Mother Board repair - advice needed - Page 1
Forum section: electronics / repair

author: Furna
author_rank: Frequent Contributor
timestamp: June 08, 2025, 02:57:39 pm
content: Hello evryone,First post in this section of the forum; I usually spend my time and money on the "Test Equipment" section.Anyway I also spend time and money in repairing stuff; this time a motherboard.While from the attached image you might think the issue is on the pad in the yellow rectangle, actually the issue is with the one in the red rectangle.The yellow rectangled still make connection with the destination and the via to other side of the motherboard is working. I am inclined to not touching it at least at the moment.Indeed the red rectangled on the left shuold connect with the other red rectangled on the right through the other side of the motherboard, but the via to the other side of the motherboard is broken/missing.I could just run a wire jump but I am evaluating the opportunity to go down the rabbit hole of "serious" mother board repairs.I am quite good at micro soldering; I usually do SMD down to 0402, I have a binocular microscope (no camera yet).I would need link to documentation (videos or blog posts everything will work) and also links to shops were to buy dedciated materials in Europe.Thank you for your suggestions!

author: coromonadalix
author_rank: Super Contributor
timestamp: June 09, 2025, 12:31:10 am
content: when vias are destroyed i use wire wrap wires in the hole to connect both sides, and after you put the part in it/themnormally if it is not an huge supply connection it is enough, in some case i'm able to insert at least 4 to 6 wires, sometimes more

author: wraper
author_rank: Unknown
timestamp: June 09, 2025, 12:40:37 am
content: If a via does not make connection from one side to another, just run a thin wire through it and solder on both sides. As it's close to another solder joint, you could run a jumper wire as well. You're way overthinking the solution to fix it. If a pad on the solder joint side is broken like in yellow rectangle, I would run a thin wire through the hole, solder it on the component side to a trace after removing a few mm of solder mask from it. Then insert a component, wrap a few turns of the wire around the terminal and solder it.QuoteWhat dedicated materials? it's not like you need to replace a piece of PCB substrate. Do you think of replating the via hole?.

author: MarginallyStable
author_rank: Regular Contributor
timestamp: June 09, 2025, 12:46:03 am
content: Can get more complicated if this is/were a multi-layer board with possible connections to internal layers.

author: Furna
author_rank: Frequent Contributor
timestamp: June 09, 2025, 12:39:58 pm
content: Thank you everybody for your answers.Quote from: coromonadalix on June 09, 2025, 12:31:10 amThank you for the advice; Where do you buy the wrap wire?QuoteIn this case it's just a signal connection, no power.Quote from: wraper on June 09, 2025, 12:40:37 amI am ware of "overthinking" the solution. I am just exploring to see if there are better technics.QuoteSomething similar to replacment pads? For vias?Quote from: MarginallyStable on June 09, 2025, 12:46:03 amSure multi-layer boards are another step ... maybe 10 steps.EDIT: fixed the quotations

author: wraper
author_rank: Unknown
timestamp: June 09, 2025, 01:33:10 pm
content: Quote from: Furna on June 09, 2025, 12:39:58 pmThere are hollow rivets but those are only for larger holes and make little sense for repairs if pads are still in place.https://docs.voltera.io/v-one/getting-started/punk-console-project/6.-adding-rivets

author: GGMM
author_rank: Frequent Contributor
timestamp: June 09, 2025, 04:09:25 pm
content: re,I’m wondering if there is a rule of multilayer design.That is to say one can connect together the layers 1 and 4 by a via. On the other hand not the layers 2 and 3 with a via.I’m not sure, we should do a kicad test.If anyone knows.A piece of wire welded on each side is what I docdt

author: GGMM
author_rank: Frequent Contributor
timestamp: June 09, 2025, 04:50:19 pm
content: re,I go back to what I said.You will find the differents possibilities of vias.From what I understood, there would be via "blind" connection between 2 internal layers, 1/2 via connection between an external and internal layer, and the via through connection between 2 external layers, etc...In conclusion: So if you can see through the via, you can weld a wire.https://pcbonline.com/blog/pcb-vias-and-their-types.htmlcdt

author: coromonadalix
author_rank: Super Contributor
timestamp: June 09, 2025, 04:52:16 pm
content: multi layers rules ...... mm depends of your designs, we have 10 and a 12 layer (very thick board) here in a new design, very hard or almost impossible to repair, 0402, and mostly 0201 parts, a nightmare. Dissipate heat pretty darn fastit's a carrier board, some layers are simply grounds and supply, still under prototypes, i think well trash, not doing repair on this one ??we thought of putting passive parts in the vias ...can't say more ...

