Brief review of the Zhengbang ZB2520HL reflow oven (T-962A alternative)

[BreakingOhmsLaw]

Hi everyone, i recently acquired a ZB2520HL and wanted to give a brief review since there is not too much information out there.

Purchase and shipping
The only source for the unit seems to be buying it directly from the manufacturer. I haven't seen any resellers yet. I purchased it through their Aliexpress store. For six days, shipping status did not change, almost hitting the 7-day refund period from Aliexpress. When it was shipped on day six, things went really fast. It took FedEx less than a week to ship it to Germany and bring it to my doorstep. The unit came extremely well packed, as it should, as it weighs in at 19kg. A really sturdy 15mm thick cardboard box, wrapped in 20 layers of plastic. The unit itself was nested in custom styrofoam pieces and wrapped in a plastic bag. No complaints there, I've seen worse shipping from R&S. 


Contents
The oven comes wit a power chord, a serial cable, 1,5m of aluminium flex tube for the exhaust, and a brief english manual. You can tell that was not translated by a native speaker, but is significantly better than the traditional "chinglish" manual we see with a lot chinese products. No worries there.


Quality
The unit is built very well. Chassis is earthed, although the earting does not extend to the one thing you are guaranteed to touch: the drawer. That sits on two rails with some plastic parts, mounted in separate shafts to precent it from heating up. My guess is that the plastic coasters prevent the earthing. The drawer grip is separated by a couple of fibre board washers to prevent it heating up. It does get warm, but not too warm to touch.
Some cosmetic issues with my unit: The front decal was loose in a corner. The drawer has some sputter from the laser cutting. The entire drawer is covered by a fibre glass sheet, so the PCB does not sit on the metal. I'm guessing this aids even heating, as the IR now does not reflect off the shiny drawer surface, but is converted to heated air. The cooling fan for the control unit is always on one you power the unit, and it is rather loud.
The oven has an internal fan that spreads the hot air around. So far, I've not been able to find any cold spot in the drawer, it seems to work well all the way into the corners. The unit does not emit any bad smells, all materials seem to hold up to the temperature, not like the T962, that tries to kill everyone in the room by vaporizing some shoddy masking tape.
Overall, the build quality is very good for the price class. You get a really solid unit, powder coated all around and the construction is solid as a rock. The exhaust fan is made of metal to withstand the temperature of the expelled air.
     


Performance
The unit comes with four preinstalled temperature profiles, with profiles 3 and 4 for unleaded  soldering. It is advertised as a 1,6kW unit, and the power analyzer reports 1628 Watts when the  unit is heating. So the power is spot on 
Peaking through the double glass window, we see four IR heaters and a fan.
I ran a couple of test boards with both leaded and unleaded paste. The leaded out-of-the-box profile seemed a litte too cold for the paste. I don't have a thermocouple available to check the temperature, so I'm not sure whether that's the paste or the ovens fault. The unleaded profiles all worked very well. JST connectors stayed white and did not melt. the soldering was perfect with the exception of some balling which I attribute to myself not baking the boards beforehand. The oven does have a fixed temperature mode that allow you to prebake components and boards to drive the moisture out. The power seems ample for an oven of this size, but i haven't run any huge boards through it yet. I will update this review as information becomes available.
The menu is a bit wonky. It has a lot of unnecessary button presses, and when the text is scrolling, the buttons do nothing, which is mildly annoying.
I did not test the software yet, mainly due to the fact that the interface is RS232. An USB or Ethernet connection would be a nice upgrade, although  RS232 does have the advantage of longer cable lengths over USB. (EDIT: The software was not supplied by ZB and there seems to be no download available)
     

Conclusion
The ZB2530HL is a decent oven for hobbyist or even small professional labs on a budget. While not without flaws, considering the price point of €385 + taxes, you get a lot of (zheng-)bang for your buck. Aliexpress actually deducted the Chinese VAT due to the purchase being above €250, so I paid €385. Depending on where you are, import VAT may apply.
It certainly blows the T-962A out of the water, and the €100 or so premium over the T-962A is well spent. The extra 100Watts may not be very significant, but the internal fan sure does make a world of difference. And more importantly: it is not a death trap out of the box, as is the T-962A.
The only major issue may be the volume of the control unit fan, which is a bit on the loud side. All in all, it's a solid unit for a good price for everybody that just wants something that works out of the box without having to tear it apart and do several mods to make if safe or performant.
As i use this unit, i will amend this post with information that occurs in long term use.

