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

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Solder joint strength

EA

#33344

Solder joint strength | 22 March, 2005

Hi,

We are trying to break a component ( SMT component ) off the printed circuit board and measure the quality of the solder joint. But, after breaking off and having the reading, we do not know whether the reading is it within the component specification. Appreciate someone could advise where can I find all the component specification.

Thanks.

reply »

#33349

Solder joint strength | 22 March, 2005

There is no standard. This is a relative test. If you wish to do tests of this kind, we suggest to pay attention to the following points: * Shear strength of soft solder depends on the deformation speed applied. The faster the material is deformed the higher the shear strength. * Deformation behavior ( load / deformation rate relationship ) is temperature dependent. * Point, where the shear force is applied is important regarding the state of stress in the solder connection ( shear stress / tensile stress ).

Here's what you should do periodically: * Get a pair of pliers and a sacrificial board * Use the pliers to rip some parts from the board

If: * You can remove parts easily, you have problems. * You struggle removing parts, break parts, lift pads, and the like and when you see solder, it's gainy and coarse; you've got good process.

reply »

pmd

#33369

Solder joint strength | 23 March, 2005

Sounds like EA has way too much free time on his hands. How are you taking a reading. What instruments are you useing to get a reading. What are you looking for? Voids? Adhearsion? Contamination? Why would you need to know what it takes to break a component from a board anyway. What application is this board going to be used in. Just cureious.

reply »

EA

#33390

Solder joint strength | 24 March, 2005

Hi,

We are running the automotive product and question was throw to us how do we ensure that our solder joint are good enough after reflow.....and during the sealant process, there's a bit of bend on the nozzle and it toughes the component and customer so worry it willaffect the solder joint. We did a measurement by pushing the nozzle till it break at 1.5kg, with this force, will it affect the solder joint. So, in order to prove to our customer even with this force able, the solder joint is not affected......

Not that I have too much free time with me.....

reply »

EA

#33391

Solder joint strength | 24 March, 2005

Hi davef,

Appreciate your advise......

reply »

chon

#33417

Solder joint strength | 28 March, 2005

So far I've been working with a xtal. I've been placing this on a board and the part was falling from the board. We found residues on leads and notified vendor as contamination, after that 100% of our production has been verified with a perpendicular push test to the part. After lots of test we found that 6lbs-inch was enough force to find if the part remains attached to the board. I hope helps

reply »

Indy

#33431

Solder joint strength | 29 March, 2005

chon, we do a similar kind of perpendicular test, but have not found any kind of specifications to determine if the force is good eoungh. Since you mentioned that 6 pound-inch was enough for your application, could you provide some insight on how you decided on that. Did you just perform a set of test, as mentioned by you, and saw if the reading were consistent. OR Did you set any kind of criteria.

Thanks Indy

This message was posted Add this forum to your site! Click to learn more. the Electronics Forum @

reply »

chon

#33432

Solder joint strength | 29 March, 2005

Indy, Please refer to IPC-TM-650 TEST METHOD MANUAL Number 2.4.21.1, this is the closest written procedure I've found and used for this. I hope helps or if someone has any other input please advise. On more thing I have this file just let me know if someone want me to attached it to an email please provide an address. chon

reply »

#33440

Solder joint strength | 29 March, 2005

IPC-TM-650 TEST METHODS MANUAL Number 2.4.21.1 Subject: Bond Strength, Surface Mount Lands Perpendicular Pull Method

1 Scope This test method is used to determine the bond strength (breakaway strength) of surface mount lands from substrate materials by a perpendicular pull and force measurement.

It is designed to test solderable metals on any type of substrate in a variety of surface mount land sizes. The surface finish shall be the same as the board it represents.

reply »

chon

#33452

Solder joint strength | 30 March, 2005

Davef That's why I mentioned that this was the "Closest" written procedure I've found related to this type of tests.

reply »

Dreamsniper

#33457

Solder joint strength | 30 March, 2005

If there's no shear strength standard for solder joint, how will I define my pad width and length then. I have a 8.5 mils width and my component lead width is 8.66 mils based on manufacturer's minimum width specification. How will I identify that it is not a suuficient pad width for that part. What test do I need to use? How will I justify to our designers that it is a sub-standard solder joint. How will I defend my stand then. They can easily say that there's no standard solder joint strength.

regards, Dreamy

reply »


URL

#33459

Solder joint strength | 30 March, 2005

There is no spec because solder is designed to provide an electrical connection not a mechanical connection to hold the part on. If it where mechanical we�d be welding our parts on. Your pad width and length are derived from your component manufacturer. I haven�t found a part yet that didn�t have this. That along with your IPC guidelines, a pad design can be verified pretty easily. IPC also gives good guidelines to see what a class 1,2 and 3 solder joint looks like and how to measure it. There should be no reason to mechanically test the shear strength of a solder joint unless your board is designed to be subjected to a sand iron every so often. Otherwise solder is just there to provide and electrical connection to the board, period.

reply »

toromaster

#33536

Solder joint strength | 4 April, 2005

we also have a need to measure the solder bond strength of our gull wing parts on our pwb.

there are many published comparisons between eutectic SnPb and no Pb solders out there. the number that comes to mind is about 10N to 15N.

I have not looked but H.H. Manko, Soldering Handbook for Printed Circuits and Surface Mounting, Van Nostrand Reinhold, 1995 may have the data you seek.

reply »

Reflow Oven