PTH08T220W: Solderability issue - Using selective wave solder pins don't seem to support out-gassing

Hi,

Is there any update or anything I can do further to help resolve the issue?

Regards,
Alejandro

Hello Alejandro,

Thank you for your messages. The board is very thick insomuch that when the component is inserted the pins barely reach the other side of the board. From the manufacturing engineer I don't believe it is always the same pin. He indicated that if we used wave versus selective soldering the wave will pick up the board and this issue would disappear. Unfortunately, with the current machine (selective solder) during soldering the gas is unable to escape because the pins cover the holes; currently, the process is to put our boards through the x-ray machine and then rework any pins exhibiting the issue. The x-ray image I sent initially shows other pins with solder and one of the pins (bottom right) without any solder. I noticed there were soldering recommendations for these devices (see link below); however, the document does not talk about through hole components. Could I request that soldering recommendations be provided for the through hole parts?

http://www.ti.com/lit/an/slta054a/slta054a.pdf

Hi,

Unfortunately, we do not have a document that provides recommendations on soldering for through-hole components. But, below I've attached links in which can be beneficial.

• http://www.ti.com/lit/an/snoa550e/snoa550e.pdf
• http://www.ti.com/lit/an/snoa292j/snoa292j.pdf

Note, there shouldn't be a gas problem in pins that are not getting any solder.

Regards,
Alejandro

Alejandro,

I appreciate the links you provided. We certainly are having issues with outgassing; my observation is that the pins are designed in such a way they do not properly allow gas to escape during the soldering process. As I mentioned initially, we are having to rework 30% of our boards; the X-ray picture I sent in the original message is a classic example where one pin did not get filled but the others did. We also see other issues with voids. We have 6 of these components on one of our boards and we are seeing the issue repeatedly. I would like to escalate the issue and I'm happy to provide additional information. What would TI need to take a closer look at this? Is the forum not the proper avenue?

Michael

Hi Michael,

Have the components gone through a Dip-and-look solderablity test Per J-STD-002?

TI values you as a customer; Please contact me directly at a-iraheta@ti.com.

Regards,
Alejandro

Alejandro & E2E community,

This issue has not been resolved yet. We have been experiencing issues for about 2 years on this and we certainly need your assistance. I'm currently trying to get additional information on the last question from you but it takes time to dig for this information.

In the meantime, I would like to request TI's soldering recommendations for through-hole to be written up. Below is what I previously said about this to which I was told there wasn't one. I appreciate your support.

I noticed there were soldering recommendations for these devices (see link below); however, the document does not talk about through hole components. Could I request that soldering recommendations be provided for the through hole parts?

http://www.ti.com/lit/an/slta054a/slta054a.pdf

Respectfully,

Michael

Hi Michael,

As you stated previously, this is most likely due to a manufacturing issue. Without knowing the full extent of the issue, we can best conclude that the PCB is not reaching proper temperatures due to thickness of the board, therefore, causing the device to not reach proper solder-able temperature.

We are still waiting to hear back from your results based on the Dip-and-Look test to verify if this is a product issue. In the meantime, I went ahead and searched for more documents in regards to soldering through-hole components; attached you will find the two standard documents:

1. J-STD-001E: this document will point out that the pin extending from the board must be in the solder flow or at least a length where it could be crimped. (Hence our conclusion and the manufacturing engineering)
   1. J-STD-001E.pdf
2. J-STD-002D: this document will support that a solder-able area of a component can be proven to hold solder and thus has no reliability concern if it passes the methods of Dip-and-Look suggested.
   1. J-STD-002D.pdf

I also sent these files directly to your email as discussed offline.

Regards,
Alejandro

Hello Alejandro,

Thank you for the additional documents. I couldn't find anywhere where I stated this was most likely a manufacturing issue. As far as your conclusion that the PCB is not reaching the proper temperatures, if that were the case how would you explain that some pin barrels get filled all the way? In the X-ray picture I sent with my first communication the other pins were filled while the one pin had 0% solder. What do you have to say about my request to have soldering recommendations for through-hole components? Is there another preferred method to request this? To reiterate, the soldering recommendations related to these devices currently exclude through-hole components. I'm planning on meeting with Dennis this week and I will inform you about it. Please recall that we are having to rework 30% of our boards due to this issue. SCI would like your help to go from this reactive approach (X-ray and rework) to a proactive approach; I would like to request that an expert on outgassing review pin construction and provide feedback. As a result, I would hope a PCN could alter the leads to help with outgassing.