[asmi]

You can use an FTDI's USB to RS232 cable if you want. I don't honestly remember where did I get the software (I got my oven back in 2020), perhaps I contacted the seller and he provided it. Attached are a couple of screenshots (the oven was not connected when I took them). The only interesting feature (not available via controls on the oven itself as far as I can tell) is that it seems to allow PID tuning. But to be honest I never felt the need to do that, not to use the software once I tuned the profile. I only use room temperature stable lead free SAC paste - TS391SNL50, since pretty much all of my boards have at least one BGA and so I don't want to deal with any potential issues arising out of mixing different alloys (all BGAs I ever worked with ship with balls out of SAC).

Overall after over 3 years of use I don't really have much to complain, I've ran up to 5 LF reflow profiles back-to-back (letting oven to cool down PCB to 50°C as a part of profile), and hadn't had any issues (my T962 was seriously overheating after just two profile runs). The only things I can think of in terms of improvements are either cosmetic (I wish it would have larger window so that I can mount a camera and see what's happening inside), or perhaps revamping a GUI to make it more user-friendly, but the latter is something I got used to eventually. I also wanted to replace the annoying fan, but decided to leave it be since I only ever have the oven on when I'm reflowing, and it's off at other time, so I can live with a bit of noise for few minutes.

[BreakingOhmsLaw]

They actually did not supply the software, and I haven't found a download for it yet. But you can access the PID parameters by holding the SET button while switching it on.

[Kean]

I have not yet tried the software with my ITECH RF-A350, but a download for the software is available at https://www.itechsmt.com/pages/download

The ITECH RF-A series reflow ovens are the same units sold under a different brand name, and still shipped by Zhengbang.  I doubt there are any differences other than labeling.
I still need to clear some bench space for the oven, but your experiences match up with mine so far - although I have not reflowed any production PCBs yet.

Over the last year before buying the oven I have bought more than 40 CL feeders from ITECH on AliExpress.  As you mentioned they can be a bit slow to ship an order, but once shipped the packages have arrived quickly with no problems.

[JURP]

 The drawer grip is separated by a couple of fibre board washers to prevent it heating up.

Note:
1) Not fibre board, but mika paper.
2) The password for the SW from iTech will be sent to you by e-mail upon request.

[hp23]

Old thread I know (Apologies). What is the password for the software at ITECH? I have a ZB3530 on my bench (same as  ITECH RF-A350 I assume). Was prompted when extracting the files.

[JURP]

Reply in PM.

[dave_k]

I have the RF-100 version of this product (2.4kw) and  concur with the review posted by BreakingOhmsLaw.

May I also request a PM with the password please? Thanks!

[hp23]

I have the ZB3530HL & have attempted to use the software provided for the ITECH RF-A350. The software connects ok (the ZB3530HL displays "PC Link" on the LCD). I'm using a USB-Serial lead on Windows 11. When I press "Run" with a suitable configuration, the machine does nothing & the "Now" section at the top shows nothing in the Temperature field. I've tried with flow control & as admin.

I've tried searching for an answer online to no avail. Has anyone been able to get this working successfully & what's the trick?

Pete

[MR]

Cheap IR heater ... no thanks. might be okay for some easy PCBs without special requirements. And no one can convince me that unshielded IR will be good (or good at all for components).
Conventional is much less troublesome, the next level of that seems to be Vapor Phase Soldering.

One of those IR modules probably costs around 5-7$ (just that you know what the engine of that IR heater costs). Multiply it with 4 and that's it the rest is enclosure and the controller.

