Shadowing Practice: PCB Inspection Methods & Common PCB Defects - Learn English Speaking with Video
בחר מצב תרגול
כל מצב פותח חדר תרגול במסך מלא.
140 משפטים
אם המשפטים קצרים או ארוכים מדי, לחץ על ערוך כדי להתאים אותם.
1
This is the next video in the PCB series.
2
Here we're going to be looking at printed circuit board assemblies and the inspection methods and common defects.
3
So checking solder paste process.
4
There are a number of points to check for with the solder paste process.
5
1. We need to be looking at the paste stencil alignment.
6
If an automatic solder paste machine is being used, the general method is to use a camera to determine the position of the PCB by checking for the dooshals,
7
alignment dots on the PCB.
8
We covered this in a previous video.
9
The manual method of setting up the stencil is to align the stencil with the PCB printed pads.
10
then set the clamp stops to hold the PCB in the correct place.
11
What to check for?
12
Well you need to check the solder paste is correctly aligned to all of the pads on the PCB.
13
Over on the right here we can see three images.
14
The top image, which is good, shows that all of the paste is aligned with the pads.
15
The middle shows some errors we can see here, slight misalignment and one bridge between two solder plates.
16
The bottom one is just a mess, i.e. the ugly looking thing, with solder all over the place.
17
Two, the squeegee speed and pressure.
18
The squeegee speed should not be too fast that the paste does not roll as it moves across the stencil
19
or too slow
20
that the print cycle time does not keep up with the manufacturing line The blade pressure is usually set
21
so that no paste remains on the stencil behind the squeegee
22
Higher pressures will not only damage the stencil but also shear thin the paste
23
to such an extent that the flux will separate from the metal and problems such as paste sticking to the blade,
24
lack of tack at placement or poor solderability will occur further down the assembly line.
25
What to check for?
26
We need to check for solder paste is not left on the stencil after a pass
27
and that all the solder pads have adequate paste deposited.
28
Again on the right hand side here, going from the top left, 1, the alignment gasket of apertures to the pad.
29
2, we need to check the squeegee motion, things paste so it flows into the apertures.
30
3, bottom left, paste, recovers, stiffens up.
31
And of 4, the bottom right, the stencil separates from PWB, paste deposits release from the stencil into the pads.
32
Now let's have a look at the five major issues with pick and place machines.
33
Fault number one, loss of vacuum.
34
What to check for?
35
Or primary process set up areas to check.
36
Is nozzle damaged and will not sit flush against the component's surface?
37
Or damaged vacuum hoses or a vacuum system?
38
Fault number two, short or worn nozzles.
39
What to check for?
40
Short nozzles will result in components not being placed correctly resulting in component shift and movement.
41
Worn nozzle tips result in loss of vacuum and you will see components being dropped.
42
Measure nozzles against dimensional acceptance.
43
Thought number 3.
44
Sticking nozzles.
45
What to check for?
46
Damaged nozzles that do not fit correctly into their holders.
47
old and non-maintained nozzles.
48
On the right hand side there you can see the top image showing the nozzle area.
49
Make sure these are not worn or damaged in any way.
50
The bottom image just shows a variety of different nozzles that can be used.
51
Thought number four, higher than normal reject rates at inspection.
52
What to check for components were not presented to the nozzle in a consistent position,
53
poor nozzle alightening from degradation of reflective discs or nozzle face over time,
54
dirty reflective discs or nozzle face, a poor quality of reflective disc or nozzle face,
55
nozzle height is incorrect, And finally, stuck nozzles from part height incorrect setting program.
56
Nozzle worn beyond their tolerances or incorrect length tolerance on nozzles.
57
Fault number 5.
58
Component and circuit board damaged caused by ESD.
59
What to check for?
60
Ensure nozzles are manufactured from electrostatic dissipating materials.
61
manufacturing manufacturers data sheet for this.
62
What to check for with incorrect wave solder profile.
63
Default here is bridging.
64
What to check for?
