跟读练习: What is SMT (Surface Mount Technology)? PCB Assembly (Part 3) - 通过视频学习英语口语
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Welcome to this video.
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This is part 3 of using surface mount technology to assemble PCBs.
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Electrical testing process.
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This is the last section of the process as you can see here.
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So So physical testing of printed circuit boards can also be carried out within the SMT production line.
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This is known as inline testing.
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However, it is more common for physical testing to be carried out offline in a separate area or test station.
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This is known as in-circuit testing.
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Although the generic term in-circuit testing or ICT is widely used within the electronics manufacturing industry,
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there are actually several different types of tester that are available.
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The type of tester required is dependent upon the manufacturing test process used, the volume and the boards that are used.
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Let's have a look at the different types of in-circuit tester.
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Let's start with the flying probe tester.
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In view of the issues of developing and manufacturing complete bed of nail access fixtures,
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they are costly and difficult to change if any component positions or tracks are moved.
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Another approach is to use a roving or flying probe.
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This has a simple fixture to hold the board
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and contact is made via a few probes that can move around the board and make contact as required.
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These are moved under software control so any board updates can be accommodated with changes to the software program.
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Another reason to use flying probes is the shrinking component size and denser chip scale packaging technologies.
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Manufacturing Defect Analyzer or MDA.
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The tester makes contact to the board under test using a bed of nails fixture
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and this means that a different fixture is generally required for each board.
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It needs to make contact with specific points on the board where often there may be test point
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or a land area for the probe.
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This form of tester offers a basic in circuit test of resistance, continuity and insulation.
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As the name implies it is just used for detecting the manufacturing defects like short circuits across tracks and open circuit connections.
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Automated X-ray inspection.
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AXI as is known is a technology based on the same principles as automated optical inspection or AOI.
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It uses x-rays as its source instead of visible light to automatically inspect features which are typically hidden from view.
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Automated x-ray inspection equipment can not only check the solder joints under components,
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but also reveal any defects in solder joints that may not be visible with ordinary optical inspection equipment.
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First off, sample inspection.
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The inspection microscope is generally used in FAI or first article inspection,
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which is required to ensure that the first product produced is 100% correct.
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In the SME industry, there is a need to ensure
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that the first off from any SMT assembly line is perfect before running the rest of the batch.
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Functional testing.
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At the end of the line, there needs to be a functional test to establish if the PCB actually functions and conforms to specification.
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The key features of the functional test are Identify errors in all functional aspects of the PCB
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Identify failure thresholds in the PCB when both upper and lower voltages are applied Simulate the operating environment for the PCB
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Verify speed, frequency, oscillations and other onboard timing elements Verify all input and output features conform to specification
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and establish all communication features are operational.
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Burn-in testing.
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Burn-in is a technique used as part of the quality insurance
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procedures where assembled printed circuit boards are operated under both normal and accelerated environmental conditions prior to shipment.
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Theoretically, any weak components would fail during the burn-in time allowing those parts to be replaced.
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Replacing the weak components would prevent premature failure, infant mortality failure, or other latent defects.
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On the right-hand side here, we can see a typical burn-in bathtub graph.
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We can see that the decreasing failure rate shows the early infant mortality failures.
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The constant failure rate covers the constant or random failures, whereas the increasing failure rate shows the wearout failures.
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This graph is failure rate over time
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Don't forget to check out our other videos in this PCB series
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You can contact us if you need any help with your projects at all in China And don't forget to like, share and subscribe to our channel
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And you see this little bell symbol If you hit that you'll get a notification each time we upload new content
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So thanks for listening, my name is Paul Adams from SofEast and I shall see you in the next video
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本课的词汇与口语要点
这节 C1 级别的口语课以视频“What is SMT (Surface Mount Technology)? PCB Assembly”为素材。 视频中反复出现的词有：failure, board, circuit, testing, inspection。 这段视频共有 56 个句子、769 个单词可供跟读。 讲话部分时长为 5:51。 说话人语速平稳，每分钟约 131 个词，很适合跟读。 只有 77% 的单词属于英语最常用的 3,000 词，词汇难度较高。
视频中的重点词汇
视频中最难的 15 个单词，附发音和释义：
| 单词 | 发音 | 释义 |
|---|---|---|
| automate 动词 | /ˈɔ.təˌmeɪt/ | 自動化 /自动化 |
| defect 名词 | /ˈdiːfɛkt/ | 缺點 /缺点, 問題 /问题 |
| solder 名词 | /ˈsɒl.də(ɹ)/ | 焊料 |
| conform 动词 | /kənˈfɔɹm/ | 遵从 |
| assemble 动词 | /əˈsɛm.bəl/ | 收集, 組合 /组合 |
| specification 名词 | 規格 /规格, 規範 /规范 | |
| mortality 名词 | /mɔɹˈtælɪti/ | 必死 |
| infant 名词 | /ˈɪn.fənt/ | 嬰兒 /婴儿 |
| graph 名词 | /ɡɹæf/ | 圖表 /图表 |
| bathtub 名词 | /ˈbæθtʌb/ | 浴缸, 浴盆 |
| latent 形容词 | /ˈleɪ.tənt/ | 潛在 /潜在 |
| oscillation 名词 | /ˌɒ.sɪˈleɪ.ʃən/ | 振盪 /振荡 |
| microscope 名词 | /ˈmaɪ.kɹəˌskoʊp/ | 顯微鏡 /显微镜 |
| inspect 动词 | /ɪnˈspɛkt/ | 調查 /调查, 檢查 /检查 |
| theoretically 副词 | 理論上 /理论上 |
视频中出现的短语动词
| 单词 | 发音 | 释义 |
|---|---|---|
| carry out 动词 | /ˈkæ.ɹi aʊt/ | 進行 /进行 |
| check out 动词 | 退房 |
需要注意的发音
说话人用了 3 次缩略和弱读形式，例如 don't, you'll。请按听到的简短形式来说。
- “th” 音: bathtub /ˈbæθtʌb/, threshold /ˈθɹɛʃ(h)oʊld/
- “sh” 和 “zh” 音: oscillation /ˌɒ.sɪˈleɪ.ʃən/, insulation /ˌɪnsəˈleɪʃən/, shipment /ˈʃɪpmənt/, notification /ˌnoʊtɪfɪˈkeɪʃn̩/, threshold /ˈθɹɛʃ(h)oʊld/
- 长单词——注意重音位置: mortality /mɔɹˈtælɪti/, oscillation /ˌɒ.sɪˈleɪ.ʃən/, accelerate /ɪkˈsɛl.əˌɹeɪt/, insulation /ˌɪnsəˈleɪʃən/, continuity /ˌkɑn.tɪˈn(j)u.ə.ti/
如何用这段视频练习
- 先完整听一遍视频，不要开口，记下不认识的单词。
- 用正常速度逐句跟读，每句重复到你的节奏与说话人一致为止。
- 录下自己的声音并与原声对比，特别注意 automate, defect, solder 这类单词。
什么是跟读法？
跟读法 (Shadowing) 是一种有科学依据的语言学习技巧，最初开发用于专业口译员的培训，并由多语言者Alexander Arguelles博士普及。这个方法简单而强大：您在听英语母语原声的同时立即大声重复——就像是一个延迟1-2秒紧跟说话者的影子。与被动听力或语法练习不同，跟读法强迫您的大脑和口腔肌肉同时处理并模仿真实的讲话模式。研究表明它能显着提高发音准确性，语调，节奏，连读，听力理解和口语流利度——使其成为雅思口语备考和真实英语交流最有效的方法之一。