Shadowing Practice: What is SMT (Surface Mount Technology)? PCB Assembly (Part 2) - Learn English Speaking with Video
Choose a practice mode
Each mode opens a full-screen practice room.
60 sentences
If sentences are too short or too long, click Edit to adjust them.
1
Welcome to this video where we're going to be looking at what is an SMT
2
and this is using the surface mount technology to assemble PCBs part 2.
3
So here we're going to be looking at the PCBA production process.
4
We're going to be focusing on these next two elements within the process.
5
So there's reflow soldering process and the cleaning process.
6
So let's start with the reflow soldering process.
7
The circuit board assemblies need to be preheated to activate the flux in the solder paste.
8
Then they need to be heated at a higher temperature to reflow the solder.
9
A cooling step follows that allows a solder to solidify.
10
The The preheating, heating and cooling down cycles in the reflow machine are defined by the thermal profile.
11
We'll have a look at that in more detail in the following slides.
12
Let's have a look at the cleaning process.
13
So the PCB cleaning is the process of removing solder flux residues from the PCB after the SMT process.
14
The flux present in the solder paste reacts with the metal oxide during the reflow process
15
and prevents further oxidization of the solder metal.
16
The byproduct of this reaction is the solder flux residue that gets trapped beneath components and near the undersides of solder balls.
17
Let's have a look at the reflow thermal profile.
18
We're going to break this down into the separate zones.
19
So to start with we have the preheat zone.
20
The highest temperature is 2.5 degrees centigrade per seconds in the preheat area.
21
Over rising rate will cause solder balling.
22
In this image we have the recommended reflow soldering temperature profile.
23
We'll be focusing on this throughout this thermal profiling overview.
24
The next zone we're going to be focusing on is the soak zone.
25
Here we need to keep the temperature within a range of 150 to 210 degrees centigrade
26
and the temperature rise rate under 2.5 degrees centigrade per second during the soak zone
27
which lasts regularly from 60 seconds to 90 seconds and again we can see that here in this temperature profile.
28
The next zone is the reflow zone.
29
The peak temperature in the reflowing zone changes in the range of 230 to 255 degrees centigrade.
30
Temperature stays above 217 degrees centigrade for 40 to 70 seconds.
31
You can see this peak temperature here.
32
The final zone is the cool down zone.
33
The temperature dropping rate during cool down zone should be kept under 4 degrees centigrade per second.
34
Note the curve varies according to the shape of the plate and function of the devices.
35
The circumstance parameter is suggested to be 25 plus or minus 2 degrees centigrade by temperature,
36
and 45% and 65% by humidity.
37
You can see the overall time in this profile is around 270 seconds.
38
Let's switch over to the importance of cleaning.
39
Cleaning the PCB.
40
The solder flux residue, which is trapped between the components of the PCB substrate and the near underside of the solder balls,
41
is electrically conductive, as it is made up of ions.
42
As PCBs and modules are subjected to an external electric field,
43
the diffusing flux residue particles get excited by the momentum transfer of the conducting electrons in the circuit.
44
This leads to the particles getting displaced from their position.
45
A problem may arise when these particles cause bridging between two parts of the circuit.
46
This problem is known as electro migration.
47
Now the best practice, let's have a look at that.
48
Now there is a no clean solder paste available.
49
If possible you should be using this.
50
So many of the best performing lead free and lead containing solder pastes today are no cleans.
51
They have been designed to solve assembly problems described previously.
52
For the vast majority of applications the small amount of residue left by non-clean is not a problem.
53
However some assemblers want the performance of no cleans
54
but need to clean the no clean residue as they have extreme reliable or cosmetic requirements.
55
You can see how clean this no clean solder is in this image here.
56
So don't forget to check out our other videos in this PCB series
57
and you can contact us if you need any help with your projects at all in China.
58
So don't forget to like, share and subscribe to our channel and if you hit this little bell symbol
59
that will notify you each time we upload new content.
