Cynwysyddion Electrolytig ESR Isel ▏6.3 ~ 100V ▏4,000 ~ 7,000Hrs |CADE
Bywyd hir, 105℃, 4,000 ~ 7,000 oriau sicr
ESR isel, addas ar gyfer newid cyflenwadau pŵer
Smallersize gyda largepermissibleripplecurrent
MANYLEBAU
Eitem | Perfformiad | ||||||||||
Temp Gweithredu | -55° C ~ + 105 ° C. | ||||||||||
Toloerance Capacitance | ± 20% (120Hz, 20° C) | ||||||||||
gollyngiadau cyfredol (ar 20 ° C.) | I = 0.01CV neu 3 (mA) pa un bynnag sydd fwyaf (ar ôl 2 munudau) Lle, C = cynhwysedd graddedig yn mF. V = foltedd gweithio DC â sgôr yn V.. | ||||||||||
Ffactor Dissipation Tan ceirch 120Hz, 20° C |
Foltedd Rated | 6.3 | 10 | 16 | 25 | 35 | 50 | 63 | 100 | ||
Felly neu(mwyafswm) | 0.22 | 0.19 | 0.16 | 0.14 | 0.12 | 0.10 | 0.09 | 0.08 | |||
Pan fydd y cynhwysedd yn fwy na 1000mF, 0.02 yn cael ei ychwanegu bob cynnydd o 1000mF. | |||||||||||
Tymheredd Isel Nodweddion (ar 120Hz) |
Foltedd Rated | 6.3 | 10 | 16 | 25 | 35 | 50 | 63 | 100 | ||
GYDA(-25° C)/GYDA(+20° C) | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | |||
Ni fydd cymhareb rhwystriant yn fwy na'r gwerthoedd a roddir yn y tabl. | |||||||||||
Llwytho Prawf Bywyd |
Amser Prawf |
4,000 oriau ar gyfer φD≤6.3mm 5,000 oriau ar gyfer φD = 8mm 6,000 oriau ar gyfer φD = 10mm 7,000 oriau ar gyfer φD≥12.5mm | |||||||||
cynhwysiant Newid | O fewn ± 25% o'r gwerth cychwynnol | ||||||||||
hoferedd Ffactor | Llai na 200% o werth penodedig | ||||||||||
gollyngiadau cyfredol | O fewn gwerth penodedig | ||||||||||
Bodlonir neuadd y manylebau uchod pan fydd y cynwysyddion yn cael eu hadfer i 20 ° C ar ôl y cerrynt crychdonni graddedig ar gyfer 4,000 ~ 7,000 awr ar 105 ° C.. | |||||||||||
Prawf Bywyd Silff |
Amser Prawf | 1,000 oriau | |||||||||
cynhwysiant Newid | O fewn ± 25% o'r gwerth cychwynnol | ||||||||||
hoferedd Ffactor | Llai na 200% o werth penodedig | ||||||||||
gollyngiadau cyfredol | O fewn gwerth penodedig | ||||||||||
Bodlonir y manylebau uchod pan adferir y cynwysyddion i 20 ° C ar ôl eu datgelu 1,000 oriau ar 105 ° C heb foltedd wedi'i gymhwyso. | |||||||||||
Ripple Cerrynt & Lluosyddion Amledd |
Freq. (Hz)
Cap. (mF) |
120 |
1K. |
10K. |
100K i fyny |
||||||
Dan ~ 33 | 0.42 | 0.70 | 0.90 | 1.0 | |||||||
39 ~ 270 | 0.50 | 0.73 | 0.92 | 1.0 | |||||||
330 ~ 680 | 0.55 | 0.77 | 0.94 | 1.0 | |||||||
