An insulated metal substrate separates its copper circuit from an aluminium or copper base with a thermal dielectric. The laminate’s conductivity, thickness and electrical test data describe different properties; the finished assembly still needs a defined heat path into its heatsink. Read the VT-4B3 material example separately from QueenEMS’s fabrication claims, then specify the exact stack and acceptance tests.
CNFX editorial research · Sources checked October 12, 2026 · 15 sources
See which layers carry current, insulation, heat and identification
The three-layer IMS description concerns the circuit copper, thermal dielectric and metal base. Soldermask and legend are separately specified surface features; they should not be mistaken for extra circuit-copper layers or for the circuit-to-base dielectric [2][3][4].
Layer / BOM reference
Role in this board construction
Material evidence and order boundary
Metal core / base
Provides the metal backing beneath the insulating dielectric; alloy choice affects thermal spreading, mass and expansion [1].
VT-4B3 offers specified aluminium grades or C1100 copper. Use the ordered alloy, temper and thickness, not the generic term “metal core” [1].
Thermal dielectric
Separates circuit copper from the metal base while transferring heat. Its thickness, conductivity and breakdown data must be read together [1].
VT-4B3 is described as ceramic-filled and halogen-free. The sheet does not identify a complete proprietary resin recipe; do not infer that every IMS uses the same epoxy formulation.
Circuit copper
Forms the circuit tracks and pads in the single-sided stack described by the fabricator [2].
Ventec lists copper-weight options; QueenEMS lists 1–6 oz. The reviewed data do not establish the exact foil-manufacturing route for every board [1][2].
Soldermask, where specified
Protects covered circuit areas while the layout defines openings for pads and other required exposed features [3].
Colour alone does not establish a specific ink formulation, reflectivity or insulation qualification. Agree the mask system and openings with the fabricator.
Legend / silkscreen, where specified
Identifies components, polarity and other marking information; Eurocircuits describes print on soldermask and advises avoiding pads/exposed copper [4].
The exact ink resin, colour and marking method are not established for the offered MCPCB. Provide the required legend data and obtain the fabricator’s clipping approval.
This is a layer/function reference, not a component-populated assembly BOM. LED/MOSFET parts, heatsink and interface material belong to the specified assembly; multi-layer hybrid constructions require their own stack drawing.
02
Three layers, and the conductivity number belongs to one of them
An insulated metal substrate stacks a copper circuit layer, a thermally conductive dielectric and a metal base that acts as a built-in heatsink [2].
Ask which material makes the dielectric
Request the laminate manufacturer, grade, dielectric thickness and dated TDS so that a conductivity claim can be tied to an identifiable material. The 2023 VT-4B3 sheet prints UL file E214381; this is the laminate maker’s statement, not a CNFX check of the current independent file or approval of a fabricated/assembled board [1].
Ventec lists densities of 8.9 g/cm³ for this copper and 2.7 g/cm³ for its aluminium options. The same volume weighs approximately 3.3 times as much [1].
03
For VT-4B3, read thickness with its typical thermal and breakdown data
Ventec’s 23 August 2023 sheet lists six dielectric thicknesses for VT-4B3. It labels its data as typical and not intended as specification values, so the comparison below does not establish guaranteed working voltages or finished-board acceptance criteria [1].
Start from insulation
Provide working circuit-to-base voltage, the required insulation function and applicable end-product requirements. Agree the material and test conditions; a typical breakdown value is not a working-voltage rating.
Then estimate the temperature rise
CNFX’s simplified estimate: ΔT ≈ P × ZθA / A, with ZθA in °C·in²/W and A in in². Using the 75 µm entry, 1 W × 0.040 / 0.1 ≈ 0.4 °C. This assumes that area carries the heat under the simplified model; it is not a measured junction or board temperature. Real spreading, solder, contacts, base and heatsink are outside this estimate [1].
Compare an alternative stack with the same test basis
Changing grade or dielectric thickness requires fresh electrical and thermal checks. QueenEMS recommends ≤75 µm when quoting above 3.0 W/m·K, but this vendor guideline does not establish that such a stack meets your insulation requirements [2].
Dielectric thickness
Thermal impedance (°C·in²/W)
AC breakdown voltage
50 µm
0.027
4000 V
75 µm
0.040
7000 V
100 µm
0.053
8000 V
125 µm
0.067
9000 V
150 µm
0.080
10000 V
180 µm
0.095
11000 V
Values from the VT-4B3 data sheet (version 23/08/2023); the maker states they are typical values, not specification values [1].