60
So thanks for listening my name is Paul Adams from I'm SoftEast and I shall see you in the next video.
Download App
Everything you need to speak fluently
AI PronunciationScore every sentence
IPA PracticeMaster every sound
VocabularyBuild your word bank
Vocab GameLearn while playing
Same Channel
B2Sofeast PCB Video Series Introduction
Daily ConversationWorking Adults
C12
DFM And DFA Explained
Daily ConversationWorking Adults
C13
What is SMT (Surface Mount Technology)? PCB Assembly (Part 3)
Daily ConversationWorking Adults
C14
PCB Inspection Methods & Common PCB Defects
Daily ConversationWorking Adults
C13
NPI Process 1: Why A Pilot Run Before Mass Production Is Very Useful
Business EnglishWorking Adults
C15
What is SMT (Surface Mount Technology)? PCB Assembly (Part 1)
Business EnglishUniversity StudentsWorking Adults
B2BONUS: Should we do PCB or enclosure design first? (Feat Andrew Amirnovin)
Business EnglishUniversity StudentsWorking Adults
B2What are PCBs and PCBAs? The 'PCB basics'
University StudentsWorking Adults
B1Don’t Approve a Product Until You’ve Lived With It
Business EnglishWorking Adults
B1The Product Passed the Safety Test, But Was Still Too Hot to Hold
Business EnglishWorking Adults
B2The Product Worked, But the Packaging Made It Look Dead
Business EnglishWorking Adults
B2Why User Experience Is Harder Than Engineering
Business EnglishUniversity StudentsWorking Adults
C14 NPI Tips Before You Move Into Mass Production
Business EnglishWorking Adults
C1The Production Validation Test (PVT) Phase of the NPI Process
Business EnglishWorking Adults
C1The Three NPI Phases Explained
Business EnglishUniversity StudentsWorking Adults
C1When Can The NPI Process Begin?
Business EnglishUniversity StudentsWorking Adults
C1NPI Process #3: Why A Feasibility Study With Suppliers Saves Time & Prevents Issues
Business EnglishWorking Adults
C1NPI Process 2: New Product Development Process (Why Planning Before Prototyping Saves Time)
Business EnglishUniversity StudentsWorking Adults
C1PCBs | Electronic Goods Reliability Testing
Business EnglishUniversity StudentsWorking Adults
FOR YOU
Recommend Video
C12
150 sentences
15 IT Terms Everyone In Tech Recruitment Should Know – IT & Tech Recruitment Insights
Business EnglishWorking Adults
C11
4 sentences
Ambr®️ 250 High Throughput Perfusion Product Tutorial - Learn with Sartorius
Business EnglishUniversity StudentsWorking Adults
C1288 sentences
Using Selection & Scan Processing tools for reverse engineering | Geomagic Design X
Business EnglishWorking Adults
C12
306 sentences
Deep Dive: Investigating Thermal Cycling Failures Cracked MSOP Solder Joints
Business EnglishUniversity StudentsWorking Adults
C14
36 sentences
Overcoming Service Blueprinting Frustrations
Business EnglishWorking Adults
C13
50 sentences
✅ Coil Coating Process
Business EnglishUniversity StudentsWorking Adults
C11
443 sentences
Functional-Oriented Documentation in Automation - Eplan & IEC 81346 Explained
Business EnglishWorking Adults
C12
123 sentences
Order-to-Cash Process in SAP SD – Step by Step (Full Beginner Guide 2025)
Business EnglishUniversity StudentsWorking Adults
C13
115 sentences
Introduction 1, Context
Business EnglishUniversity StudentsWorking Adults
C13
131 sentences
Understanding BGA Pads: Solder Mask Defined vs Non-Defined
Business EnglishUniversity StudentsWorking Adults
Vocabulary and speaking notes for this lesson
This video has 60 sentences and 742 words to shadow. The speech runs for 5:34. The speaker talks at a steady 133 words per minute, a comfortable pace for shadowing. Only 78% of the words are among the 3,000 most common in English, so the vocabulary is demanding.
