Solder Paste Print Test Boards

We're looking for a better way to manage solder-paste print test boards. Can we use a general test board, not a real board? How can we eliminate a test board in the future before a line changeover?

W.H.

Expert Panel Responses

Modern day solder pastes are generally ready to use right out of the jar or cartridge with no mixing, kneading or test prints required. That being said the biggest headache with printing test vehicles, or an actual production board is the clean-up afterwards. If you want to continue the practice, you might want to investigate Bean International’s Adhesive Roll for Testing Print, AS-600. It a low adhesion sheet for running solder paste print test. Afterwards you can peel the tape off and discard it with your solder paste recycling waste stream.

Mike Burgess
Regioanl Sales Manager
ASM Assemby Systems

Mike Burgess is the ASM Assembly Systems PSP Regional Sales Manager, who has numerous years of experience in the electronics industry as a user and supplier. He is responsible for stencils, screens, tooling, chemistries, fabric rolls, and stencil coatings.

There is no good way to eliminate the use of a test board. If cost is an issue, you can request the PCB supplier to provide you with 1-2 scrap boards (clearly marked and separately packaged). But in order to set up the line and verify print parameters for the paste printing operation, you will need a board from the same lot and same PN. This is important because PCB's are different from lot to lot as well as from part number to part number.

A general test board will only be useful if you are evaluating the Solder Paste itself, but you are evaluating the paste printing process. Board condition, such as flatness, topography, legend height, board support, Surface finish, Design, etc. all can impact the outcome of the printing process and that would change from Project to Project and lot to lot. Using a General test board only tells you that you can print on the General test board.

Sven Bock
Director of Quality / CLSSMBB
FCT Companies

Mr. Bock has worked in the Electronics Manufacturing Industry since 1996. He has extensive experience in the PCB manufacturing industry along with PCB Assembly. He has spent 6 years working in Southeast Asia.

When changing over a line for a new PCBA, it is best to use the real PCBs, stencil, and printer setup. This is the best way to test the entire print process. Test print boards will not be representative of printing on the real PCBs. However, test print boards could be used to test the printability of the solder paste. This could be useful when using old/expired solder paste, or solder paste that has been used, stored, and used again.

Use of a clear plastic sheet with low residue adhesive on the PCB allows for printing on real PCBs without the solder paste touching the PCB. This can be done to check alignment, printer parameters, stencil design etc. The clear plastic sheet is removed from the PCB and leaves little to no adhesive residue. This clear plastic sheet method is commonly used by some contract manufacturers.

Tony Lentz
Field Applications
FCT Assembly

Tony has worked in the electronics industry since 1994. He worked as a process engineer at a circuit board manufacturer for 5 years. Since 1999, Tony has worked for FCT Companies as a laboratory manager, facility manager, and most recently a field application engineer. He has extensive experience doing research and development, quality control, and technical service with products used to manufacture and assemble printed circuit boards. He holds B.S. and M.B.S. degrees in Chemistry.

IMO nothing serves better than the real board. Test boards do not provide representations of the actual product.

Jerry Karp
President
JSK Associates

Based in. Northern California since 1971. Founded JSK Associates in 1979. Actively involved in soldering, cleaning, chemistries. 30 years experience in EOS/ESD control.

For stencil printing it is always recommended to use a test board as your first print. Many companies use the "solder sample" board. This is usually a board that the PCB manufacturer provides for developing solder reflow profiles and other operations.

If you want to break away from using a dedicated test board, you need to make sure that the general test board include a pattern of the most difficult component that will be paste-printed on the regular board. For example, BGAs, CGAs, and fine pitch components. The stencil printer (depending on the brand) can do a solder deposition inspection or you can run the test board through other optical inspection equipment.

Edithel Marietti
Senior Manufacturing Engineer
Northrop Grumman

Edithel is a chemical engineer with 20 year experience in manufacturing & process development for electronic contract manufacturers in US as well as some major OEM's. Involved in SMT, Reflow, Wave and other assembly operations entailing conformal coating and robotics.

Using the real boards to perform test print to simulate the setup and parameters. The problem can be detected before the production starts.

While, the general test boards are completely different in dimensions / thickness / fiducials and etc. Suggest to request the solder samples for each PCB design from the PCB suppliers to use as the test print boards. They can be kept for to be used for setup printing.

Patinya Srianan
Customer Technical Support Engineer
Alpha Assembly Solution

Mr. Srianan is a Customer Technical Support Engineer for Alpha Assembly Solution. He has 15-years of experience in SMT and soldering fields. He takes care of all technical inquiries and problems for customers in Southeast Asia and Australia.

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