820 ~ 1,800 | 0.60 | 0.80 | 0.96 | 1.0 | |||||||
2,200 ~ 15,000 | 0.70 | 0.85 | 0.98 | 1.0 | |||||||
Safonau | Boddhad Nodweddion JIS C. 5101-4 |
DIMENSIYNAU
φD | 5 | 6.3 | 8 | 10 | 12.5 | 16 | 18 |
P. | 2.0 | 2.5 | 3.5 | 5.0 | 5.0 | 7.5 | 7.5 |
φd | 0.5 | 0.6 | 0.8 | ||||
a | 1.0 | 1.5 | |||||
b | 0.5 |
DIMENSIYNAU & PERMISSIBLE RIPPLE PRESENNOL
VDC
Eitem
μF |
6.3V (0J.) | 10V (1A) | 16V (1C) | 25V (1E.) | ||||||||||||
φDx L. |
Rhwystr
(Ω, Max / 100KHz) |
Ripple Cerrynt (mA / rms, 105° C) |
φDx L. |
Rhwystr (Ω,
Max / 100KHz) |
Ripple Cerrynt (mA / rms, 105° C) |
φDx L. |
Rhwystr
(Ω, Max / 100KHz) |
Ripple Cerrynt (mA / rms, 105° C) |
φDx L. |
Rhwystr
(Ω, Max / 100KHz) |
Ripple Cerrynt (mA / rms, 105° C) | |||||
20° C | -10° C | 100kHz | 20° C | -10° C | 100kHz | 20° C | -10° C | 100kHz | 20° C | -10° C | 100kHz | |||||
4.7 | 5 x 11 | 0.6 | 1.2 | 180 | ||||||||||||
10 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 0.6 | 1.2 | 180 | ||||||||
22 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 0.6 | 1.2 | 180 |
33 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 0.6 | 1.2 | 180 |
39 | 5 x 11 | 0.6 | 1.2 | 180 | ||||||||||||
47 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 0.6 | 1.2 | 180 |
56 | 5 x 11 | 0.6 | 1.2 | 180 | ||||||||||||
82 | 5 x 11 | 0.6 | 1.2 | 180 | 6.3 x 11 | 0.25 | 0.5 | 290 | ||||||||
100 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 0.6 | 1.2 | 180 | 6.3 x 11 | 0.25 | 0.5 | 290 | 6.3 x 11 | 0.25 | 0.5 | 290 |
120 | 6.3 x 11 | 0.25 | 0.5 | 290 | 6.3 x 15 | 0.23 | 0.46 | 430 | ||||||||
150 | 6.3 x 11 | 0.25 | 0.5 | 290 | 6.3 x 11 | 0.25 | 0.5 | 290 | 6.3 x 11 | 0.29 | 0.5 | 290 | 8 x 11.5 | 0.117 | 0.234 | 555 |
180 | 6.3 x 11 | 0.25 | 0.5 | 290 | 6.3 x 15 | 0.23 | 0.46 | 430 | ||||||||
220 |
6.3 x 11 | 0.25 | 0.5 | 290 | 6.3 x 11 | 0.25 | 0.5 | 290 | 8 x 11.5 | 0.117 | 0.234 | 555 | 8 x 11.5 | 0.117 | 0.234 | 555 |
6.3 x 15 | 0.23 | 0.46 | 430 | |||||||||||||
330 |
6.3 x 11 | 0.25 | 0.500 | 290 | 8 x 11.5 | 0.117 | 0.234 | 555 | 8 x 11.5 | 0.117 | 0.234 | 555 | 10 x 12.5 | 0.090 | 0.18 | 755 |
6.3 x 15 | 0.23 | 0.46 | 430 | 8 x 15 | 0.085 | 0.17 | 730 | |||||||||
470 | 8 x 11.5 | 0.117 | 0.234 | 555 | 8 x 11.5 | 0.117 | 0.234 | 555 | 10 x 12.5 | 0.090 | 0.18 | 755 | 10 x 16 | 0.068 | 0.136 | 1,050 |
