Tech-dat/waterproof-dat/waterproof-dat.md
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@@ -25,6 +25,10 @@
25 25
26 26
- [[SMO1085-dat]]
27 27
28
+- [[led-strip-dat]]
29
+
30
+
31
+
28 32
## waterproof level
29 33
30 34
- IP69
engineering-dat/PCB-potted-dat/2025-12-13-18-12-22.png
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Binary files /dev/null and b/engineering-dat/PCB-potted-dat/2025-12-13-18-12-22.png differ
engineering-dat/PCB-potted-dat/PCB-potted-dat.md
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1
+
2
+# PCB-potted-dat
3
+
4
+![](2025-12-13-18-12-22.png)
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+
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+
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+
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+
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+
10
+
11
+## ref
12
+
13
+- [[engineering-dat]]
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\ No newline at end of file
engineering-dat/electrochemical-corrosion-dat/electrochemical-corrosion-dat.md
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1
+# electrochemical-corrosion-dat
2
+
3
+
4
+- [[oil-mineral-dat]] - [[oil-soaking-dat]]
5
+
6
+## What actually works (ranked by effectiveness)
7
+
8
+✅ 1. Remove the water source (most critical)
9
+
10
+Vacuum bake PCB before coating (e.g. 80–100 °C, many hours)
11
+
12
+Dry mineral oil before use
13
+
14
+Seal the oil container
15
+
16
+Without this, no coating will succeed.
17
+
18
+✅ 2. Eliminate wet components
19
+
20
+Replace electrolytic capacitors with:
21
+
22
+Solid polymer capacitors
23
+
24
+Ceramic capacitors
25
+
26
+This alone often stops the problem.
27
+
28
+✅ 3. Use a true moisture barrier (if immersion is required)
29
+
30
+Conformal coatings are insufficient. Better options:
31
+
32
+Parylene (C) coating (near-hermetic)
33
+
34
+Fully potted power section (epoxy or silicone gel)
35
+
36
+- [[PCB-potted-dat]] - [[oil-soaking-dat]]
37
+
38
+
39
+## 4. Oil immersion changes coating behavior
40
+
41
+In mineral oil:
42
+- Coatings can swell or soften
43
+- Adhesion to copper decreases
44
+- Micro-cracks form (not visible)
45
+
46
+These micro-paths are enough for ion migration.
47
+
48
+---
49
+
50
+## 5. Why green deposits can appear “on top” of coating
51
+
52
+What often happens:
53
+- Copper ions migrate under the coating
54
+- They precipitate at coating defects or edges
55
+- The deposit appears external, but origin is beneath
56
+
57
+---
58
+
59
+## 6. This confirms the dominant mechanism
60
+
61
+This behavior strongly confirms:
62
+```text
63
+Electrochemical Migration (ECM)
64
+driven by:
65
+- trapped moisture
66
+- continuous DC bias
67
+- electrolyte vapor from capacitors
68
+```
69
+
70
+
71
+
72
+## Unsealed oil = moisture absorption (major cause)
73
+
74
+Since the oil is not sealed:
75
+
76
+Mineral oil slowly absorbs moisture from air
77
+
78
+Humidity continuously diffuses into the oil
79
+
80
+Daily temperature changes cause condensation
81
+
82
+⚠️ This creates a persistent micro-electrolyte environment.
83
+
84
+
85
+
86
+
87
+**This is very likely NOT classic electrolysis.**
88
+It is most likely **electrochemical corrosion combined with ion migration**, caused by **trace water and contaminants** in the mineral oil, and it is **most visible at the power-supply area**.
89
+
90
+---
91
+
92
+## Overview
93
+
94
+The green buildup observed on PCBs immersed in mineral oil is primarily a form of copper corrosion driven by electrochemical processes enabled by trace moisture and contaminants. It is most apparent near the power input where electric fields and current densities are high.
95
+
96
+---
97
+
98
+## 1. Why does green residue appear?
99
+
100
+Green deposits on PCBs are **typically copper corrosion products**, such as:
101
+
102
+- Basic copper carbonate (verdigris)
103
+- Copper oxides / hydroxides
104
+- Copper salts
105
+- Copper soaps (reaction between copper and degraded oil additives)
106
+
107
+These deposits commonly appear:
108
+- Green or blue-green in color
109
+- Powdery or paste-like in texture
110
+
111
+---
112
+
113
+## 2. Can mineral oil itself undergo electrolysis?
114
+
115
+**Pure mineral oil cannot be electrolyzed**, because it:
116
+- Is non-polar
117
+- Is electrically insulating
118
+- Contains no free ions
119
+
120
+However, **real systems are never perfectly pure** — trace water and contaminants can enable electrochemical reactions.