author: GGMM
author_rank: Frequent Contributor
timestamp: June 09, 2025, 06:26:07 pm
content: Coromonadalix,I was talking about vias in general.Then I don’t know what you do.If you design pcb with with 12 layers and SMD types 0201, yes it becomes impossible to repair.Do not hesitate to put examples, I at worst I weld by hand only from 1206 and sometime of 0402. For the layers I am at 4 maxi with kicad.see example

author: coromonadalix
author_rank: Super Contributor
timestamp: June 10, 2025, 11:03:23 am
content: for the vias as written, you may have simple say 2 layers, normally easy to repairs, but if you have 4 and more layers doing some vias repairs could be harder ...sometime you get an idea when you check on the pcb thickness, sometimes you can see the layersyou need to decipher where are the traces going to ...really depend of the problems, and how you address themor find some guy who can help you, helping someone remotely is not always easy, we need to get the hole picture, could be an easy repair or not ...sorry

author: daisizhou
author_rank: Super Contributor
timestamp: June 10, 2025, 11:48:56 am
content: Let me see the tool you used to remove this pad, such as a soldering iron or other type of tool.It seems that you don't control the temperature properly.And improve the fluidity of solder

author: Furna
author_rank: Frequent Contributor
timestamp: June 10, 2025, 05:58:27 pm
content: Quote from: coromonadalix on June 10, 2025, 11:03:23 amIn my case it is an easy repair ... the board is just 2 layers. The trace goes on the other side of the board just to reach the yellow rectangled spot.So a simple straigh jump wire will work.Quote from: daisizhou on June 10, 2025, 11:48:56 amDid I gave you the impression I did the damange? I didn't.This is how I found the board ... non working.For obvious reasonsA couple of questions:- how are pads/traces glued to the board? If you replace a pad what material do you use to glue it to the board?- can you share a link to a site where you buy replacement pad?Thank you

author: daisizhou
author_rank: Super Contributor
timestamp: June 10, 2025, 06:22:38 pm
content: You need to use 0.05mm copper wire to make pads and vias.All problems start from your incorrect disassembly or using incorrect tools and accessoriesIf you are unwilling to share or correct it, you will encounter the same thing again next time.

author: Furna
author_rank: Frequent Contributor
timestamp: June 10, 2025, 06:25:04 pm
content: Quote from: daisizhou on June 10, 2025, 06:22:38 pmWhat part of "I didn't make the damage" you do not understand?

author: Furna
author_rank: Frequent Contributor
timestamp: June 10, 2025, 09:33:48 pm
content: OK I went for 0.1mm jump wire through the via.I now have connectivity between the red rectangles.Comments are welcome; I understand it is not a perfect job ...I have to wait delivery of a few components before for the final assembly.@daisizhou I am using an Aixun T3A soldering iron with a K200 tip on a T245 handleSolder wire is a 1.0mm Pb38 Sn60 Cu2 280°CI understand the solder wire is way too thick but it is the only Pb solder wire I currently have.Also the tip and the handle are not the best tools for this job ...

author: daisizhou
author_rank: Super Contributor
timestamp: June 10, 2025, 10:33:13 pm
content: Quote from: Furna on June 10, 2025, 09:33:48 pmI drew a simple diagram, I hope you can understand it.Small signals or weak currents are shown in Figure 1, and large currents are shown in Figure 2It is recommended that you use S-sn60pbAA solder wire 1.0-RAHQ

author: Furna
author_rank: Frequent Contributor
timestamp: June 11, 2025, 02:21:59 pm
content: Thank you daisizhouYes I can understand your drawing.The via in the yellow rectangle doesn't have anything connected on the other side of the board; i run a single 0.5mm wire just to practice ...Also the second via from the left (the one that is most damaged) has nothing connected on the other side of the board and beside its condition it has contact with the other side.The forth via in the red rectangle is the one that is carrying a signal to the other point marked by a red rectangle passing by the other side of the board; it is connected now (via a single 0.5mm wire).I am pretty confident it will work.S-sn60pbAA ... anything that contains lead (Pb) is forbidden for hobby here in Europe since 2016... it can be sold to professionals only.Could you please specify what you mean with RAHQ? Rosin Activated?The Pb38 Sn60 Cu2 I am using is an old (pre 2016) roll that I still have.What I could use is Sn99Ag0,3Cu0,7; 500um; 100g; reel; 216÷227°C; 3% that I also own ... but I found easier to use the Pb one.Thank you

author: daisizhou
author_rank: Super Contributor
timestamp: June 11, 2025, 09:56:56 pm
content: I know the "ROHS" standard, but in actual use I found that (pb) cannot be replaced.For example, the solder beads in the "BGA" package.Solder without "pb" is more likely to cause cold solder joints and has very poor fluidity.S-sn60pbAA is the best solder I have ever used. From the effect of soldering, gloss, cracking degree, etc., I have not found a better solder than it."RAHQ" is a general term for active substances, which should include rosin and some other ingredients. This may be the manufacturer's trade secret. I have not found a public formula.I also have some other lead-free solders, but I am not used to using them because the soldering effect is very poor. The soldering is not round and full after completion. It looks like low-quality solder. The key problem is that the fluidity is very poor.I know we need to protect the environment, but sometimes we have to compromise.

author: Furna
author_rank: Frequent Contributor
timestamp: June 12, 2025, 05:14:07 pm
content: I totally agree but I have no choice.