04
Hi-pot and breakdown are different tests
Supplier listings can quote a single kilovolt figure. The laminate data sheet explains the two tests behind such numbers [1].
Make the purchase order say which test you mean
For a finished-board proof test, agree circuit-to-base connections, voltage, AC/DC, ramp/dwell, leakage limit, coverage and pass/fail record. Do not infer them from a laminate’s destructive sample test or a supplier’s “Hi-Pot breakdown” wording; the two reviewed sources describe different specimens [1][2].
Hi-pot proof test
Ventec’s footnote describes 600 VDC testing on 100% of working panels with copper foil; the table entry separately reads >600 VDC, citing IPC-TM-650 2.5.7.2. Obtain the agreed test record rather than treating these as a guaranteed finished-board test [1].
Breakdown voltage
Ventec describes a destructive FQC laboratory test on a random substrate sample without copper foil, citing IPC-TM-650 2.5.6.3. Its AC table is typical material data, not a permitted operating voltage [1].
Board maker's figure
QueenEMS calls ≥3.0 kV “Dielectric Breakdown Voltage (Hi-Pot tested)” and elsewhere describes testing every PCB above 3.0 kV. The page does not establish AC/DC, duration, leakage limit, ramp, specimen or whether the procedure is a proof or destructive test [2].
05
Choose the base metal for heat, weight and expansion
The following entries belong to Ventec’s VT-4B3 metal-plate availability table. Its listed base alloys, thermal conductivity, density and CTE are separate from the dielectric’s 3.0 W/m·K property. Ask the fabricator to confirm that the ordered laminate uses the selected combination [1].
Request a thermal-cycling report for the actual assembled stack
QueenEMS flags CTE mismatch and thermal-cycling failures, but the reviewed page does not supply a traceable test report for your stack, component package, solder process or operating cycle. Treat this as a verification task, not evidence that a particular design has passed [2].
Temperature limits come from the laminate
VT-4B3 lists MOT 130 °C, Tg 130 °C by DSC and 145 °C by DMA, and electrical/mechanical RTI 130 °C under the stated test labels. These are different material properties. Compare the intended laminate temperature and duty with the approved material/application limits; the hottest component’s case temperature alone does not establish the laminate temperature [1].
Base metal
Thermal conductivity
CTE
Standard thickness
Aluminium 5052-H32
138 W/m·K
23.8 ppm/°C
1.0, 1.5, 2.0, 3.0 mm
Aluminium 6061-T6
167 W/m·K
23.6 ppm/°C
1.0, 1.5, 2.0 mm
Ventec aluminium option labelled CTE II
170 W/m·K
19 ppm/°C
1.0, 1.5, 2.0 mm
Copper C1100
386 W/m·K
16.8 ppm/°C
1.0, 1.5, 2.0 mm
06
Keep material data separate from fabricated-board acceptance
Specify the stack, artwork and test specimen along with each value. A supplier’s capability table, a laminate’s typical laboratory result and an agreed acceptance limit answer different questions.
Parameter
Unit / field
Meaning and supported example
Dielectric thermal conductivity
W/(m·K)
VT-4B3 lists 3.0 using its ISO 22007-2 test label; this is a typical material value. Request grade, method and thickness; do not substitute metal-base conductivity [1].
Metal core thickness
mm; alloy/temper
Ventec offers discrete thicknesses by metal grade. QueenEMS’s 0.4–3.0 mm fabrication range is a vendor claim, not a guarantee for every laminate [1][2].
Copper weight / thickness
oz; µm; finished condition
QueenEMS lists 1–6 oz (35–210 µm); agree the ordered starting/finished copper and geometry. A copper-weight option does not by itself fix a trace-current rating [2].
Dielectric thickness
µm; tolerance
VT-4B3 options are 50/75/100/125/150/180 µm. The typical thermal/breakdown table is specific to this grade; request ordered tolerance and process control [1].
Maximum operating temperature
°C; material/duty
VT-4B3 lists MOT 130 °C. Tg/RTI and a component’s case or junction temperature are separate; confirm the laminate’s intended duty [1].