8 x 15 | 0.085 | 0.17 | 730 | 8 x 20 | 0.065 | 0.130 | 995 | |||||||||
560 | 8 x 11.5 | 0.117 | 0.234 | 555 | 10 x 20 | 0.052 | 0.104 | 1,220 | ||||||||
680 |
10 x 12.5 | 0.090 | 0.180 | 755 | 10 x 12.5 | 0.090 | 0.180 | 755 | 10 x 16 | 0.068 | 0.136 | 1,050 | 10 x 20 | 0.052 | 0.104 | 1,220 |
8 x 15 | 0.085 | 0.170 | 730 | 8 x 20 | 0.065 | 0.130 | 995 | |||||||||
820 |
8 x 15 | 0.085 | 0.170 | 730 | 10 x 20 | 0.052 | 0.104 | 1,220 | 10 x 25 | 0.045 | 0.090 | 1,440 | ||||
10 x 12.5 | 0.090 | 0.180 | 755 | |||||||||||||
1,000 |
10 x 12.5 | 0.090 | 0.180 | 755 | 10 x 16 | 0.068 | 0.136 | 1,050 | 10 x 20 | 0.052 | 0.104 | 1,220 | 12.5 x 20 | 0.038 | 0.076 | 1,655 |
8 x 20 | 0.065 | 0.130 | 995 | 10 x 30 | 0.035 | 0.070 | 1,815 | |||||||||
1,200 |
8 x 20 | 0.065 | 0.130 | 955 | 10 x 20 | 0.052 | 0.104 | 1,220 | 10 x 25 | 0.045 | 0.090 | 1,440 | ||||
10 x 16 | 0.068 | 0.136 | 1,050 | |||||||||||||
1,500 |
10 x 20 | 0.052 | 0.104 | 1,220 | 10 x 20 | 0.052 | 0.104 | 1,220 | 12.5 x 20 | 0.038 | 0.076 | 1,655 | 16 x 25 | 0.022 | 0.044 | 2,555 |
10 x 25 | 0.045 | 0.090 | 1,440 | 10 x 30 | 0.035 | 0.070 | 1,815 | 12.5 x 25 | 0.030 | 0.060 | 1,945 | |||||
12.5 x 30 | 0.025 | 0.050 | 2,310 | |||||||||||||
1,800 | 16 x 20 | 0.029 | 0.058 | 2,205 | ||||||||||||
2,200 |
10 x 25 | 0.045 | 0.090 | 1,440 | 12.5 x 20 | 0.038 | 0.076 | 1,655 | 12.5 x 25 | 0.030 | 0.060 | 1,945 | 16 x 25 | 0.022 | 0.044 | 2,555 |
12.5 x 20 | 0.038 | 0.076 | 1,815 | 10 x 30 | 0.035 | 0.070 | 1,815 | 18 x 20 | 0.028 | 0.056 | 2,490 | |||||
12.5 x 35 | 0.022 | 0.044 | 2,510 | |||||||||||||
10 x 30 | 0.035 | 0.070 | 1,815 | 12.5 x 25 | 0.030 | 0.060 | 1,945 | 12.5 x 30 | 0.025 | 0.050 | 2,310 | 16 x 25 | 0.022 | 0.044 | 2,555 | |
2,700 | 16 x 20 | 0.029 | 0.058 | 2,205 | ||||||||||||
3,300 |
12.5 x 20 | 0.038 | 0.076 | 1,655 | 12.5 x 25 | 0.030 | 0.060 | 1,945 | 16 x 25 | 0.022 | 0.044 | 2,555 | 16 x 31.5 | 0.018 | 0.036 | 3,010 |
12.5 x 30 | 0.025 | 0.050 | 2,310 | 12.5 x 35 | 0.022 | 0.044 | 2,510 | 18 x 25 | 0.020 | 0.040 | 2,740 | |||||
3,900 |
12.5 x 25 | 0.030 | 0.060 | 1,945 | 12.5 x 35 | 0.022 | 0.044 | 2,510 | 16 x 25 | 0.022 | 0.044 | 2,555 | 16 x 35.5 | 0.016 | 0.032 | 3,150 |
16 x 20 | 0.029 | 0.058 | 2,205 | 18 x 20 | 0.028 | 0.056 | 2,490 | 18 x 31.5 | 0.016 | 0.032 | 3,635 | |||||
