RE7500 Improvments, retrofits, suggestions, and tips

[Dan Collins]

I think we need a topic on what we have done to make the RE7500 and the whole BGA replacement process more effective. There have been some posts on this topic, but they are scattered and hard to find.

Any ideas to help improve our yield is appreciated.

Here's my entry:

I make board fixtures for any board more than 60 sq cm to prevent warping.

I have cut the legs down and added adjustable feet to the board holder which gives me more control with the lower heater.

I use a second T/C on the opposite side of the BGA to make sure that there is an even temperature around the chip. I have found from experimentation that the center of the BGA can run 5-15C hotter than where the probes are. Take that into consideration.
A second T/C is a must have with the RE7500. I suggest Thermoworks. They have a great selection and low prices. You need to use TWO T/C's to insure that your temps are in range. I use a bendable wire probe similar to the RE7500 T/C and hold it down on the board holder with a spring clamp.

In a perfect world it would be better to use an oven for reflow and the RE7500 for parts removal. I have a T-962A oven which works well because I can set the profile and walk away. But the prep time is huge due to all the heat sensitive parts. But even with an oven, you need to run test boards with T/C's to insure the heat is correct. The oven just measures air temp in the chamber and not the board temp. I use a wire probe and attach it to the board with kapton tape and make adjustments to the profile as needed. The oven is much better for reballing.

I also highly recommend a good ultrasonic cleaner to clean the boards. That way you can use some of the more aggressive fluxes and properly clean the board without rubbing off the pads with an alcohol wipe. I use Branson EC cleaner for my solution.

To remove the excess solder after BGA removal, I find a flux impregnated solder wick works best with a big flat tip on your iron. Less heat can be used too. Bring the iron up to a temp where the solder just starts to flow freely on the tip and make sure the solder is wet on the tip before using the wick. let the wick clean the tip, don't use a tip cleaner before wicking. It will draw up the solder much better.

Anyone have any suggestions on fluxes? I have been experimenting with different fluxes and so far have found the water soluble to be the most effective. The no-clean fluxes are not aggressive enough. Of course, with the water soluble you need to properly clean the board after reflow. My ultrasonic tank works great for that process.
I have had many problems with the widely used Amtech RMA223. This flux does not remove much oxidation which is very common when reworking. Their 4200 series is much better in my opinion. I am also testing the Qualitek fluxes. Flux is a very crucial part of the reflow process and can make the difference between a good or bad reflow.

Ok, enough babbling from me, lets hear other success or failure stories.

Dan

[linears4]

in lead free soldering i suggest to consider the use of soldering paste instead of flux.

on leaded isn't so necessary but, in all cases use of solder paste will add total reliability in solder joint.

the drawback is that solder paste need special care to store and apply the product during the process, and also, the shelf life is very poor, max 6 months if correctly stored in a cold place.

an easy way to apply solder paste to the balls befor positioning the bga on the board is made with dipping tecnique, but the correct way is to use special stencils.


as i said in a previous post, with re 7500 and generally with all tipe of reflow stations, it is very important the board temperature. 140/150 celsius degrees is needed, more for lead free. you have to be shure that the real temp of the board is in that range before start reflowing adding heat on the top.

cutting the leg of the holder, or simply lifting the whole re 7500 with some spacer will do the job.

[Dan Collins]

If you use the lower heater only to get the board to 140-150C, then you must preheat the upper heater and not start it from cold. Otherwise the upper temp will not reach temp until after the lower has met threshold. I can see how appling as little upper heat as short a time as possible can aid in reducing damage to the BGA, but if the BGA temp and the board temp do not match then the adhesion is not good.

When it comes to the RE7500, or any infrared rework station, lots of trial and error is expected to find that perfect setup.

Seems to me though, if the RE7500 acted more like a reflow oven in controlling temps, we would get much better yields. Both are made in China, you would think someone there would combine the two technologies to make a better product.

[Dan Collins]

Another tip to mention that I found out the hard way.

Do not cool off an Nvidia BGA using the fan until the temp drops to 100C.
If you cool the BGA too quickly the surface could swell up damaging the chip.
I guess the Nvidia chips do not like rapid heat change up or down. Be aware of this.

So.... the IPC specs aren't always on the money. They say to cool the chip as quickly as possible. Not so.

[Raheeeeb]

Originally Posted by Dan Collins

Seems to me though, if the RE7500 acted more like a reflow oven in controlling temps, we would get much better yields. Both are made in China, you would think someone there would combine the two technologies to make a better product.

Are you sure RE7500 is a chinese technology ? Just question come up..

[Dan Collins]

I assume it is since Jovy's main site is from China. Anyway, that wasn't the point of my statement.

[Deusjevoo]

@Dan Collins:

Have you tested out that Qualitek flux?
Which type exactly?
What you think of it?
Or found something better maybe?

Regards,

[Trion]

A handheld IR thermometer like those sold on some websites like IP mart can be useful to check the BGA temperature. I use one now as sometimes the Jovy probe may not be showing the correct temperature. Much more expensive machines use several temperature probes.

[bhartek]

Originally Posted by Dan Collins

I think we need a topic on what we have done to make the RE7500 and the whole BGA replacement process more effective. There have been some posts on this topic, but they are scattered and hard to find.

Any ideas to help improve our yield is appreciated.

Here's my entry:

I make board fixtures for any board more than 60 sq cm to prevent warping.

I have cut the legs down and added adjustable feet to the board holder which gives me more control with the lower heater.

