跟读练习: What are PCBs and PCBAs? The 'PCB basics' - 通过视频学习英语口语
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Welcome to this video series where we're going to be looking at PCBs.
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This is the first video and we're going to be looking at PCB basics.
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So what's the difference between a PCB and a PCBA?
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Well you can generally refer to a blank unstuffed and unsoldered printed circuit board as a PCB.
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You can see an example of this on the top image here.
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The assembled and soldered assembly is then known as a PCBA or a board assembly or simply a PCA.
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And you can see an example of this on this bottom image.
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So if we look at the two differences,
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the top one clearly has no components on it whereas the bottom has a fully populated set of components.
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So the basic understanding of a PCB.
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A basic PCB consists of a flat sheet of insulating material and a layer of copper foil laminated to the substrate.
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Chemical etching divides the copper into separate conducting lines called tracks or circuit tracers,
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pads for connections, wires to pass connections between layers of copper.
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The tracks function as wires fixed in place and are insulated from each other by air and the bored substrate material.
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The surface of the PCB may have a coating
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that protects the copper from corrosion and reduces the chances of solder shorts between traces
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or undesired electrical contact from stray bare wires.
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This coating is called the solder resist.
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You can see an example of a bare PCB here on the right
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where we can clearly see the tracks and the holes
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or the wires going from one side of the board to the other.
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So what makes up a PCB?
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The basic PCB consists of four layers, which are heat laminated together into a single board.
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The four layers are substrate, copper, solder mask and silk screen.
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The substrate needs to be thermally stable and the most common material used is FR4.
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FR4 is a glass epoxy high pressure thermoset plastic laminate with good strength to weight ratio with near zero water absorption.
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FR simply stands for Flame Retardant.
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And you can see the basic layers here in this image, where we have the substrate, the copper, the solder mask and the silkscreen on top.
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So what are the different layers on top of the FR4?
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First we have the copper layer, which is the electrical conductor where the tracks are etched, which make up the circuit.
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The thickness can vary depending on the power requirements, but in general the thickness is around 35 microns or equivalent to 1.4 thou.
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Second is the solder mask layer and this gives the PCB its green color.
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Its purpose is to insulate the copper tracks from contact with metal, solder or other conductive items.
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And third, the silkscreen layer is a combination of shapes, letters, symbols and instructions.
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It provides identification for each part and you can clearly see
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that in this image where we have part identifications don't forget to check out our other videos in this series
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and you can always contact us
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if you need any help with your projects in China
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so don't forget to a like share and subscribe
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if you hit this little bell symbol
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that will notify you of any new content that we upload
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so thanks for listening my name is Paul Adam from South East and I shall see you in the next video
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本课的词汇与口语要点
这段视频共有 42 个句子、567 个单词可供跟读。 讲话部分时长为 3:55。 说话人语速平稳，每分钟约 145 个词，很适合跟读。 只有 73% 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 15 个值得学习的单词，附发音和释义：
| 单词 | 发音 | 释义 |
|---|---|---|
| layer 名词 | /ˈleɪ̯ɚ/ | 層 /层 |
| copper 名词 | /ˈkɒpə/ | 銅 /铜 |
| substrate 名词 | /ˈsʌbˌstɹeɪt/ | 底層語言 /底层语言 |
| wire 名词 | /ˈwaɪɚ/ | 線 /线, 鐵絲 /铁丝 |
| mask 名词 | /mæsk/ | 面具, 面罩 |
| coat 名词 | /ˈkoʊ̯t/ | 外衣, 大衣 |
| component 名词 | /kəmˈpoʊ.nənt/ | 元件, 部件 |
| symbol 名词 | /ˈsɪmbəl/ | 符號 /符号 |
| identification 名词 | /aɪˌdɛn(t)ɪfɪˈkeɪʃn̩/ | 辨識 /辨识, 鑑定 /鉴定 |
| consist 名词 | /kənˈsɪst/ | 編組 /编组 |
| thickness 名词 | /ˈθɪknəs/ | 厚度 |
| stable 名词 | /ˈsteɪ.bəl/ | 馬厩, 馬棚 /马棚 |
| refer 动词 | /ɹɪˈfɜː/ | 談到 /谈到 |
| whereas | /(h)wɛɹˈæz/ | 然而 |
| sheet 名词 | /ʃit/ | 篇, 張 /张 |
视频中出现的短语动词
| 单词 | 发音 | 释义 |
|---|---|---|
| make up 动词 | /ˌmeɪk ˈʌp/ | 組成 /组成 |
| check out 动词 | 退房 |
视频中的语法
说话人最常用的结构，并附上视频中的原话：
| 结构 | 视频中的用法 |
|---|---|
| 被动语态 be + 过去分词 — 强调发生了什么，而不是谁做的 | are insulated · is called · are etched |
| 定语从句 who / which + 从句 — 补充说明人或事物 | layers, which are · layer, which is |
需要注意的发音
说话人用了 4 次缩略和弱读形式，例如 don't, we're。请按听到的简短形式来说。
- “sh” 和 “zh” 音: identification /aɪˌdɛn(t)ɪfɪˈkeɪʃn̩/, sheet /ʃit/, ratio /ˈɹeɪ.ʃoʊ/, instruction /ɪnˈstɹʌkʃən/, absorption /æbˈsɔɹp.ʃn̩/
- 长单词——注意重音位置: electrical /ɪˈlɛktɹɪkəl/, identification /aɪˌdɛn(t)ɪfɪˈkeɪʃn̩/
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 layer, copper, substrate 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。