Real PCB Stackup

26. Real PCB Stackup

What a fabricated rigid board is made of, from the top legend to the bottom legend, for 2, 4, 6, 8, 10, 12 and 16 copper layers. Each board is drawn from a stack-up that a fabricator publishes, and every layer that is made separately is drawn separately.

KiCad's stack-up lists only some of these layers, and KESE builds its solids from KiCad's stack-up (Stack-Up Model). This page shows what stands behind those numbers; 26.13 says which of the layers a KESE model holds.

Copper layers	Stack-up drawn	Section
2	OSH Park, 2 Layer Prototype Service, 1.6 mm	26.5
4	JLCPCB, JLC04161H-2116C, 1.6 mm	26.6
6	JLCPCB, JLC06161H-3313, 1.6 mm	26.7
8	JLCPCB, JLC08161H-2116, 1.6 mm	26.8
10	JLCPCB, JLC10161H-2116, 1.6 mm	26.9
12	JLCPCB, JLC12161H-2313, 1.6 mm	26.10
16	JLCPCB, JLC16161H-2313, 1.6 mm	26.11

Each picture opens at full size when it is clicked.

26.1 What A Board Is Made Of

From the outside in. The thicknesses are typical values; a fabricator's own stack-up sheet gives the real ones for a board.

Layer	In KiCad	What it is	Thickness
Legend ink	F.SilkS, B.SilkS	Ink printed on top of the solder mask, by ink-jet or as a photo-imaged coat, then cured.	about 15 µm (10 to 20 µm)
Solder mask	F.Mask, B.Mask	One photo-imageable coat (LPI) per side. It follows the surface, is thinner over copper than on the laminate, and is opened at the pads.	30 µm on the laminate and 15 µm on copper (JLCPCB); 15 µm (OSH Park)
Gold	the copper finish	Immersion gold, the top of the ENIG finish. Only on copper that the mask leaves open.	0.05 to 0.1 µm
Nickel	the copper finish	Electroless nickel under the gold, on the top and the sides of the open copper.	3 to 6 µm
Plated copper	part of F.Cu, B.Cu	Electroplated after drilling: one deposit that lines every hole (the via barrel) and covers the outer foil.	about 20 to 25 µm
Seed	not listed	A film that makes the drilled hole wall conductive, so that copper can be plated on it: carbon, or electroless copper.	nanometres (carbon), or a thin copper film
Outer copper foil	part of F.Cu, B.Cu	Copper foil pressed onto the prepreg, its rough treated side down, and etched together with the plating on it. On a two-layer board it is the laminate's own foil.	12, 18 or 35 µm before plating
Prepreg ply	a dielectric sub-layer	A sheet of woven glass cloth carrying epoxy resin that is not yet cured. Its glass style sets its thickness and its share of resin, and with that its εr.	about 0.05 mm (106 glass) to 0.2 mm (7628 glass)
Resin between traces	not listed	Resin that flowed out of the prepreg in the press and filled the gaps in the inner copper. There is no glass in it.	as high as the inner copper
Inner copper	In1.Cu, In2.Cu, ...	The core's own copper foil, etched before pressing. It is not plated. Its open faces are treated so that the resin grips.	15.2 µm (half-ounce foil, JLCPCB) or 30.5 µm (one ounce)
Core	a dielectric of type core	Glass cloths in resin, pressed and fully cured by the laminate maker, and sold with copper on both faces.	0.075 to 1.5 mm in the boards below
Hole	the drill of a via or pad	Drilled through the pressed board, then plated. It stays open, is covered by the mask, or is filled.	0.2 mm and up for a via

The glass style of a ply is a number that names its cloth. The finer the cloth, the thinner the ply and the more of it is resin; glass has an εr of about 6 and the resin of about 3, so a ply with more resin has a lower εr. The same cloth also has another εr in another maker's resin: JLCPCB's calculator assumes Nan Ya NP-155F laminate for four to eight layers and Shengyi S1000-2M from ten layers up.

