QualiEco PCB Design Tips
Thinking of a Cost Effective and Manufacturing Friendly Designs? Here are some tips for you...
General Tips:
- It is advisable, and in most cases highly convenient, to use gerber in RS274-X (extended gerber) format. However, we do accept gerber in RS274-D format, which will require a separate aperture list/report file so that we can fetch information about the pad and line sizes you have used to design PCB. If the PCB has been designed in Protel/DXP software, there is nothing to worry about it !!! We can use .pcb or .pcbdoc files straight away.
- It is good to supply:
- Tool file/chart, telling us which tool is what size and how many of each tool is used
- Fabrication drawing or Manufacturing Requirements
- NC Drill file in ASCII format
- Example:
%
T01
X035Y0075
X03525Y01225
M30 - Readme file. It is a good idea to include a readme file with information such as; contact person’s name, phone/fax number and other information about your board requirements, this would aid in quickly moving your job from pre-engineering to production floor. This file can be in either ASCII (*.TXT) or Microsoft Word (*.DOC) format
- Please keep in mind that price varies with following factors:
- PCB Type (Single Layer/Double Layer/Multi Layers)
- Laminate Material (e.g. thicker than 1.6mm laminate and 1oz finish copper, Tg greater than 130 to 135 degree etc)
- Colour of Solder Mask and/or overlay (green for solder mask and white for overlay is our standard)
- Peelable Solder Mask
- Special Surface Finish like Immersion SILVER, Immersion GOLD, Lead-FREE HASL. These finish are used mainly to comply RoHS and/or to achieve flat finish for fine pitch components
- Extensive & Very Complex routing
- Number of slots
- Number of v-cut lines
- No SMD, SMD on one or two sides for multilayer PCBs
- Blind and Buried Via holes in multilayer PCBs
- It is normal procedure to send written confirmation about our commercial and technical acceptance within 24 to 36 hours of receiving purchase order. However, it is highly recommended that customer insist these documents in case of non-availability in above-mentioned time frame. This will avoid most of the bottleneck that could create in the event of any misunderstanding or missing emails.
Design Tips:
- We prefer your maximum design area fits well with our standard panel size 208mmx215mm (particularly for prototype boards). So, keep the board size in such a way that maximum yield can be achieved in lowest price. However, we can easily accept larger panel sizes. Refer our technical guide for further information.
- It is very much convenient to have:
- Clearly mentioned cut mark (If possible use "keep out layer" or "mechanical layer". Note that, we measure PCB/Panel dimension from the centre of the cut mark. This means, at the time of cutting, outer edge of the router will fall right over the centre of the cut mark.)
- Continuous borderline, if the shape of PCB is odd. This will help us a lot in creating a rout program.
- Information about NPTH holes (in protel/DXP, click on the pad needs NPTH hole – go to "Advanced" menu and untick "Plated" option. While generating NC drill file from protel/DXP design, this change will write "NPTH" against that specific tool. Apart from this, it is very much advisable to create separate tool for NPTH holes for better clarity.)
- Slot information, if any, on the same layer where the cut mark has been specified (it is better to draw actual slot shape in solid so that routing program is easy to generate). Also, we must be advised whether slots required are PTH or NPTH.
- Drill drawing or any other layer, where information about PCB type, PCB material, Copper-Solder Mask-Overlay requirement, tool table (if possible) and any other special requirement (e.g. high Tg laminate, gold platting, peelable solder mask, flood coat, different colour of masking or overlay, allowable tolerances, manufacturing standards etc.) and relevant information that helps manufacturer to understand the design requirements in a better way. This procedure can avoid unnecessary communication gaps.
- Break off tab locations, if there is any constraint where placing tab at any particular position can cause practical problem in breaking boards apart after assembly.
- When designing a PCB, try to limit the amount of draws you use. Draws use a lot of memory and slows the programming time. Ex.: Use a flash for pads instead of draws. If for some reason we need to increase or decrease that pad size, it can easily be done by changing the D-code but if they are done with draws it could be a nightmare.
- If you are using old protel (DOS version), keep in mind that it restricts font sizes to 36, 48, 60, 72, 84, 96, 108 (all sizes are in mil i.e. thou). Let’s say, if you have used font size 39 thou, it changes that particular font to 48 thou i.e. one step higher in rank when we generate gerber data out of your protel document. This can create shorts if any font has been used in copper layer and becoming larger in size may touch nearby track or pad.
- Using hexagonal pads in protel software could be a disaster sometime because while generating gerber data from protel document it can cause two major problems: (1) Rotating hexagonal pad, which can cause short if any track is closely (2) Hexagonal pad size changes to the smallest size of the hexagonal pad, if more than one size of hexagonal pads have been used. We have found way to get rid of this problem but it is always advisable to avoid it in first place.
- It has been noticed at few occasions that overlay font has been rotated 90 degree while generating gerber from DXP. Unfortunately, it is not possible to detect this error unless an engineer doubts the overlay structure. No remedy to this error has been found so far. However, if anyone knows more about this, please do let us know so that we can post your suggestions for everyone's benefit.
- Ensure that no silkscreen falls on any pads or say, mask opening. This could affect the bare board testing and soldering process. We have specialized software to clip such overlay text at our end. As a rule of thumb, clipping is done in such a way that 0.1mm area is clear around the solder mask pad.
- Make sure that nearest copper area (i.e. pad, track or ground) is at least 0.3mm away from center of the cut mark, if routing is required. In case of v-grooving, at least 0.7-0.8mm distance would require for the same.
- Add some text to copper layer wherever possible. This will help CAD engineer to identify top and bottom copper in case of any confusion.
- If design is sensitive and contains isolation barrier, please advise us at the time of placing the design first time in production. In this case, we make sure no copper is accidently placed or added in copper either in the form of date code or any other way.
- At the time of making prototypes, try to design the PCB as if you are finalizing design for production. This will save you additional set up cost if the prototype turns up into production without any design changes. This relates mainly to those designs, which are into panel form and effective panelization at first instance can save a lot at the time of normal production.
- Version control is very critical to anyone who deals with various modifications. It is better to add "R1" or "V1" suffix after the PCB description to identify the most recent design. The moment you realize that the old version is of no use at all, inform us as quickly as you can so that we can discard the complete record and artwork at our end. This can save you from real disasters when your purchasing system generates order with old version by mistake.
- It is interesting to know that protel keeps new dates on record even if you view your designs and not editing them at all!! Therefore, it is tough to pick up most recent design just from the date of modification.
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Our Capabilities
We have capability to manufacture Single Sided/Layer (SS), Double Sided/Layer (DS-NPTH & DS-PTH) and MultiLayer (up to 24 layers) PCBs with RoHS as an option.
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