65
Well the primary process setup areas to check are conveyor speed too slow or other incorrect solder wave settings,
66
time Overheat is too long causing flux to be burnt off.
67
Dwell time is too long causing the flux to burn off before exiting the wave.
68
Top side board temperature too low.
69
Not enough flux applied to the flux activity is too low.
70
You can see here in this image solder bridging between two points.
71
the incorrect wave soldering profile issue, the fault being insufficient solder on topside fillet.
72
What to check for?
73
Conveyor speed is too low.
74
Check the time over preheat too long, causing the flux to be burned off.
75
Dwell time is too long, causing flux to be destroyed before exiting the wave.
76
The conveyor speed is too fast.
77
Dwell time is too short.
78
topside board temperature too high for flux causing it to burn off before the wave, not enough flux or the flux is not active enough,
79
solder temperature too low it cools in the barrel before it reaches the topside,
80
and wave height too low in one or both waves so the solder does not contact the board properly.
81
In this image it clearly shows there is insufficient solder to make this a good contact.
82
Another incorrect wave solder profile issue
83
so the fault here is insufficient solder bottom side fillet conveyor
84
speed is too slow time over preheat too long causing the
85
flux to be burnt off dwell time is too long causing flux to be destroyed before it exits the wave.
86
Bottom side board temperature is too high causing flux to be burnt off before the wave
87
and not enough flux or flux activity.
88
The wave height is too low on one or both waves.
89
And we can see here on the right hand side we've got problems with that connector.
90
On the bottom is insufficient solder where this component is placed.
91
Another incorrect wave solder profile issue, the fault here, is de-wetting or non-wetting.
92
What to check for?
93
Usually the board related due to contamination on the surface of the pads.
94
Solder temperature too low, solder wave height too low, contaminated flux or contaminated solder.
95
Or the conveyor speed is too high or too low.
96
And again, we can see examples here of solder de-wetting or non-wetting in the bottom instance.
97
Another incorrect wave solder profile issue is solder voids.
98
Now what to check for here.
99
Topside or overall board temperature is too low in trapping moisture that is outgassed at the wave.
100
Entrapped fluid by component in through hole.
101
Chemical contaminants not removed during PC fabrication process.
102
Contamination in the hole.
103
Top side of the hole covered by component body or flashing.
104
You can see an example of a solder void here.
105
Another fault is solder skip.
106
Now what to check for?
107
Conveyor speeds too fast.
108
so the dwell was too short in the wave.
109
Make sure the chip or turbine wave is turned on.
110
Not enough flux for the solder to bond.
111
Wave height too low on one or both waves.
112
You can clearly see here this pad has no solder at all.
113
Another fault is icicles or flags or horns.
114
Now what to check for?
115
conveyor speeds too slow.
116
Time over preheat too long causing flux to burn off.
117
Dwell time too long causing flux to be destroyed before exiting to the wave.
118
Solar temperature too low, not enough flux.
119
The use of nitrogen will help prevent icicles.
120
You can see a good example here of what we're talking about when we mention solar flags.
121
Another fault is solder on mask Poor flux application Flux and resist incompatibility Poor cure of the solder mask
122
Preheat temperatures too high Solder temperature too high This image just shows the solder on the mask itself
123
another fault is rough or disturbed solder check conveyor for vibration or jerky motion
124
removal of the board prior to the solder solidifying solder temperature too low conveyor speed too high and wave run uneven
125
you can see what we're talking about with rough solder in this image
126
just to summarize here's an image of some common faults I'm
127
just going to go through these with the top left moving to the right
128
so we've got lifted component we've got tombstone effect
129
wrong polarity upside down mounting in the second row we have a missing component
130
we have that missing solder that we saw earlier we have a lifted lead
131
we've got that solder bridging again
132
on the bottom row we've got billboarding then we have shifted or twisted component we have our solder flags again
133
and that solder void
134
don't forget to check out our other videos in this PCB series
135
and you can contact us if you need any help with your projects at all in China.
136
Don't forget to like, share and subscribe to our channel.
