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June 16, 2008
Solder Components to Thin Flexible Circuits
What is the best way to solder fine pitch surface mount connectors to thin flexible circuits?
S. S.
This "Ask the Experts" page has been viewed 518 times.
Ask the Experts Comments
June 16, 2008
Solder will not attach to non-metallic surfaces. Therefore the component body need not be masked. On the other hand solder bridge between component pins is a definite possibility, which can only be alleviated by proper component layout or orientation.
Also as a general design rule try to place SMT ICs on the top side of the PCB so that it does not have to be soldered using wave process. If the design does not allow this then specialized fixtures or masking becomes necessary to avoid any bridging of the leads.
Bjorn Dahle, President
KIC
bdahle@kicmail.com
 Bjorn Dahle is the President of KIC. He has 20 years experience in the electronic manufacturing industry with various manufacturing equipment companies covering pick & place, screen printers and thermal process management. Bjorn Dahle has been with KIC for 11 years, where he initially started as Director of Sales and Marketing. He has led the company's evolution from a profiling company to a thermal process development and process control company.
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June 16, 2008
How thin is the flexible section? Can you support the area with FR4 material? This way you can create a pallet and mount via SMT machines.
Hand assembly using a stencil/paste will help and don’t forget to bake first 2hrs @ 250 degrees.
James Mahoney, Applications Project Manager
Quick Turn Flex Circuits LLC
jmm3559@verizon.net
 James Mahoney is a Technical Operations Manager with a 20 year proven track record in managing new product introduction processes. He is a skilled leader, motivator and problem solver with a strong background in Product Knowledge and Engineering Management. Development areas include High Volume Manufacturing, Electro-mechanical and Printed Circuit Board environments. Large record of accomplishments in Design for Manufacturing, Concurrent Engineering, Quality Improvements, Cost Reduction and Project Management.
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June 16, 2008
The best way we’ve found to do that type of assembly is with fixturing to hold the flex in place, then paste it with solder paste, position the components and reflow in a preset profile oven.
The thing you want to do is hold the flex from moving during the paste deposition and component placement process. Once this is done, submit the entire assembly to the reflow process.
Leo Lambert, Vice President, Technical Director
EPTAC Corporation
leo@eptac.com
 At EPTAC Corporation, Mr. Lambert oversees content of course offerings, IPC Certification programs and provides customers with expert consultation in electronics manufacturing, including RoHS/WEEE and lead free issues. Leo is also the IPC General Chairman for the Assembly/Joining Process Committee, covering areas of mounting, soldering, solderability and assembly.
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June 16, 2008
I would suggest that this is completed in a traditional SMT process with solder paste and an oven with blow speed control. The flex circuits are than placed into a "boat " fixture that carries them through the oven and allows for soldering. The boat is also used to keep the flex on a flat surface and at times used to hold the assembly.
John Norton, Eastern Manager
Vitronics Soltec
jnorton@vsww.com
John Norton started his soldering career in 1983 for Hollis Engineering. He has also worked with Electrovert as a technical training manager and Vitronics Soltec for the last ten years. He has held varoius technical development and sales positions. He received a patent related to selective de-bridging technology for wave soldering applications.
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June 16, 2008
Once the flex circuit material is secured, you can align the component by hand, apply liquid flux and using a hoof or mini-hoof soldering tip to hand solder the component in place.
The biggest concern you will have is overheating the flex material. I would suggest a Direct Power soldering iron with a 600 series tip cartridge. This combination will provide the speed that you need along with the low temperatures that will keep the assembly safe.
Edward Zamborsky, Regional Sales Manager
OK International Inc.
 Mr. Zamborsky serves as one of OK's technology advisors to the Product Development group. Ed has authored many articles, and has presented many papers on topics such as; Low Volume SMT Assembly, Solder Fume Extraction, SMT Rework, BGA Rework, Lead Free Hand Soldering, Lead Free Visual Inspection and Lead Free Array Rework.
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June 16, 2008
Using a Vapor Phase will provide an Oxygen free solder environment for best solder joint results. It will also guarantee 0 Deg delta T and provide a controlled ramp rate.
Vapor Phase systems are available as batch systems or in-line and so if this is a relatively low volume application, you could chose to run a batch system. This would save space and power when compared to a typical reflow oven.
Allen W. Duck, CEO
ATEK llc
allen@atekllc.com
 Allen Duck is a 20-year Electronics Industry veteran with Global experience in multiple fields of technology and management. He started A-Tek in 2006 to provide a sales and service channel for international equipment companies wishing to offer value based solutions to USA companies.
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