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Solder mask

Views: 9170

#57694

Solder mask | 30 December, 2008

Hi all,

I have couple of questions/doubts on solder mask, please clarify. Why green color solder mask is popular when compared to other solder mask (RED, PURPLE, BLUE etc.). Are there any performance issues with other solder mask if I use them. Please send me your valuable comments on the same.

Thanks in advance.

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#57695

Solder mask | 30 December, 2008

People use green soldermask because people use green soldermask. In the 1950s, the US military selected green, because they liked green better than other colors. So, here we are.

We believe the performance of red and blue is comparable with green. The issue is delivery. Green is not a concern. Whereas red and blue often require longer lead time, because fabs prefer to run larges batches of a color.

Here's an article that may help move you along http://www.dbmpcb.com/pdfs/2005/0503soldermask.pdf

We have no relationship, nor receive benefit from the company referenced above.

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#57706

Solder mask | 2 January, 2009

Hi,

From a Manufactures choice - Green is the best due to it is the most commonly used mask color in the industry & cheapest. Kind a like Red paint for Barns.

For US shops, most only have one LPI machine and to continually switch from Green to other colors adds down time due to the time it takes to clean the machines out to switch colors. due to this if you are requesting Blue or Red there could be delays due to they would probably not run them until they had a batch of panels to do or they would due them on a certain night of the week.

Other issues that we ran into in the States is with ENIG Lines. The nickle baths had an issue of breaking down the mask enough to contaminate the immersion gold bath. due to this, a lot of U.S. shops will not run Red or blue mask down their gold lines. This means they would mask after Enig, which would add cost to the product due to they would be covering all the circuits in Gold then mask.

The Asian Manufactures do not have any issues with Green, Red or Blue due to most shops have more than one LPI machine and due to volume of product run there is enough product running in all colors. And regarding the Immersion Gold lines I have not herd any issues with mask break down.

My suggestion if you are using a US Manufacture, and you are looking to show a difference in Lead and Lead free product would be to change letter screen color. This is a Simple change for the board house and would add no cost or delay's to product.

Just my 2 cents.

My disclosure,

20 years US Board sales and currently 2 years selling for and offshore manufacture.

Best Regards and Happy New years,

Boardhouse

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#57713

Solder mask | 5 January, 2009

HI, i work for an EMS company and i got a few remarks on the solder mask question. In the manufacturing of PCBs there should be no difference if they use other color solder mask, but in the production of electronic assembly it could make a difference. All 2D inspection and AOI machines are made for the most popular green color, if the color changes just a little bit there could be huge false call problems with these machines. At our company went so far that the AOI engineers had to make 3 different programs for one product, because of the different colors. (It was clearly the PCB manufacturers problem) BR Konrad

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#57739

Solder mask | 9 January, 2009

Hello,

Hey friend i also wonder why always green , recently i purchased blue solder mask for my brother, it looks more attractive and lively.

Regards, sarah_9

www.museoshop.com/

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#57742

Solder mask | 9 January, 2009

Hi Konrad,

Nothing is ever Clearly one persons issue.

Color differences could be caused by many things.

1) Being the solder mask is a two part mix, there is never a 100% guarantee that the color will be the same from lot to lot.

2)the Manufacture of the solder mask will have color variance from lot to lot they ship the Pcb shops.

3) Material color could come in lighter of darker which could affect the look and color of the solder mask.

4)Most Customer call outs on fabrication drawing only ask for green of either Matte or gloss finish. No call out for what shade they need to hold to.

Like everything on the PCB Manufacturing side these are custom products and slight changes from lot to lot can happen.

Its to easy to always blame your board manufacture for things you have issues with on the assembly side.

Best thing you can do is go tour you board manufacture and go over these issues with them and let them give you the reasons why like above that this could be happening. .

Sorry for the Vent, just tired of comments like its the board manufactures fault.

Regards, Boardhouse

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#57744

Solder mask | 12 January, 2009

Hi Konrad, I would suggest you include a clear mention of your requirement towards mask color as a "Special Note" in PCB Gerber / PCB drawing, for ready reference by your PCB manufacturing during fabrication. However, slight changes in color shade could be always be handled thru' minor adjustment to brighness, hue level, and contrast within your existing program, or accepted as is by extending parametric tolerences. Re-programming may be necessary only if the basic mask color has changed, which can be avoided as mentioned above.

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#57748

Solder mask | 12 January, 2009

Sorry, if my first comment was a bit offensive against PCB manufacturers (it was not really intended :( ).

We have already discussed the above mentioned issues with the manufacturer, and they stated, that everything is within specification... (and yes, our department forgot to mention the desired color in the specials) Actually we could agree with the them. The real problem was that the color of the solder mask changed between two packs of PCBs (from light green to almost deep blue). AOI machines were adjusted as the above mentioned, and we found a solution for the 2D system of the printer. Thank you for your advices

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#57758

Solder mask | 13 January, 2009

konrad,

why did you change your mind now? Now you can agree with PCB manifacturerers? I didn;t hear anything in their defense and you gave up. If colour is not the same each time, that means they don't have standarts or knowledge to control it, and it is definitely not your fault. go and paint your car in a colour you want. You order light green and they give it to you back in dark green - because paint is mixture of components :) Come on guys, be serious. Don't tell me how it is not gonna work. Tell me how it will. Emil

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#57761

Solder mask | 13 January, 2009

Emil,

Part of the problem it sounded like is that the color was not clearly defined as light or dark in Matte or gloss.

Your example of car paint would have the same issue if you just ask them to paint your car green. What color of green would you receive?

My guess the reason that they received closer to Deep blue is that the board shop just finished screening some boards with blue mask then they switched back to Green and did not clean the solder mask machine very well, which left a blue hue or TEAL color to the Green mask. But still could be called Green.

My recommendation would be to spec out Light or Dark green in Matte or Semi gloss finish. you still could have shade difference with this but they would be minor. Only major change would be caused if Manufacture switch brands of Solder mask.

My main comment was that you should work with your board shop so you do not have these issues. Best way is to clearly define on fabrication drawing. And work with them. Touring a PCB Manufacture is a good way to get an understanding of why they do what they do.

Regards, Boardhouse

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#57766

Solder mask | 14 January, 2009

I did not change my mind, I just said that we sat down with the manufacturer and showed them the 3-4 different color PCBs for one product. They agreed that it is not acceptable... and supply us only from one of their sites. (the different manufacturing sites used different solder mask finishes - different green colors). We did not mention the color in the specification so it was not only the manufacturers fault! Now we have one color, which has a small variation depending on the manufacturing date, but it is not affecting our SMT line. It was a while ago when I worked in PCB production. Which factors affect the color of the mask in the PCB production? The obvious is the materials used, but what are the other?

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#57775

Solder mask | 14 January, 2009

konrad, Here are a couple of things that can affect color. 1) Material color is the major, 2) Matte green from Enthone would be different in shad than Matte green from Taiyo. 3) Solder mask is two parts, One the green mask, two the hardner, having to much of one or the other can cause variance in color. 4) Copper from outer layers can cause color differences, if the outer layer have large copper plains they will look different in color than a board with outer layers that have less copper showing. 5) Hot air level machines have also been known to change the color of the mask due to the stress of the process.

I'm sure there are a few others not listed but these are off the top of my head,

Regards, Boardhouse

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