JLCPCB Stencils always being bent

[sinewave]

I've just got 5 SMT Stencils (one being in the wood material) and they were all slightly bent, one almost unusable due to how much it shifts, anyone else gets stencils bent? Stencils from my other fabricator would always arrive in good condition.

[Jackster]

Never had a problem with JLCPCB stencils or warped PCBs as others have claimed to have.

[wraper]

Do you mean framed stencils? I've unbent some just fine. Put on a flat surface to find which 2 opposite corners don't stay flat on the surface (move when pushed on top). Put diagonally with corners which were steady on edge of the desk and push on two corners which were moving. Then re-check flatness and then depending on results either repeat with pushing stronger or do this with opposite corners if you bent it too much.

[Kean]

I’ve never had an issue either. I almost always get the 380x280 as frameless for prototypes/small runs or framed for ongoing production.  I rarely get them cut down, and they have always arrived flat between a pair of the “wood” backing boards used during drilling.

[mikeselectricstuff]

Never had an issue with unframed ones, my only complaint is that stupid sticky film they put on, which risks creasing when peeling off

[SMTech]

Never had an issue with unframed ones, my only complaint is that stupid sticky film they put on, which risks creasing when peeling off

More of a PCBWay shop than a JLC one here, but I'd say all "framed" stencils are at least a bit warped, its unavoidable given the tension, assembly technique and lightweight materials used. On larger framed stencils I have noticed JLC uses heavier frames than PCBWay, much closer to what I would normally expect from a domestic more expensive stencil and pretty rigid&flat. They still suck and I continue to request not to receive them on anything fine pitch or high volume (and certainly never a combination of both). At that point the extra £100GBP is EASILY worth it.

Never seen a kinky unframed stencil tho' the bits of wood always do their trick.

[sinewave]

These were all frameless stencils, one was a 420mm by 320mm that was only slightly bent probably as it was in the wood, enough that it doesn't matter, but the other ones were 80mm by 50mm and those ones were packaged in thick plastic bags and they were all bent, I think they are more warped than bent.

[Rat_Patrol]

I gave up on the Chinese cheap framed stencils, and go frameless and frameless manual machine. Just seems to work better to stretch them out as needed, and the stencils last a lot longer before falling apart or getting damaged (if you use them more than a couple times).

[Mangozac]

I gave up on the Chinese cheap framed stencils, and go frameless and frameless manual machine. Just seems to work better to stretch them out as needed, and the stencils last a lot longer before falling apart or getting damaged (if you use them more than a couple times).

It must be something to do with the manual printing setup. We have JLC PCB stencils that have done several thousand boards and still going strong, but that's in an MPM UP2000 automatic printer with integrated cleaning.

[JLCPCB Official]

I've just got 5 SMT Stencils (one being in the wood material) and they were all slightly bent, one almost unusable due to how much it shifts, anyone else gets stencils bent? Stencils from my other fabricator would always arrive in good condition.

dear friend, check here to get quick answer on this site https://jlcpcb.com/help/answers?k=SMT-Stencil

[girts]

dear friend, check here to get quick answer on this site https://jlcpcb.com/help/answers?k=SMT-Stencil

By the way - even if *.GTP layer provided, your engineers are always trying to do stencil according to pads.
That's common practice or must ask specially to use GTP layer?
There is no such option on your automated order form.

Another recommendation - if extra outline space (edge rails) for panel is requested (10mm instead of 5mm by default) it is a good idea to place fiducials closer to boards, not outline.... 

[wraper]

dear friend, check here to get quick answer on this site https://jlcpcb.com/help/answers?k=SMT-Stencil

By the way - even if *.GTP layer provided, your engineers are always trying to do stencil according to pads.
That's common practice or must ask specially to use GTP layer?
There is no such option on your automated order form.

Another recommendation - if extra outline space (edge rails) for panel is requested (10mm instead of 5mm by default) it is a good idea to place fiducials closer to boards, not outline....

I suggest ordering stencil separately from PCB with its own file and write in the comments you want it made exactly as is, with no changes.

[girts]

I suggest ordering stencil separately from PCB with its own file and write in the comments you want it made exactly as is, with no changes.

For single PCB - yes, you are right.
About panelized ones - nobody knows they add 0.2mm for V-cut or not.
Not a problem anyway, last 6 months they always ask which gerber to use, just thinking about their defaults...
 

[wraper]

I suggest ordering stencil separately from PCB with its own file and write in the comments you want it made exactly as is, with no changes.

For single PCB - yes, you are right.
About panelized ones - nobody knows they add 0.2mm for V-cut or not.
Not a problem anyway, last 6 months they always ask which gerber to use, just thinking about their defaults...
 

I always panelize myself. Otherwise you will need to reorder stencil if you want PCBs made by another PCB house.