4,700 |
16 x 25 | 0.022 | 0.044 | 2,555 | 16 x 25 | 0.022 | 0.044 | 2,555 | 16 x 31.5 | 0.018 | 0.036 | 3,010 | 18 x 35.5 | 0.015 | 0.030 | 3,680 |
12.5 x 30 | 0.025 | 0.050 | 2,310 | 18 x 25 | 0.020 | 0.040 | 2,740 | |||||||||
5,600 |
12.5 x 35 | 0.022 | 0.044 | 2,510 | 16 x 25 | 0.022 | 0.044 | 2,555 | 18 x 35.5 | 0.016 | 0.032 | 3,150 | ||||
16 x 20 | 0.029 | 0.058 | 2,205 | 18 x 20 | 0.028 | 0.056 | 2,490 | 18 x 31.5 | 0.016 | 0.032 | 3,635 | |||||
6,800 |
16 x 25 | 0.022 | 0.044 | 2,555 | 16 x 31.5 | 0.018 | 0.036 | 3,010 | 18 x 35.5 | 0.015 | 0.030 | 3,680 | 18 x 40 | 0.014 | 0.028 | 3,800 |
18 x 20 | 0.028 | 0.056 | 2,490 | 18 x 25 | 0.020 | 0.040 | 2,740 | |||||||||
8,200 |
16 x 31.5 | 0.018 | 0.036 | 3,010 | 16 x 35.5 | 0.016 | 0.032 | 3,150 | 18 x 35.5 | 0.015 | 0.030 | 3,680 | ||||
18 x 31.5 | 0.016 | 0.032 | 3,635 | |||||||||||||
10,000 |
16 x 31.5 | 0.016 | 0.032 | 3,150 | 18 x 35.5 | 0.015 | 0.030 | 3,680 | 18 x 40 | 0.014 | 0.028 | 3,800 | ||||
18 x 25 | 0.020 | 0.040 | 2,740 | |||||||||||||
12,000 | 18 x 31.5 | 0.016 | 0.032 | 3,635 | ||||||||||||
15,000 | 18 x 35.5 | 0.015 | 0.030 | 3,680 | 18 x 40 | 0.014 | 0.028 | 3,800 |
DIMENSIYNAU & PERMISSIBLE RIPPLE PRESENNOL
VDC
Eitem
μF |
35V (1V) | 50V (1H.) | 63V (1J.) | 100V (2A) | ||||||||||||
φDx L. |
Rhwystr (Ω,Max / 100KHz) | Cyfredol Ripple
(mA / rms, 105° C) |
φDx L. |
Rhwystr
(Ω, Max / 100KHz) |
Cyfredol Ripple
(mA / rms, 105° C) |
φDx L. |
Rhwystr
(Ω, Max / 100KHz) |
Cyfredol Ripple
(mA / rms, 105° C) |
φDx L. |
Rhwystr
(Ω, Max / 100KHz) |
Cyfredol Ripple
(mA / rms, 105° C) |
|||||
20° C |
-10° C |
100kHz |
20° C |
-10° C |
100kHz |
20° C |
-10° C |
100kHz |
20° C |
-10° C |
100kHz |
|||||
0.47 | 5 x 11 | 43 | 86 | 20 | ||||||||||||
1 | 5 x 11 | 20 | 40 | 30 | ||||||||||||
2.2 | 5 x 11 | 9.8 | 19.6 | 44 | ||||||||||||
3.3 | 5 x 11 | 6.6 | 13.2 | 58 | ||||||||||||
4.7 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 2.3 | 4.6 | 90 | 5 x 11 | 4.7 | 9.4 | 68 | 5 x 11 | 4.6 | 9.2 | 74 |
6.8 | 5 x 11 | 1.4 | 2.8 | 120 | 5 x 11 | 2.5 | 5.0 | 95 | 5 x 11 | 3.5 | 7.0 | 95 | ||||
10 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 2.1 | 4.2 | 110 | 6.3 x 11 | 1.8 | 3.6 | 130 | ||||
12 | 5 x 11 | 2 | 4.0 | 145 | ||||||||||||