Glass style	Cloth	Resin by weight (Kingboard KB-6167F)	As a ply in the boards below
1080	fine	62 to 70 %	0.0764 mm, εr 3.91 (NP-155F)
2313, 3313	medium-fine	52 to 58 % (3313)	3313: 0.0994 mm, εr 4.1 (NP-155F); 2313: 0.0964 mm, εr 4.31 (S1000-2M)
2116	medium	50 to 58 %	0.1088 to 0.124 mm, εr 4.16 (NP-155F); 0.1194 mm, εr 4.29 (S1000-2M)
7628	the heaviest common cloth	42 to 50 %	Drawn in the cores; JLCPCB's default four-layer build has it as a ply of 0.2104 mm

A ply is pressed thinner where it lies on inner copper, because part of its resin goes into the gaps between the traces. In JLCPCB's tables a ply with one face on inner copper is 7.6 µm thinner than the same ply with none, half of the copper's 15.2 µm: the 2116 ply is 0.124 mm between an outer foil and another ply, and 0.1164 mm with one face on inner copper. For a ply between two inner copper layers its tables give both: the six-layer build below is listed with its 2116 ply at 0.1088 mm, both faces taken off, and also at 0.1164 mm.

26.2 How A Board Is Put Together

A board of four layers or more:

1. Cores. Each core arrives cured, with copper on both faces, and the inner layers are etched from that copper: L2 and L3 of a four-layer board come from its one core.
2. Lay-up. Prepreg plies go between the cores, and on each outer face prepreg plies and a copper foil.
3. Press. Under heat and pressure the resin of the prepreg melts, fills the gaps between the inner traces, and cures.
4. Drill. The holes go through the whole pressed board.
5. Plate. A seed makes the hole walls conductive; then copper is electroplated in the holes and on the outer foil, in one go.
6. Etch. The outer copper is cut to shape. That makes L1 and the last layer.
7. Coat. The solder mask, then the finish on the copper the mask leaves open (nickel and gold for ENIG), and the legend ink.

A two-layer board has no cores to etch, no lay-up and no press at the fabricator: it starts as one cured laminate of the board's thickness with copper foil on both faces, and goes on at step 4.

26.3 What Ends Up As One Piece

• All the copper of one connection is one piece of metal. The plating grows on the outer foil and on the hole wall, and joins the inner copper that the hole cuts through.
• The resin of the prepreg melts together and cures as one mass. Each ply still keeps its own glass cloth, so its mix of glass and resin and its εr stay its own.
• Each core stays its own layer. It was cured before the board was pressed; the prepreg bonds onto it, and it keeps its own glass and εr.
• Nickel, gold, solder mask and legend ink are separate coats. Different materials, put on one after the other, each only where it is wanted.

26.4 The Seven Boards Side By Side

All seven are sold as 1.6 mm boards. The last three columns are each material's share of the thickness from copper to copper, taken where every layer has copper.

Copper layers	Cores	Prepreg plies	Copper to copper	Copper share	Prepreg share	Core share
2	1 of 1.524 mm	none	1.595 mm	4.5 %	0.0 %	95.5 %
4	1 of 1.065 mm	4 (2116, 1080 glass)	1.566 mm	6.4 %	25.6 %	68.0 %
6	2 of 0.55 mm	3 (3313, 2116 glass)	1.538 mm	8.5 %	20.0 %	71.5 %
8	3 of 0.3 mm	6 (2116, 1080 glass)	1.600 mm	10.1 %	33.7 %	56.3 %
10	4 of 0.2 mm	5 (2116 glass)	1.589 mm	12.1 %	37.6 %	50.4 %
12	5 of 0.15 mm	6 (2313, 2116 glass)	1.642 mm	13.5 %	40.8 %	45.7 %
16	7 of 0.075 mm	8 (2313 glass)	1.579 mm	17.9 %	48.8 %	33.2 %

With more layers the cores get thinner, and from six layers up less and less of the thickness is core. The cores of the sixteen-layer board are thinner than its prepreg plies, and copper is 18 % of its thickness.

26.5 Two Layers

The board of OSH Park's 2 Layer Prototype Service, sold as 1.6 mm (63 mil): one cured laminate of 1.524 mm (60 mil), Kingboard KB-6167F, with copper on both faces. OSH Park gives the copper as one figure, 35.6 µm (1.4 mil); the picture shows it as the laminate's foil with the plating on it. Kingboard lists its 1.6 mm laminate as eight 7628 glass cloths, as drawn.