Key vocabulary in this video
15 words from the video worth learning, with pronunciation and meaning:
| Word | Pronunciation | Meaning |
|---|---|---|
| flux noun | /flʌks/ | The act of flowing; a continuous moving on or passing by, as of a flowing stream. |
| residue noun | /ˈɹɛzɪduː/ | That which persists or remains following the removal or elimination of other elements. |
| circuit noun | /ˈsɝ.kɪt/ | The act of moving or revolving around, or as in a circle or orbit; a revolution |
| thermal adjective | /ˈθɜːməl/ | Pertaining to heat or temperature. |
| pasta noun | /ˈpɑ.stə/ | Dough made from wheat and water and sometimes mixed with egg and formed into various shapes; often sold in dried form and typically boiled for eating. |
| particle noun | /ˈpɑɹtək(ə)l/ | A very small piece of matter, a fragment; especially, the smallest possible part of something. |
| trap noun | /tɹæp/ | A machine or other device designed to catch (and sometimes kill) animals, either by holding them in a container, or by catching hold of part of the body. |
| component noun | /kəmˈpoʊ.nənt/ | A smaller, self-contained part of a larger entity. Often refers to a manufactured object that is part of a larger device. |
| soak verb | /soʊk/ | To be saturated with liquid by being immersed in it. |
| vast adjective | /væst/ | Very large or wide (literally or figuratively). |
| mount verb | /maʊnt/ | To get upon; to ascend; to climb. |
| element noun | /ˈɛləmənt/ | One of the simplest or essential parts or principles of which anything consists, or upon which the constitution or fundamental powers of anything are based. |
| solve verb | /sɒlv/ | To find an answer or solution to a problem or question; to work out. |
| define verb | /dɪˈfaɪn/ | To determine with precision; to mark out with distinctness; to ascertain or exhibit clearly. |
| symbol noun | /ˈsɪmbəl/ | A character or glyph representing an idea, concept or object. |
Phrasal verbs you will hear
| Word | Pronunciation | Meaning |
|---|---|---|
| cool down verb | /kuːl ˈdaʊn/ | To become cooler; to be reduced in temperature. |
| check out verb | To record the departure or withdrawal of someone or something (such as guests, employees, books, etc.). | |
| keep under verb | To hold in subjection; hence, to oppress. |
Pronunciation to watch
The speaker uses 10 contractions and reduced forms, such as we're, don't, we'll. Say them the short way, as you hear them.
- The “th” sounds: thermal /ˈθɜːməl/, beneath /bɪˈniːθ/
- The “sh” and “zh” sounds: migration /maɪˈɡɹeɪʃ(ə)n/, oxidization /ˌɑksɪdɪˈzeɪʃ(ə)n/
- Long words — get the stress right: momentum /ˌmə(ʊ)ˈmɛntəm/, humidity /hjuːˈmɪd.ə.ti/, parameter /pəˈɹæm.ə.tɚ/, assembler /əˈsɛmb(ə)lɚ/, electrically /ɪˈlɛk.tɹɪk.li/
How to practise with this video
- Listen to the whole video once without speaking and note the words you do not know.
- Shadow it sentence by sentence at normal speed, repeating each one until your rhythm matches the speaker.
- Record yourself and compare with the original, paying attention to words like flux, residue, circuit.
What is the Shadowing Technique?
Shadowing is a science-backed language learning technique originally developed for professional interpreter training and popularized by polyglot Dr. Alexander Arguelles. The method is simple but powerful: you listen to native English audio and immediately repeat it out loud — like a shadow following the speaker with just a 1–2 second delay. Unlike passive listening or grammar drills, shadowing forces your brain and mouth muscles to simultaneously process and reproduce real speech patterns. Research shows it significantly improves pronunciation accuracy, intonation, rhythm, connected speech, listening comprehension, and speaking fluency — making it one of the most effective methods for IELTS Speaking preparation and real-world English communication.