121
+
122
+---
123
+
124
+## 3. Key real-world causes (most important)
125
+
126
+### 3.1 Trace moisture (critical factor)
127
+
128
+Even very small amounts of water can come from:
129
+- Air humidity
130
+- Cable interfaces and connectors
131
+- Leakage or outgassing from electrolytic capacitors
132
+- Moisture absorbed by PCB materials
133
+
134
+Once **water + voltage + metal** are present,
135
+**electrochemical reactions become possible**.
136
+
137
+---
138
+
139
+### 3.2 Strong electric field at the power section
140
+
141
+The issue is often **at the power input**, which is typical because:
142
+- Voltage is highest
143
+- Current density is highest
144
+- Electric field gradient is strongest
145
+
146
+This promotes:
147
+- **Electrochemical Migration (ECM)**
148
+- Localized corrosion
149
+
150
+This is similar in mechanism to electrolysis, but **not a true electrolyte bath**.
151
+
152
+---
153
+
154
+### 3.3 Mineral oil contamination and aging
155
+
156
+Over long-term immersion:
157
+- Mineral oil can oxidize slowly
158
+- Sulfur compounds or organic acids may form
159
+- These react with copper surfaces
160
+
161
+Result:
162
+- Formation of green copper compounds
163
+
164
+---
165
+
166
+## 4. Is this electrolysis?
167
+
168
+Strictly speaking:
169
+
170
+❌ **Not electrolysis in pure mineral oil**
171
+✅ **Electrochemical corrosion + ion migration enabled by moisture and contaminants**
172
+
173
+Common engineering terms:
174
+```text
175
+Electrochemical corrosion
176
+Electrochemical Migration (ECM)
177
+Copper corrosion in insulating oil
178
+```
179
+
180
+---
181
+
182
+## 5. Why is the residue green?
183
+
184
+Because PCB traces and pads are mainly copper, and copper corrosion products are naturally green or blue-green.
185
+
186
+---
187
+
188
+## 6. Is it dangerous or progressive?
189
+
190
+⚠️ Yes, it can worsen if left untreated.
191
+
192
+Possible risks:
193
+- Continued corrosion
194
+- Conductive dendrite growth
195
+- Increased contact resistance
196
+- Leakage currents
197
+- Short circuits
198
+
199
+Risk is highest under continuous power and in sealed oil immersion where moisture and contaminants persist.
200
+
201
+---
202
+
203
+## 7. Mitigation (high-level, safe recommendations)
204
+
205
+- Avoid exposed bare copper
206
+- Apply conformal coating on critical areas
207
+- Minimize moisture ingress (sealed system)
208
+- Thoroughly dry PCBs before immersion
209
+- Use electronics-grade mineral oil or transformer oil
210
+
211
+---
212
+
213
+## Summary
214
+
215
+The green buildup is not classic electrolysis, but moisture-enabled electrochemical corrosion that is intensified at the power section. Drying, contamination control, and protective coatings reduce risk and slow or prevent progression.
engineering-dat/engineering-dat.md
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1
+
2
+# engineering-dat
3
+
4
+- [[oil-soaking-dat]] - [[electrochemical-corrosion-dat]]
5
+
6
+- [[PCB-potted-dat]]
7
+
8
+## ref
9
+
10
+- [[mechanics-dat]] - [[tech-dat]]
11
+
12
+
13
+- [[engineering]]
14
+
engineering-dat/oil-soaking-dat/2025-12-04-00-46-41.png
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engineering-dat/oil-soaking-dat/oil-soaking-dat.md
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1
+
2
+# oil-soaking-dat.md
3
+
4
+
5
+- [[electrochemical-corrosion-dat]]
6
+
7
+## power burned
8
+
9
+![](2025-12-04-00-46-41.png)
10
+
11
+
12
+It looks like your 12V camera, after being soaked in mineral oil for a while, fails to start up after being powered off and on again.
13
+
14
+This situation is very common in electronics "oil immersion" experiments. Let me help you analyze the most likely causes and troubleshooting methods.
15
+
16
+✅ Why does soaking in mineral oil cause startup failure?
17
+
18
+1. Oil enters the interior, causing poor heat dissipation → Chip overheating and damage
19
+
20
+Mineral oil is insulating, but its heat dissipation is worse than air.
21
+Inside the camera, there are usually:
22
+
23
+- Image sensor (CMOS)
24
+- ISP chip
25
+- DC-DC power supply
26
+- Voltage regulator IC
27
+
28
+These components are already prone to heating. After oil immersion, the temperature rises, which may cause:
29
+
30
+- Chip solder balls to fall off (especially BGA packages)
31
+- Voltage regulator damage
32
+- Capacitors aging due to long-term overheating
33
+
34
+👉 Symptoms: The camera lights up for a few seconds after powering on, then slowly goes dark or doesn't light up at all.