Respectully,

Michael

Hi Michael,

Attached below are words highlighted in regards to a statement you provided of fixing the issue through manufacturing changes.

There can be many possibilities on why some pin barrels are getting filled and some are not. Here are just a few of our conclusions:

1. The thickness of the PCB: the pins are not extending past bottom surface of board, therefore making soldering wetting more difficult (optimal joint not achievable).
2. The pins of the device might be corroded or not properly cleaned, therefore solder does not stick (wet). Hence, our request for the Dip-and-Look test. But, if reworking the boards also solves the issue, then that can be an indication of no issue with the pin/device.
3. The PCB itself might not be clean properly (surface contamination).
4. Solder mask can be in the barrel of the hole, therefore preventing proper barrel wetting
5. The level of flux activity being used can play a factor

The possibilities can be many; that is why checking the pins of the device is a good starting point.

We do not have an Application Report on Soldering requirements for through-hole products. There are global standard soldering requirements for through-hole components provided by IPC. The standard documents can be found on the web as well (I have attached some of them previously in the conversation).

I have sent this same response and requests offline, but still not update or response. Also, I have been in contact with our engineers specialized on out gassing, Hence, our requests.

Regards,
Alejandro

Alejandro,

I appreciate your feedback. This issue has not been resolved as of yet. Respectfully, I also have made some requests for which I have not received answers; I have included one at the end. To provide some details on your feedback; I'll let Dennis comment on the rest through the email thread.

1. PCB thickness - I agree with you that the PCB is too thick. However, this in our customer's design and thus we cannot change the PCB. In addition, although we have other machines to fabricate these boards our customer has requested to use the selective solder machine. Hence, I am requesting additional support due to the out-gassing we are observing; to explain it in a different way, during soldering gas is trapped and does not allow solder to flow properly into the barrel. Our Senior manufacturing engineer is hoping the pins could be altered to either be larger and/or to change the design to allow for more effecting out-gassing. I mentioned earlier that we have struggled with this for about 2 years and we have done testing in our lab sometime ago but it is difficult to retrieve the data.

2. Pins (corroded or not properly cleaned) - As you mentioned on this point "if reworking the boards also solves the issue, then that can be an indication of no issue with the pin/device". As mentioned previously we have to rework 30% of these boards after x-ray. So, 7 out of 10 are coming out okay. My hope is to eliminate having to x-ray and especially rework.

3. PCB not cleaned properly - The product is ran through 2 inline wash clean cycles before through hole using the Soponifer Zestron AC205.

4. Solder mask & flux - In the barrels that no solder fills has never been examined but the repair operator has never indicated any obstruction within the barrel when hand soldering.

5. We are using Indium 1095 flux (ORH1). The specification has been provided to you in email form.

Could you give me an update on my request to have soldering recommendations for through-hole components? Is there another preferred method to request this? The current procedure only addresses surface mount parts (listed below).

http://www.ti.com/lit/an/slta054a/slta054a.pdf

Michael Casos

To prevent duplicate emails/posts, this post is being handled offline.

Hello Michael, 

It sounds like some of the communication was handled directly offline. Let us know if you still need help with this on the forum.

Regards, 

Denislav

Denislav,

Thank you for reaching out. Actually, let's keep the forum. There's been a lot of back and forth on this through email. Alejandro sent an email earlier this month asking some additional questions which I haven't answered. It would be great if we could get greater proactive support from TI. My hope is:

1. Having TI take a look at the pin design and see possible modifications to allow for outgassing. Currently when the devices are placed on the PCB we are having outgassing issues and we are having to rework 3 out of 10 boards (post X-ray).

2. Could TI make the pins larger? We use these devices on several boards for one customer and unfortunately the pins do not protrude sufficiently on most of the boards.

Also, I requested to have TI provide soldering recommendations on these through hole devices but Alejandro said this was not possible. Why couldn't TI update the soldering recommendations to include through hole components; the current document (noted earlier) only covers surface mount.

Respectfully,

Michael Casos

Hello Michael,

If there is additional information requested by Alejandro via email, it would be great if you can send him a note.

Both 1. and 2. above will require modifications on an existing product, potentially affecting other customers. It sounds like making a custom part which usually has to be justified business-wise.

Regards,
Denislav