Six Layer Board With Lead Free HASL For Larger Controllers
A six layer FR4 board finished with lead-free hot air solder levelling. Four routing layers and two planes let a large controller fit into a narrow outline without pushing to a gold finish, which keeps the board affordable on longer production runs.
What This Board Is
Six layers is where board area stops being the constraint. The long narrow board shown here packs a controller, memory and several connector banks into a strip that would need twice the width on four layers. Because the parts on it are not fine pitch, lead-free HASL is the sensible finish, and it keeps the price well below an equivalent gold board.
Two lamination-ready inner cores are pressed with prepreg, drilled, then plated through in a single PTH pass.
- Rigid PCB
- 6 layer
- Lead-free HASL
- RoHS
What You Get From This Build
- Four signal layers let a wide board shrink into a narrow strip that fits a slot or rail mount
- Two internal planes hold supply impedance down across a physically long board
- Lead-free HASL keeps the cost per board low on a six layer build
- Minimum board thickness for six layer construction is published at 1.00 mm (40 mil)
Who Specifies This Board
- Industrial automation makers building rack and DIN rail cards
- Telecom OEMs with line cards that must fit a fixed slot pitch
- Equipment builders replacing two stacked four layer boards with one six layer board
- Buyers who need six layers but do not need a gold surface
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.
A board that will not fit the slot
Moving from four to six layers releases enough routing space to cut board width, which is usually cheaper than redesigning the enclosure.
Voltage drop at the far end of a long board
Dedicated plane layers carry supply current with far lower resistance than routed rails, which matters most on boards that are physically long.
Paying for gold on a board that does not need it
If the finest pitch on the board is a 0.65 mm QFP there is no assembly benefit in gold. Lead-free HASL does the same job for less.
Solder bridging between close pads
Minimum solder bridge is held at 0.10 mm (4 mil), so the mask keeps adjacent pads separated through reflow.
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 | 6 Layer Rigid PCB |
| Legacy catalogue reference | 6 Layer |
| Product family | Rigid PCB |
| Layer count | 6 layer |
| Surface finish | Lead-free HASL |
| 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 |
|---|---|---|---|
| 6 Layer Rigid PCB | 6 | Lead-free HASL | Dense routing without a gold finish |
| 4 Layer Rigid PCB | 4 | Immersion gold | Fine pitch parts and BGA sites |
| 8 Layer Rigid PCB | 8 | Gold plating | Boards with edge fingers or contact surfaces |
What To Send With Your Enquiry
Four things that decide whether the quote comes back right the first time.
- Supply the layer order explicitly. Do not leave us to infer which layer is ground.
- Mark blind or buried via requirements clearly, or confirm that all vias are through holes.
- Give the finished board thickness and the tolerance you can accept on it.
- State the solder mask and legend colours you want rather than assuming green and white.
6 Layer Rigid PCB Questions
What is the minimum thickness for a six layer board?
1.00 mm, which is 40 mil, as published in our rigid capacity table. Four layer boards go down to 0.40 mm and eight layer boards start at 1.20 mm.
Can I mix HASL and gold on the same panel?
No. A panel takes one surface finish. If different boards in a project need different finishes they run as separate jobs.
Do you do automated optical inspection on inner layers?
Inner layers are checked before lamination because a defect buried in the stack cannot be repaired afterwards.
What is the largest six layer panel you can build?
Our published maximum panel dimension is 450 x 660 mm, which is 18 x 26 inches, across the rigid range.
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
Eight Layer Board With Electroplated Gold For Contact Surfaces
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
Layer count is the single decision that most affects the price and the electrical behaviour of a board. This guide sets ...
Most quote delays are caused by missing information rather than by difficult boards. This is the list of what we need, w...
Get 6 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.