FR4 Semiflex - cheaper than a cable harness?...FR4 Semiflex - cheaper than a cable harness? Terms and definitions System comparision: cable harness versus FR4 Semiflex Design process

FR4 Semiflex - cheaper than a cable harness?

Webinar May 06, 2014 Speaker: Andreas Schilpp

07.05.2014 page 1 of 30 www.we-online.com

FR4 Semiflex - cheaper than a cable harness?

Terms and definitions

System comparision: cable harness versus FR4 Semiflex

Design process

Design rules, layer stack-up

Production process

„Cost- / performance-“ relations

processing FR4 Semiflex boards

Application examples

Outlook


Terms and definitions 1

semi is a latin Prefix meaning „half“ (Wikipedia)

Flexibility : if you try to find this in Wikipedia you will find yourself in „Stiffness“

(lat. flectere‚ bending) (Wikipedia) not very precise and helpful

So in this context everything is flexible ???

Definition: FR4Semiflex = bendable

Thin or partially thin with a special soldermask without flexible foils like PI



Partial thickness reduction typically performed by depth routing

– Normally using a special routing bit (bevel, radius) (recommended!)

Sometimes also using seperating foils or release lacquer

pictures: Ruwel, WE



Clarification regarding „Duraflex (Isola 2005): never produced in serie

Today Isola advertises „Semiflex“ special FR4 thin laminates

Influences on bendability are:

– thickness

– Resin and glas quality

– Mechanical design and routing

– Copper quality

source: Isola, WE


Big influence: Prepreg construction

FR4 prepreg type 106

dielectric thickness

50 – 55 µm



60 - 70 µm



85 – 100 µm


NOT suitable for

• microvias

• FR4 Semiflex

Source: Isola


System comparison: cable harness versus FR4 Semiflex

Heterogeneous system

Homogeneous system


System comparison: cable harness versus FR4 Semiflex

Heterogeneous system

Cheaper for very few contacts

Lot of solder and contact points

Detachable in case of connector

Very robust (pulling on the cables)

Homogeneous system

Less components, logistics easier

Saving area for connector footprint or

solder joints

The best wiring safety

Perfect testability

Better signal integrity


System comparison: angled connector vs. FR4 Semiflex


http://www.google.ch/url?sa=i&rct=j&q=&esrc=s&frm=1&source=images&cd=&cad=rja&docid=OhXHxxGriZBk6M&tbnid=cgcNFxlyGSd-RM:&ved=0CAUQjRw&url=http://sweetclipart.com/black-car-silhouette-1335&ei=LeKIUYGYLsbbOZXcgaAH&bvm=bv.45960087,d.ZGU&psig=AFQjCNFGFfMvCzcpF4YAJw-DbY6bpKV-Cg&ust=1368011686753804

Production process: FR4 Semiflex multilayer 8 layers








Next up, we do a…

For an easy communication we use a logical structure for the naming of

the stack-up comparable to flex-rigid

What do you mean:

Which one is the correct nomenclature of a FR4 Semiflex multilayer with

- 8 layers, of which are

- 1 copper layer in the bending area on TOP and

- 1 copper layer in the bending area on Bottom?


Design process

Our vision of a

system house:


Design rules, layer stack-up

WE Design rules always up-to-date on internet!

unfavourable:

copper free areas, small contour radii

good:

bending area filled with copper, large contour radii

Layer stack-up: ask for proposal from WE!


Design rules

Regard bending direction

S-shape bending with 2 bending areas!

Optimize bearing construction


Bending radii, bending angles, length of bending area

Minimum bending radius R with bending area…

– 1-layer: standard 5mm (as a comparison: flex-rigid 1mm)

– 1-layer with special adapted WE stack-up: 4mm

– 2-layers: after consultation (strongly dependant from stack-up)

Count of bending cycles: typically 10 x with minimum bending radius

Lengt L of bending area


FR4 Semiflex: Pre-pending and fixation

Well defined pre-bending prior to box installation!

Assembly on

plastic housing:


Design: hints and tipps

Linked chain – reduced milling expenditure

– Single segments bended only some degrees!

Replace big 180° areas by 2 x 90° with rigid intermediate section


Cost- / performance-“comparison: FR4 Semiflex vs. cable harness

Cost

Performance


Cost- / performance-“comparison: FR4 Semiflex vs. flex-rigid

Cost

Performance


Next up, we do a….

Where do you personally expect the biggest potential in

changing from a cable harness to FR4 Semiflex?

Multiple answers are possible!


Measurement unit hydraulic drive

Old solution!


Application expample

Semiflex bare board… …assembled… …built in

Measurement unit hydraulic drive - NEW



„TPC84“ Touchscreen control panel with Ethernet / TCP/IP connection



Applications:

Groundwater exploration,

geotechnical investigation,

monitoring of dams and dikes,

environmental studies,

geological survey,

mineral prospecting,

archaeology,

detecting of cavities and buried

objects,

underwater, marine, borehole

and cross-hole measurements.

Switchbox 12 x 13



Switchbox 12 x 13




Switchbox 12 x 13


Outlook

In development: bending area with 3 layers

„Power“ Semiflex:

– combination with welded WIRELAID wires


Documents

FR4 Semiflex - cheaper than a cable harness?...FR4 Semiflex - cheaper than a cable harness? Terms and definitions System comparision: cable harness versus FR4 Semiflex Design process