Layer	Made of	Thickness	εr
L1 · F.Cu	Copper: foil and plating	0.0356 mm
	Core	1.524 mm	4.5 at 10 MHz
L2 · B.Cu	Copper: foil and plating	0.0356 mm

Copper to copper the board is 1.595 mm thick; with 15 µm of solder mask on the copper of each side, 1.63 mm.

26.6 Four Layers

JLCPCB's JLC04161H-2116C, one of the builds it publishes for a 1.6 mm four-layer board: one core of 1.065 mm, and on each side of it a 1080 ply against the inner copper and a 2116 ply under the outer foil. The two plies of a side have different cloths, so each has its own εr: 4.16 for the 2116 ply and 3.91 for the 1080 ply. JLCPCB's default four-layer build is JLC04161H-7628, with one 7628 ply of 0.2104 mm on each side of the same core.

Layer	Made of	Thickness	εr
L1 · F.Cu	Copper: foil and plating	0.035 mm
	Prepreg ply, 2116 glass	0.124 mm	4.16
	Prepreg ply, 1080 glass	0.0764 mm	3.91
L2 · In1.Cu	Copper: the core's foil	0.0152 mm
	Core	1.065 mm	4.6
L3 · In2.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 1080 glass	0.0764 mm	3.91
	Prepreg ply, 2116 glass	0.124 mm	4.16
L4 · B.Cu	Copper: foil and plating	0.035 mm

Copper to copper the board is 1.566 mm thick; with 15 µm of solder mask on the copper of each side, 1.60 mm.

26.7 Six Layers

JLCPCB's JLC06161H-3313, its default build for a 1.6 mm six-layer board: two cores of 0.55 mm, one 2116 ply between them and one 3313 ply on each side. The 2116 ply lies between two inner copper layers and gives resin to both. JLCPCB's page lists the build twice: as JLC06161H-3313 with that ply at 0.1088 mm, as drawn, and as "No requirement" with it at 0.1164 mm.

Layer	Made of	Thickness	εr
L1 · F.Cu	Copper: foil and plating	0.035 mm
	Prepreg ply, 3313 glass	0.0994 mm	4.1
L2 · In1.Cu	Copper: the core's foil	0.0152 mm
	Core	0.55 mm	4.6
L3 · In2.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2116 glass	0.1088 mm	4.16
L4 · In3.Cu	Copper: the core's foil	0.0152 mm
	Core	0.55 mm	4.6
L5 · In4.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 3313 glass	0.0994 mm	4.1
L6 · B.Cu	Copper: foil and plating	0.035 mm

Copper to copper the board is 1.538 mm thick; with 15 µm of solder mask on the copper of each side, 1.57 mm.

26.8 Eight Layers

JLCPCB's JLC08161H-2116, its default build for a 1.6 mm eight-layer board: three cores of 0.3 mm, two 1080 plies between neighbouring cores, and one 2116 ply on each side. 26.12 says where the numbers of this board and of the three after it come from.

Layer	Made of	Thickness	εr
L1 · F.Cu	Copper: foil and plating	0.035 mm
	Prepreg ply, 2116 glass	0.1164 mm	4.16
L2 · In1.Cu	Copper: the core's foil	0.0152 mm
	Core	0.3 mm	not listed
L3 · In2.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 1080 glass	0.0764 mm	3.91
	Prepreg ply, 1080 glass	0.0764 mm	3.91
L4 · In3.Cu	Copper: the core's foil	0.0152 mm
	Core	0.3 mm	not listed
L5 · In4.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 1080 glass	0.0764 mm	3.91
	Prepreg ply, 1080 glass	0.0764 mm	3.91
L6 · In5.Cu	Copper: the core's foil	0.0152 mm
	Core	0.3 mm	not listed
L7 · In6.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2116 glass	0.1164 mm	4.16
L8 · B.Cu	Copper: foil and plating	0.035 mm

Copper to copper the board is 1.600 mm thick; with 15 µm of solder mask on the copper of each side, 1.63 mm.

26.9 Ten Layers

JLCPCB's JLC10161H-2116, its default build for a 1.6 mm ten-layer board: four cores of 0.2 mm, one 2116 ply between neighbouring cores and one on each side. This is the first of the builds on Shengyi S1000-2M: its 2116 ply has an εr of 4.29, where the 2116 ply of the eight-layer board has 4.16.

