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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Comparison between Glue & solderpaste process

Surinder Kumar

#20426

Comparison between Glue & solderpaste process | 19 June, 2002

Is somebody has Comparison data between SMT Glue & Solderpaste process.I know,the paste printing process is better to achieve high yields,but I want to see some Comparison data in terms of rework.

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Hussman69

#20443

Comparison between Glue & solderpaste process | 20 June, 2002

When you ask for data in terms of rework, do you want reflow solder yields versus wave solder yields? Or do you want repair data from each process, or yield data that shows actual glue defects from screen printing versus solder paste screen printing process?

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surinder

#20444

Comparison between Glue & solderpaste process | 20 June, 2002

Thanks for the reply,Yes the data should show the yield difference from Paste printing process to wave solder process.I mean if we have Low yield that means more rework in that Case-Thanks & looking forward to get more information Surinder

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#20449

Comparison between Glue & solderpaste process | 20 June, 2002

We look at gluing and pasting second side components as two different processes, NOT alternative processes. Given our drothers, we'd paste / place / reflow all day long, before we'd want to glue. We glue because we have to glue. The main driver to us gluing is the need to attach PTH components to the board. No PTH, no glue.

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surinder

#20454

Comparison between Glue & solderpaste process | 20 June, 2002

Hi Dave, I am agree with you,but one of my customer want to know the difference in terms of rework/Quality,if we go for Glue process in place of solder paste and want to see some data We have board ,which have Through hole components and smt comp. on Top & bottom side & using Solder paste process. Thanks - Surinder

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RDR

#20457

Comparison between Glue & solderpaste process | 21 June, 2002

A lot of your success with waving SMT components is dependent upon design and what type of wave forms you use. Without knowing how the board is laid out or what type of wave you have it is pretty difficult to determine what the yield differences will be. for example if you have a lot of SOT23, QFP, etc... whith one of the old style "bubbler" chip waves you will not get a good yield as compared with reflow. Are all of the components laid out with optimum orientations, solder thieving pads etc... for wave?

As a general rule your yield will be lower waving SMT but not knowing the layout of board I would not be able to give you any data. I have waved boards and had product yields anywhere from 0 to 100% Your DPMO can also have a very high range based upon design etc...

Russ

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surinder

#20458

Comparison between Glue & solderpaste process | 21 June, 2002

Hi Russ, Thanks for your input.My board has SMT Chip components, SOT23,SOIC's & 2QFP (25MIL PITCH). Also,taking consideration that the board is well design for Wave.This board has been designed end of last year. We have latest model of Electrovert machine,which have all the feature like lamda wave/Chip wave ,Air knifes etc..Will it okay for you to provide some data for reference,if any for average type of board,which should have around 200 components on bottoms side & 600 comp. on Top side & 63 mil thickness. Thanks & Rgds, Surinder

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Stephen

#20459

Comparison between Glue & solderpaste process | 21 June, 2002

When you say well designed for wave, does that include "extra" solder pads for the IC's for solder thieving? And Boards that are well designed for wave don't have QFP's on the bottom. They might be ok but then the board would be "ok for wave", but not "well designed" for wave. Bascally your customer wants to know exactly how much worse wave soldering is than reflow? I know of a case where a board had to be waved because of the amount of TH parts and a selective solder pallet wouldn't work, so the company relfowed both sides and put a large amount of masking on the board to avoid waving the TH parts. Stephen

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surinder

#20460

Comparison between Glue & solderpaste process | 21 June, 2002

Hi Stephan, Thanks,Yes there are thieving pads on Ic's .Also the two QFP, which mention,that will be removed by modifying the design in long run ,if the results/Yields are okay as with Glue as Compared to solderpaste process. Yes you are right here,basically they want to know,how bad the yield would be ,if they go for Glue process with the existing design. Thanks- Surinder

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#20462

Comparison between Glue & solderpaste process | 21 June, 2002

If your wave machine has the new style Rotary Chip Wave and the Hot Air De-Bridging Knife options you can expect good yields. However, depending on the PCB design, double-sided solderpaste reflow and selective solder pallets for wave solder is a better process. Can't give you any specific defect numbers but from my experience they are significantly lower with douple-sided solderpaste reflow and selective wave process than with adhesive-attach wave solder process. Especially if 0603 size and low-profile mini-SOT23 components are on the bottom side. Adhesive dispensing repeatability is critical for 0603.

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#20463

Comparison between Glue & solderpaste process | 22 June, 2002

I agree with PJC.. The mention of 2 QFPs to wave = more than likely rework to remove bridges and a potential to scrap the board, 25mil isnt as bad as 20 or less.. but the potential is still very real.$$$$$$ reflow/reflow is my 2 cents with the possibility of a wave fixture.. to protect the QFPs or any other sensitive areas if the board design allows it.. also with Epoxy and paste process(on the same side) in SMT you can reduce the opportunities for voiding and bridging in the wave process... gluck

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Stephen

#20464

Comparison between Glue & solderpaste process | 23 June, 2002

I worked at a place where a customer complained that the resistance of some components was lowered. It was found to be flux entrapped from the wave solder process. The tube of epoxy, didn't have a date of manufacture, shelf life, or use by date on the tube. The QA manager was told by the manufacturer that the shelf life was 6 months. The supplier couldn't tell us when it had been made but did tell us we hadn't bought any in the previous 9 months. We ended up removing about 50 R&C's per board and repopulating them. If you go with glue be very carefull about shelf life, but then we didn't use a lot of it and therefore didn't go through it very quickly. Stephen

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