Electronics > Manufacturing & Assembly

Pick&Place assembly line

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EEVblog:

--- Quote from: Rundstedt on July 15, 2012, 09:15:00 pm ---Well there are many factors:
- there are little to no after-warranty services. Since we didn't design product there isn't a lot what we can do to repair it.
- there are some little difficulties with our contractors (some minor errors in product that they refuse to acknowledge)
- we export a lot to China/India/Thailand and other cost sensitive markets, and producing in-house will cut expenses (you say that outside companies have better machines, but we are looking at similar line)
- we have no control over producing capabilities of companies we hire, sometimes when they have too much other orders they will put ours at back burner.
There are a few other reasons to.

--- End quote ---

Fair enough of course.
Have you actually been tasked with looking into this?
Your manager needs to be made aware that this is a big, expensive, and complex undertaking that will take a lot of work, time and support to get running smoothly. You can't just buy the machines and expect magic to happen  ;D

Dave.

IanB:

--- Quote from: Rundstedt on July 15, 2012, 09:15:00 pm ---Well there are many factors:
- there are little to no after-warranty services. Since we didn't design product there isn't a lot what we can do to repair it.
- there are some little difficulties with our contractors (some minor errors in product that they refuse to acknowledge)
- we export a lot to China/India/Thailand and other cost sensitive markets, and producing in-house will cut expenses (you say that outside companies have better machines, but we are looking at similar line)
- we have no control over producing capabilities of companies we hire, sometimes when they have too much other orders they will put ours at back burner.

There are a few other reasons to.
--- End quote ---

It seems a little odd to me that if your company didn't design the product and doesn't make the product, what does your company actually do? What is the value add?

Rundstedt:

--- Quote from: EEVblog on July 15, 2012, 10:39:50 pm ---Fair enough of course.
Have you actually been tasked with looking into this?
Your manager needs to be made aware that this is a big, expensive, and complex undertaking that will take a lot of work, time and support to get running smoothly. You can't just buy the machines and expect magic to happen  ;D
Dave.

--- End quote ---
Yep, but when I learn to operate such line it will be just awesome.
--- Quote from: IanB on July 15, 2012, 11:40:09 pm ---
It seems a little odd to me that if your company didn't design the product and doesn't make the product, what does your company actually do? What is the value add?

--- End quote ---
Well they started from trading parts, later they started to order custom parts for them and "making" complete kits for lpg/cng conversion. We assemble some parts, but mostly we are just the middleman.

Actually I grossly underestimated how much production capabilities we need, we need about 100k small boards 40x60 mm with about 10 different parts, 100k 120x70 mm with 40 different components and another 100k of 25x25 mm boards with 15 components (both sides). And a few thousands of other boards. Currently some company offered us ax-501 (used 10 months). Can anyone suggest me how many zones will I need in reflow oven, and do we need to solder in protection of nitrogen (led free solder of course), what types of transport for pcb there are?. Should paste dispenser be vacuum cleaned or wet cleaned.

Sorry for all those questions, Jarek.

mikeselectricstuff:

--- Quote from: Rundstedt on July 16, 2012, 08:56:17 am ---
--- Quote from: EEVblog on July 15, 2012, 10:39:50 pm ---Fair enough of course.
Have you actually been tasked with looking into this?
Your manager needs to be made aware that this is a big, expensive, and complex undertaking that will take a lot of work, time and support to get running smoothly. You can't just buy the machines and expect magic to happen  ;D
Dave.

--- End quote ---
Yep, but when I learn to operate such line it will be just awesome.
--- Quote from: IanB on July 15, 2012, 11:40:09 pm ---
It seems a little odd to me that if your company didn't design the product and doesn't make the product, what does your company actually do? What is the value add?

--- End quote ---
Well they started from trading parts, later they started to order custom parts for them and "making" complete kits for lpg/cng conversion. We assemble some parts, but mostly we are just the middleman.

Actually I grossly underestimated how much production capabilities we need, we need about 100k small boards 40x60 mm with about 10 different parts, 100k 120x70 mm with 40 different components and another 100k of 25x25 mm boards with 15 components (both sides). And a few thousands of other boards. Currently some company offered us ax-501 (used 10 months). Can anyone suggest me how many zones will I need in reflow oven, and do we need to solder in protection of nitrogen (led free solder of course), what types of transport for pcb there are?. Should paste dispenser be vacuum cleaned or wet cleaned.

Sorry for all those questions, Jarek.