Layer	Made of	Thickness	εr
L1 · F.Cu	Copper: foil and plating	0.035 mm
	Prepreg ply, 2116 glass	0.1194 mm	4.29
L2 · In1.Cu	Copper: the core's foil	0.0152 mm
	Core	0.2 mm	not listed
L3 · In2.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2116 glass	0.1194 mm	4.29
L4 · In3.Cu	Copper: the core's foil	0.0152 mm
	Core	0.2 mm	not listed
L5 · In4.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2116 glass	0.1194 mm	4.29
L6 · In5.Cu	Copper: the core's foil	0.0152 mm
	Core	0.2 mm	not listed
L7 · In6.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2116 glass	0.1194 mm	4.29
L8 · In7.Cu	Copper: the core's foil	0.0152 mm
	Core	0.2 mm	not listed
L9 · In8.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2116 glass	0.1194 mm	4.29
L10 · B.Cu	Copper: foil and plating	0.035 mm

Copper to copper the board is 1.589 mm thick; with 15 µm of solder mask on the copper of each side, 1.62 mm.

26.10 Twelve Layers

JLCPCB's JLC12161H-2313, its default build for a 1.6 mm twelve-layer board: five cores of 0.15 mm, one 2116 ply between neighbouring cores, and one 2313 ply on each side.

Layer	Made of	Thickness	εr
L1 · F.Cu	Copper: foil and plating	0.035 mm
	Prepreg ply, 2313 glass	0.0964 mm	4.31
L2 · In1.Cu	Copper: the core's foil	0.0152 mm
	Core	0.15 mm	not listed
L3 · In2.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2116 glass	0.1194 mm	4.29
L4 · In3.Cu	Copper: the core's foil	0.0152 mm
	Core	0.15 mm	not listed
L5 · In4.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2116 glass	0.1194 mm	4.29
L6 · In5.Cu	Copper: the core's foil	0.0152 mm
	Core	0.15 mm	not listed
L7 · In6.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2116 glass	0.1194 mm	4.29
L8 · In7.Cu	Copper: the core's foil	0.0152 mm
	Core	0.15 mm	not listed
L9 · In8.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2116 glass	0.1194 mm	4.29
L10 · In9.Cu	Copper: the core's foil	0.0152 mm
	Core	0.15 mm	not listed
L11 · In10.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2313 glass	0.0964 mm	4.31
L12 · B.Cu	Copper: foil and plating	0.035 mm

Copper to copper the board is 1.642 mm thick; with 15 µm of solder mask on the copper of each side, 1.67 mm.

26.11 Sixteen Layers

JLCPCB's JLC16161H-2313, its default build for a 1.6 mm sixteen-layer board: seven cores of 0.075 mm, one 2313 ply between neighbouring cores and one on each side. Its default for a 2.0 mm sixteen-layer board is the same build with cores of 0.13 mm.

Layer	Made of	Thickness	εr
L1 · F.Cu	Copper: foil and plating	0.035 mm
	Prepreg ply, 2313 glass	0.0964 mm	4.31
L2 · In1.Cu	Copper: the core's foil	0.0152 mm
	Core	0.075 mm	not listed
L3 · In2.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2313 glass	0.0964 mm	4.31
L4 · In3.Cu	Copper: the core's foil	0.0152 mm
	Core	0.075 mm	not listed
L5 · In4.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2313 glass	0.0964 mm	4.31
L6 · In5.Cu	Copper: the core's foil	0.0152 mm
	Core	0.075 mm	not listed
L7 · In6.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2313 glass	0.0964 mm	4.31
L8 · In7.Cu	Copper: the core's foil	0.0152 mm
	Core	0.075 mm	not listed
L9 · In8.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2313 glass	0.0964 mm	4.31
L10 · In9.Cu	Copper: the core's foil	0.0152 mm
	Core	0.075 mm	not listed
L11 · In10.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2313 glass	0.0964 mm	4.31
L12 · In11.Cu	Copper: the core's foil	0.0152 mm
	Core	0.075 mm	not listed
L13 · In12.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2313 glass	0.0964 mm	4.31
L14 · In13.Cu	Copper: the core's foil	0.0152 mm
	Core	0.075 mm	not listed
L15 · In14.Cu	Copper: the core's foil	0.0152 mm
	Prepreg ply, 2313 glass	0.0964 mm	4.31
L16 · B.Cu	Copper: foil and plating	0.035 mm

Copper to copper the board is 1.579 mm thick; with 15 µm of solder mask on the copper of each side, 1.61 mm.