137
And you see there's a little bell symbol.
138
If you hit that, you'll get a notification every time we upload new content.
139
Thanks for listening.
140
My name is Paul Adams from South East and I shall see you in the next video.
הורד אפליקציה
כל מה שאתה צריך כדי לדבר בשטף
הגיית AIציון לכל משפט
תרגול IPAשלוט בכל צליל
אוצר מיליםבנה את מאגר המילים שלך
משחק אוצר מיליםלמד תוך כדי משחק
אותו ערוץ
C17
What is SMT (Surface Mount Technology)? PCB Assembly (Part 2)
Business EnglishWorking Adults
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
C13
NPI Process 1: Why A Pilot Run Before Mass Production Is Very Useful
Business EnglishWorking Adults
C16
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
המלץ על סרטון
C11
128 משפטים
Fire Pump Monthly Churn Test
Daily ConversationWorking Adults
C15
94 משפטים
Your AI broke the layout. Now what?
Daily ConversationWorking Adults
C158 משפטים
Repairing Big Dents with Body Filler: Full Auto Body Tutorial
Daily ConversationWorking Adults
C15
188 משפטים
Fix your Trousers Fitting Issues | Body Specific Adjustments (Part 1)
Daily ConversationWorking Adults
C141 משפטים
🚨 Most organizations don't fail ISO/IEC 27001 because they don't understand the standard...
Daily ConversationWorking Adults
C15
123 משפטים
QC 7 tools – Cause and Effect Analysis (Fishbone) Diagram Introduction
Daily ConversationWorking Adults
C14
39 משפטים
How to Avoid Common Mistakes During Insertion in Colonoscopy (Using the Olympus CM-15 Colon Phantom)
Daily ConversationWorking Adults
C11
19 משפטים
I Made an EMP Device... It Actually Works
Daily ConversationUniversity StudentsWorking Adults
C12
43 משפטים
SDLC Vs STLC: Software Development Life Cycle and Software Testing Life Cycle
Daily ConversationUniversity StudentsWorking Adults
C11
181 משפטים
Aircraft General Knowledge | PPL Expert Online Ground School FREE Sample
Daily ConversationWorking Adults
אוצר מילים והערות הגייה לשיעור הזה
שיעור הדיבור הזה ברמה C1 מבוסס על הסרטון “PCB Inspection Methods & Common PCB Defects”. המילים שחוזרות הכי הרבה: solder, wave, flux, nozzle, paste. בסרטון הזה יש 140 משפטים ו-1559 מילים לתרגול Shadowing. הדיבור נמשך 12:27. הדובר שומר על קצב יציב של כ-125 מילים בדקה, קצב נוח לתרגול Shadowing. רק 76% מהמילים נמצאות בין 3,000 המילים הנפוצות ביותר באנגלית, כך שאוצר המילים מאתגר.
אוצר מילים מרכזי בסרטון הזה
15 המילים המתקדמות ביותר בסרטון, עם ההגייה והמשמעות שלהן:
| מילה | הגייה | משמעות |
|---|---|---|
| solder שם עצם | /ˈsɒl.də(ɹ)/ | לחם |
| nozzle שם עצם | /ˈnɒzəl/ | מַזְנֵק |
| pasta שם עצם | /ˈpɑ.stə/ | פַּסְטָה |
| stencil שם עצם | /ˈstɛnsəl/ | סְטֶנְסִיל, שַׁבְּלוֹנָה |
| squeegee שם עצם | /ˈskwiˌd͡ʒi/ | מַגֵּב |
| vacuum שם עצם | /ˈvæ.kjuːm/ | ואקום, ריק |
| contamination שם עצם | /kənˌtæm.əˈneɪ.ʃən/ | קוֹנְטֶמִינֶצְיָה |
| tolerance שם עצם | /ˈtɑ.lə.ɹəns/ | סובלנות |
| connector שם עצם | /kəˈnɛktɚ/ | מחבר |
| summarize פועל | /ˈsʌməˌɹaɪz/ | סיכם |
| tombstone שם עצם | /ˈtuːmstoʊn/ | מַצֵּבָה |
| disturb פועל | /dɪˈstɜːb/ | הפריע |
| vibration שם עצם | /vaɪˈbɹeɪʃən/ | תנודה, ריטוט |
| turbine שם עצם | /ˈtɜː.baɪn/ | טוּרְבִּינָה |
| defect שם עצם | /ˈdiːfɛkt/ | פגם |
Phrasal verbs שתשמעו
| מילה | משמעות |
|---|---|
| check out פועל | בדק |
הגייה ששווה לשים לב אליה
הדובר משתמש ב-12 קיצורים וצורות מקוצרות, כמו we've, we're, don't. אמרו אותם בצורה הקצרה, כפי שאתם שומעים אותם.