15 | 6.3 x 11 | 1.2 | 2.4 | 160 | 8 x 11.5 | 0.83 | 1.66 | 180 | ||||||||
18 | 5 x 11 | 1.3 | 2.6 | 155 | 6.3 x 15 | 0.80 | 1.60 | 200 | ||||||||
22 | 5 x 11 | 0.6 | 1.2 | 180 | 5 x 11 | 1.2 | 2.4 | 170 | 6.3 x 11 | 0.71 | 1.42 | 250 | 8 x 11.5 | 0.68 | 1.36 | 230 |
27 | 5 x 11 | 0.6 | 1.2 | 180 | ||||||||||||
33 | 5 x 11 | 0.6 | 1.2 | 180 | 6.3 x 11 | 0.43 | 0.86 | 300 | 6.3 x 11 | 0.71 | 1.42 | 250 | 10 x 12.5 | 0.46 | 0.92 | 320 |
8 x 15 | 0.45 | 0.90 | 360 | |||||||||||||
39 | 6.3 x 15 | 0.70 | 1.40 | 330 | ||||||||||||
47 | 6.3 x 11 | 0.25 | 0.5 | 290 | 6.3 x 11 | 0.43 | 0.86 | 300 | 8 x 11.5 | 0.342 | 0.684 | 405 | 10 x 16 | 0.37 | 0.74 | 420 |
8 x 20 | 0.37 | 0.74 | 420 | |||||||||||||
56 | 6.3 x 11 | 0.25 | 0.5 | 290 | 6.3 x 15 | 0.4 | 0.80 | 360 | 0.234 | |||||||
68 | 8 x 11.5 | 0.342 | 0.684 | 405 | 10 x 20 | 0.30 | 0.60 | 490 | ||||||||
82 | 6.3 x 11 | 0.25 | 0.500 | 290 | 8 x 11.5 | 0.234 | 0.468 | 485 | 10 x 25 | 0.25 | 0.50 | 540 | ||||
100 | 8 x 11.5 | 0.117 | 0.234 | 555 | 8 x 11.5 | 0.234 | 0.468 | 485 | 10 x 12.5 | 0.256 | 0.512 | 535 | 12.5 x 20 | 0.18 | 0.36 | 580 |
8 x 15 | 0.230 | 0.460 | 535 | |||||||||||||
120 | 8 x 15.0 | 0.155 | 0.31 | 635 | 10 x 16 | 0.194 | 0.388 | 600 | ||||||||
10 x 12.5 | 0.162 | 0.324 | 615 | |||||||||||||
150 | 8 x 11.5 | 0.117 | 0.234 | 555 | 10 x 12.5 | 0.162 | 0.324 | 615 | 10 x 16 | 0.194 | 0.388 | 660 | 12.5 x 25 | 0.13 | 0.26 | 710 |
180 | 8 x 20 | 0.12 | 0.240 | 860 | 10 x 20 | 0.147 | 0.294 | 885 | 12.5 x 30 | 0.12 | 0.24 | 790 | ||||
10 x 16 | 0.119 | 0.238 | 850 | 12.5 x 16 | 0.150 | 0.300 | 1,020 | 16 x 20 | 0.13 | 0.26 | 750 | |||||
220 | 10 x 12.5 | 0.090 | 0.180 | 755 | 10 x 16 | 0.119 | 0.238 | 850 | 10.0 x 20 | 0.147 | 0.294 | 885 | 16 x 25 | 0.10 | 0.20 | 890 |
8 x 15 | 0.085 | 0.170 | 730 | 10 x 20 | 0.090 | 0.180 | 1,030 | 10 x 25 | 0.130 | 0.260 | 1,050 | 18 x 20 | 0.11 | 0.22 | 850 | |
270 | 10.0 x 25 | 0.082 | 0.164 | 1,200 | 16 x 16 | 0.090 | 0.180 | 1,410 | ||||||||
330 | 10 x 16 | 0.068 | 0.136 | 1050 | 10 x 20 | 0.09 | 0.180 | 1,030 | 12.5 x 20 | 0.085 | 0.170 | 1,285 | 16 x 25 | 0.090 | 0.180 | 1,080 |
8 x 20 | 0.065 | 0.130 | 995 | 10 x 30 | 0.060 | 0.120 | 1,610 | |||||||||
390 | 10 x 20 | 0.052 | 0.104 | 1,220 | 12.5 x 20 | 0.063 | 0.126 | 1,480 | 12.5 x 25 | 0.070 | 0.140 | 1,720 | 18 x 25 | 0.083 | 0.166 | 1,260 |
