造，重点介绍组装工艺控制要点与典型缺陷焊点。 本书可供从手电子制造、可靠性、失效分析工作的工程师学习与参考。

贾忠中中兴通讯股份有限公司首席工艺专家，从事电子制造工艺研究与管理工作近40年。在中兴通讯工作期间，见证并参与了中兴工艺的发展历程。历任工艺研究部部长、副总工艺师、总工艺师、首席工艺专家。担任广东电子学会SMT专委会副主任委员、中国电子学会委员。对SMT、可制造性设计、失效分析、焊接可靠性等有着深入、系统的研究,擅长组装不良分析、焊点失效分析。出版作品有:《SMT工艺质量控制》《SMT可制造性设计》《SMT工艺不良与组装可靠性》《SMT核心工艺解析与案例分析》等，发表论文多篇，被粉丝誉为“实战专家”。

第一部分 焊点失效机理与裂纹特征
第 1 章 焊点的可靠性 ............................................................................................ 3
1.1 焊点 ...........................................................................................................................................3
1.1.1 焊点的微观组织结构及常见失效位置 ........................................................................4
1.1.2 焊点的失效标准 ............................................................................................................4
1.1.3 焊点的断裂类型 ............................................................................................................5
1.2 导致焊点失效的载荷条件 .......................................................................................................7
1.3 焊点失效机理 ...........................................................................................................................7
1.3.1 温度循环引发的焊点失效机理 ....................................................................................7
1.3.2 机械应力引发的焊点失效机理 ..................................................................................10
1.3.3 热冲击引发的焊点失效机理 ......................................................................................12
1.3.4 蠕变引发的焊点失效机理 ..........................................................................................13
1.4 焊点的可靠性评价 .................................................................................................................14
1.4.1 焊点的可靠性取决于 PCBA 的互连结构设计 ..........................................................14
1.4.2 焊点的可靠性工作 ......................................................................................................14
1.4.3 焊点失效原因分析流程 ..............................................................................................15
案例 1：某单板上的 BGA 使用两年后失效 .............................................................15
第 2 章 温度循环导致的焊点失效........................................................................... 17
2.1 疲劳失效的典型场景 .............................................................................................................17
2.1.1 整体热膨胀失配 ..........................................................................................................17
2.1.2 局部热膨胀失配 ..........................................................................................................18
2.1.3 内部热膨胀失配 ..........................................................................................................18
2.2 疲劳失效的裂纹演进过程与特征 .........................................................................................18
2.2.1 片式元件焊点疲劳失效典型裂纹特征 ......................................................................19
2.2.2 翼形引脚焊点疲劳失效典型裂纹特征 ......................................................................19
2.2.3 BGA 焊点疲劳失效典型裂纹特征 .............................................................................20
SMT 单板互连可靠性与典型失效场景
2.2.4 QFN 焊点疲劳失效典型裂纹特征 .............................................................................21
2.2.5 CBGA 焊点疲劳失效典型裂纹特征 ..........................................................................22
2.2.6 CCGA 焊点疲劳失效典型裂纹特征 ..........................................................................23
2.2.7 通孔插装焊点疲劳失效典型裂纹特征 ......................................................................24
2.2.8 焊接工艺对裂纹特征的影响 ......................................................................................24
2.3 小结 .........................................................................................................................................25
第 3 章 机械应力导致的焊点失效........................................................................... 27
3.1 机械应力失效的典型场景 .....................................................................................................27
3.1.1 冲击 ..............................................................................................................................27
案例 2：BGA 脱落 ......................................................................................................27
3.1.2 瞬时弯曲 ......................................................................................................................29
案例 3：插件操作导致 BGA 焊点开裂 .....................................................................29
3.1.3 循环弯曲 ......................................................................................................................31
3.1.4 振动 ..............................................................................................................................31
3.2 机械应力失效的裂纹特征 .....................................................................................................31
3.3 脆性的界面 IMC ....................................................................................................................33
3.3.1 ENIG 镀层形成的焊点具有脆性 ................................................................................34
案例 4：Ni 氧化导致焊点界面脆化 ...........................................................................37
3.3.2 不连续的块状 IMC ......................................................................................................40
3.4 典型应力敏感元件及应力失效 .............................................................................................41
3.4.1 应力敏感封装 ..............................................................................................................41
3.4.2 片式电容 .....................................................................................................................41
3.4.3 球栅阵列封装 ..............................................................................................................46
案例 5：ICT 测试导致 BGA 焊点开裂 ......................................................................46
案例 6：压接导致 BGA 焊点开裂 .............................................................................48
第 4 章 焊点失效分析方法.................................................................................... 51
4.1 失效分析及方法 .....................................................................................................................51
4.1.1 失效分析 ......................................................................................................................51
