In this webinar we review key flex and rigid-flex technical items that we routinely encounter during the design review and production tooling engineering processes. These items often require technical questions to be asked and answered which in turn delays the production release and delivery of an order. The objective is to address these items, if necessary, early on during the design phase and in advance of an order being placed so as not to incur any delays. The most common items fall into 4 groups: Manufacturability, Materials, Functionality, and Reliability. For more information on our flex and rigid-flex PCB solutions visit http://www.epectec.com/flex/

1. Manufacturing That Eliminates Risk & Improves Reliability
How to Ensure Your Flex Circuit
Quick-Turn Will Not Get Delayed
04.26.18

2. Manufacturing That Eliminates Risk & Improves Reliability
2
Introduction
 Challenges arise from:
– Design complexity
– Wide variety of available design options
– End use mechanical bend requirements
– Engineering timelines
– Knowledge base
 Many designs have technical issues that require:
– Q/A with customer engineering
– Data modifications and or re-design
– Increased levels of design review
 End result: Timeline delays

3. Manufacturing That Eliminates Risk & Improves Reliability
3
 Most common technical issues fall into 4 groups:
1. Manufacturability:
• Excessive complexity
• Potential yield issues
2. Materials:
• Non-stock specific brands & thicknesses
Agenda

4. Manufacturing That Eliminates Risk & Improves Reliability
4
Agenda (continued)
3. Functionality:
• Bend requirements
• Electrical performance
4. Reliability:
• Mechanical bend
• Electrical

5. Manufacturing That Eliminates Risk & Improves Reliability
5
Manufacturability

6. Manufacturing That Eliminates Risk & Improves Reliability
6
Manufacturability
 IPC 2223 Design Standard:
– Defines best Design, Gerber
layout and construction
practices to eliminate short and
long term reliability issues.

7. Manufacturing That Eliminates Risk & Improves Reliability
7
Manufacturability (continued)
 Rigid-Flex Example:
– Design:
• Air Gap flex layers (> 2 layers)
– Materials:
• Adhesiveless flex core(s)
• Low flow prepreg in rigid areas
– Construction:
• Selective Coverlay

8. Manufacturing That Eliminates Risk & Improves Reliability
8
Manufacturability (continued)
 Rigid-Flex Example:
– Gerber Layout:
• Min. Plated Thru Hole (PTH) / Via hole to flex transition spacing

9. Manufacturing That Eliminates Risk & Improves Reliability
9
Manufacturability
 Part Size & Shape:
– Large designs:
• Material and manufacturing tolerances
• Manufacturing tooling and equipment limits
• Available Material sizes
– Complex shapes:
• Not all configurations are manufacturable.

10. Manufacturing That Eliminates Risk & Improves Reliability
10
Manufacturability
 Stiffener Requirements:
– Overlapped stiffeners
– Stiffener to Flex outline mismatch
– Unique materials

11. Manufacturing That Eliminates Risk & Improves Reliability
11
Manufacturability
 Min. Flex Length:
– Rigid – Flex Min. flex length = 3 mm
• Due to Selective Coverlay requirement
• Required to maintain positional accuracy
of Coverlay
 Pressure Sensitive Adhesives (PSA):
– Not all materials stocked
– May not withstand assembly re-flow

12. Manufacturing That Eliminates Risk & Improves Reliability
12
Materials

13. Manufacturing That Eliminates Risk & Improves Reliability
13
Materials
 Specific Brand / Part Number Callouts:
– Not all materials are available or stocked
– Geographical restrictions
– Material format availability
• Panels vs rolls
– Manufacturing methods:
• Tooling systems and equipment / process configurations dependent
upon material format
– Define per IPC Specification call outs or allow
for equivalent IPC certified materials

14. Manufacturing That Eliminates Risk & Improves Reliability
14
Materials
 Excessive Material & Copper Thickness(s):
– Not all thicknesses, both thicker & thinner, are stocked or
commonly utilized
– Impact on mechanical
capabilities, reliability & cost

15. Manufacturing That Eliminates Risk & Improves Reliability
15
Functionality

16. Manufacturing That Eliminates Risk & Improves Reliability
16
Functionality
 Bend Requirements:
– Not defined:
• Type: “Bend to fit” or “Dynamic flex”
• Min. Bend radius
• Bend location(s)

17. Manufacturing That Eliminates Risk & Improves Reliability
17
Functionality
 Controlled Impedance:
– Not Defined:
• Values & tolerances
• Specific trace locations

18. Manufacturing That Eliminates Risk & Improves Reliability
18
Reliability

19. Manufacturing That Eliminates Risk & Improves Reliability
19
Reliability
 ZIF (Zero Insertion Force) Contacts:
– Gerber layout issue
– Connector make & part number not defined in data set
– Flex requirements defined by connector spec.
• Coverlay opening min.
• Stiffener dimension min.
– Tight tolerances:
• Contact Fingers to outline
• Outline width
• Finger area thickness with
stiffener

20. Manufacturing That Eliminates Risk & Improves Reliability
20
Reliability
 Material Stackup:
– Flex material stack up configuration
and or flex area thickness may not
meet the bend requirements
resulting in part breakage.
 IPC 2223:
– Violations may lead to short or long
term via reliability issues.
– Min. 0.050” as measured from edge
of hole

21. Manufacturing That Eliminates Risk & Improves Reliability
21
Reliability
 Component Area Stiffeners:
– Missing or incorrectly defined stiffeners may lead to solder joint
reliability issues due to flex being bent adjacent to components.

22. Manufacturing That Eliminates Risk & Improves Reliability
22
Reliability
 Gerber layout:
– Layer to layer offset traces
– Arced corner traces
– Trace to pad fillets

23. Manufacturing That Eliminates Risk & Improves Reliability
23
Reliability
 Hybrid Coverlay / Soldermask:
– High density SMT components
– Soldermask in component areas
– Coverlay in flex sections
– Common requirement but not
defined in supplied data set.

24. Manufacturing That Eliminates Risk & Improves Reliability
24
Summary
 All of the items reviewed are part of the design review process
implemented initially at the quoting stage and verified at the production
engineering process.
 Any items identified:
– Will delay the processing of an order
– Must be resolved to prevent negatively impacting performance and
reliability of the finished parts
 Recommend working with supplier during the design process to
address all issues early.
– Prevents issues from arising at the order process stage.

25. Manufacturing That Eliminates Risk & Improves Reliability
25
Our Products
Custom Battery Packs Flex & Rigid-Flex PCB’s High Reliability SMART HMIs
RF Product Solutions Cable Assemblies Printed Circuit Boards

26. Manufacturing That Eliminates Risk & Improves Reliability
26
Q&A
 Questions?
– Enter any questions you may have
in the Control Panel
– If we don’t have time to get to it, we
will reply via email

27. Manufacturing That Eliminates Risk & Improves Reliability
27
Thank You
Check out our website at www.epectec.com.
For more information email sales@epectec.com.
Stay Connected with Epec Engineered Technologies
Follow us on our social media sites for continuous technical updates and information: