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 FAQ's

  . COMPONENTS (8 questions)
  . HAND SOLDERING AND DE-SOLDERING (3 questions)
  . INSPECTION (3 questions)
  . PRINTED BOARD DESIGN (3 questions)
  . PRINTED CIRCUIT BOARDS (6 questions)
  . REFLOW SOLDERING (5 questions)
  . REWORK (1 questions)
  . SCREEN PRINTING (2 questions)
  . WAVE SOLDERING (4 questions)
  . X-RAY INSPECTION (1 questions)





PRINTED BOARD DESIGN

1 . I am working in design and would like to produce a lead-free printed board specification for my supplier. How can I get some guidance?
2 . In a resent article you gave size tolerances for hole size in circuit boards. I currently use much larger sizes that you have suggested for single sided boards. Is there a difference for single side and double sided plated through hole.
3 . Our new designs will not allow the traditional screen print legend to be used on our boards to identify components. We have also seen yellow legend change colour at lead-free soldering processes. What options can be used?

 

I am working in design and would like to produce a lead-free printed board specification for my supplier. How can I get some guidance?
Well the first thing is to obtain a copy of the relevant IPC or British/European Standard for the type of board you require this will help you produce a customer detailed specification. You can then consider the specific surface mount and lead-free requirements not covered by any specifications. Issues that exist would be surface finish, laminate type, testing of board for delamination, copper plating thickness etc.
Before finalising the document discuss the draft specification with some board manufacturers and some members of the SMART Group. SMART Group committee members will be able to provide detailed input on your document.

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In a resent article you gave size tolerances for hole size in circuit boards. I currently use much larger sizes that you have suggested for single sided boards. Is there a difference for single side and double sided plated through hole.
A single sided board is generally made of material which is not as dimensionally stable as FR4 fibre glass hence some design engineers use larger hole sizes. When soldering single sided boards, this can lead to high levels of incomplete joints. Many specifications require that there must not be any voids present in single side board. I would recommend that making hole sizes just 0.010” bigger than the pin sizes be used as a good guide.
In the case of lead-free try to make sure that you set you process to achieve good wetting of the pins into the hole to increase the fillet size, this will make a more reliable joint.

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Our new designs will not allow the traditional screen print legend to be used on our boards to identify components. We have also seen yellow legend change colour at lead-free soldering processes. What options can be used?
Component identification can often be etched into the copper foil. Simple pin one identification can also be etched into the foil eliminating the legend stage in PCB manufacture. It can save time and the cost of you boards. Alternatively you could use map referencing, this is where 1,2,3,4 etc. is printed and the top of the board with A, B, C etc. down one side. Components are identified by grid reference.

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