4.1.2 失效分析思路 ..............................................................................................................51
4.1.3 失效分析基本流程与方法 ..........................................................................................51
4.1.4 焊点失效分析的常用方法 ..........................................................................................52
4.2 X 射线检测 .............................................................................................................................53
4.2.1 X 射线图像的采集原理...............................................................................................54
4.2.2 X 射线图像的分析.......................................................................................................56
4.3 超声扫描显微镜 .....................................................................................................................58
4.3.1 超声扫描显微镜概述 ..................................................................................................58
4.3.2 超声扫描显微镜的工作原理 ......................................................................................58
4.3.3 分析步骤 ......................................................................................................................60
4.3.4 超声扫描显微镜和 X 射线的对比..............................................................................61
4.4 切片 .........................................................................................................................................62
4.4.1 切片样品的制备 ..........................................................................................................62
4.4.2 切片分析应用 ..............................................................................................................64
4.5 扫描电子显微镜 .....................................................................................................................65
4.5.1 扫描电子显微镜概述 ..................................................................................................65
4.5.2 扫描电子显微镜的工作原理 ......................................................................................66
4.5.3 SEM 的优点 .................................................................................................................66
4.5.4 样品的制备 ..................................................................................................................66
4.5.5 应用 ..............................................................................................................................67
4.6 染色渗透 .................................................................................................................................69
4.7 光学检测 .................................................................................................................................70
4.8 傅里叶变换红外光谱仪 .........................................................................................................71
案例 7：PCBA 白色污染物成分的分析 ....................................................................71
案例 8：材料一致性检验 ............................................................................................72
第 5 章 失效原因的基本判定................................................................................. 73
5.1 焊接问题与组装问题的判定 .................................................................................................73
5.1.1 焊接合格的标准 ..........................................................................................................73
5.1.2 组装应力引诱或导致的焊点失效 ..............................................................................75
5.2 焊点开裂裂纹特征图谱 .........................................................................................................77
5.2.1 典型热 / 机疲劳断裂焊点切片图 ...............................................................................77
5.2.2 典型机械应力导致的焊点断裂切片图 ......................................................................79
5.2.3 熔断焊点切片图 ..........................................................................................................80
5.2.4 枕头效应焊点内窥镜图与切片图 ..............................................................................82
5.2.5 无润湿开焊（NWO）焊点内窥镜图与切片图 .........................................................83
5.2.6 冷焊点切片图 ..............................................................................................................83
5.2.7 Au 镀层引起的焊点开裂 .............................................................................................84
5.2.8 小结 ..............................................................................................................................85
第二部分 高可靠性产品的焊点设计
第 6 章 高可靠性 PCBA 的互连结构设计 ...............................................................89
6.1 设计步骤 .................................................................................................................................89
6.2 影响焊点可靠性的设计因素 .................................................................................................91
6.2.1 主要设计参数 ..............................................................................................................92
6.2.2 次要设计参数 ..............................................................................................................93
6.3 提升热膨胀匹配性的设计 ..................................................................................................... 94
6.3.1 PCB 的类型 .................................................................................................................. 94
6.3.2 有机 PCB ...................................................................................................................... 95
6.3.3 约束芯 PCB .................................................................................................................. 97
6.3.4 陶瓷 PCB ...................................................................................................................... 99
6.3.5 柔顺性 PCB .................................................................................................................. 99
6.4 可靠性加固 ........................................................................................................................... 100
6.4.1 表面组装元器件的可靠性加固 ................................................................................100
6.4.2 插件的点胶加固 ........................................................................................................106
6.4.3 关于可靠性加固的应用 ............................................................................................108
6.5 增强抗振动 / 冲击能力的设计——应力槽 ........................................................................ 109