26.12 How To Read The Pictures

• Scale. The big drawing has its thin layers thickened so that they can be seen. The narrow strip at its left is the same board to scale, cut where every layer has copper.
• Typical values. The nickel and the gold are as IPC-4552 gives them; the plating, the solder mask and the legend ink as JLCPCB, Eurocircuits and OSH Park publish them. The finish drawn is ENIG; with HASL, tin, silver or OSP that one coat takes the place of the nickel and the gold.
• The cloths in a core. A fabricator's sheet does not list them. They are drawn as Kingboard lists the make-up of its KB-6167F laminate of the nearest thickness.
• The via. It is drawn open, with the solder mask over its ends.
• The 2, 4 and 6 layer boards are as OSH Park's and JLCPCB's pages gave them in November 2026.
• The 8, 10, 12 and 16 layer boards are the builds JLCPCB's order page calls "No requirement". JLCPCB's page lists its builds for four and six layers only; the others are inside its impedance calculator, so they are taken from a public project, jlcpcb_autogenerated_stackups, which read the calculator on 9 May 2025. Three limits follow:
  • A fabricator changes its builds; the calculator may give other values today.
  • A ply between two inner copper layers is drawn with one face's 7.6 µm taken off, as that project has it. JLCPCB lists such a ply both ways (26.7), so the inner plies of the 10, 12 and 16 layer boards may be listed 7.6 µm thinner than drawn.
  • No εr is given for the cores. JLCPCB's page gives 4.6 for the cores of its four- and six-layer builds; for eight layers and more no table of JLCPCB's could be read.

26.13 What KESE Builds From These Layers

Real layer	In a KESE model today
Legend ink	One part per side, off by default (Silkscreens)
Solder mask	One part per side that follows the copper, with one thickness on the laminate and one on copper; off by default (Solder Masks)
Nickel, gold	One part per side and metal, on the copper the mask leaves open (Finish)
Outer foil, plated copper, via barrels, inner copper	One solid per net by default (Copper And Traces)
Seed	Not built
The prepreg plies of one gap between two copper layers	One solid, with the first ply's material, εr and tanδ (Stack-Up Model)
Resin between traces	Part of the dielectric solid beside it: the prepreg's, where one of the two is a prepreg
Core	One solid
The glass cloth inside a ply or a core	Not built: each dielectric solid is one uniform material

Building every ply, every core and the resin between the traces as solids of their own is planned in 25.2.1.

26.14 Sources

Read in November 2026.

Source	Used for
OSH Park, 2 Layer Prototype Service	The two-layer stack-up; legend and solder mask of 0.6 mil
Kingboard, KB-6167F datasheet	The glass cloths of a laminate of each thickness; the resin content of each prepreg
JLCPCB, Controlled Impedance PCB Layer Stackup	The four- and six-layer builds and which of them is the default; solder mask of 1.2 mil on the laminate and 0.6 mil on copper
JLCPCB, User Guide to the JLCPCB Impedance Calculator	Inner copper of 15.2 µm; NP-155F for four to eight layers and S1000-2M from ten; 3313 in place of 2313
jlcpcb_autogenerated_stackups, normalised JSON (public domain), data of 9 May 2025	The 8, 10, 12 and 16 layer builds
JLCPCB, Choose Right Prepreg for Reliable Multilayer PCB	The resin of the prepreg melts, flows around the copper and fills the gaps
JLCPCB, Optimize PCB Plating Thickness	Hole wall copper of about 20 to 25 µm
JLCPCB, High-Speed PCB Routing Guidelines	Glass with an εr of about 6, resin of about 3
NCAB Group, PCB stackups: What designers need to know about prepregs	A prepreg is pressed thinner where its resin fills the etched copper
Eurocircuits, Making a PCB, step by step	The order of the steps; the carbon film on the hole walls; about 20 µm of plating; nickel and gold
IPC-4552 with Amendments 1 and 2, table of contents and scope	Nickel of 3 to 6 µm; gold of 0.05 µm at the least

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