English
Deutsch
Français
简体中文
繁體中文
Categories
Technical
Study
Novel
Nonfiction
Health
Tutorial
Entertainment
Business
Magazine
Arts & Design
Audiobooks & Video Training
Cultures & Languages
Family & Home
Law & Politics
Lyrics & Music
Software Related
eBook Torrents
Uncategorized
Study
Novel
Nonfiction
Health
Tutorial
Entertainment
Business
Magazine
Arts & Design
Audiobooks & Video Training
Cultures & Languages
Family & Home
Law & Politics
Lyrics & Music
Software Related
eBook Torrents
Uncategorized
Share With Friends
Archive by Date
2012-08-06
2012-08-05
2012-08-04
2012-08-03
2012-08-02
2012-08-01
2012-07-31
2012-07-30
2012-07-29
2012-07-28
2012-08-05
2012-08-04
2012-08-03
2012-08-02
2012-08-01
2012-07-31
2012-07-30
2012-07-29
2012-07-28
Search Tag
rush
Dysmorphic
seduce
Salaire
Dietric
reign
CURVE
barde
hysteria
导向
Degats
Altsysteme
Governances
Flashpoints
Begruessungsheft
Djokic
Borish
mage
生产力
abstauben
Marilee
Moyles
Inzest
Laborwerte
Liesl
ANTENA
SHOWCASE
Townend
Intuit
arming
Informationsabkommen
Epidemiologie
Hawthorn
Mohammadian
伯恩斯新情绪疗法
Singe
PsyShark
laterizio
Sergiu
梨子小姐
Alami
InstallShield
metalwork
prezzo
Thomzik
Artension
Telfer
Norderney
Palecek
Meinolf
Newest
Lectures on Numerical Methods in Bifurcation Problems
Methods for Finding Zeros in Polynomials
Lectures on Stochastic Flows and Applications
Educational Psychology by Edward L. Thorndike
The Last Days of Tolstoy by V. G. Chertkov
Globalization and Responsibility
Lectures on Siegel Modular Forms and Representation by Quadratic Forms
Lectures on Topics In One-Parameter Bifurcation Problems
History of the Incas by Pedro Sarmiento de Gamboa
Linear Algebra: Theorems and Applications
Lectures on Stochastic Differential Equations and Malliavin Calculus
A Short Biographical Dictionary of English Literature
Lectures on Sieve Methods and Prime Number Theory
Dollars and Sense by William Crosbie Hunter
The Theory of the Theatre by Clayton Hamilton
The Mathematics of Investment
Occupiers of Wall Street: Losers or Game Changers
The Solution of the Pyramid Problem
Lectures on Moduli of Curves
Walden by Henry David Thoreau
Methods for Finding Zeros in Polynomials
Lectures on Stochastic Flows and Applications
Educational Psychology by Edward L. Thorndike
The Last Days of Tolstoy by V. G. Chertkov
Globalization and Responsibility
Lectures on Siegel Modular Forms and Representation by Quadratic Forms
Lectures on Topics In One-Parameter Bifurcation Problems
History of the Incas by Pedro Sarmiento de Gamboa
Linear Algebra: Theorems and Applications
Lectures on Stochastic Differential Equations and Malliavin Calculus
A Short Biographical Dictionary of English Literature
Lectures on Sieve Methods and Prime Number Theory
Dollars and Sense by William Crosbie Hunter
The Theory of the Theatre by Clayton Hamilton
The Mathematics of Investment
Occupiers of Wall Street: Losers or Game Changers
The Solution of the Pyramid Problem
Lectures on Moduli of Curves
Walden by Henry David Thoreau
Useful Links
手工无铅焊接过程控制分析
Posted on 2010-04-28
|
由于很多公司开始面对无铅焊接的工艺挑战，手工焊接以及相关技术已经被认为是制造中的关键因素，需要更过的研究与发展。手工焊接一般发生在生产线的末端，这时的PCB板已经具有很高的内在价值，所以手工焊接的过程控制是否正确对生产率与成本的高低有重要的影响。过程控制现在许多生产商对衡量手工焊接质量的标准主要靠检查烙铁头的温度。随着无铅焊接温度比传统焊接温度的提高，焊接熔点的提高，需要一种更为全面的衡量标准参数。IPC 要求在一个固定时间段，手工焊接根据经验要达到最佳的焊点连接温度。它不是强调绝对的焊接温度，而是强调焊点的热交换效率。诸如烙铁头的形状尺寸，焊接时的功率输出与焊接的时间长短都对焊点的热交换效率有影响， 所以这些因素在检测，控制与分析无铅焊接过程时都应该考虑进去。手工焊接过程可以分为以下几步：A) 烙铁头应该清理干净，上锡，选择合适的形状以保持和焊点/焊盘最大的接触面积。(B) 烙铁头与焊点的接触点的温度应该在焊锡丝熔点以上40℃ 保持2-5秒，在此期间助焊剂产生作用并挥发，焊锡丝熔化。(C) 焊锡丝熔化以后，开始覆盖焊点焊盘与通孔。(D) 烙铁头离开焊点，熔化的焊锡凝固。焊接处的温度 对任何手工焊接过程，焊接点形成的正确温度对于形成优质的焊点都是至关重要的，通过检查焊接点金属层的厚度与内部金属结构可以清楚地分析出焊接中传递给焊点的热量是否正确。焊接表面可以反映出焊点焊盘在电路板上形成是否良好。控制焊点处金属层厚度对于形成可靠的连接是很重要的。焊点内部金属形成速率与焊接温度与焊接时间有关。如果烙铁提供的热量过大，会增大焊点金属层的体积，从而导致焊点产生易脆的缺陷。提供的热量过小，会使焊点熔化不足。如下图，焊脚处的焊点形状与外观可以反映出焊点的质量，不幸的是无铅焊接焊脚与有铅焊接的焊脚外观很不一样
Rating:
2.5 out of 5 by Book123 |
| Download Links | |
| Server | Status |
|---|---|
| Direct Download Link 1 | Alive |
| Direct Download Link 2 | Alive |
| Download Link 1 | Alive |
|
Buy This Book at Best Price >> | |
Like this article?! Give us +1:
Related Articles
 | Security/Hacking 4899远程控制软件入侵 4899远程控制软件入侵 |
| 汽车制动防抱死系统(ABS)制动控制过程分析 汽车制动防抱死系统(ABS)制动控制过程分析 |
| Programming VB网络与远程控制编程 VB网络与远程控制编程 |
| 钢结构手工电弧焊焊接工艺标准 钢结构手工电弧焊焊接工艺标准 |
| 电气控制及可编程控制器 电气控制及可编程控制器 |
| 关联规则挖掘及其在复杂工业过程控制中的应用研究 关联规则挖掘及其在复杂工业过程控制中的应用研究 |
Comments (0)