18 x 16 | 0.086 | 0.172 | 1,690 | |||||||||||||
470 |
10 x 20 | 0.052 | 0.104 | 1,220 | 12.5 x 20 | 0.06 | 0.120 | 1,500 | 12.5 x 25 | 0.070 | 0.140 | 1,720 | 16 x 31.5 | 0.076 | 0.152 | 1,310 |
12.5 x 30 | 0.055 | 0.110 | 2,090 | |||||||||||||
16 x 20 | 0.059 | 0.118 | 1,765 | |||||||||||||
560 | 10 x 25 | 0.045 | 0.090 | 1,440 | 12.5 x 25 | 0.05 | 0.100 | 1,832 | 16 x 25.0 | 0.050 | 0.100 | 2,160 | 18 x 31.5 | 0.068 | 0.136 | 1,370 |
18 x 35.5 | 0.064 | 0.128 | 1,410 | |||||||||||||
680 | 12.5 x 20 | 0.038 | 0.076 | 1,655 | 12.5 x 25 | 0.05 | 0.100 | 1,832 | 12.5 x 35 | 0.047 | 0.094 | 2,265 | ||||
10 x 30 | 0.035 | 0.070 | 1,815 | 16 x 20 | 0.048 | 0.096 | 1,835 | 18 x 20.0 | 0.055 | 0.110 | 2,290 | |||||
820 | 12.5 x 35 | 0.035 | 0.068 | 2,285 | 16 x 31.5 | 0.043 | 0.086 | 2,670 | 18 x 40 | 0.047 | 0.094 | 1,520 | ||||
18 x 20 | 0.042 | 0.084 | 2,420 | 18 x 25 | 0.043 | 0.086 | 2,585 | |||||||||
1,000 | 12.5 x 25 | 0.030 | 0.060 | 1,945 | 16 x 25.0 | 0.034 | 0.068 | 2,235 | 16 x 31.5 | 0.043 | 0.086 | 2,670 | ||||
16 x 35.5 | 0.036 | 0.072 | 2,770 | |||||||||||||
1,200 | 12.5 x 30 | 0.025 | 0.050 | 2,310 | 16 x 31.5 | 0.028 | 0.056 | 2,700 | 18 x 31.5 | 0.032 | 0.064 | 2,950 | ||||
16 x 20 | 0.029 | 0.058 | 2,205 | 18 x 25 | 0.029 | 0.058 | 2,610 | |||||||||
1,500 | 16 x 25 | 0.022 | 0.044 | 2,555 | 16 x 31.5 | 0.028 | 0.056 | 2,700 | 18 x 35.5 | 0.030 | 0.060 | 3,095 | ||||
12.5 x 35 | 0.022 | 0.044 | 2,510 | 16 x 35.5 | 0.025 | 0.05 | 2,790 | |||||||||
1,800 | 16 x 25.0 | 0.022 | 0.044 | 2,555 | 18 x 31.5 | 0.025 | 0.05 | 3,000 | ||||||||
18 x 20 | 0.028 | 0.056 | 2,490 | |||||||||||||
2,200 | 16 x 31.5 | 0.018 | 0.036 | 3,010 | 18 x 35.5 | 0.023 | 0.046 | 3,100 | 18 x 40 | 0.028 | 0.056 | 3,200 | ||||
18 x 25.0 | 0.02 | 0.040 | 2,740 | |||||||||||||
2,700 | 16 x 35.5 | 0.016 | 0.032 | 3,150 | ||||||||||||
18 x 31.5 | 0.016 | 0.032 | 3,635 | |||||||||||||
3300 | 18 x 35.5 | 0.015 | 0.030 | 3,680 | ||||||||||||
4700 | 18 x 40 | 0.014 | 0.028 | 3,800 |
ENGHRAIFFT RHIF RHIF
CADE 102 M. 1C BK 100 200
NODWEDDION
◆ oes hir,105℃,4,000~ 7,000hours sicr
◆ LowESR, cyflenwadau pŵer forswitching addas
◆ maint llai gyda gyfredol crych mawr a ganiateir
◆ Cydymffurfiad Rohs