[niebieski201]

Hi.
I just collect my RF-A350 oven, I did not try any PCBs yet but when I checked build in reflow profile without any modifications and with thermocouples stick to bottom plate it doesn't look good.
Temperature in the middle is follow the profile but overshoot 5-6 deg. Temperatures 10 cm from middle, each side, seems to also follow profile but are under the line sometimes 10-15 deg, but within few extra seconds they starts following middle temperature.
Can someone share settings or other tweaks for this oven as factory one seems to be not perfect.

Attached factory profile 4 with empty tray.
Regards

[Kean]

I have the ZB3530HL & have attempted to use the software provided for the ITECH RF-A350. The software connects ok (the ZB3530HL displays "PC Link" on the LCD). I'm using a USB-Serial lead on Windows 11. When I press "Run" with a suitable configuration, the machine does nothing & the "Now" section at the top shows nothing in the Temperature field. I've tried with flow control & as admin.

I've tried searching for an answer online to no avail. Has anyone been able to get this working successfully & what's the trick?

Pete

I've been meaning to try the PC software myself, so last night I asked ITECH for the RAR file password and today I hooked up a laptop with a USB to RS232 cable and the cable provided with the oven.

I started the software, selected COM4, and clicked Open to open the port, then click Link and I for the same "PC Link" message on the oven LCD.  That is a good sign it is communicating.

I entered some reflow parameters (similar to the built-in Curve 4 that I've been using) and hit Run.  Everything worked as expected, with the set points and hold times as specified.

Screenshots attached.  The Y axis of the graph is 25C per div, and X axis is 45 seconds per div.

My main complaints are:
- You can only specify set point and hold times, but I guess that makes sense as it can only ramp up or down so fast.
- It is quite slow in the cooling phase, taking 9 or 10 minutes to cool to 100C in my case unless I open the door.  Would be nice if it ran the fan faster.
- The PC software is really basic.
- The graphed temperature curve is restarted if the time exceeds the full width (900 sec/15 mins) which my settings do (only just).
- The graph also blanks after the run is complete.

[Kean]

Hi.
I just collect my RF-A350 oven, I did not try any PCBs yet but when I checked build in reflow profile without any modifications and with thermocouples stick to bottom plate it doesn't look good.
Temperature in the middle is follow the profile but overshoot 5-6 deg. Temperatures 10 cm from middle, each side, seems to also follow profile but are under the line sometimes 10-15 deg, but within few extra seconds they starts following middle temperature.
Can someone share settings or other tweaks for this oven as factory one seems to be not perfect.

Attached factory profile 4 with empty tray.
Regards

I've not done any tweaks, just been using curve 4 and getting good results.  It works so much better than my 6 year old T-962A which would either burn connectors or not fully melt the solder, both happening on the same PCB unless is was really small and placed close to the center of the tray.  I've not run any large inductors, but I've had some batches with various SMT inductors, relays, electrolytic caps, and connectors go through it fine.

You really need some thermal mass and the thermocouples attached to that to get any real sense of how well it follows the profile.  I did a trial run some time ago with a temperature logger, but I don't seem to have saved the data.  I'll have to do that again when I get a chance.

The curve I posted above as measured by the ovens own thermocouple was pretty accurate to the settings - it will never be perfectly even in every part of the oven.  You can see it did overshoot a little at the start of the soak phase.

I sit my pcbs on small metal standoffs under the corners or edge rails to keep the PCB slightly above the tray.  Possibly not as critical as on the T-962A which just had bare metal.

[Kean]

Cheap IR heater ... no thanks. might be okay for some easy PCBs without special requirements. And no one can convince me that unshielded IR will be good (or good at all for components).
Conventional is much less troublesome, the next level of that seems to be Vapor Phase Soldering.

One of those IR modules probably costs around 5-7$ (just that you know what the engine of that IR heater costs). Multiply it with 4 and that's it the rest is enclosure and the controller.

I'm not sure why you post these negative comments all the time.  If you really think the cost to build, market, and support these is so small, then you should be able to make a very profitable business selling your own "perfect" design...

