Resistor manufacturing flow example
SMD Resistor
<Chip Resistor Structure>
Resistor Manufacturing Flow Example
The following illustrates the manufacturing flow of a typical SMD Resistor (MCR Series).
![Raw Materials](/documents/11303/3707243/en_r_what3_img1.jpg/96614336-5afc-43c9-b621-05a247ac369a?t=1542704199320)
![Next](/documents/11303/3707244/r_arrow_big.gif/3da4e77c-e914-4106-8c1a-47bb03371c7b?t=1542704193233)
In actuality the entire alumina substrate is processed at one time, but for illustrative purposes only one chip will be shown.
![Printing I (Conductor/Resistive Element/Undercoat)](/documents/11303/3707243/en_r_what3_img2.jpg/cef21e3b-a14c-45f6-b7ea-59ba46200128?t=1542704198397)
![Next](/documents/11303/3707244/r_arrow_big.gif/3da4e77c-e914-4106-8c1a-47bb03371c7b?t=1542704193233)
![Laser Trimming](/documents/11303/3707243/en_r_what3_img3.jpg/0a6ccb2f-b90e-4f99-aaaa-972e8261f01d?t=1542704197580)
![Next](/documents/11303/3707244/r_arrow_big.gif/3da4e77c-e914-4106-8c1a-47bb03371c7b?t=1542704193233)
![Printing II (Middle Coat/Overcoat/Marking Code)](/documents/11303/3707243/en_r_what3_img4.jpg/c82f2586-81d7-4a9b-84d7-ff0657e96780?t=1542704196863)
![Next](/documents/11303/3707244/r_arrow_big.gif/3da4e77c-e914-4106-8c1a-47bb03371c7b?t=1542704193233)
![Bar Break/Side Electrode Formation/Chip Break](/documents/11303/3707243/en_r_what3_img5.jpg/d6382022-77e3-487d-84aa-f0498b3b94ba?t=1542704196140)
![Next](/documents/11303/3707244/r_arrow_big.gif/3da4e77c-e914-4106-8c1a-47bb03371c7b?t=1542704193233)
![Plating](/documents/11303/3707243/en_r_what3_img6.jpg/d6d4faaf-8dc2-4d1b-bc2c-5f0afc2e583e?t=1542704194997)
![Next](/documents/11303/3707244/r_arrow_big.gif/3da4e77c-e914-4106-8c1a-47bb03371c7b?t=1542704193233)
![Resistance Measurement/External Inspection/Taping](/documents/11303/3707243/en_r_what3_img7.jpg/babfca74-e378-46bc-9cc1-8fec638c7cdc?t=1542704194173)
![Next](/documents/11303/3707244/r_arrow_big.gif/3da4e77c-e914-4106-8c1a-47bb03371c7b?t=1542704193233)
![Shipping](/documents/11303/3707243/en_r_what3_img8.jpg/9bbaedae-9557-44fb-96a5-2090cbe825ba?t=1542704192397)
What is Screen Printing?
Each layer of a ROHM chip resistor is formed by screen printing. Screen printing involves creating a print pattern on the mesh surface of a screen mask, then applying paste, then transferring the pattern onto a target object (alumina substrate) by scraping the paste with a squeegee.
Screen Printing Flow
![1.A screen mask is placed on top of the alumina substrate](/documents/11303/3707283/en_r_what4_img1.jpg/cc6c956a-4ce5-4db4-ad2d-fabb0c45f449?t=1542704191647)
![2.Paste is applied on top of the screen, then scraped by a squeegee](/documents/11303/3707283/en_r_what4_img2.jpg/76126c81-0454-4ca1-b044-ab0276327f42?t=1542704190857)
![Side View of Screen Printing Process/ Alumina Substrate - Top View screen printing](/documents/11303/3707283/en_r_what4_img3.gif/41c6b8a7-1244-4122-8d8c-a382f4f8dcf5?t=1542704190060)
![3.Printing Completed](/documents/11303/3707283/en_r_what4_img4.jpg/e39be960-76a0-4140-9209-62fc4a71a2b4?t=1542704189180)
Laser trimming
The Need for a Laser Trimming Process
Screen printing is used to form each layer of a thick film chip resistor and involves placing paste on the alumina substrate. Hundreds of chips are processed at the same time, inevitably leading to slight variations in printing conditions (i.e. paste thickness).
This results in varying resistance values, making it impossible to ensure optimum resistances. Therefore, an additional process is required to adjust the resistance values to within specified tolerances.
![Hundreds of chips are processed at the same time, leading to resistance variations in single chips Laser trimming](/documents/11303/3707302/en_r_what5_img1.jpg/78938296-334e-455f-a910-09d8fe9f44b9?t=1542704188370)
![Large variations occur with respect to the target resistance value Resistance Value Distribution Graph](/documents/11303/3707302/en_r_what5_img2.jpg/d02b9fa6-7bd3-4fca-bfa8-42df21cc8593?t=1542704187230)
The Laser Trimming Process
A laser cuts the resistive element while the resistance is measured in order to achieve target resistance values with minimal variation. Laser trimming narrows the current pathway, which increases resistance. Once the target resistance has been met the laser is stopped to reduce variations between chips.
![Current Flow Resistance Increase](/documents/11303/3707302/en_r_what5_img3.jpg/914f5936-18d9-45b5-9686-bbcc9b519947?t=1542704186467)
![*Resistances are spread out over a wide horizontal axis Resistance Value Distribution (Before Trimming/ After Trimming)](/documents/11303/3707302/en_r_what5_img4.jpg/5cde451d-3d70-4489-a8f0-598c86dc9d6c?t=1542704185603)