35
+
36
+2. Oil dissolves certain materials → Causes short circuits or failure
37
+
38
+Although mineral oil is insulating, it is not friendly to some component materials:
39
+
40
+- Rubber seals may swell and soften → Oil seeps into the lens and sensor area
41
+- Some plastic housings may soften → Component displacement
42
+- Thermal paste / thermal grease dissolves → Chips lose heat dissipation path
43
+- Adhesive for lens attachment swells → Lens shifts or even falls off
44
+
45
+👉 Lens misalignment can also cause the camera to fail to start (auto-calibration fails).
46
+
47
+3. Oil enters connectors → Poor contact
48
+
49
+Typical examples:
50
+
51
+- FPC (flex cable) connectors get oil inside → Poor contact of spring contacts
52
+- Lens module to mainboard interface gets oil → Abnormal resistance values
53
+- DC plug / solder joints get oil in the gaps → Increased contact resistance
54
+
55
+👉 Symptoms: Completely dark, almost no current flows, or current instantly drops to 0 when plugged in.
56
+
57
+4. Electrolytic capacitors affected by oil (severe cases)
58
+
59
+Although mineral oil is non-conductive, long-term soaking can cause the rubber seal of electrolytic capacitors to age, leading to:
60
+
61
+- Internal electrolyte evaporation
62
+- Capacitor ESR increases → Unstable power supply
63
+
64
+Cannot power on or keeps rebooting
65
+
66
+🔍 Troubleshooting you can do (safe, non-destructive)
67
+
68
+① Measure the power-on current (most important)
69
+
70
+If you have a multimeter, measure the camera's current:
71
+
72
+| Current Behavior | Suspected Fault |
73
+|------------------------------------|----------------------------------------|
74
+| 0 mA | Interface open, fuse blown, DC/DC front-end failure |
75
+| Power on: tens of mA → drops to 0 | Startup failure/auto-protection |
76
+| Stable 200–300 mA, no change | Chip short circuit/internal damage |
77
+| Regular 100–200 mA fluctuations | Unstable power, capacitor ESR increased|
78
+
79
+② Low-temperature drying
80
+
81
+Although mineral oil does not evaporate, a layer of oil may remain on the PCB and affect contact.
82
+
83
+You can:
84
+
85
+- Use a napkin to absorb surface oil
86
+- Place in a 40–50°C environment for 24 hours to slowly remove oil
87
+ (Do not exceed 60°C, or plastic parts may deform)
88
+
89
+③ Clean flex cables and connectors
90
+
91
+The most vulnerable part is the "flex cable + connector".
92
+
93
+Method:
94
+
95
+- Remove the flex cable
96
+- Clean the cable's gold fingers with isopropyl alcohol (IPA)
97
+- Gently blow air into the connector, let it dry
98
+- Reinsert
99
+
100
+80% of "oil immersion failures" in cameras are caused by poor flex cable contact.
101
+
102
+④ Open and check if the lens module has oil ingress
103
+
104
+If the lens group has oil inside:
105
+
106
+- Internal blades will be contaminated by oil
107
+- Optical module cannot work properly
108
+- Sensor cannot initialize → Camera does not power on or freezes
109
+
110
+💡 If you like, I can continue to help you:
111
+
112
+Please tell me the current when you power on.
113
+For example:
114
+
115
+- 0 mA
116
+- 0 → 200 mA → 0
117
+- Stable 150 mA
118
+- Irregular fluctuations
119
+
120
+As long as you provide the power-on current, I can further determine if it is:
121
+
122
+- Power stage failure
123
+- Connector contact issue
124
+- Sensor module damage
125
+- Chip overheating damage
126
+- DC-DC power instability
127
+
128
+
129
+## ref
130
+
131
+- [[oil-mineral-dat]]
... ...
\ No newline at end of file
mechanics-dat/oil-mineral-dat/2025-12-04-00-46-41.png
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mechanics-dat/oil-mineral-dat/oil-soaking-dat.md
... ...
@@ -1,131 +0,0 @@
1
-
2
-# oil-soaking-dat.md
3
-
4
-
5
-
6
-
7
-## power burned
8
-
9
-![](2025-12-04-00-46-41.png)
10
-
11
-
12
-It looks like your 12V camera, after being soaked in mineral oil for a while, fails to start up after being powered off and on again.
13
-
14
-This situation is very common in electronics "oil immersion" experiments. Let me help you analyze the most likely causes and troubleshooting methods.
