Advise needed urgently in making of this PCB

lm2937 replacement



I actually had a development board, in which one SMT IC was damaged. I wanted to replace the IC, but unfortunately doing so, I had permenantly damaged the LQFP 64 IC legs and now the board is gone and my all work is stuck now. I email to Europe to their company to send me another one, but those guys are not replying. Even though the board cost around 35US$ with 75US$ of shipping. Beside all this, I want to have the board as soon as possible, so I will be placing a order soon, as I have talk with that company.
But what I have seen is that their PCB was designed very good. Very nice routing and few VIAS, my layout board is very bad comparative to the board I have on my hand. Every thing very nice done. Few VIAS, where as in mine, there are hell lot of vias. The tracks also runs at 45' in the board, but in Orcad, the lines are mostly either horizontal or vertical. Every where I see copper pours polygon. I don't know how to make such a nice PCB in Orcad. First tell me how can I restrict the VIAS. In my screwed up development board, there's only 4 VIAS inside the 64 pin controller, but in my orcad design there are 15 VIAS inside the microcontroller.

Added after 2 minutes:



This is the schematic of the board, if you see, it's really simple.

douglas brooks pcb

it is easy to make pcb layout on eagle...

howard johnson rod strange

I can make PCB on Eagle,Easy PC and Orcad. It's not the point. The point right now is that, how can I make this PCB look good, both for sight and for EMC.

Added after 59 minutes:

In my development board, I can see decoupling capacitors connected to Microcontroller on both sides of the PCB. How to attach components on two sides of PCB using Orcad Layout Plus?

signal copper pours bad design practice

Everyboy can do pcb layout with 'Eagle', 'Orcad" or whatever software they use. But if you are doing it for fun/hobby, or once in a while, be happy with the results.

Pcb layout is a real profession. You need a lot of knowledge and experience to become a good pcb designer. If you want to become a pcb designer start by studying some books like;


Signal Integrety Simplified, by Eric Bogatin
High Speed Circuit Design, by Stephen Thieraf
High Speed Digital Design, a handbook of black magic, by Howard Johnson
Printed Circuit Handbook, by Clyde F. Coombs jr.
Signal Integrety issues and PCB Design, by Douglas Brooks
Printed Circuit Board designer Reference Guide, by Christopher T. Robertson


I am designing PCB's for 25+ years now, and when I look back at the designs that i did in my starting years, I can assure you that they look quit different from the designs i am doing now.


Good Luck

rod strange + signal integrity

25+ Years of experiemence. That's so immense. I want to ask few more questions.
(1) Is this PCB designing taught as a major in university? like we have RF engineer,civil engineer, do we have PCB engineer?
(2) Do you do manual routing or automatic routing? Which one you prefer.
(3) How do you practice designing of PCB, do you have machines at home?

I had asked these questions to some body else on the internet, I found it's profile, but he didn't answered that questions to me. You can see his profile.

my-64 pcb

- Over here, in the Netherlands, we do not have a educational program to become a pcb engineer. it is more or less an 'on the job' thing.

you will need a electronics education, to understand the schematics. The IPC has a training program that wil teach you the basics. But you will develop your skills 'on the fly' as you are doing the job.
There are some specialized courses you can do like the one given by Rod Strange (High Speed Design). But there are others out there.


- Almost every design I do is manualy routed. A "GOOD" pcb designer will beat an autorouter (imho). I use the auto router just a a tool in my toolbox.

- i am doing pcb desing for a living. At home I have the same software as at work, so that i can investigate the tools and try things out.

lqfp64

If you look at the schematic of the circuit, what do you think, how much time should it take to make a good PCB in a software, which accounts for signal integrity and has good EMC and a designer has taken other consideration in it too. Suppose you have been given this job, what would be your idea about it.

What different thoughts will come to your mind, by looking at the PCB?
Even though, we don't have specialized courses over here.

making vias

@umery2k75

Why don't you just tell us, which board from which manufacturer you are talking about. I'm located in Europe, maybe I can help you.

Second, post a good picture of your damaged board. There might be a way to fix it.

ep20k

lm7833 circuit

This is a very SIMPLE board .it can prototyped by hand i have in the past used cynal chips and wire them by hand . Ity can be done all in needed is a very sharp solderin iron .i better to use reflux soldering paste .not wire .And wire wrap wire.

Added after 1 minutes:

This is a very SIMPLE board .it can prototyped by hand i have in the past used cynal chips and wire them by hand . Ity can be done all in needed is a very sharp solderin iron .i better to use reflux soldering paste .not wire .And wire wrap wire.

