Advise and suggestions for assembly using 01005 capacitors.

I have just been asked to quote a project with assemblies which include 01005 capacitors. We have never built a board with these components. Can you offer advise or suggestions for my stencil printing process, pick and place and reflow. How much more difficult are these components to process than 0201's?

R.P

Expert Panel Responses

Some thoughts from a Reflow perspective: 1)Paste will probably need to change to a version with smaller balls. Sony in Japan (I mean, the larger Japanese customers) are looking at Type 5 and Type 6 paste now. I am not a paste expert but I believe that Type 4 is around 25 micron in diameter and type 6 goes down to near 10 micron.

2) Smaller balls in the paste means greater surface area per volume. In other words, the surface to volume ratio goes screaming up. More surface area means more work for the flux. But this is typically contradictory as the weaker no cleans are already working about as hard as they can. So, even the Japanese (who HATE to use nitrogen) are looking to start using nitrogen in these applications.

3) Smaller parts in nitrogen means tombstoning. So nitrogen PPM inside the oven is important. It has been seen that PPM levels of 500-1000 have helped to reduce tombstoning. This may require some experimentation at the particular customer's facility as Stencil design, pick and place accuracy (this one is HUGE), paste volume, etc all play a part in this.

4) Strange as it seems, smaller parts don't tend to move around so air blowing on them should not be a concern. The solder holds on very tightly (and even pops the parts up to tombstone them) so the surface tension is your friend and will hold on - top side or bottom side in any convected air oven.

Summary:

1) Might need to check out a paste with Smaller dia balls. (I am NOT the expert on this so that is the reason for my "might". Solder guys should weigh in) 2) Pick and place needs to be very accurate. 3) Take a look at nitrogen to overcome the surface to volume ratio issue. 4) Nitrogen at elevated PPM to reduce tombstoning.

Hope this helps. If there are any questions or if more info is needed, please feel free to ask.

Marc Peo
President
Heller Industries Inc.

Mr. Peo has been with Heller Industries for over 20 years and has been President for the past 8 years. Marc has authored several industry articles on Soldering, Flux collection, nitrogen use and Lead Free conversion.

01005's are much more difficult. Most current p&p systems do not handle these parts. One of our customers who is running them says he uses a 3 mil stencil with a very fine mesh paste for printing. He ordered a 01005 feeder and nozzle set from us to place the parts on his 2050R, and uses a normal reflow profile. Accurate printing and placement are vital as these parts can easily tombstone.

Hope this info helps.

Bob Black
North America Sales Manager
Essegi Automation

Mr. Black was the President and Co-Founder of Zevatech in 1977 and introduced first Pick and Place System at Nepcon West 1980. Bob is now the President, CEO and Co-Founder of Juki Automation Systems. He is also a Co-Founder of the SMEMA Council of IPC. He serves as a member of SMTA and SEMI..

01005 are very small components with small pads. Area Ratio is less than .66 which is required for good paste release for Laser-Cut stencils. I would recommend an Electroform stencil 3 mil thick with aperture sizes in the 6.5 to 7.5 mil range either circle or oval.

Bill Coleman
Vice President Technology
Photo Stencil

For over 18 years, Dr. Coleman has been the vice president of technology for Photo Stencil, working closely with customers to understand their printing requirements. His efforts have resulted in several new stencil products.

My observations thus far with regard to establishing a robust printing process include the following.

1. Assemblers demanding the use of 4 mil thick stencils need to ensure that pads are designed large enough for scaling to aperture dimensions that provide acceptable area ratios.

2. 3 mil thick stencils are promoted in a review of the limited 01005 assembly studies so far publicized.

3. Testing by some equipment manufacturers has shown enclosed print head systems to provide increased solder paste deposit uniformity compared to squeegees.

4. Type 4 solder paste will be most likely be recommended for 01005 assembly.

5. Solder mask between component terminations is not recommended.

Richard Heimsch
Director
Protean Marketing

Now a director at Protean Marketing, Mr. Heimsch has worked in the electronics industry 25+ years in a wide variety of international sales, marketing and operations roles. Rich spearheads Protean's international business development, specializing in Brand Management and Strategic Communications.

In a word: precision. You need to make sure that your stencil can deposit the correct volume of paste. This requires a solder paste that has the rehological properties so you have good apature release (and the correct powder size). At these dimensions, and depending on the other devices on the PWB a Type IV powder solder paste may be needed.

Next insure the vision system on the pick and place machine is capable of registering and orienting the component. The other aspect to consider in the pick and place operation is if the tool can find and pick the component. With reflow the key is a good profile. The components are low mass and therefore will heat up quicker than some larger thermal mass devices that may also be on the PWB. Therefore making sure a profile monitors those devices specifically is important. Depending on the design this should not be too difficult.

Dr. Brian Toleno
Application Engineering
Henkel Electronics

Dr. Brian Toleno is the Application Engineering Team leader for Henkel Technologies. He is responsible for the technical service and application engineering for Henkel's electronics assembly materials, including solder paste, underfills, PCB protection materials, and underfills.

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