--- End quote ---

If you are talking these volumes (I assume annual) you need to pay an expert to advise you, as you will be spending well into six digits on setting up a line for this capability, and mistakes can be very expensive.  You will need to employ several full-time staff to run the assembly line, manage inventory, handle QC and test.

This would be a massive investment -  it sounds to me like both you and your management are hopelessly out of your depth.

For these volumes, outsourcing to a Far East assembly house would seem to be the obvious solution.

EEMarc:

--- Quote from: Rundstedt on July 16, 2012, 08:56:17 am ---Actually I grossly underestimated how much production capabilities we need, we need about 100k small boards 40x60 mm with about 10 different parts, 100k 120x70 mm with 40 different components and another 100k of 25x25 mm boards with 15 components (both sides). And a few thousands of other boards. Currently some company offered us ax-501 (used 10 months). Can anyone suggest me how many zones will I need in reflow oven, and do we need to solder in protection of nitrogen (led free solder of course), what types of transport for pcb there are?. Should paste dispenser be vacuum cleaned or wet cleaned.

Sorry for all those questions, Jarek.

--- End quote ---

That is a cool PnP machine. Parallel placement means substantial throughput. This means that you can still have a substantial amount of downtime and catch back up with ease. Also, having spare capacity gives opportunity for getting outside contracts to have boards built on your assembly line. This will help offset the amortization of the machine's cost to your favor and provide a potentially valuable revenue stream for your company. In other words, outside contracts could potentially pay for the machine and then some. Running your own boards will then be reduced to the simple cost of labor and utilities. This will also help make the cost benefit analysis look more appealing. Just don't forget about gluing larger parts down for 2 side component applications.

The paster, stencil cleaner, reflow oven, and use of nitrogen are all interrelated issues. Changing one will likely change the choice of others. It's hard to make recommendations here without a full knowledge of the product running through the machine. Nitrogen will get better RoHS solder wettability and solder joint quality as well as have a higher surface tension which is useful for holding upsidedown parts through the reflow. It also will screw with the reflow oven's temperatures, and have higher quality requirements for paste application and stencil cleaning.  The goal is to not need to use nitrogen since it is an additional expense. Selection of a good solder paste may or may not negate the need for it. You will also want more zones particularly for just after reflow to prevent popcorning/tombstoning of the components as they go through the temperature cooling. You'll see this when one side cools faster than the other side, usually during too fast of a cooling rate before solder solidification. If the leads are at too much of a different temperature, the torque caused by the cooling and contraction of the solder will cause it to lift the opposite end of the part off of the board. This is common with hand soldering surface mount components if you don't hold the part down. It is particularly bad with tiny components.

RoHS is slow to wet out without nitrogen and you wil need to take care else you willl have some thermal issues with nitrogen. Also, look at how much your components size vary. If you are combining small resistors and capacitors with DPAK, D2PAK, or IC's with thermal pads soldered to the board or have multilayered boards, you will want more zones. Each device has an acceptable thermal profile for reflow. you will need to find a line that is acceptable for all components used on a given board. The more zones you have, the easier it is to get a good reflow for all components, tiny and heavy. Going outside of the envelop will increase the failure rate.  Also, remember that each part and pad has a thermal capacity, small parts will heat up quickly while heavy parts will take longer. One problem that you may run into is heating up enough to solder heavy components while not cracking Multi-Layers Ceramic Capacitors (MLCC) for example. Having more zones available will help you optimize the machine so that you can heatsoak the board enough to allow the heavy parts to reflow properly and keep the ceramic caps safe. Nitrogen will help with this.

In general, more zones will give you better control. Keep in mind that not all zones are made alike. A cheap machine could have 50 zones yet do a terrible job because of thermal shock. The key to reflow is controlling and limiting the rate of change of the temperature to precisely match predetermined temperature profile. A good machine will be able to do this with minimal zones in some cases, but more zones does help especially with more demanding requirements. If not careful with nitrogen, you can cause thermal shock regardless of how many zones you have. In general, if you get the minimum number of zones that you need, you'll always end up wanting another one to help tweak the machine's operation.

To determine the precise setup, you will want the advice from someone that has setup a number of successful RoHS PnP lines and has full knowledge of your application. They will be able to help you hone the fine details out for the equipment that you need. Always seek unbiased advice from someone that isn't getting a sales commission. This conflict of interest won't work to your company's benefit even though it may seem cheaper upfront.

-Marc

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