Eight Layer Board With Electroplated Gold For Contact Surfaces
An eight layer FR4 board with an electroplated nickel gold finish. Plated gold is harder and thicker than an immersion deposit, which is what edge connector fingers, switch contacts and repeatedly mated surfaces need to survive their rated insertion count.
What This Board Is
The panel shown runs two boards up, each with a high density digital section. What separates this build from the other multilayer boards is the finish. Electroplated nickel gold is a mechanical surface, not just a solderable one. Where a board has gold fingers, a membrane switch contact area or a pogo pin landing pad, plated gold is the finish that survives use.
Graphic plating puts copper and then nickel gold only where the pattern needs it, before film and tin stripping.
- Rigid PCB
- 8 layer
- Gold plating
- RoHS
What You Get From This Build
- Electroplated gold resists wear, so edge fingers survive repeated insertion cycles
- Eight layers allow separate analogue and digital return planes on the same board
- Hard gold also works as a wire bonding surface where a chip is mounted directly on the board
- Panel utilisation improves when boards run two up, which reduces the cost per board
Who Specifies This Board
- Makers of plug-in cards with gold edge connectors
- Instrument manufacturers with membrane keypad contact areas on the main board
- Test and measurement builders needing separated analogue and digital grounds
- Equipment makers whose boards are removed and re-seated during service
Four Failures This Build Is Designed Against
Each one is a real way this class of board goes wrong, and the tolerance or process decision that prevents it.
Edge fingers that fail after a few hundred insertions
Electroplated gold over nickel gives a hard, thick contact surface. Immersion gold is too thin to survive repeated mating and wears through to the nickel.
Analogue noise picked up from digital switching
Eight layers give enough plane count to keep analogue and digital returns on separate copper rather than splitting one plane and hoping.
Inner layers drifting out of alignment in a thick stack
Hole position tolerance across the stack is held to ±0.05 mm, which keeps drilled vias inside their inner layer pads.
Paying full price for a small board
Small boards are panelised in arrays so that one panel carries several units, which is how the cost per board comes down.
Technical Specification
Product detail from the catalogue record, followed by the published process capability for the Rigid PCB family. Anything the legacy catalogue did not record is marked TBC rather than filled in.
| Item | Technical specification |
|---|---|
| Product name | 8 Layer Rigid PCB |
| Legacy catalogue reference | 8 Layer |
| Product family | Rigid PCB |
| Layer count | 8 layer |
| Surface finish | Gold plating |
| RoHS | RoHS compliant process, as recorded on the legacy catalogue |
| Layer count | 1 to 16 layers |
| Maximum panel dimension | 450 x 660 mm (18 x 26 in) |
| Minimum board thickness | 4 layers 0.40 mm (16 mil) / 6 layers 1.00 mm (40 mil) / 8 layers 1.20 mm (48 mil) |
| Minimum trace width | 0.075 mm (3 mil) |
| Minimum trace space | 0.075 mm (3 mil) |
| Minimum finished hole | 0.20 mm (8 mil) |
| Plated hole wall thickness | 0.025 mm (1 mil) |
| Plated hole diameter tolerance | ±0.075 mm (3 mil) |
| Non-plated hole diameter tolerance | ±0.05 mm (2 mil) |
| Hole position tolerance | ±0.05 mm (2 mil) |
| Outline dimension tolerance | ±0.10 mm (4 mil) |
| Minimum solder bridge | 0.10 mm (4 mil) |
| Warpage | ≤0.75% |
| Isolation resistance | >1012 Ω at normal condition |
| Hole resistance | <300 Ω at normal condition |
| Flammability rating | 94V-0 self-extinguishing |
| Open / short test voltage | 50 to 300 V |
What The Board Is Made Of
| Material | Specification |
|---|---|
| Base laminate | FR4 glass reinforced epoxy, 94V-0 self-extinguishing |
| Copper | Weight confirmed against the current your rails carry |
| Solder mask | LPI solder mask, green as standard, other colours on request |
| Legend | Silk screen legend ink, white as standard |
| Surface finish | Lead-free HASL, immersion nickel gold or electroplated nickel gold |
What Can Be Changed
- Layer count from 1 to 16
- Solder mask colour including blue and other colours
- Legend colour
- Lead-free HASL, immersion gold or electroplated gold
- Copper weight to suit the current your rails carry
- Delivery as singles, V-cut arrays or routed tab arrays
How This Board Is Made
Eight stages on equipment sourced from the USA, Japan, Germany and Israel. Every stage listed runs inside our own plant.