- הצלילים של “sh” ו-“zh”: insufficient /ɪnsəˈfɪʃənt/, contamination /kənˌtæm.əˈneɪ.ʃən/, fabrication /fæbɹɪˈkeɪʃən/, vibration /vaɪˈbɹeɪʃən/, degradation /ˌdɛɡɹəˈdeɪʃən/
- מילים ארוכות — שימו לב להטעמה: insufficient /ɪnsəˈfɪʃənt/, contaminate /kənˈtæmɪneɪt/, contamination /kənˌtæm.əˈneɪ.ʃən/, contaminant /kənˈtamɪnənt/, fabrication /fæbɹɪˈkeɪʃən/
צלילים שדוברי עברית מתקשים בהם:
- /w/ — שפתיים מעוגלות, לא /v/: dwell /dwɛl/, squeegee /ˈskwiˌd͡ʒi/, adequate /ˈæd.ə.kwɪt/
- /æ/ — פתוח יותר מה-“אֶ” העברית, לא כמו “a” ב-“cup”: pad /pæd/, vacuum /ˈvæ.kjuːm/, aperture /ˈæp.ɚˌt͡ʃʊɹ/, contaminate /kənˈtæmɪneɪt/, contamination /kənˌtæm.əˈneɪ.ʃən/
- /r/ — הלשון לא נוגעת בשום מקום, לא ה-“ר” הגרונית: solder /ˈsɒl.də(ɹ)/, incorrect /ˌɪn.kəˈɹɛkt/, preheat /pɹiːˈhiːt/, reflective /ɹɪˈflɛktɪv/, aperture /ˈæp.ɚˌt͡ʃʊɹ/
איך לתרגל עם הסרטון הזה
- הקשיבו לכל הסרטון פעם אחת בלי לדבר, ורשמו את המילים שאתם לא מכירים.
- תרגלו Shadowing משפט אחר משפט במהירות רגילה, וחזרו על כל משפט עד שהקצב שלכם תואם את הדובר.
- הקליטו את עצמכם והשוו למקור, תוך תשומת לב למילים כמו solder, nozzle, pasta.
מהי טכניקת השאדואינג?
שאדואינג היא טכניקת למידת שפה מבוססת מדע שפותחה במקור להכשרת מתורגמנים מקצועיים ופופולרית על ידי הפוליגלוט ד"ר אלכסנדר ארגואלס. השיטה פשוטה אך עוצמתית: אתה מקשיב לאודיו באנגלית ילידית וחוזר עליו בקול רם מיד — כמו צל העוקב אחרי הדובר עם עיכוב של 1–2 שניות בלבד. בניגוד להאזנה פסיבית או תרגילי דקדוק, שאדואינג מכריח את המוח והשרירים בפה לעבד ולשחזר דפוסי דיבור אמיתיים בו זמנית. מחקרים מראים שזה משפר משמעותית את דיוק ההגייה, האינטונציה, הקצב, הדיבור המחובר, הבנת השמיעה ושטף הדיבור — מה שהופך אותו לאחת השיטות היעילות ביותר להכנה לIELTS Speaking ולתקשורת באנגלית בעולם האמיתי.