6.6 禁限设计 ............................................................................................................................... 110
第 7 章 高可靠制造的组装热设计.......................................................................... 117
7.1 热风再流焊接热特性 ........................................................................................................... 117
7.2 热设计对焊接的影响及典型设计场景 ............................................................................... 117
7.2.1 与焊盘紧连接过孔的影响 ........................................................................................ 117
7.2.2 盘中孔 /POFV 孔的影响 ........................................................................................... 118
7.2.3 表层大铜皮的影响 .................................................................................................... 119
案例 9：BGA 四角焊点连接有长的导线，在特定工艺条件下会发生
缩锡断裂 ...................................................................................................... 119
案例 10：QFN 与大铜皮紧连的焊点容易发生虚焊 ............................................... 120
案例 11：热沉焊盘热设计不当导致 QFN 倾斜和虚焊 .......................................... 120
7.2.4 屏蔽盖的影响 ............................................................................................................122
7.2.5 高大封装的密集布局 ................................................................................................122
7.3 热设计总结 ........................................................................................................................... 123
第 8 章 高可靠 PCBA 的封装选型........................................................................124
8.1 封装对焊点可靠性的影响 ................................................................................................... 124
8.2 封装特性 ............................................................................................................................... 124
8.2.1 封装可靠性 ................................................................................................................124
8.2.2 封装的固有疲劳寿命 ................................................................................................125
8.2.3 封装的热变形 ............................................................................................................126
8.3 封装的选型 ........................................................................................................................... 129
8.3.1 封装类别的选择 ........................................................................................................129
8.3.2 工艺性的选择 ............................................................................................................129
8.4 不推荐的封装应用场景 ....................................................................................................... 129
第 9 章 陶瓷封装应用要领................................................................................... 131
9.1 陶瓷封装的结构与工艺特性 ............................................................................................... 131
9.2 LCCC 工艺要领...................................................................................................................131
9.3 CBGA 工艺要领 ..................................................................................................................134
案例 12：边缘点胶（也称为围堰胶）对 CBGA 可靠性的影响研究① ..............136
9.4 CCGA 工艺要领 ..................................................................................................................137
案例 13：CBGA、CCGA 器件植球 / 植柱工艺可靠性研究① ............................138
9.5 CQFP 工艺要领 ...................................................................................................................139
案例 14：CQFP 器件板级温度循环可靠性的设计与仿真① ................................140
案例 15：航天大尺寸 CQFP 器件引脚断裂失效分析① .......................................142
第 10 章 焊点可靠性仿真分析与试验评估..............................................................149
10.1 可靠性试验 ........................................................................................................................149
10.1.1 可靠性试验的分类 .................................................................................................149
10.1.2 可靠性加速试验 .....................................................................................................150
10.2 焊点可靠性仿真技术 ........................................................................................................150
10.2.1 焊点可靠性仿真分析步骤 .....................................................................................151
10.2.2 焊点疲劳寿命模型 .................................................................................................151
10.3 温度循环试验 ....................................................................................................................155
10.3.1 温度循环试验简介 .................................................................................................155
10.3.2 加速系数的计算 .....................................................................................................156
10.3.3 焊点可靠性评估试验方案 .....................................................................................158
第三部分 环境腐蚀与三防处理
第 11 章 环境因素引起的失效..............................................................................163
11.1 环境引起的失效 ................................................................................................................163
11.1.1 电化学腐蚀 ..............................................................................................................163
11.1.2 化学腐蚀 ..................................................................................................................164
11.2 枝晶生长 ............................................................................................................................165
11.2.1 枝晶形貌 ..................................................................................................................165
11.2.2 枝晶生长的 3 个要素 ..............................................................................................165
11.2.3 枝晶生长的 3 个阶段 ..............................................................................................166
11.2.4 影响枝晶生长的因素 ..............................................................................................167
11.2.5 枝晶生长测试 ..........................................................................................................168
案例 16：在高温、高湿试验环境下出现绝缘电阻下降 .......................................169
案例 17：常见的枝晶生长现象 ...............................................................................169