15
-
16
-✅ Why does soaking in mineral oil cause startup failure?
17
-
18
-1. Oil enters the interior, causing poor heat dissipation → Chip overheating and damage
19
-
20
-Mineral oil is insulating, but its heat dissipation is worse than air.
21
-Inside the camera, there are usually:
22
-
23
-- Image sensor (CMOS)
24
-- ISP chip
25
-- DC-DC power supply
26
-- Voltage regulator IC
27
-
28
-These components are already prone to heating. After oil immersion, the temperature rises, which may cause:
29
-
30
-- Chip solder balls to fall off (especially BGA packages)
31
-- Voltage regulator damage
32
-- Capacitors aging due to long-term overheating
33
-
34
-👉 Symptoms: The camera lights up for a few seconds after powering on, then slowly goes dark or doesn't light up at all.
35
-
36
-2. Oil dissolves certain materials → Causes short circuits or failure
37
-
38
-Although mineral oil is insulating, it is not friendly to some component materials:
39
-
40
-- Rubber seals may swell and soften → Oil seeps into the lens and sensor area
41
-- Some plastic housings may soften → Component displacement
42
-- Thermal paste / thermal grease dissolves → Chips lose heat dissipation path
43
-- Adhesive for lens attachment swells → Lens shifts or even falls off
44
-
45
-👉 Lens misalignment can also cause the camera to fail to start (auto-calibration fails).
46
-
47
-3. Oil enters connectors → Poor contact
48
-
49
-Typical examples:
50
-
51
-- FPC (flex cable) connectors get oil inside → Poor contact of spring contacts
52
-- Lens module to mainboard interface gets oil → Abnormal resistance values
53
-- DC plug / solder joints get oil in the gaps → Increased contact resistance
54
-
55
-👉 Symptoms: Completely dark, almost no current flows, or current instantly drops to 0 when plugged in.
56
-
57
-4. Electrolytic capacitors affected by oil (severe cases)
58
-
59
-Although mineral oil is non-conductive, long-term soaking can cause the rubber seal of electrolytic capacitors to age, leading to:
60
-
61
-- Internal electrolyte evaporation
62
-- Capacitor ESR increases → Unstable power supply
63
-
64
-Cannot power on or keeps rebooting
65
-
66
-🔍 Troubleshooting you can do (safe, non-destructive)
67
-
68
-① Measure the power-on current (most important)
69
-
70
-If you have a multimeter, measure the camera's current:
71
-
72
-| Current Behavior | Suspected Fault |
73
-|------------------------------------|----------------------------------------|
74
-| 0 mA | Interface open, fuse blown, DC/DC front-end failure |
75
-| Power on: tens of mA → drops to 0 | Startup failure/auto-protection |
76
-| Stable 200–300 mA, no change | Chip short circuit/internal damage |
77
-| Regular 100–200 mA fluctuations | Unstable power, capacitor ESR increased|
78
-
79
-② Low-temperature drying
80
-
81
-Although mineral oil does not evaporate, a layer of oil may remain on the PCB and affect contact.
82
-
83
-You can:
84
-
85
-- Use a napkin to absorb surface oil
86
-- Place in a 40–50°C environment for 24 hours to slowly remove oil
87
- (Do not exceed 60°C, or plastic parts may deform)
88
-
89
-③ Clean flex cables and connectors
90
-
91
-The most vulnerable part is the "flex cable + connector".
92
-
93
-Method:
94
-
95
-- Remove the flex cable
96
-- Clean the cable's gold fingers with isopropyl alcohol (IPA)
97
-- Gently blow air into the connector, let it dry
98
-- Reinsert
99
-
100
-80% of "oil immersion failures" in cameras are caused by poor flex cable contact.
101
-
102
-④ Open and check if the lens module has oil ingress
103
-
104
-If the lens group has oil inside:
105
-
106
-- Internal blades will be contaminated by oil
107
-- Optical module cannot work properly
108
-- Sensor cannot initialize → Camera does not power on or freezes
109
-
110
-💡 If you like, I can continue to help you:
111
-
112
-Please tell me the current when you power on.
113
-For example:
114
-
115
-- 0 mA
116
-- 0 → 200 mA → 0
117
-- Stable 150 mA
118
-- Irregular fluctuations
119
-
120
-As long as you provide the power-on current, I can further determine if it is:
121
-
122
-- Power stage failure
123
-- Connector contact issue
124
-- Sensor module damage
125
-- Chip overheating damage
126
-- DC-DC power instability
127
-
128
-
129
-## ref
130
-
131
-- [[oil-mineral-dat]]
... ...
\ No newline at end of file