BGA器件無鉛再流焊溫度場仿真研究

頁數(shù)：59 字?jǐn)?shù)：28859

摘 要

盡管焊接缺陷、焊點(diǎn)可靠性等焊接質(zhì)量仍然與焊膏印刷、 貼片等前面多道工序有關(guān)，但據(jù)研究結(jié)果和生產(chǎn)統(tǒng)計(jì)表明，更多的焊接缺陷來源于再流焊工藝本身。再流焊是預(yù)先在PCB(Printed Circuit Board)板的焊接部位(焊盤)放置適量和適當(dāng)形式的焊料，然后貼放表面組裝元器件，經(jīng)固化(在采用焊膏時(shí))后，再利用外部熱源使焊料再次流動(dòng)達(dá)到焊接目的的一種成組或逐點(diǎn)焊接工藝。只要設(shè)置合適的再流焊設(shè)備的各區(qū)溫度，幾乎能完全滿足各類表面組裝元器件對(duì)焊接的要求，實(shí)現(xiàn)可靠的連接。但目前在國內(nèi)還沒有建立再流焊接溫度場的模型，仍采用反復(fù)試驗(yàn)的方法制定再流焊接工藝，造成了巨大的財(cái)力和人力的浪費(fèi)。因此，對(duì)再流焊溫度場的仿真研究極其重要。
本文研究的是BGA器件無鉛再流焊過程中的溫度場仿真。用ANSYS軟件，根據(jù)所用無鉛釬料的性能，分析了獲得良好焊點(diǎn)性能的再流焊溫度曲線；利用傳熱學(xué)的理論，將再流焊中紅外加熱轉(zhuǎn)化為對(duì)流加熱，結(jié)合再流焊設(shè)備對(duì)PCAs(Printed Circuit Assemblis)加熱的實(shí)際物理過程，建立了紅外熱風(fēng)再流焊方法的傳熱數(shù)學(xué)模型；根據(jù)再流焊設(shè)備的尺寸，結(jié)合獲得良好性能產(chǎn)品的再流焊焊膏熔化溫度曲線的要求，根據(jù)BGA的封裝，建立仿真所用的PCAs有限元模型；獲得再流焊爐各區(qū)的加載溫度：進(jìn)一步對(duì)PCAs的再流焊接溫度場進(jìn)行了動(dòng)態(tài)模擬，獲得了PCAs整體組件的動(dòng)態(tài)溫度場和比較滿意的再流焊工藝仿真。
通過對(duì)兩種加載曲線的仿真結(jié)果的比較，獲得適合無鉛加載的曲線設(shè)置以及曲線的優(yōu)化方法

關(guān)鍵詞： 無鉛；再流焊；仿真；溫度場；表面組裝；建模


Abstract

Although the welding defects, welding quality solder joint reliability is still with the solder paste printing, placement, etc. in front of the multi-channel processes, but according to research results and production statistics show that more of welding flaws from the reflow process itself. Reflow soldering is a solder that connect SMD or SMC with PCB by melting the solder utilize external heat sonrce make solder reflow and solidify the solder by cooling it (while adopting the soldering paste)．Reliable connection of various components is attainable when the temperature section of flow oven is setup suitably．The traditional approach of experimentally analysing production defects would be costly and virtually impossible for the temperature field model is not built homeland inside．An alternative to this approach is to derive computational and numerical models to simulate the reflow soldering process．
This study is lead-free BGA devices during reflow temperature field simulation. With ANSYS software, according to the performance of lead-free solder analysis analysis for good performance of the reflow solder temperature curve ;whit the heat transfer theory, we will go in the infrared reflow into a convection heating, combined with the reflow equipment of the PCAs (Printed Circuit Assemblis) the actual physical process of heating, the establishment of an infrared hot air reflow method of heat transfer model; according to the size of the reflow equipment, combined with performance products for good solder paste reflow melting temperature curve requirements, according to BGA packages, the establishment of simulation by the finite element model used in PCAs; access various parts of the reflow furnace load temperature: further PCAs re-flow soldering temperature field in the dynamic simulation, the dynamic component of the overall temperature of PCAs field and more satisfied with the reflow process simulation. By comparison of two kinds of load curves’ simulation results. The study can obtain the curve for lead-free settings, and load optimization curve.

Key words: Lead-free; Refolw soldering ;Simulation; temperature field; SMT; Modeling

目 錄

1 緒論 1
1.1無鉛軟釬焊研究的背景 1
1.1.1 無鉛釬料的種類 1
1．2 PCB組件概述 3
1.2.1PCB的結(jié)構(gòu) 3
1.2.2PCB的分類 4
1.3 BGA的概述 5
1.4 再流焊接建模與仿真的意義 6
1．5 研究發(fā)展現(xiàn)狀 6
1.5.1國外研究發(fā)展現(xiàn)狀 6
1.5.2國內(nèi)研究發(fā)展現(xiàn)狀 9
1．6 本課題研究的內(nèi)容 10
2 再流焊設(shè)備及工藝要求 10
2.1再流焊熱源 10
2.1.1再流焊熱源類型與主要特點(diǎn) 10
2.1.2 紅外加熱風(fēng)再流焊原理 11
2.1.3 紅外線輻射加熱風(fēng)再流焊設(shè)備 12
2.2無鉛釬料的選擇及其特性 14
2.2.1選擇背景 14
2.2.2選擇的原則 15
2.3再流焊溫度曲線 16
2.3.1無鉛再流焊接溫度關(guān)鍵參數(shù)的確定 17
2.3.2無鉛再流焊溫度曲線參數(shù)的設(shè)定 17
2.3.3無鉛再流焊接溫度曲線的管理 19
2.4 本章小結(jié) 20
3 再流焊數(shù)學(xué)模型的建立 20
3.1基本理論 20
3.2熱傳遞的基本方式 21
3.3邊界條件 22
3.4再流焊溫度場的數(shù)學(xué)模型 23
3.5小結(jié) 26
4 PCAs的溫度場仿真 27
4.1 定義材料類型和材料屬性 27
4.1.1所需材料清單 27
4.1.2 Cu箔的熱參數(shù) 27
4.1.3 FR-４的熱特性 28
4.1.4無鉛焊料的熱特性 29
4.1.5 BGA的熱參數(shù) 29
4.2 ANSYS軟件介紹 30
4.2.1ANSYS軟件分析方法 30
4.2.1關(guān)于ANSYS的熱分析 31
4.3 創(chuàng)建有限元幾何模型 32
4.4 邊界條件 35
4.5 加載和求解 36
4.5.1加載過程 36
4.5.2求解過程 37
4.5.3求解的結(jié)果及分析 39
4.5.4 加載曲線的選取及優(yōu)化 47
4.6 本章小結(jié) 48
5 結(jié)論 49
謝辭 51
參考文獻(xiàn) 52