11.3 CAF ....................................................................................................................................170
11.4 银离子迁移 ........................................................................................................................171
11.5 Ag 的硫化腐蚀 ..................................................................................................................173
案例 18：片式电阻上硅胶覆盖导致硫化腐蚀 .......................................................174
11.6 爬行腐蚀 ............................................................................................................................177
11.6.1 爬行腐蚀的概念 ......................................................................................................177
11.6.2 发生场景 ..................................................................................................................178
11.6.3 爬行腐蚀机理 ..........................................................................................................178
11.6.4 爬行腐蚀与枝晶、CAF 的对比 .............................................................................179
11.6.5 硫化亚铜的危害 ......................................................................................................179
11.6.6 防护措施 ..................................................................................................................179
11.6.7 关于爬行腐蚀的研究 ..............................................................................................180
11.7 实际环境下的腐蚀 ............................................................................................................180
案例 19：充电桩单板的“湿尘”腐蚀 ...................................................................180
案例 20：电源单板的“湿尘”腐蚀 .......................................................................181
案例 21：阻焊层（绿油）内 Cu 迁移 ....................................................................181
第 12 章 锡须...................................................................................................183
12.1 关于锡须 ............................................................................................................................183
12.2 锡须产生的原因 ................................................................................................................184
12.3 锡须产生的 5 种基本场景 ................................................................................................186
12.4 室温下锡须的生长 ............................................................................................................186
12.5 温度循环（热冲击）作用下锡须的生长 ........................................................................187
12.6 氧化腐蚀引起的锡须生长 ................................................................................................188
案例 22：某轻触开关因锡须短路 ...........................................................................189
12.7 外界压力作用下的锡须生长 ............................................................................................190
12.8 控制锡须生长的建议 ........................................................................................................191
第 13 章 清洗工艺 ............................................................................................193
13.1 清洗的作用 ........................................................................................................................193
13.2 清洗剂的选择 ....................................................................................................................193
13.2.1 常见污物类型 .........................................................................................................193
13.2.2 清洗剂选择的考虑因素 .........................................................................................194
13.2.3 清洗剂的种类及特点 .............................................................................................194
13.3 清洗设备的选择 ................................................................................................................195
13.3.1 清洗方法与工艺 .....................................................................................................195
13.3.2 清洗设备的选择要求 .............................................................................................196
13.4 超声清洗工艺流程与参数设置 ........................................................................................196
13.5 助焊剂的选配 ....................................................................................................................197
13.6 清洗要求与常见不良 ........................................................................................................197
13.6.1 清洗要求 .................................................................................................................197
13.6.2 常见的清洗不良现象 .............................................................................................198
案例 23：清洗不干净，有明显可见的松香残留物 ...............................................198
案例 24：清洗剂与镀层不兼容或漂洗不干净，引起镀层变色腐蚀 ...................198
案例 25：元器件损坏 ...............................................................................................199
13.7 关于人工清洗 ....................................................................................................................199
第 14 章 敷形涂覆工艺 ......................................................................................201
14.1 敷形涂覆的目的 ................................................................................................................201
14.2 敷形涂覆材料的分类与特性 ............................................................................................202
14.2.1 敷形涂覆材料的分类 .............................................................................................202
14.2.2 常用敷形涂覆材料的物理性能 .............................................................................202
14.2.3 敷形涂覆材料的性能特性 .....................................................................................203
14.2.4 敷形涂覆材料的认证 .............................................................................................203
14.3 敷形涂覆材料的选择 ........................................................................................................204
14.4 敷形涂覆工艺与方法 ........................................................................................................206
14.4.1 免洗工艺条件下涂覆前是否需要清洗 .................................................................206
14.4.2 涂覆工艺 .................................................................................................................208
14.4.3 常见的涂覆不良 .....................................................................................................211