Film and tooling
Artwork plotted on a Mania 8850-P film plotter and the panel laid out for the order quantity.
Inner layers
Imaged, etched and checked before lamination, because a defect buried in the stack cannot be repaired.
Lamination
Cores and prepreg pressed on the MLB laminator to build the stack-up.
Drilling
Mania, Hitachi and domestic CNC drillers, thirteen machines in total, to a 0.20 mm minimum hole.
Plating
Desmear, automatic PTH line and graphic plating to a 0.025 mm barrel wall.
Mask and legend
Automatic screen printing and roller coating, then exposure and developing.
Surface finish
Lead-free HASL, immersion gold or electroplated gold according to the order.
Profile and test
CNC routing or V-cut to ±0.10 mm, then open and short testing at 50 to 300 V.
What Is Checked Before It Ships
- Inner layer inspection before lamination, because buried defects cannot be repaired
- Open and short testing at 50 to 300 V on every board
- Hole resistance verified below 300 Ω at normal condition
- Isolation resistance verified above 1012 Ω at normal condition
- Warpage held at ≤0.75% across the panel
What The Plant Holds
- ISO 9001:2000. Quality management system certification recorded by the company. Current revision year available on request.
- ISO 14001:1996. Environmental management system certification recorded by the company.
- UL. Certification recorded by the company. File number available on request.
- RoHS and lead free. Listed in the company environmental policy alongside pollution prevention and resource reduction.
Certificate numbers, issue dates and current revision years are not published on the legacy site. Ask for copies with your enquiry and they will be sent with the quotation.
How It Compares With The Alternatives
Three boards from our own catalogue, side by side, so the trade-off is visible rather than argued.
| Board | Layers or build | Finish | Best suited to |
|---|---|---|---|
| 8 Layer Rigid PCB | 8 | Gold plating | Edge fingers and mechanical contact surfaces |
| 10 Layer Rigid PCB | 10 | Immersion gold | Very dense routing, flat SMD surface |
| 4 Layer Rigid PCB | 4 | Immersion gold | Mainstream fine pitch SMD boards |
What To Send With Your Enquiry
Four things that decide whether the quote comes back right the first time.
- Mark the gold finger area on a separate layer and give the bevel angle if the connector needs one.
- State the gold thickness the connector specification calls for.
- Confirm whether hard gold is required across the whole board or only on the contact area.
- Give the array drawing if you want the boards delivered two up as photographed.
8 Layer Rigid PCB Questions
What is the difference between gold plating and immersion gold?
Electroplated gold is deposited thicker and harder and is meant to be touched and mated. Immersion gold is a thin flat film meant to be soldered. Our 8 layer board uses plating, the 4, 10 and 12 layer boards use immersion.
Can you bevel edge connector fingers?
Send the bevel angle and depth with the drawing and we will confirm it against the routing setup.
What is the minimum eight layer board thickness?
1.20 mm, which is 48 mil, from our published rigid capacity table.
Is the board flammability rated?
The laminate is rated 94V-0 self-extinguishing, as listed in our rigid capacity table.
Other Boards In The Rigid PCB Family
Boards built on the same line, with the same tolerances, in a different configuration.
Double Sided FR4 Board With Lead Free HASL
Four Layer Immersion Gold Board For Dense SMD Routing
Six Layer Board With Lead Free HASL For Larger Controllers
Ten Layer Immersion Gold Board For High Density Digital Designs
Where This Board Is Used
The fields the legacy catalogue records for this class of board.
This Board In Context
Background Reading
Three surface finishes cover almost every board we build. Choosing between them is not a quality decision, it is a fitne...
A capability table is a list of numbers until you know which failure each one prevents. This walks through the rigid PCB...
Get 8 Layer Rigid PCB Priced Against Your Own Files
Send Gerber RS-274X with an NC drill file, or an ODB++ package, with the layer count, thickness, copper weight, surface finish and quantity. We check it against the published capability before quoting.