Thermal resistance / impedance
°C/W or area-normalised °C·in²/W
VT-4B3 gives area-normalised dielectric impedance. Converting it with an assumed heat-transfer area is a model, not a measured total assembly thermal resistance [1].
Board thickness
mm; complete stack drawing
Finished-board thickness includes the specified construction. Do not substitute metal-base thickness; confirm tolerances and any hybrid layers [2].
Minimum trace width / spacing
µm; copper weight and layer
QueenEMS publishes 100/100 µm. Its applicability must be confirmed for the selected copper weight, stack and artwork [2].
Peel strength
lb/in; foil and test condition
VT-4B3 lists typical 11 lb/in for 1 oz, as received, under IPC-TM-650 2.4.8. This is not a finished-pad pull test after assembly or ageing [1].
Flammability rating
Material/configuration; test label
VT-4B3 lists UL 94 V-0 and UL file E214381. CNFX has not independently checked the current file or a finished-board approval; match the actual grade and configuration [1].
Surface finish
Process; coverage; thickness requirements
QueenEMS offers HASL/OSP/ENIG/immersion silver. Specify the finish and acceptance requirements on the circuit pads; metal-base brushing/anodising in Ventec’s table is a different surface [2][1].
Maximum board / panel size
mm; usable outline and process borders
QueenEMS publishes a 500 × 600 mm panel limit. Ventec’s stock laminate dimensions are a different input; confirm usable panel area and fabrication rails [2][1].
07
Design inside the factory's window
These are QueenEMS’s self-published fabrication limits, not independently tested capabilities or rules for every metal-core board. Confirm their applicability to one stack and copper weight before placing the order [2].
Base metals
Aluminium 5052 / 6061 and C1100 copper; base thickness 0.4 to 3.0 mm [2]
The table lists a 0.3 mm minimum drill; its DFM tips discourage holes below 0.5 mm for single-sided aluminium. Confirm the proposed hole’s role, finished size, insulation and construction rather than treating the two statements as one universal limit [2].
Edge clearance
Keep copper at least 0.5 mm from the routed edge to avoid shorts to the exposed metal base [2]
Finish and mask
QueenEMS lists HASL, OSP, ENIG and immersion silver, with a choice of mask colours. Its white-mask suggestion is not a measured reflectivity or thermal-performance guarantee for the ordered material [2].
Ventec lists 460 × 610, 510 × 610 and 533 × 610 mm stock sheet sizes. These are laminate sizes, not automatically usable finished-board outlines; confirm process borders, panel rails and the fabricator’s nesting plan [1].
08
Copy this RFQ and fill in the brackets
Paste it into your enquiry below or into an email to a maker, then replace every bracket.
Product: insulated metal substrate PCB, quantity [ ], Gerber/drill/stack drawing [revision]
Construction: [single circuit layer / specified hybrid], board thickness/tolerance [ ]
Base metal: alloy/temper [ ], thickness [ ], back surface/interface requirements [ ]
Dielectric: maker/grade [ ], thickness/tolerance [ ], conductivity and test basis [ ]
Copper: starting/finished weight [ ], minimum trace/gap [ ], pad/edge clearances [ ]
Electrical: circuit-to-base working voltage and insulation function [ ], applicable product requirements [ ]
Acceptance: finished-board proof test [AC/DC, voltage, ramp, dwell, leakage, coverage, connections, record]
Thermal: intended laminate temperature/duty [ ], heatsink/interface [ ], assembly thermal-cycle qualification [ ]
Finish/mask/legend: process [ ], mask system/colour [ ], approved marking and clipping [ ]
Documents: dated laminate TDS, material traceability, applicable current approval scope, test reports and pre-production drawing [ ]
Delivery: destination [ ], date [ ]
12 companies list this product among what they make. Company figures are quoted from each
company's own website; every card states where the relationship came from.
QueenEMS
Shenzhen, Guangdong, China
QueenEMS lists aluminium 5052/6061 and C1100 copper, single/two-layer and hybrid boards, plus 1–6 oz copper. Its conductivity options do not identify every laminate grade, and its “Hi-Pot breakdown” wording leaves the test procedure unresolved.
Bomin’s current official introduction explicitly includes metal-base/core boards alongside its other PCB products. The reviewed introduction does not give an MCPCB stack, dielectric grade or acceptance-test specification; request those for the proposed board.
