JPH0653643A - Structure of printed solder resist - Google Patents

Abstract

PURPOSE:To secure a soldering area on a pad without increasing the accuracy necessary for printing a solder resist and prevent a solder from bridging the pads, by so printing the solder resist that both its ends overlap with the pads respectively. CONSTITUTION:Pads 5a, 5b are formed on a printed-circuit board 3, and a solder resist 4 is so printed between the pads 5a, 5b that both the ends of the solder resist 4 overlap with the pads 5a, 5b respectively. A pad width m1 is made larger than a soldering width m0, and the spacing pitch of the pads and the printing width of the solder resist 4 are so designed as to be (p) and (n) respectively. Thereby, such effects are obtained that without increasing the accuracy necessary for printing the solder resist 4 it is printed easily k between the pads provided at the fine spacing pitch and that a soldering area on the pad is secured and a solder is prevented from bridging the pads. Further, since the height of the bank of the solder resist 4, whose two ends overlap with the pads respectively, is raised more highly than the surfaces of the pads, the effect of cutting off the solder is made large and the effect of preventing the solder from bridging the pads is further improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solder resist printing structure in printed circuit board manufacturing.

[0002]

2. Description of the Related Art Conventionally, when printing a solder resist after pattern formation, as shown in FIG. 4, the solder resist 4 is printed like a bank between a pad 5 and a pad adjacent to the pad 5, as shown in FIG. The so-called solder bridge, in which the solder is spread between the lead 2 of the IC 1 and the lead next to the lead 2 which is soldered on the pad at the time of mounting, is attempted. However, the printed structure was formed so that the solder resist 4 printed between the pads on the printed circuit board 3 did not touch the pads as shown in FIG.

[0003]

However, in the above-mentioned conventional printing structure, the pattern density of the printed circuit board is increased,
If the pitch between the pads is a fine pitch such as 0.5 mm or less, when the solder resist is printed, the solder resist may get stuck to the pads due to misalignment and the soldering area cannot be secured. Yield will be poor. Therefore, it is necessary to raise the precision of the solder resist printing extremely,
In the mass production process, there has been a limit to increase the printing accuracy as the pad pitch becomes smaller.

Further, in the conventional printing structure, even when the solder resist can be printed between the pads so as not to cover the pads, as shown in FIG. Solder bridges still occurred because the height could not be made extremely large.

Therefore, in order to solve such a conventional problem, the present invention prints a solder resist between the pads of the printed circuit board to secure a soldering area on the pads without increasing the printing accuracy. Moreover, it is an object of the present invention to provide a printing structure capable of preventing a solder bridge.

[0006]

In order to solve the above problems, the solder resist printing structure of the present invention has a large pad width when printing the solder resist between the pads formed on the printed circuit board. The solder resist is printed on the pads so that a bank higher than the pad surface is formed between the pads to secure a soldering area on the pads and prevent solder bridging. And

[0007]

EXAMPLES Examples of the present invention will be described below. Figure 1
It is sectional drawing of a printed circuit board when the printed structure of this invention is used for the subtractive method printed circuit board.

As shown in FIG. 5, it is a design value in the conventional printing structure.

The pattern design for ensuring the soldering width m0 on the pad pitch p between the pads is applied to the printing structure according to the present invention as follows.

In FIG. 1, pads 5a and 5b are formed on a printed circuit board 3, a solder resist 4 is placed between the pads, and both ends thereof are pads 5a and 5b, respectively.
It is printed so that it hangs over.

The pad width m1 is set larger than the soldering width m0, and the pad pitch is designed to be p and the solder resist printing width is to be n.

In the present printing structure, as shown in FIG. 2 as an example, even if the solder resist is printed in the right direction with respect to FIG.
If the length of the print misalignment is within the range until the left end of the solder resist 4 contacts the pad 5a, the soldering width m0 on the pad does not change, so the soldering area on the pad does not change, and You don't have to worry about print misalignment. Therefore, the positional accuracy of the solder resist printing with respect to the pad printing can be significantly relaxed, for example, the position accuracy can be made effective as long as the solder resist is applied to the pads.

Further, the printing structure of the present invention has been described above by taking the subtractive method printed circuit board as an example.
The printed structure can be used in printed circuit boards of other manufacturing methods such as an additive method printed circuit board in the same manner. FIG. 3 shows the main printing structure of the additive method printed circuit board.

[0014]

As described above, according to the present invention, the solder resist is easily printed between the pads having a fine pitch without increasing the printing accuracy by the simple structure of printing the solder resist so as to hang on the pads. Is printed, a soldering area on the pads is secured, and a solder bridge between the pads is prevented.

Further, the height of the bank of the solder resist applied to the pad is raised higher than the pad surface, so that the effect of blocking solder is increased and the effect of preventing solder bridge is further enhanced.

[Brief description of drawings]

FIG. 1 is a sectional view of a printed circuit board showing a printing structure according to the present invention.

FIG. 2 is a cross-sectional view of a printed circuit board illustrating a printing structure according to the present invention.

FIG. 3 is a sectional view of a printed circuit board showing an embodiment of the present invention in an additive method board.

FIG. 4 is a plan view of an IC placed on a printed circuit board.

FIG. 5 is a sectional view of a printed circuit board having a conventional printing structure.

[Explanation of symbols]

 1 IC 2 Lead 3 Printed circuit board 4 Solder resist 5 Pad

Claims (1)

[Claims] 1. A structure for printing a solder resist between pads patterned on a printed circuit board, wherein the solder resist is printed so as to hang on the pads.