14.5 PCBA 常见的环境失效模式.............................................................................................212
14.5.1 影响 PCBA 的环境因素 .........................................................................................212
14.5.2 典型的失效模式 .....................................................................................................214
第四部分 高可靠性产品的制造
第 15 章 潮敏元器件的应用 ................................................................................221
15.1 概述 ....................................................................................................................................221
15.2 潮湿敏感度等级 ................................................................................................................222
15.3 潮湿敏感度等级的评定 ....................................................................................................222
15.4 干燥包装 ............................................................................................................................224
15.5 烘干 ....................................................................................................................................227
15.6 使用 ....................................................................................................................................228
15.7 吸潮失效案例 ....................................................................................................................231
案例 26：BGA 芯片与载板之间分层 ...............................................................................231
案例 27：塑封 BGA 载板分层现象 ..................................................................................232
案例 28：钽电容过炉冒锡珠 ............................................................................................232
案例 29：SIP 内部空洞会导致过炉后冒锡珠 ..................................................................234
案例 30：光驱动器件的焊接 ............................................................................................235
| 目 录 |
SMT 单板互连可靠性与典型失效场景
第 16 章 组装工艺控制 ..................................................................................... 238
16.1 组装工艺对可靠性的影响 ................................................................................................238
16.2 SMT 前工艺 .......................................................................................................................240
16.2.1 去金工艺 .................................................................................................................241
16.2.2 搪锡工艺 .................................................................................................................241
16.2.3 引线成形 .................................................................................................................242
16.3 SMT 工艺 ...........................................................................................................................246
16.3.1 表面组装元器件的焊接 .........................................................................................246
案例 31：BGA 的球窝与开焊 .................................................................................246
16.3.2 焊膏印刷 .................................................................................................................247
16.3.3 钢网设计 .................................................................................................................252
16.3.4 再流焊接 .................................................................................................................255
16.3.5 工艺关注点 .............................................................................................................259
16.4 SMT 后工艺 .......................................................................................................................262
16.4.1 印制电路板和模块的分板 .....................................................................................262
16.4.2 检测技术 .................................................................................................................262
16.4.3 筛选 .........................................................................................................................262
16.4.4 加速可靠性测试 .....................................................................................................263
第 17 章 缺陷焊点 ........................................................................................... 264
17.1 组装缺陷焊点的分类 ........................................................................................................264
17.2 虚焊 ....................................................................................................................................264
17.2.1 冷焊 .........................................................................................................................264
17.2.2 无润湿开焊 .............................................................................................................265
17.2.3 枕头效应 .................................................................................................................266
17.2.4 焊点应力开裂 .........................................................................................................267
17.3 形态缺陷 ............................................................................................................................268
17.3.1 片式元件葡萄球焊点 .............................................................................................268
17.3.2 片式元件两端焊点爬锡高度悬殊较大 .................................................................268
17.3.3 QFP 多锡 .................................................................................................................269
17.3.4 J 形引脚多锡 ...........................................................................................................269
17.3.5 插件包焊 .................................................................................................................270
17.4 熔断焊点 ............................................................................................................................270
17.4.1 冷撕裂（缩锡开裂） .............................................................................................270
17.4.2 热撕裂 .....................................................................................................................271
17.5 脆性界面焊点 ....................................................................................................................271
参考文献 ......................................................................................................... 273