Kinwong publishes a metal-substrate capability table: up to 8 layers, 4.0 mm board thickness and 740 × 540 mm delivery panels, with copper/aluminium/stainless-steel/iron options. These are supplier capability claims. Its 12 W/m·K “heat dissipation performance” entry does not identify the material or method, and 6000 VAC breakdown does not establish a working-voltage rating.
The Metal Core PCB capability page lists aluminium/copper cores and 1–10 layers. It gives 1.0–2.0 for thermal conductivity while the homepage advertises 1.0–7.0 W/m·K. Obtain a dated, grade-specific stack specification rather than choosing the larger figure.
This catalog lists copper-core, aluminium-core and single/double-sided LED boards. It uses a different website/contact from the other Beton record. The reviewed pages do not resolve whether the two listings represent distinct manufacturing operations; do not count them as two independently verified factories.
ChinaPCBOne’s aluminium-PCB page supports an aluminium-base product enquiry and shows board examples. It does not publish a dielectric grade, measured thermal impedance or finished-board electrical-test method on that page.
EBest lists single-layer, COB, double-sided, multilayer and SinkPad variants, with design/fabrication/assembly services. Those constructions require separate stack drawings; its broad conductivity and temperature comparisons are not measurements for the board being ordered.
High Quality PCB’s EFPCB catalog lists aluminium- and copper-core products, including double-sided aluminium and copper countersunk-hole boards. Confirm the exact product construction and laminate; catalog options do not establish one shared thermal or insulation rating.
ELEPCB publishes an MCPCB/IMS capability table. It lists 0.5–3 oz copper in one row and 1–7 oz foil in another; confirm the applicable stack and finished copper. Its “maximum working voltage” entries need an identified laminate, insulation function and test basis before use in a design.
Fulltronics has an aluminium-PCB service page, but its technical text calls HASL an aluminium-base membrane and its copper ranges differ between the main text and FAQ. Use the page as evidence of an offered service, then obtain a corrected grade-specific stack and fabrication specification.
Geyuan offers MCPCB fabrication/assembly. Its capability table lists 1–2 layers while the text also offers multilayer builds; it both rules out plated vias and later describes double-sided PTH connections. Confirm the proposed stack and insulated-hole construction directly, rather than applying either statement to all boards.
Explore company information and manufacturing capabilities, then discuss the scope of your project with a relevant supplier.
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
Is a 3 W/m·K metal core PCB the whole board's conductivity?
No. In the VT-4B3 example, 3.0 W/m·K is a typical dielectric-material value. Ventec separately lists base-metal properties; neither is a measured effective conductivity or total thermal resistance of the finished assembly. [1][2]
Does a thinner dielectric always perform better?
Not as an unconditional design rule. VT-4B3 lists lower typical dielectric thermal impedance and lower typical AC breakdown voltage for its thinner options. Those breakdown values are destructive material-test results, not working-voltage ratings; select the stack against its intended insulation and thermal requirements. [1]
Aluminium or copper base?
Ventec’s plate table lists 386 W/m·K for C1100 copper and 138/167 W/m·K for its two named aluminium options, with densities 8.9 and 2.7 g/cm³. Those material figures inform heat/weight choices but do not prove the finished board’s thermal performance. [1]
Does a laminate hi-pot record prove every finished board was tested?
No. Ventec’s footnote describes 600 VDC on all working panels with copper foil; its destructive breakdown test uses random substrate samples without foil. Agree the finished-board specimen, connections, AC/DC voltage, ramp/dwell, leakage limit and coverage separately. [1]
Sources and what still needs a direct check
Sources checked 2026-10-12. The VT-4B3 sheet supplies grade-specific typical material data. QueenEMS supplies fabrication claims; Eurocircuits explains mask and legend features. The remaining links document individual suppliers’ current product ranges and the conflicts noted above.
Current independent approval scope for the exact laminate/board construction; the printed 2023 UL file is not a CNFX verification.
QueenEMS’s laminate maker/grade at each conductivity level, and the actual finished-board electrical test procedure; its “Hi-Pot breakdown” wording does not establish the method.
Supplier-specific conflicts: Beton conductivity ranges, ELEPCB copper rows, Fulltronics membrane terminology and copper ranges, Geyuan layer/via statements. The two Beton listings’ manufacturing identity has not been independently resolved. Supplier certification and sales claims are not independent product qualification.
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