Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Component soldering strength ?

Kenny Tan

#7459

Component soldering strength ? | 30 July, 2001

Dear All,

I'm now facing with 0805's component missing problem at the production after mounting. In able to containing the defect I'm been trying to increase the soldering strength by changing the stencil thickness from 6mil to 8 mil on a step down stencil.

My question is :-

(1)Any specification (or) standard available to justify a component soldering strength is sufficient ?

(2)What kind of test normally industry conduct to justify the component soldering strength ?

Kindly advise me. Thank you !

Best Regard, Kenny Tan

reply »

Michael Parker

#7479

Component soldering strength ? | 30 July, 2001

Kenny- there are a few standards by IPC and EIA that address the strength of solder. A pull test (which is a destructive test) will average 1500 PSI per joint.

My concern is that you are wanting to increase solder volume for an 0805 component by incorporating a step stencil. I have successfully used 6 mil stencils for much larger components for quite some time. Are you sure you want to go that expense for a new stencil? There are many parameters that affect the solderability of the part.

What steps have you followed in your investigation that leads you to believe you must increase the stencil thickness?

Have you considered other factors? Are you getting good wetting on the part and the pads? Are the parts getting knoked off by some other process? What quality of paste are you using? Is placement accuracy proven? Is the reflow profile verified good?

The list can get long for the questions of all possibilities that cause "missing parts". Please fill in the blanks so that others here can help you directly.

reply »

#7484

Component soldering strength ? | 30 July, 2001

So, yer loosing parts between place and reflow?

That would seem to say yer: * Paste has lost tackiness [check the fine SMTnet Archives for a sample test.]. * Really not placing the parts that you think yer placing. * Knocking the parts out of place with poor handling practices, reflow fan speed too high, etc.

reply »

Kenny Tan

#7489

Component soldering strength ? | 30 July, 2001

Hello Michael & All,

Thanks for the feedback. Months ago we receive a number of reject concerning one of the 0805 & 0603 chip capacitor mising (with joint remain on pad)and seriously solder joint fracture.

From there I had do some investigation on the problem. I found that there are mainly two area which is the contribution to this problem. One is due to SMT poor joint and the other is the depanelling process cutting tools.

That's why from previously 6 mil thickness stencil I had increased them to 8 mil (on 0805 only) The solder paste that using is from Multicore type-3 (Sn62-CR3637-AGD89.5) Using a RTS Profile with a peak temperature of 218��C.

Kindly comment on the issue mention above so that we could discuss this together here. Thanks !

Best Regard, Kenny Tan

reply »

Kenny Tan

#7490

Component soldering strength ? | 30 July, 2001

> Kenny- there are a few standards by IPC and EIA > that address the strength of solder. A pull test > (which is a destructive test) will average 1500 > PSI per joint. > > My concern is that you are > wanting to increase solder volume for an 0805 > component by incorporating a step stencil. I have > successfully used 6 mil stencils for much larger > components for quite some time. Are you sure you > want to go that expense for a new stencil? There > are many parameters that affect the solderability > of the part. > > What steps have you followed in > your investigation that leads you to believe you > must increase the stencil thickness? > > Have you > considered other factors? Are you getting good > wetting on the part and the pads? Are the parts > getting knoked off by some other process? What > quality of paste are you using? Is placement > accuracy proven? Is the reflow profile verified > good? > > The list can get long for the questions > of all possibilities that cause "missing parts". > Please fill in the blanks so that others here can > help you directly.

reply »

#7511

Component soldering strength ? | 31 July, 2001

Figuring-out ways to increase the solder connection strength when you are fracturing the component package is aaaah, umm, er, has you pointed in the wrong direction. ;-)

Listen, if you still have solder on the pad after someone smashed the component so hard that it is no longer on this planet, putting more solder on the pad is not going to help. You need to determine who or what is physically damaging the component and make them quit doing it. Start by finding the pile of busted components on the floor.

Consider this analogy �

SITUATION #1: You are riding your bicycle and a 50 ton dump truck loaded with animal waste smashes in to you and knocks you and your bike over a cliff => you look like a pizza with bicycle parts, instead of anchovies.

SITUATION #2: You are riding your bicycle with �souper woad gwabber� tires and a 50 ton dump truck loaded with animal waste smashes in to you and knocks you and your bike over a cliff => you still look like a pizza with bicycle parts, instead of anchovies. Trust me!!!

reply »

mugen

#7553

Component soldering strength ? | 3 August, 2001

*Laughs* thats a good one Dave! me like your wicked sense of humour!

reply »

PCB Routers

SP700avi inline smt screen printer