Weakness in 4 layer motherboards stun many newbies?

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Weakness in 4 layer motherboards stun many newbies?

Postby atang1 » Fri May 17, 2002 8:47 am

Motherboards are made about 0.060" thick when they were 1 layer. Now that 4 layers are common; we have to recognize that each single copper layer fiberglass pcb is only 0.015" thick. Even though they are glued together, the strength to resist bending is poor to say the least.

When you push the sdram or DDR memory into their sockets on a bench, everything should work fine. But when you push the memory while the motherboard is in a computer case. Everyone bends the motherboard. And it is a fatal mistake.

Luckily, some one discovered the cardboard trick in 1999-2000. And they rescued many motherboards that had been bent. You stuff cardbopards below the motherboard to push the motherboard up and straighter.

So, if you can not boot. And you took the motherboard out and the memory does not sit in the socket squarely. You can bend it back slightly with the momory in the socket. Your motherboard may work again. Think of the cardboard trick, and what it does and how it works, to straighten the motherboard.

Good luck. Some cpus are now built with 30-40 layers of pcbs.
Last edited by atang1 on Thu Aug 22, 2002 4:44 pm, edited 1 time in total.
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Postby CzarDadius » Wed Jun 05, 2002 10:39 pm

a question. Where is it you can find out the information on how cpu's are built? basically, i have always been interested in how my computer mangages to do what it does and is there somewhere to get a basic idea with out going to college for 4 years?

Also, does the cardboard cause heating problems or air circulation problems?

thanks.
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Postby evasive » Mon Aug 12, 2002 6:14 am

The cardboard is underneath your motherboard if you have read the posting correctly and it is only needed if you already cracked your motherboard. In general there is little to no airflow under the mainboard, so the influence of the cardboard will be virtually zero.
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Postby atang1 » Mon Aug 12, 2002 11:00 am

The cheapest way to find basic computer info is go to Compusa or local library, to look up some of the repair manuals. As you flip over the pages, your knowledge will grow by leaps or bounds.

Regarding the card board trick, it is under the sdram socketrs, no one define the card board size needed. So, its basically trial and error. But definitely has to straighten out the sdram sockets on the motherboard.

I have developed technique where you can straighten out the motherboard, by bending with the sdrams in their sockets. The cure is to make sure the sdram sits squarely in the socket., which eliminate the middle bow(downward), preventing the sockets to have full contact with the sdrams and their gold fingers.
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Postby atang1 » Mon Oct 21, 2002 3:17 am

The weakness of the 4 layer motherboards are all in the warpage of the 4 layer boards.

The hardware soldered on changed the temperature in the wave soldering machine. Which is caused by setting the soldering temperature too hot to compensate for the cooling effect of the large hardware of the ATX I/O connectors. Inspection of the flatness of the motherboard will tell you how good the quality is in manufacturing of these motherboards.

Some sat the glue between the layers are too thick?

Some say the vias are not filled with solder?

But it is still the wave soldering temperature that controls the warpage.

So if you want to buy quality motherboards, buy the flatest motherboards. We will list a few motherboard manufacturers who make flater motherboards?
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Postby atang1 » Mon Oct 21, 2002 3:34 am

Good quality control motherboard manufacturers:

Intel

FIC

MSI


Insufficient quality control:

Pcchips, edge warpage

Giga-byte, warp on the opposite side of the I/O hardware

Soyo. bios trace to chipset separated in use, video card not recognised afterwards.

Please add to this list with your experience?
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Postby atang1 » Mon Nov 18, 2002 5:12 am

Recently a large batch of Alton motherboards were studied for the failure mode. These boards were made by Pcchips.

The intimate story is that Alton dumped Pcchips as an OEM supplier and contracted some one else.

As first looks, chipset failure is evedent with post codes revealed. However, the chipsets were hardly hot at all. Further visual inspection revealed the weakness of the pcboard construction. The edge of the pcboard has relief(glue too thick) where the thin 4 layer boards were glued together. The edge also reveal the fiber glass size and orientation. The V605A motherboards were easily bent without too much force. Many copper traces could have been broken, resulting in failure of the bios functions.

Quality of motherboards depends on stiffness of the motherboard to resist bending and thus shearing of copper traces to have broken connections.

The recommendation is to look for heavy fiber glass pcboard and a minimum of glue thickness. The shear stragth of the glue and its elongation characteristics has to be selected. Quality motherboards had to be stiff and resist bending and broken circuits.

I think the industry needs a tightening of pcboard contruction quality control standards.
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motherboard construction

Postby Roger Jones » Tue Nov 19, 2002 3:14 pm

I agree entirely with what you have said. Over the years motherboards have become more multi layered and of thin composition compared with the old boards that housed DX2's etc. problem comes from various areas;
Heat -melting bonding resin, rubbish curing techniques of fibreglass, hamfisted people putting in SDRAM etc and insufficient support of the motherbard to the case (Where i have known people put ram in with power still on and shorted out through case!!!)

On rubbish motherboards PCChips takes gold medal place for construction.

I have a piece of high density rubber strip to ease under board when I add ram.

Also I always insert processor and ram on board before fitting in case.
Also never forget heatsink- I have seen damage to motherboards where a screwdiver was used to put heatsink clip on and slipped damaging the motherboard.
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Postby atang1 » Thu Dec 05, 2002 4:29 am

The problem with flexible 4 layer motherboards is the fact that the traces are on the top of the motherboard. So when you push the edge of it down, you put tension on the traces, and they may break.

Pushing the motherboards the other way, puts compression on the traces and it will reconnect the broken traces. The well known and famous card board trick proved the case, when broken traces on memory sockets were fixed by pushing back with card boards restoring the shear breakage at the vias connections between layers of traces.

I have been more successful bend the edge upwards with the power on to restore the connections by arcing and welding them together so to speak. The bypass capacitors seem to protect the ICs adequately, so far. Otherwise, the motherboards were useless anyway.

Next we will talk about the usual faults found on defective 4 layer motherboards?
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Postby atang1 » Mon Mar 10, 2003 10:18 am

When the plug and play cards came along, the original concept was to build in the safety of buffers so that cards can be hot swapped.

Unfortunately, many of the motherboard designers did not take that in their consideration. While the cards can be hot swapped, the motherboards and the chipsets especially can not be zapped. I have often wondered how many of the motherboards, I have studied for failure mechanism had dead chispsets.

Yesterday, I was working with a MS6195 K7 pro, and the power was shut off and the wall plug was not removed. A connnexant modem was inserted. The result was the motherboard was turned on by the zap. One volt wake on power was zapped to 5-6 volts. That extra energy caused the keyboard port failure. The modem port can not be opened. Otherwise it runs with the mouse drag and drop commands. This motherboard is extremely fast and can overclock easily. Runs at least 4 time faster than FIC SD11 in overall performance. Memory(sdram) has to be selective(only one type worked out of three) due to 200mhz ddr data bus to sdram slots.

The conclusion is that, many people had zapped their motherboards and caused damages. Of course, cmos transistor fails if the capacitance of the gate oxide can store the energy of the zap. After 4 weeks of siting in a dark place, the energy would have dissiipated. It may be able to be low voltage annealed by the same 1 volt wake on power, with everything connected(pull up resistors in place). Fixed many printers which had the parallel port zapped, after one week of annealing.

Stay tune to see if it could be resurrected.

Footnote: Dark place is to prevent X ray and ultra violet rays from continuing to do current injection on the cmos gates. It is theorectically possible to delay discharging the gate saturation.
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