A better option is to buy a prototyping board for that footprint. And with reflux paste solder it

how to make pcb vias

umery2k75 said:

I actually had a development board, in which one SMT IC was damaged. I wanted to replace the IC, but unfortunately doing so, I had permenantly damaged the LQFP 64 IC legs and now the board is gone and my all work is stuck now. I email to Europe to their company to send me another one, but those guys are not replying. Even though the board cost around 35US$ with 75US$ of shipping. Beside all this, I want to have the board as soon as possible, so I will be placing a order soon, as I have talk with that company.
But what I have seen is that their PCB was designed very good. Very nice routing and few VIAS, my layout board is very bad comparative to the board I have on my hand. Every thing very nice done. Few VIAS, where as in mine, there are hell lot of vias. The tracks also runs at 45' in the board, but in Orcad, the lines are mostly either horizontal or vertical. Every where I see copper pours polygon. I don't know how to make such a nice PCB in Orcad. First tell me how can I restrict the VIAS. In my screwed up development board, there's only 4 VIAS inside the 64 pin controller, but in my orcad design there are 15 VIAS inside the microcontroller.

Added after 2 minutes:



This is the schematic of the board, if you see, it's really simple.

Click to expand...

You might have damaged few wires/tracks of pcb. the best is to manage those fw tracks rather than making the whole pcb. Yeah, I know, it calls for lot of planning and patience. may be some expert of computer servicing with smd rework station on hand or at lest an hot air re-soldering station could be of immense help.

with little patches and wires hanging the item could be brought back to working, though not beautiful.

lm7833 schematic

**broken link removed**

This is the board.Thanks for your replies.I'll post the picture soon. I forget to mention about the board, it's from Silabs and it's a mixed signal microcontroller 8051, but the board I had is the same, but it was manufactured in Shinghai,China. They manufacture Silabs MCU,development board and other things and supply them to Asia.The board was running fine, but when I tried to connect the development board with my custom made hardware, the development kit slowly deteoriate without me knowing, first case was seen, when I found 500mV AC ripple on the regulate output. I then look carefully at the regulator, I found out AMS1117 3.3V, where as in schematic manual Silabs had used LM2937 3.3V. I was stunned to see this, then I replace the regulator with a new one, it was LM7833 3.3V regulator. The board began to work perfectly, then within 2 days, I found out the MCU was getting Lava hot and the regulator too, then I realized MCU must have gone. Then I made a more shocking discovery, the PIN comming to header from MCU were routed differently from the one shown in the manual. I mean suppose if Vcc is coming on Pin3, then it was coming on Pin5. I followed the manual, but I didn't know the chinese board was different. Then I telephone the Silab Europe and I explain them my problem, then they said, email me, then I emailed them. I recieved answer 2 days later, then Silab Europe said, you are using Chinese verison of the board, I said I don't know if this board is Chineese or not.Then he showed me indication of it and it was then confirmed I had Chinese board, then I asked them for help, then they said, we have no consulation with Chineese Silab manufacturer. They might have made changes, but we are not known of any, they deal with it, so you better contact them, then I emailed to Chineese people ,waited around a week, got no response, then I telephoned them, those chineese guy were not even able to speak English. I tried to explain him in a very slow english, but his english was very poor. Most of the chineese I have seen are not good in English, even the team of Civil engineers Chineese I met a month ago, no body was good in English. So Chineese people were not giving me any response either on phone and neither on email, so then I place a phone call to Europe company again, then they said, I can't help you, if they are not helping, what I can offer is that, you buy our product, then we will assist you. As you see, we are not in co-ordination with Chineese company. My dad ordered that board from the internet. He didn't know all about these, if we would know, the board was about to come from China, we would never purchase from it and Chinese people had created problem. What they did, they used the European manual and changed the PCB accroding to their condition, if they had changed the PCB, then they must inform customer of their changes, but they didn't inform. Just because of them, I had accidentaly destroyed my MCU installed in the board, it wasn't my fault.My MCU got damaged, because of my custom made hardware connected on wrong PINS, it was correct if schematic was consult, but hell wrong in real, because PCB had different routed PINs. Then I made the new layout by checking the pins and output and made a new schematic, I then tried to replace the bad MCU with the new one I had, I then damaged the PCB while replacing the MCU, the face of the tracks are very badly damaged.Now I'm stuck, so that's why I'm making a new PCB.This was bad experience with Chinese company.
www.silabs.com European Silab
**broken link removed** Chineese Silab

making vias in pcb

hi

can I get a ebook of Integrity Issues and Printed Circuit Board Design by ?[/color][/b] Douglas Brooks?[/color][/b]
Where can I get to improve my knowledge in PCB design, SI ?

thanks