Most owners of these ovens seem to agree they do a fine job, much better than other cheap ovens like the Puhui range.  And not everyone has the time or tools to construct a DIY reflow oven.  I've built one using a Reflow Master controller, but the toaster oven I used is crap and I didn't want to waste more time on perfecting it.  I just use it for low temperature part drying/baking now.

[hp23]

I agree. They're not great out of the box. Some post factory tuning is required. I'm getting good yields. 4 layer smts with some hefty inductors and plastic connectors. Still having no joy with the PC interface though (hint).

[Kean]

Still having no joy with the PC interface though (hint).

Any chance you have access to a Win 10 machine that you can try?  It worked fine on my cheap Dell workshop laptop under Win10.

[MR]

I'm not sure why you post these negative comments all the time.  If you really think the cost to build, market, and support these is so small, then you should be able to make a very profitable business selling your own "perfect" design...

Most owners of these ovens seem to agree they do a fine job, much better than other cheap ovens like the Puhui range.  And not everyone has the time or tools to construct a DIY reflow oven.  I've built one using a Reflow Master controller, but the toaster oven I used is crap and I didn't want to waste more time on perfecting it.  I just use it for low temperature part drying/baking now.

do some research it's not hard to build a small reflow oven, get one from your local home appliance store. Our local ones offer IR and resistive heating modules inside.
I used 2 IR and 2 resistive lab reflow ovens, the ones with resistive modules always outperformed the IR heaters. IR nor resistive modules are expensive, you can easily source them yourself.
Depending on the parts on your PCB you might get away with an IR reflow oven but for sure they will kill and or degrade more components than the ones with resistive modules.
Try it yourself with mixed pcbs ICs, inductors with plastic head (they're excellent to verify the health of the PCB/components).
We have some PCBs which are almost impossible to reflow reliably with those cheap IR module ovens, especially with non shielded ones. While they are absolutely no problem with ovens with resistive heating modules..

To sum up:
if you want a harder life .. go for cheap chinese IR, surely you'll get some result.
if you want it easier .. pick an oven with resistive modules

and I heard good stories about vapor phase soldering..

[BreakingOhmsLaw]

and I heard good stories about vapor phase soldering..

Comparing apples and oranges.
Vapor phase is out of the question for hobbyists, and the chemicals involved add a cost to each run. Not to mention the problems that come with fumes.
And VP has limitations, open MEMS devices like microphones should not be soldered with VP.

Lastly, the ZB2520 has a convection fan, so it is not a pure IR oven, it's a hybrid between IR and HAC because the IR heats up the fiber glass floor and distributes the heat with the fan.
I've now run several dozen different boards through it, from 2 to 6 layers, and they all soldered just fine.

[BreakingOhmsLaw]

I'm not sure why you post these negative comments all the time.  If you really think the cost to build, market, and support these is so small, then you should be able to make a very profitable business selling your own "perfect" design...

Yeah, I'm getting strong "I can't afford it, so i'll piss all over it" vibes too.

[MR]

The price is not so much different for resistive or IR modules, so there's no such think like "cannot afford".

I dumped the first 300 EUR IR oven because it was crap with our PCBs and depend a lot on the ambient temperature (we would have had to completely overhaul the oven, and yes there were alternative firmwares available we applied it all), the second one cost a few thousand dollars and it's spot on with repeatability - never had any issue with it. Currently we have another reflow oven but it's from a household appliance store for another lab and it also works fine - the plastic components are a lot lighter than with the IR module based oven.

I did not write you cannot make PCBs with IR ovens but they are not in the same class as resistive module ovens. Neither of those ovens are expensive when you have the time to build them yourself. Nor are they complicated in any way.
Also the SMT equipment area in Asia is still highly profitable, don't even think that things are given away for cheap or free in that area.
Europe was more/extremely profitable (overpriced) certainly in the past decades.

IR heater is not an air heater, so where do you place the temperature sensor - it must be attached to the PCB every time otherwise the temperature readout can just be anything depending on how the k-probe is deployed

Anyone who's doing serious business will dump IR reflow ovens.
However I won't stop anyone using IR ovens of course, keep going sooner or later you will learn it (some sooner some other ones later).