[Styno]

I gave up on the Chinese cheap framed stencils, and go frameless and frameless manual machine. Just seems to work better to stretch them out as needed, and the stencils last a lot longer before falling apart or getting damaged (if you use them more than a couple times).

It must be something to do with the manual printing setup. We have JLC PCB stencils that have done several thousand boards and still going strong, but that's in an MPM UP2000 automatic printer with integrated cleaning.

Many commercial (semi-)automatic printers use one of the two common frame sizes (afaik mostly 20"x 20" or 29"x 29"), I assume yours does as well? Our AVP300 uses 20" x 20" (internal). I looked at the JLCPCB website to find the matching frame size but could not find it. Can you elaborate on how you purchase those?

Another recommendation - if extra outline space (edge rails) for panel is requested (10mm instead of 5mm by default) it is a good idea to place fiducials closer to boards, not outline....

That is a good point. With our p&p machine the panel fiducials on the 5 mm strips almost always get obscured by the clamping rail so I default to using pcb fiducials only.

[cgroen]

I just received my order number 310 from JLCPCB, never seen that problem on (I order frameless always) stencils, always 100% perfect and well packed.

[sinewave]

Are your stencils customized size?

[girts]

I always panelize myself. Otherwise you will need to reorder stencil if you want PCBs made by another PCB house.

True.
From another point of view - no reason to order PCB's and stencil from different factories.
One China is not better than another China, prices are almost the same and quality acceptable (had only 3 faulty PCB's last year, about 10000 PCB's ordered). 
Local PCB makers - in my opinion they are useless now. Too much quality issues and 3x higher prices. I always prefer to support local business, but... it's not serious if 50 boards from 100 ordered goes directly to trash.

[wraper]

One China is not better than another China, prices are almost the same and quality acceptable (had only 3 faulty PCB's last year, about 10000 PCB's ordered)

They're very different, even when price is similar. JLCPCB, PCBWAY and ALLPCB are far from the best, the only advantage is very low price, and speed for JLCPCB. WELLPCB for example produces much nicer boards but still not the best.

[Rat_Patrol]

I gave up on the Chinese cheap framed stencils, and go frameless and frameless manual machine. Just seems to work better to stretch them out as needed, and the stencils last a lot longer before falling apart or getting damaged (if you use them more than a couple times).

It must be something to do with the manual printing setup. We have JLC PCB stencils that have done several thousand boards and still going strong, but that's in an MPM UP2000 automatic printer with integrated cleaning.

Many commercial (semi-)automatic printers use one of the two common frame sizes (afaik mostly 20"x 20" or 29"x 29"), I assume yours does as well? Our AVP300 uses 20" x 20" (internal). I looked at the JLCPCB website to find the matching frame size but could not find it. Can you elaborate on how you purchase those?

Another recommendation - if extra outline space (edge rails) for panel is requested (10mm instead of 5mm by default) it is a good idea to place fiducials closer to boards, not outline....

That is a good point. With our p&p machine the panel fiducials on the 5 mm strips almost always get obscured by the clamping rail so I default to using pcb fiducials only.

I just order the smallest size frameless stencils they carry, and notch out the corners with a tin snips to fit into the clamps of my frameless manual stencil machine. Works well enough.

[Mangozac]

Many commercial (semi-)automatic printers use one of the two common frame sizes (afaik mostly 20"x 20" or 29"x 29"), I assume yours does as well? Our AVP300 uses 20" x 20" (internal). I looked at the JLCPCB website to find the matching frame size but could not find it. Can you elaborate on how you purchase those?

Yeah our UP2000 takes the 29x29 stencils but it would be a massive waste in terms of shipping cost and storage space if we had them made that size. I built a special stencil adaptor to accept 550x450mm stencils, as I determined that to be a good trade-off. MPM did offer universal stencil adaptors for their machines.

[NorthGuy]

By the way - even if *.GTP layer provided, your engineers are always trying to do stencil according to pads.
That's common practice or must ask specially to use GTP layer?
There is no such option on your automated order form.

I always put a note not to change things and provide the GTP. Nothing helps. They still do it their own way. They think they know better. There's absolutely no way to get what you want from JLCPCB.

Ordering stencils separately doesn't look like a good idea - you have to pay shipping twice, and their shipping is expensive.

How about PCBWay? Are their stencils the same way?

Anyway, I can live with Oshstencils. They're expensive, but you always get what you want. Always.

[wraper]

Ordering stencils separately doesn't look like a good idea - you have to pay shipping twice, and their shipping is expensive.

In the same order but as a separate item with its own files uploaded.

[loki42]

I get the 29" ones from jlcpcb.  My printer can use other sizes but 29" are the easiest to set up in it.  Choose framework then it's as the metric equivalent.

[pdp11]

In 2021 I have ordered 1 pcb and 1 stencil at jlcpcb.
Superimposing the stencil, is not fit exactly the pcb.
That was my last order at jlcpcb