I use a second T/C on the opposite side of the BGA to make sure that there is an even temperature around the chip. I have found from experimentation that the center of the BGA can run 5-15C hotter than where the probes are. Take that into consideration.
A second T/C is a must have with the RE7500. I suggest Thermoworks. They have a great selection and low prices. You need to use TWO T/C's to insure that your temps are in range. I use a bendable wire probe similar to the RE7500 T/C and hold it down on the board holder with a spring clamp.

In a perfect world it would be better to use an oven for reflow and the RE7500 for parts removal. I have a T-962A oven which works well because I can set the profile and walk away. But the prep time is huge due to all the heat sensitive parts. But even with an oven, you need to run test boards with T/C's to insure the heat is correct. The oven just measures air temp in the chamber and not the board temp. I use a wire probe and attach it to the board with kapton tape and make adjustments to the profile as needed. The oven is much better for reballing.

I also highly recommend a good ultrasonic cleaner to clean the boards. That way you can use some of the more aggressive fluxes and properly clean the board without rubbing off the pads with an alcohol wipe. I use Branson EC cleaner for my solution.

To remove the excess solder after BGA removal, I find a flux impregnated solder wick works best with a big flat tip on your iron. Less heat can be used too. Bring the iron up to a temp where the solder just starts to flow freely on the tip and make sure the solder is wet on the tip before using the wick. let the wick clean the tip, don't use a tip cleaner before wicking. It will draw up the solder much better.

Anyone have any suggestions on fluxes? I have been experimenting with different fluxes and so far have found the water soluble to be the most effective. The no-clean fluxes are not aggressive enough. Of course, with the water soluble you need to properly clean the board after reflow. My ultrasonic tank works great for that process.
I have had many problems with the widely used Amtech RMA223. This flux does not remove much oxidation which is very common when reworking. Their 4200 series is much better in my opinion. I am also testing the Qualitek fluxes. Flux is a very crucial part of the reflow process and can make the difference between a good or bad reflow.

Ok, enough babbling from me, lets hear other success or failure stories.

Dan

Hi Dan,
I am using this machine but the Upper Heater has stopped working, I can purchase the element, but is it easy to install, meaning is the machine easy to dismantle/Thanks

[bhartek]

Hi, can anybody advise if the machine is easy to dismantle, I need to replace UH Element or the Board/Thanks

[pentu]

Originally Posted by bhartek

Hi, can anybody advise if the machine is easy to dismantle, I need to replace UH Element or the Board/Thanks

Hello,

it is very easy to dismantle and service it, i have done it, though for general maintenance only.

B/R
pentu

[Raheeeeb]

Hi ,

your machine under warranty or not ?

BR.

Originally Posted by bhartek

Hi, can anybody advise if the machine is easy to dismantle, I need to replace UH Element or the Board/Thanks

[badnes5]

we started this thread a while ago but it's since dissapeared - we've been adding to the improvements and now have a modified top heater with bigger heat area - pics to follow.

Modifications - xbox + ps3 improvements !

[badnes5]

we used the original bottom heater 90mmx90mm and mounted it in the top heater assembly after our 300w packed in - 2 days before christmas (with 25 ps3's still to reflow ! ) - was no need to use the internal PTC sensor (middle two wires )

has made it more stable for larger boards - but remember to increase your top heater height as the boards getting more heat faster.

[bhartek]

Originally Posted by Dan Collins

I think we need a topic on what we have done to make the RE7500 and the whole BGA replacement process more effective. There have been some posts on this topic, but they are scattered and hard to find.

Any ideas to help improve our yield is appreciated.

Here's my entry:

I make board fixtures for any board more than 60 sq cm to prevent warping.

I have cut the legs down and added adjustable feet to the board holder which gives me more control with the lower heater.

I use a second T/C on the opposite side of the BGA to make sure that there is an even temperature around the chip. I have found from experimentation that the center of the BGA can run 5-15C hotter than where the probes are. Take that into consideration.
A second T/C is a must have with the RE7500. I suggest Thermoworks. They have a great selection and low prices. You need to use TWO T/C's to insure that your temps are in range. I use a bendable wire probe similar to the RE7500 T/C and hold it down on the board holder with a spring clamp.

In a perfect world it would be better to use an oven for reflow and the RE7500 for parts removal. I have a T-962A oven which works well because I can set the profile and walk away. But the prep time is huge due to all the heat sensitive parts. But even with an oven, you need to run test boards with T/C's to insure the heat is correct. The oven just measures air temp in the chamber and not the board temp. I use a wire probe and attach it to the board with kapton tape and make adjustments to the profile as needed. The oven is much better for reballing.

I also highly recommend a good ultrasonic cleaner to clean the boards. That way you can use some of the more aggressive fluxes and properly clean the board without rubbing off the pads with an alcohol wipe. I use Branson EC cleaner for my solution.

To remove the excess solder after BGA removal, I find a flux impregnated solder wick works best with a big flat tip on your iron. Less heat can be used too. Bring the iron up to a temp where the solder just starts to flow freely on the tip and make sure the solder is wet on the tip before using the wick. let the wick clean the tip, don't use a tip cleaner before wicking. It will draw up the solder much better.

Anyone have any suggestions on fluxes? I have been experimenting with different fluxes and so far have found the water soluble to be the most effective. The no-clean fluxes are not aggressive enough. Of course, with the water soluble you need to properly clean the board after reflow. My ultrasonic tank works great for that process.
I have had many problems with the widely used Amtech RMA223. This flux does not remove much oxidation which is very common when reworking. Their 4200 series is much better in my opinion. I am also testing the Qualitek fluxes. Flux is a very crucial part of the reflow process and can make the difference between a good or bad reflow.

Ok, enough babbling from me, lets hear other success or failure stories.

Dan

Hi..I have been using Jovy for 6 months, still not 100% results. Any advise about Flux etc/Thanks